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Post-harvest floor changes and nitrogen mobilization in an Engelmann spruce-subalpine fir forest David, Clive Addison 1987

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POST-HARVEST FOREST FLOOR CHANGES AND MOBILIZATION  NITROGEN  IN A N E N G E L M A N N SPRUCE-SUBALPINE  FIR  by CLIVE B. A  ADDISON  DAVID  S c . F . , T h e U n i v e r s i t y of N e w B r u n s w i c k ,  THESIS THE  SUBMITTED  IN PARTIAL FULFILMENT OF  REQUIREMENTS DOCTOR  1975  FOR THE DEGREE  OF  OF  PHILOSOPHY  in THE  FACULTY OF GRADUATE  STUDIES  D e p a r t m e n t of F o r e s t r y  We  accept this thesis as to the required  THE  UNIVERSITY  conforming  standard  O F BRITISH  January © CLIVE ADDISON  COLUMBIA  1987 DAVID,  1987  FOREST  In presenting  this thesis in partial fulfilment  of the  requirements for an advanced  degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department  or  by  his  or  her  representatives.  It  is  understood  that  copying  or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3  DE-6G/81)  ABSTRACT  Engelmann spruce-subalpine fir [Picea engelmannil Parry ex Engelm.-A6fes lasiocarpa (Hook.) Nutt.] (ESSF) forests occupy large portions of western America, and of British Columbia (B.C.) in particular. These areas  represent a  harsh environment for plant growth. The ESSF forests of B.C. have serious  problems of regeneration following harvesting; several  speculation  as  to whether  presented  factors  N supply limitations were involved. This  intended to highlight the post-harvest N dynamics of an ESSF  North  stimulated study  forest,  was  and the  implications of the latter for silvicultural practices. Its general objectives included characterization  of  the  post-harvest  assart  effect,  and  investigation  of  the  N  status and growth of advance regeneration. These were achieved by means of a comparative study of an age sequence of harvested sites.  The assart effect -lasted for at least eight years after harvesting, with a peak of change  between years  three  and six.  There were  no major physical  changes in the forest floor. Low C/N ratios between 19 and 32 were believed to have contributed to increased N availability. ESSF forests may have a generally higher level of N availability than previously supposed. The advance regeneration benefited from the assart effect. Nutrient uptake appeared to increase generally from at least three years after harvesting; increases of up to 78% were noted for N. There appeared to be no general macronutrient or micronutrient limitation to growth. However, evidence  of S deficiencies  was encountered in some trees.  Moreover, the critical levels used for N may be in need of revision. A revised critical level of 1.40%  for foliar N concentrations is proposed for subalpine fir  n  advance  regeneration.  temporarily  If  N-limited  this  from  is  accurate,  year  eight  investigation of these possibilities is  The  cutting  method  shelterwood  method.  The  considered  a  application  would  seedbed  conditions  demonstrate make  viable  high  cultural  involve and  that  the  levels  of  practices.  expectations  silvicultural  of  some soil  after  to  as  the  for  similar  degree  of  forest  A  been  at  more  p l a n n i n g and  a  care  of  stands  what in  urgently.  iii  approximated  in  this  floor  least  rigorous  ESSF  findings  for  the  realistic zone  needs  one-cut  should  forests.  characteristics  comprises  a  Its  manipulation  The  prerequisite  the  study  ESSF  regimes. biological  second-rotation  sites  option  microclimatic  question  have  harvesting.  encountered  e n v i r o n m e n t a l and  The  may  needed.  applied  method  regeneration  not  successful to  of  improve  this  of E S S F success growth to  be  be  study forests  of  silvi-  and  yield  addressed  TABLE  OF CONTENTS  ABSTRACT  ii  LIST  OFTABLES  viii  LIST  O F FIGURES  ix  ACKNOWLEDGEMENTS  xi  Dedication Chapter  xii 1 INTRODUCTION 1.1 1.2  1.3 1.4  1  Introduction 1 D e v e l o p i n g a Research Strategy and Study Objectives 2 1.2.1 N i t r o g e n A v a i l a b i l i t y i n N o r t h e r n Forests 2 1.2.2 T h e A s s a r t Effect 7 1.2.3 T h e Impact of H a r v e s t i n g 11 1.2.4 T h e Subalpine F i r Question 14 T h e Objectives of the S t u d y 16 T h e A p p r o a c h i n Concept 17 1.4.1 A n A g e Sequence of U n i f o r m Sites 18 1.4.2 Indicative V a r i a b l e s a n d Relationships 23 1.4.3 T h e Scientific Hypotheses U n d e r Consideration . 27 Some Methodological Considerations . 27 The Scientific Hypotheses 32 IAA T h e O r g a n i z a t i o n o f the Thesis 35  Chapter  2 SITE D E S C R I P T I O N S A N D BASIC F I E L D L A Y O U T 2.1 T h e R e s e a r c h A r e a 2.1.1 L o c a t i o n 2.1.2 Geology 2.1.3 G e n e r a l C l i m a t e 2.1.4 Soils 2.1.5 V e g e t a t i o n Original Vegetation The Harvested Sites 2.2 F i e l d L a y o u t a n d S a m p l i n g Scheme 2.2.1 F i e l d L a y o u t 2.2.2 S a m p l i n g Scheme Field Phase Preparatory Laboratory Phase  37 37 37 40 42 45 46 46 49 53 53 60 60 63  Chapter  3 SEASONAL TEMPERATURE A N D MOISTURE 3.1 R e v i e w of Issues a n d Concepts 3.1.1 T e m p e r a t u r e 3.1.2 M o i s t u r e 3.1.3 Objectives a n d Hypotheses 3.2 M e t h o d s 3.2.1 T e m p e r a t u r e  66 66 67 72 78 81 81  - iv  TRENDS  3.2.2 M o i s t u r e 3.3 Results a n d D i s c u s s i o n 3.3.1 T e m p e r a t u r e 3.3.2 M o i s t u r e 3.4 Conclusions  •  82 84 84 88 97  Chapter  4 P O S T - H A R V E S T F O R E S T F L O O R P H Y S I C A L C H A R A C T E R I S T I C S .. 99 4.1 Introduction 99 4.2 Objectives a n d Hypotheses 101 4.3 Methods 102 4.4 Results a n d D i s c u s s i o n 103 4.4.1 T o t a l Depths 103 4.4.2 W e i g h t s 105 4.4.3 B u l k Densities 107 4.4.4 M o r H u m u s Groups 108 4.5 Conclusions I l l  Chapter  5 POST-HARVEST SOIL C H E M I C A L CHARACTERISTICS 112 5.1 Introduction 112 5.2 Objectives a n d Hypotheses 114 5.3 Methods 116 5.3.1 p H V a l u e s 116 5.3.2 N i t r o g e n a n d Phosphorus 117 5.3.3 C a r b o n a n d C / N Ratios 119 Carbon 119 Carbon.-Nitrogen Ratios 121 5.3.4 P o t a s s i u m , C a l c i u m , a n d M a g n e s i u m 121 5.3.5 U n i t - A r e a E l e m e n t a l Weights 122 5.4 Results a n d D i s c u s s i o n 124 5.4.1 p H V a l u e s 124 5.4.2 N i t r o g e n Concentrations 128 5.4.3 Phosphorus Concentrations 131 5.4.4 Exchangeable P o t a s s i u m , C a l c i u m , a n d M a g n e s i u m 135 5.4.5 C a r b o n Concentrations a n d C a r b o n r N i t r o g e n Ratios 139 5.4.6 U n i t - A r e a E l e m e n t a l Weights 145 Nitrogen Content 149 Phosphorus Content 150 Exchangeable Potassium, Calcium, and Magnesium Contents 150 Carbon Contents 152 5.5 Conclusions 153  Chapter  6 POST-HARVEST NITROGEN AVAILABILITY 6.1 Introduction 6.2 Objectives a n d Hypotheses 6.3 Methods  v  PATTERNS  156 156 161 162  6.3.1 Incubation Studies 6.3.2 C h e m i c a l Extractions 6.3.3 I o n Exchange Resins 6.4 Results a n d D i s c u s s i o n 6.4.1 Incubation Studies Forest Floor Materials Mineral Soil Materials Unit-Area Weights 6.4.2 C h e m i c a l E x t r a c t i o n s Forest Floor Materials Mineral Soil Materials Unit-Area Weights 6.4.3 I o n Exchange Resins 6.5 Conclusions  162 166 167 169 169 169 175 179 181 181 185 187 187 192  Chapter  7 PRE- A N D POST-HARVEST TREE GROWTH 7.1 Introduction 7.2 Objectives a n d Hypotheses 7.3 Methods 7.3.1 H e i g h t growth 7.3.2 D i a m e t e r G r o w t h a n d A g e 7.4 Results a n d D i s c u s s i o n 7.4.1 H e i g h t G r o w t h 7.4.2 D i a m e t e r G r o w t h 7.4.3 Tree A g e Considerations 7.5 Conclusions  195 195 198 199 199 200 201 207 209 210 213  Chapter  8 POST-HARVEST FOLIAR CHEMISTRY 8.1 Introduction 8.2 Objectives a n d Hypotheses 8.3 M e t h o d s 8.3.1 M a i n Foliage A n a l y s i s 8.3.2 Screening T r i a l A p p r o a c h 8.4 Results a n d D i s c u s s i o n 8.4.1 M a i n Foliage A n a l y s i s Needle weights and Nitrogen Phosphorus, Potassium, Calcium, Magnesium NIP, K/Ca, and Ca/Mg Ratios 8.4.2 M i c r o n u t r i e n t s a n d Sulphur 8.4.3 Screening T r i a l A n a l y s e s : Directional Relationships Overall Analyses 8.5 Conclusions  215 215 217 221 222 224 226 226 226 and 235 239 241 245 245 248 248  Chapter  9 GROWTH IN RELATION T O SOIL CHEMISTRY 9.1 Introduction 9.2 Objectives a n d Hypotheses  vi  FACTORS  A N D FOLIAR 252 252 253  9.3 9.4 9.5  Methods Results a n d Discussion Conclusions  Chapter  10 S Y N T H E S I S : HARVESTING EFFECTS, GROWTH, SILVICULTURE 10.1 Recapitulation of P r i n c i p a l Results 10.1.1 T h e Soil General Chemical Changes Nitrogen Availability Changes 10.1.2 T h e A d v a n c e Regeneration Post-Harvest Growth Foliar Chemistry Influences on Tree Growth 10.1.3 M i c r o c l i m a t i c Regimes 10.2 O v e r v i e w of the P o s t - H a r v e s t S i t u a t i o n 10.3 S i l v i c u l t u r a l Consequences a n d Implications 10.3.1 B a c k g r o u n d H i g h l i g h t s 10.3.2 T h e Present S y s t e m Theory Versus Reality Silvicultural Consequences 10.3.3 Prognosis The Untreated Cutovers Future Harvests 10.4 Conclusions  Chapter  11 C O N C L U S I O N S  LITERATURE  253 256 260 AND 261 261 262 262 263 264 264 265 266 266 267 270 271 275 276 281 . 284 285 287 290 292  CITED  297  vii  List of Tables Table  2.1 P h y s i c a l characteristics of the selected sites  Table  2.2 C l i m a t i c characteristics of the E S S F  Table  2.3 S u m m a r y of the basic soil characteristics of the sites  Table  2.4 Ranges of m e n s u r a t i o n a l values for Wet-Belt E S S F stands on well- a n d moderately well-drained podzolic soils w i t h south-eastern aspects 50  Table  2.5 M e n s u r a t i o n a l characteristics cutovers i n 1982  of regeneration  4.1  Means  limits  F/H  bulk densities, a n d weights  Table  and  41  biogeoclimatic zone  ......44 47  on the  three  oldest 52  9 5 % confidence  for forest  floor  total  depths, 104  Table  4.2 D i s t r i b u t i o n of m o r h u m u s  Table  5 . 1 a M e a n s a n d 9 5 % confidence limits weights for the forest floor fraction  of  the  elemental  unit-area  Table  5.1b M e a n s a n d 9 5 % confidence limits weights for the m i n e r a l soil fraction  of the  elemental  unit-area  Table  Table  groups  on the sites  109  146 147  6.1 M e a n s a n d 9 5 % confidence limits of the estimated weights o f m i n e r a l i z e d N given b y the four measures  unit-area  6.2  unit-area  Means  and  9 5 % confidence  limits  of  the  estimated  180  weights of inorganic N given b y K C 1 extraction  188  Table  7.1 S u m m a r y of response  206  Table  7.2 M e a n  Table  8.1 Means concentrations,  Table  8.2 M e a n s a n d 9 5 % confidence limits of the needle weights, foliar N concentrations, a n d foliar N contents for the grouped fertilizer plots .... 249  Table  9.1 M e a n s a n d 9 5 % confidence limits of absolute each soil attribute considered  release  delay estimates  ages for advance  regeneration  on the cutovers  211  and 9 5 % confidence limits of the micronutrient S concentrations, and N / S ratios i n the foliage sub-samples 242  viii  diameter  g r o w t h for 257  List of Figures Figure  1.1 T h e interactions availability  Figure  2.1a L o c a t i o n  of the  F i g u r e 2.1b L o c a t i o n of the Figure  among  study area  in British  2.4 T h e three-year-old cutover i n s u m m e r ,  2.6  Subalpine  summer Figure  2.7  View  mature  stand  in  fir advance  growth  regeneration  on  (a)  Exterior,  1983  the  55 1983  56  eight-year-old  eleven-year-old cutover i n s u m m e r ,  Figure  3.4 M e a n s a n d 95% confidence contents, J u l y to A u g u s t 1983  retention  3.5 Idealized moisture for the combined sites 5.1 M e a n s and age sequence  and 54  cutover, 57  3.3 M o i s t u r e cutover  Figure  1983:  six-year-old cutover i n s u m m e r ,  Figure  Figure  39  1983 of the  N 5 38  F o r e s t Region  summer,  3.1 M e a n s and 95% confidence limits for the temperatures of the sites, J u l y to A u g u s t 1983 F i g u r e 3.2 M e a n s a n d 95% confidence limits for the contents of the sites, J u l y to A u g u s t 1983  Figure  on  Columbia  Figure  Figure  effects  51  Figure  Figure  their  class frequency distributions for  2.3 V i e w s (b) Interior  of the  and  Kamloops  Figure  F i g u r e 2.5 V i e w  the  processes  study sites i n the  2.2 H e i g h t a n d diameter on the oldest cutovers of  several  curves  retention  95% confidence  for  limits  the  for  air  and  58 forest  floor 85  forest  floor  moisture 89  mature  the  1983  stand  forest  and  floor  six-year-old 91  moisture 92  curve  and  extrapolation (dashed  line) 95  limits  of the  p H values  across  the 125  5.2 M e a n s and 9 5 % confidence limits of the N concentrations forest floor a n d m i n e r a l soil m a t e r i a l s across the age sequence 5.3 M e a n s a n d 9 5 % confidence limits of the forest floor soil P concentrations, including resin-P concentrations  Figure 5.4 M e a n s a n d 9 5 % confidence limits of the forest soil exchangeable K , C a , and M g concentrations ix  floor  of 129  and mineral 132 and mineral 136  Figure  Figure  Figure  Figure  5.5 M e a n s a n d 95% confidence limits of the soil C concentrations and C / N ratios 6.1 M e a n s and 95% confidence limits concentrations given by the four measures 6.2 Means and 95% confidence concentrations given by K C 1 extraction  forest  floor  140  of  the  N  limits  of  the  Figure  7.2  Patterns  Figure  7.3 P a t t e r n s  of relative height growth of advance  Figure  7.4 P a t t e r n s  of relative diameter g r o w t h of advance  Figure  Figure  Figure  diameter  growth  limits  8.3 M e a n s and C a / M g ratios  limits  8.4 D i r e c t i o n a l and N contents  95% confidence  of  N  regeneration 202  of advance  regeneration 203  regeneration  204  foliar  of the  inorganic  advance  growth  8.1 M e a n s a n d 9 5 % confidence limits of the concentrations, and N contents 8.2 M e a n s and 95% confidence M g concentrations and contents  N  190  Patterns  annual  height  the  7.1  of absolute  annual  inorganic  182  Figure  Figure  absolute  mineralization 170  6.3 Means and 95% confidence limits of concentrations adsorbed b y the ion exchange resins of  and mineral  regeneration needle  205  weights, N 227  foliar  P,  K , C a , and 228  of the  foliar  N / P , K / C a , and 229  relationships among needle  weights,  N  concentrations, 246  x  ACKNOWLEDGEMENTS  The of  the  assistance  various  nevertheless, are  due  efforts  I  and  phases wish  support of  to  of m a n y  this  express  study. sincere  g e n e r a l l y would be difficult  comments;  Mrs.  E.  support to  It  is  thanks  to D r . G . F . W e e t m a n , m y graduate  Messrs.  Tsze and  for  assistance;  their  assistance  M r . D. Lloyd also  R.  assistance;  of the to  field  and  and  to  them  execution  name  everyone;  to  all. The  greatest  thanks  Mr.  K.  staff  to  thank  the  my  members  for their advice, assistance,  Spindler,  of Forests  present  i n the  supervisor; his contribution to  and subsequent  B . C. Ministry  past  needed  impractical  also D r . M . N o v a k  F o u r n i e r , B . von  i n the  was  to overestimate. I w i s h  of m y s u p e r v i s o r y committee and and  persons  B.  Wong,  Crystal  for  phases.  his  Thanks  (Kamloops)  members  M . Tsze  of  for  and  enthusiastic are  also  due  his invaluable  Clearwater  Timber  P r o d u c t s , L t d . —notably M e s s r s . E . R. S w a n s o n and A . K o k o s h k e .  I  cannot  encouragement,  Finally, Department financial  of  thank  my  wife,  Beverley,  sufficiently.  a n d assistance  i n typing the m a n u s c r i p t were  I  to  would  Forest  like  Sciences,  thank and  the  the  I.  University W.  of  Killam  Her  patience,  vital.  British  Columbia,  F o u n d a t i o n for  personal  support.  The  project w a s funded through research grants  xi  the  to D r . G . F . W e e t m a n .  DEDICATION  This family,  effort  is  and the  dedicated future  to  of our  xii  memories children.  of  my  CHAPTER 1 INTRODUCTION  1.1  INTRODUCTION  Engelmann lasiocarpa America, harsh cold  (Hook.) N u t t . ] and  soils  and  More  for  plantation  establishment  exhibits  Such for  i n light  tree  an  forests  for  of a  latter has  process. proven  existed  forest.  following  of  forests  in  western  slow  being  are  short,  nutrient  associated from  while  problems with  forest  and  to  to  relate  shed  problems  second-rotation  This  study  light on the findings  to  N  yields,  on the  same.  was  initiated crop  dynamics of such  possible  t Scientific nomenclature follows T a y l o r and M a c B r y d e (1977); follow the latter as well as C e s k a (1979) a n d A n g o v e (1981). n a m e differences existed Angove (1981) was given precedence. 1  hold  problems of nitrogen (N) s u p p l y  setting.  these  by  regeneration  potential  industry  the  or  foregoing characteristics  of the  a  cycling  seed  advance also  North  represent  exhibited serious  their  this  of  N supply problems existed i n a second-rotation  The intention was  harvesting,  to  and  to whether  Engelm.t-A&z'es  generally  while  There  ex  areas  regeneration  competition. T h e  growing dependence  generally  these  difficult,  rates.  ESSF  are  of B . C . h a v e  very  These  contribute  Natural  growth  vegetative  to examine whether  ESSF  forests  harvesting—many  the  portions  particular.  activity  stimulated speculation as  growth  in  large  growth; g r o w i n g seasons  post-harvest  non-crop  occupy  (B.C.)  the E S S F  the  low  with  factors  primarily in  by  implications  especially  plant  following  left  serious  forests  Columbia  specifically,  conditions  associated  fir [Picea engelmannii P a r r y  low levels of microbial  regeneration  often  (ESSF)  of B r i t i s h  environment  rates. of  spruce-subalpine  silvicultural  common names Where common  )  2 alternatives.  1.2 D E V E L O P I N G  A  review  strategy  and  overviews termed the  of  the  A RESEARCH  of  the  study the  main  "assart  of  effect",  role of advance  considerations  objectives  problem  STRATEGY  is  N  the  in  impact  the  development  here.  in  The  northern  of h a r v e s t i n g  within  STUDY OBJECTIVES  the  appropriate  availability  regeneration  AND  of  a  research  discussion  includes  forests,  on nutrient  specific context  a  phenomenon  availability,  and  of this investigation.  1.2.1 Nitrogen Availability in Northern Forests  Northern  coniferous  availability  as  Weetman,  1958  1963; been  attributed season  decomposition composition to  to several and  processes,  benefit  Meentemeyer,  to  N  its  1981; T a m m ,  1979;  1982;  short  (both  as  and  (itself l a r g e l y have  1935; Swift  all  Tamm, et  having  (Tamra,  Weetman  and  al,  N  1950;  Nykvist, N  g r o w i n g seasons, low  soil and  influences,  decomposition) (Romell,  considered  T h i s lack of plant-available  F o r example,  substrate  Pritchett,  been  and  1981).  temperatures  shortages  1978;  1964  Rapp,  mycorrhizal  organic from  and  long  g r o w t h - l i m i t i n g characteristics  Tamm,  factors.  annual  have  primary  1980a;  1979; Cole  of the  contributing  et al,  of their  and  Pritchett,  growing  stand  one  forests  has mean  air), fungal domination of the  unfavourable  chemical  derived  from  the  trees  been  noted  as  interactively  1950;  1979;  M . Alexander,  Gosz,  1982; V i t o u s e k , 1982; A l e x a n d e r , 1983).  1981;  Van  which  1977; Cleve  3 The fauna) (M.  forest  p l a y extremely  Alexander,  Anderson trees  et  is  which  occurs  term  the  "humus" to  term  used  as  portion  of  organic  by  the  soil  soils,  is widely  where  is  horizon  (Pritchett,  can  be  absorbed  the  bulk  apparently  in  surface  where  N  organic the  considered  and  (Russell,  are  no  soil  soil  which  1973;  often  Pritchett,  exclusively to endorganic  litter  the  divided  and  forested  that  is incorporated  into  Strictly  defined,  the  decomposition  recognizable;  scientists  "forest  into  which  longer  term  to  accumulated  be  in  availability  in  may  1981).  1981;  surface  which that  Gosz,  including  of  component  N  and  environment  the  part  Klinka,  residues  on  as  (Lowe  and  forest  (1979),  mineral  microflora  1979;  matter,  and  foresters  profile  Pritchett  sub-system,  that  of the  impact  (ectorganic)  (endorganic) to  on  associated  Pritchett,  their  to  all  be  soil  1979;  1984);  to  their  dynamics  Likens,  at,  may  forest  refers  i n the  resting  only  with  According  however,  means  1979).  has  any  the  organic  Throughout  m a t e r i a l while "forest  this floor"  organic layers.  accepted  that almost  largely unavailable N  of  et  refer  floor  many  "humus"  forms  to  extent  is used for surface  It  Spiers  soil  refers  an  presentation,  and  the  horizons  proceeded  Bormann  layers,  in  at  mineral  roles  forest  material  (along  important  used  organic The  humus  elaboration.  generally  ecosystems.  and  1983;  some  decomposing  organic  1977;  al,  merits  floor"  the  floor  found 1979).  to  directly by  trees  uptake  trees  ammonium  plants;  principally Though  by N  a l l of the  in  there  this  the  forest some  through  their  ( N H J -N)  acid form.  i n surface  soils is held i n  seems p a r t i c u l a r l y true  is  in  N  floor  evidence  and  uppermost  that  soluble  m y c o r r h i z a (Heal  forest Trees  soil  rooting  therefore  in  et  forest  mineral  organic al,  1982),  environments have  to  N  is  depend  4 heavily  on  Swift  et  (and  thus  al.  moisture, the  decomposition (1979) N  availability) — the  quantity  and  nature,  environment. influences  and  and  The  subject  These  be  theory  humus and  influence  the  One varying  degrees  for  Weetman, Klinka  1950; W e e t m a n ,  of the  investigators floor  i n terms of N  have  the  results in  proposed  enhancement  of great  c a n be most  expressed  the  influenced b y  should be  an  integral  and  their  form  and of  growth  Likens,  view  that  silvicultural part  on the  century. merits  has  With  to  a  concerning  such  since it is the humus  mode of  from  Gosz on  of trees  and  has  a body of  silviculturists (Romell, 1979).  of  interest  humus. of  to  Several  the  forest  (Romell,  1935;  Klinka,  1981). L o w e  uppermost  soil l a y e r  form management  management  N  undesirability  generated  productivity  and  the  origins i n E u r o p e  manipulation  site  1979; L o w e  of s i l v i c u l t u r a l  from  long-standing  management  practices,  forest  effects  growth  of m u l l  been  and  i n the  1.1  resultant  1973; Pritchett,  and  reported  tree  a  Figure  and  composition,  indication of both  practical value  1962; R u s s e l l ,  conservation  numbers),  resulting  tree g r o w t h have  foregoing  temperature,  chemical  mull)  system.  humus  and  (e.g.  (e.g. types,  the  perceived  supply  1962; B o r m a n n and  (1981)  the  of the  the  within  for more" t h a n  over  influencing decomposition  (e.g.  or  qualitative  forest  mineralization.  to be h i g h l y interactive  interactions  of the  of investigation  involved  moder,  a  levels  e m p i r i c a l knowledge  1935; T a m m ,  as  N  environment  substrate  appear (mor,  taken  of  organic  factors  availability  some  organisms  the  notably  of factors  physico-chemical  forms  S c a n d i n a v i a , arguments  of mor  end  of  humus  N  illustrates  a  quality  processes,  categories  decomposer  can generally  availability. been  the  etc.).  The  decomposition (1981)  concomitant  identified three  p H , etc.),  physical  and  in British  and which  to  this  Columbia.  LOW  HIGH N UPTAKE  N UPTAKE  /  x  LOW MX IN PLANT TISSUE  HIGH POLYPHENOL, ORGANIC ACID PRODUCTION  HIGH N WITHDRAWAL FROM OLO TISSUE  HIGH N % IN PLANT TISSUE  \ \  LOW DECOMPOSITION, DECOt MINER ALIZA ATION RATES  LOW  t  MOR  HIGH N % IN LITTERFALL, REDUCED OR UNSTABLE POLY PHENOL-PROTEIN COMPLEXES HIGH DECOMPOSITION, MINERALIZATION RATES  t  NITRIFICATION  (  LOW POLYPHENOL, ORGANIC ACIO PRODUCTION  LOW N WITHDRAWAL FROM OLD TISSUE  LOW N % IN LITTERFALL, STABLE POLYPHENOLPROTEIN COMPLEXES  V \\  ' HIGH NITRIFICATION  HUMUs\  FORMATION  Figure  t  t  LOW  V  HIGH N AVAILABILITY  N AVAILABILITY  )  1.1 T h e interactions a m o n g s e v e r a l processes a v a i l a b i l i t y ( F r o m G o s z , 1981).  /MULL  HUMUS\  (FORMATION  j  and their effects  on N  6 Manipulation  measures  Mahendrappa,  1978;  tree and other  vegetative  Hawkes,  1978;  suitable  soil  (Brown  that  can  a n d response 1982).  and  least.  forest  the  for  case  McMinn,  forest  floor  1980;  Weber  Europe  Burdett  can  floor  be  seen  1979).  availability  and  proper  that  fact  a or  also  can  other  be  such  elevation  general  tree g r o w t h is  burning  questions  another  as  of the  treatments—including  essential.  the and  can  Fournier, not  (seeding-in)  and  or  removal spots  site  at  a  concept  Golding,  effects  the  (Dobbs  removal  ( H e r r i n g and  impacts  is  preparation  a necessity  However,  the  in  status  on  century  of  in  forest humus  watershed  1981).  of intended  harvesting—on  of  McMinn,  frequently-used  with  of  is  planting  as  and forests  approximately  (Hillman  understanding  or  i n growth  is  and  they  nutritional  means  seen  i n conflict  sites  which  of the  1985).  for  minor  introduction  disturbance  been  Potts,  recognized  the  high elevations,  has  of  1950; K i m m i n s  coniferous  seedbeds  reductions  Prescribed  are  floor  1963;  additional advantage  by n a t u r a l  at  inclusion  1978; W e e t m a n  northern  forest  et at, 1984;  tool w h i c h  There  manipulations  of  lead to drastic  p a r t i c u l a r l y i n higher  therefore  in  (Viro,  under  an  measure  regeneration of  1983),  has  Stone,  establishment  et al, 1985)—a  management.  diagnostic  form  creation  the  conditions  Fertilization  r e m o v i n g organic layers  1977;  layers  of  management forest  1982),  Harrison,  ( T i m m e r and  of p l a n t a t i o n  (Pritchett,  values,  rapid  some  the  management/silvicultural form  a  F o r both  principally aimed at and  1983).  floor  establishment,  desirable In  as  and  promotion  Harrison,  serve  without difficulties.  usually  and/or  Salonius,  applications  w i t h crop trees ( T a m m ,  Brown  potential of trees  However,  plantation  1981;  fertilizer  and  components  Miles,  also  include  Mahendrappa  organisms,  flourish it  can  It  can forest  nutrient  7  1.2.2 The Assart Effect  Following increased 1938;  major  nutrient  Tamm,  disturbance  availability  1964;  1.  Inputs  of  2.  Changes  and  forest, to  there  several  Weetman,  1969;  organic  matter  is  usually  factors  Stone,  1979; V i t o u s e k , 1981 and  fresh  decomposer  the  attributable  Timmer  1977; B o r m a n n and L i k e n s ,  of  period  (Romell,  1975;  1935  Salonius  1983). These  (including  a  roots)  of and  et  al,  include:  to  organisms;  in  temperature  and  moisture  regimes  which  often enhance m i c r o b i a l activity and decomposition; 3.  Decreased  vegetative  nutrients; 4.  of  decomposition—the  This  where bed been  and  fire  effect")  1964  has has  employed  Humphreys nutrient forest through  and  been  in  and  systems  been  forestry  of great  environment of  to  moisture  and  effects  noted  by  also B e r g  been  suppression  referred  Weetman,  his  shifting  Gadgil  to  1980a;  as  1965).  (Kessell  The  the  and  magnitude  p r a c t i c a l importance advantage.  For  cultivation in  Gadgil  the  "assart  effect"  D e m o n t i g n y and  applied—particularly i n practice  and  of  and L i n d b e r g (1980).  agent of disturbance,  Lambert,  flush are  has  1979;  the  also  mycorrhizal  1978), and  liberation of nutrients  1957; T a m m ,  for  and  Relaxation  (1975  competition  term  "ash-bed  Australia, Stoate, and  to m a n ' s  centuries, Europe  Auclair, effect"  where 1938;  duration attempts  its  (Romell,  benefits 1957;  (Romell,  it  1982);  (or  "ash  has  long  Hatch, of to  the  1960; assart  modify  were  the  realized  Noirfalise  and  8 Thill,  1960);  traditional for  similarly,  agricultural  channelling  stressed  the  assart  the  term  are  effect",  might  more  literature  obscure.  by Romell  as  a n d 1938) described  term;  Romell  effect,  soil  (1938)  not y e t been  (1969)  implied  1957)  indicated  well-known  to  use  his  of the  Regardless "assart". century  back  before  as  be  other  (1957)  term  term,  of desirable  the  trees  (1964)  has  In  origin,  i n turn that  its  been  It is simple to v i s u a l i z e  however, gave  the  1930's  definitely  a  terms  the  origins  definition  of the  of the  no  as  English-language  its  origin.  he  first  phenomenon  (e.g. t h i n n i n g  i m p l y i n g t h a t the a s s a r t t e r m h a d  w a s the earliest publication found and indeed T a m m  earlier  detailed discussed  defined  survey, the  use c a n be  the term  Romell  (inter alia) b u t d i d not use the  for the  w a s made,  his  term  H o w e v e r , a s u r v e y of  yielded  construed  involved  h a d been  though  but  of  potential  i n which  a n d Pettersson (Romell,  and w a s comparatively Tamm  (1950)  phenomenon  made  itself  dated  undoubtedly  has its use i n E n g l i s h  i n French and Latin),  as  during  h a d its roots dating back  no  a n d its  i t m a y be said that the actual origin of the t e r m  of its precise  (well  coined;  s t i m u l a t i o n effect),  audience.  vague,  T h e latter  mainstay  w a s one of its first uses. H o w e v e r , the context  the  implications. Therefore, remains  been  to the a s s a r t effect  that  growth  the  management,  "assart effect"?  the processes  employed  t h a t this  of forest  into  Tamm  could  conceived. R o m e l l  direct reference  effect"  far  a c t i v a t i n g effect,  has been  its coining to L . - G . Romell.  which  (1935  it  1980a).  have  a n d attributed  available  explicit  mobilized  1950; Weetman,  ash-bed  publication  so  Tropics,  I n terms  w a s the origin of the t e r m  phrase  "assart  of the  production.  nutrients  (Tamm,  What why  i n parts  the  "assart 1950's.  i n the w o r d  to the  a n d w a s a legal t e r m  sixteenth associated  9 mainly  with  both  arable  land by  1933;  Week,  the  forests.  trees the  the  as  from  act  r e m o v a l of the from  terms  application to  it  the  term  this  report.  tree  should  where  for  of  and  magnitude  and  duration  where  growth spruce  Voss,  and  their  Vyse  and  LeLacheur,  Forests where  spruce  subalpine  fir  been  Weetman  of  the  and  of regeneration  1979; 1986a].  The  exhibits  low  rates  advance  regeneration  et  to  to  Nykvist, flush  al,  ex  been 1984;  applies  to  appears  of  this  1963).  to  E n g e l m . , P.  in  site  unresponsive  crop  coniferous deficiencies  specifically,  areas  the  to of  glauca  Columbia  cutovers with  throughout  N  successful  British  writer  phenomenon;  importance  high-elevation  very  this  realized i n  More  of  latter  misleading in  northern  contribute  the  permanence  same  effect  those  are  ingress—even often  assart  late  of  complex the  the  felling  effect"  to  to  against  Nevertheless,  refer  considering  offence  viewpoint,  "assart  practices.  not  same of  is, the  i n those  have  Burdett  that  seems  assart  plantations  unauthorized  of the  in  accumulation  the  of describing a  benefits  during  from  term  used  value  (1981),  purist's  land  English Dictionary,  serious  the  [Picea engelmannii P a r r y  hybrids]  (B.C.M.O.F.),  the  forest  most  roots;  From  of  (Oxford  James  the  and  succinct w a y have  1980a;  to  management  special  humus  1958  Columbia  forest  h a v i n g the  be  mor  and  rendering  very  (Weetman,  establishment  as  conversion  bushes  much  stumps cover.  derivatives  potential  growth  forests  its  a  as  forest  the  and  According  derived  seen  presents  and  The  be  of  assart was  the  might  that  1981).  seriousness  away  result  of trees  of a n  characteristic  feels  up  James,  creation  the  Its  conversion  of its  and  grubbing  1966;  Middle Ages, king's  the  the the  British  (Moench)  [Vyse,  1981;  Ministry latter  of  areas  treatments—and/or to  release  by  10 logging  (Herring,  regeneration benefits on  little  sites  assart (Tamm,  completed  of n o r t h e r n  and  or g r o w t h flush,  McMinn,  retarded  serious  1980;  interior.  have  The Weetman  1980a).  assart  i n c r e a s i n g importance the forests  production; greater  than  with  regeneration productive  aspects  total  t h a t of the coast  is the dominant subalpine present.  volume  fir,  (1985)  in  and/or  more  spruce-fir  types  impending  shortage  are  of operable  biogeoclimatic  zone  appears This  i n the  forests interior  timber  studies (1985)  were i n the high-  to be the only one to  is  surprising  given  has  the  F o r the past 20  portion of B . C . ' s  forests; almost  at  been  (Bickerstaff  become  higher  entirely  comprised some  lumber  consistently  1965) is  the  third  to a n y  1981). the  importance —especially future  elevations  it  advance  5 0 % to 70% of the  et al,  exhausted,  w i t h i n the near  (Krajina,  following  1980).  contributing  increasing  that  for the interior  interior  i n interior  forests  effect  t w o such  true  If  m a y develop indicated  and Haskin  yielded the major  species  productive  is still  latter.  harvest  the latter  assuming  the  (B.C.M.O.F.,  southern  of the a s s a r t  recently,  study  (1980a)  to the provincial i n d u s t r y .  S u c h spruce-firt  i n the  Very  statement  of these forests  1972 the  accessible  ESSF  (1980a)  1982).  to miss the  problems  Weetman  (1985) on the coast  of the interior have  since  Spruce occurs  forests.  of B . C . ; the H a s k i n  investigated  years,  coniferous  Monchak,  sufficiently for the trees  backlog regeneration  1950; W e e t m a n ,  i n B . C . —those of M a r t i n  elevation forests  The  Herring  i n f o r m a t i o n is available concerning the pattern  harvesting  dry  is delayed  of the  such  1977;  A s easily  more in  marginal  view  of a n  (B.C.M.O.F.,  1980).  largest  continuously  t " F i r " i n B . C . u s u a l l y refers to Douglas-fir [Pseudotsuga menziesii (Mirb.) F r a n c o ] , w h i l e " b a l s a m " has been the traditional t e r m for the Abies spp. However, throughout this presentation " f i r " refers to the Abies spp., and p r i n c i p a l l y to subalpine fir.  11 forested  zone  1983). which  In  in  the  spruce  B . C . , covering some  southern  interior,  it  (and fir) dominates.  severe  problems  hectares in  inadequately  light of the  threaten  i n terms  of its  of the  easily  the  area  of the  largest  of  apparent  regeneration With  that  the  after  the  three  ESSF  harvesting,  i n c r e a s i n g pressure  types  type  with  in  effects,  presents  thousands  on these  of information concerning disturbance  to become even more  province (Coupe,  reputation of being a h a r s h environment for  become  regenerated.!  dearth  is  Its  tree g r o w t h is w e l l k n o w n . It has  12%  areas,  of and  such problems  acute.  1.2.3 The Impact of Harvesting  In  general,  much  has  been  written  disturbances—including harvesting—on forest Bormann 1983;  and  Likens,  Vitousek  1979;  et al, 1979; Vitousek  well-known  of  which  provided m u c h  has  Bormann reviewed  these  and  Likens,  ecosystem.  t  This  generally  perhaps  the  valuable  ecosystems  1981;  Gosz,  and Melillo, Hubbard  This  extensive  rather,  only  a  sites  1981;  Brook  study Likens  body  of  selection of items  effects  (e.g. Leaf,  Vitousek,  1979; T a m m ,  i n f o r m a t i o n (e.g.  1979).  and  the  of 1979;  1981  and  1982). The most  in  New  and  Hampshire,  Bormann,  literature  will  germane  to the  1974;  not  be  subject  w i l l be highlighted.  Harvesting  are  is  i n detail here;  of this report  Covington,  concerning  initiates a complex set  is p a r t i c u l a r l y true  enhanced;  A . Vyse, B . C . M . O . F .  however,  of the for  of reactions forest  nutrients  (Kamloops), pers.  floor such  and  processes  i n the  forest  l a y e r s . Decomposition rates as  N—the  c o m m . N o v e m b e r 18,  major  1985.  component  of  which  their  is held i n organic  net  mineralization  principally  by  substrate,  and  interactively. (years)  the  a  strong  following  cutting  clearcutting can these  changed  important  role  has  noted  been  cutting 1985). thus  or  in  recovered Likens  fall)  three  (1979)  to  hypothesized  to  the  vehicle. Gosz  disturbed  reorganize  state,  conservative  use  immobilization mechanisms  with  of  and  of  nature  (1981)  10  their  in  The  and  the  organic working  over  (1978)  populations  concluded  to  the  20  latter  after  Likens,  represented  that  the  of  with forest  rapid  Vitousek  implications i n this  part  context.  the  (and  Hubbard area  had  1979).  Bormann  and  of an  effort  nutrient  system  also  F o r N , the  by  as  from  the  moves  a  competition, discussed effect  the  capital  N , towards  ingrowth,  (1982)  Martin,  area  while leaf  its  of plant-available  means  tissues.  and  cutting,  leaf In  that  following  1981;  which  is an  effect  weights  substantially.  disturbance,  suggested  at  Studies  plays  One  Covington,  point  recovered  (Bormann  following  by  the  and  that  processes  thus  harvesting.  1979;  years  floor  thickness  time  similarly  bacterial  decomposition  forest  following  beyond  have  years  element  nutrients  al.  (1981)- also  the  floor  relatively high levels that  of  Likens,  far  to  that  itself  forest and  continue  four  of  biomass  et  fauna  Vitousek  changes  in  appears  ecosystem main  other  for  fungal  Sundman  disturbances.  (Bormann  it continued  after  very  decrease  T h i s decrease can  study,  the  and  in  invertebrate and  quality  lies i n  governed  bacterial populations—particularly nitrifiers.  such  these a  both  and  is  microorganisms—these  decrease while  Matson  that  with  is  leaf  in  of  to trees  mineralization  quantity  numbers a  availability  earlier,  the  Sweden,  higher  disturbance  perhaps  Brook  to  suggest  radically  in  Finland.  lead  stated  observed  increase in  As  and  (1980)  cutting  —the k e y to their  influences,  types  Baath  following  as  rates.  environmental  observed  such  forms  is  more and  possible therefore  13 that  of a  gradual  movement, therefore and  and  its  natural  tendency  availability,  have  either  to  shallow  site  factors  restrict  nutritional  growth  from  competing  Heal  et  al.,  competition  trees  do  minor  1982). with  trees  feather  for  (Bernier and Roberge,  Cleve,  1981  vegetation  for  N  of  and  the high  1984). may  Losses  are  formation context  as  key  N  the  and  latter  to  by trees.  moisture  regimes  He  high  mosses  Timmer,  water  observed  stress  is  site;  (Cole can  and  that  of  before  demands  Rapp,  1981;  a  A  pattern  canopy  the  an  contributing  importance  however,  constitute form  Region, B . C . ,  were  also  been  1983). M o n c h a k  on cutovers.  supply. Tree  the  and have  Kamloops Forest  (1981)  soil  occupy  and  1983),  been  important  closure,  on the initial  latter  demand  Miller,  significant  in  1981;  source  of  control in this  1962; W e e t m a n and T i m m e r , 1967; Weber and V a n  Thus, be  as  of the  Timmer,  regeneration  Miller  the  is  established  temperature  available N , and/or  regard  and  by  vegetation  Even  by  fully  form.  viewed i n this  actual uptake  (Whitney  zone  situation.  not  down i n its  fluctuations i n fine root biomass have  densities,  principally  cationic  be  been  soil,  spruce  recognized  slowing  equilibrium.  1978; W h i t n e y and  ESSF  post-harvest  since  can  N deficiencies i n advance  is determined  low,  forests  as  Seasonal  stem  stages  the  such  the  or  a  1981; V i t o u s e k , 1982). M o r humus  influence the  in  time,  organic  in dynamic  uptake  in  high  to observed  considering  here.  N  that  rooting,  factors  factors  and H a w k e s ,  believed  over  mineralization levels have  effects  (Kimmins  (1982)  are  in  forest  other  and  major  observed  of  availability  coniferous  of the  net  many  Environmental  noted  maintenance  i n northern  Although  can  in its  effectively m i n i m i z e d (Gosz,  perpetuation  the  reduction  while  relatively  before high,  canopy most  of  closure this  the can  total demand be  from  by  non-crop  14 components.  The  operational being a  following  the  need  implication of the the  investigate  responses operating establishment  and  the  ESSF  areas  forest  importance  whether  major  and  where  subalpine  factors  may  the  B . C . referred  advance  assart  short,  to  the  This  may  be  be crop  there and  i n relation  aspects  assume  as  at  to for  even  involve decisions  retained  is  tree  p a r t i c u l a r l y true  options  should  that  effect  be  may tree  processes,  these  management  the  indicate  assart  earlier;  regeneration  effect  militate against  mechanisms,  of regeneration.  second-growth  fir  while the  foregoing considerations  harvesting—in  growth of  is t h a t  understand  following  the  to  other  p r i n c i p a l beneficiary. The to  greater  harvest,  above  as  least  a  component.  1.2.4 The Subalpine Fir Question  Advance North  growth  American  higher-elevation subalpine the  fir  widest  Young, 1982;  contempt trend  and  to  is  However, 1982;  use  or  (Smith,  proportion any  indispensable  of B . C . , this of the  true  particularly  ignoring its  of  an  forests  types  major  1983).  (Haddock,  toward  objections  a  distribution  1985),  played  spruce-firt spruce-fir  as  Watts,  has  in  Handley,  fir  abundant B.C.  eradicating  include alleged  in  option  would  North in  the  subalpine  1982); the  in  in  1962);  second  in  role  the  species  slow g r o w t h  the  the  crop.  ESSF  and  of  similar  involve acceptance The  latter  America  is  (Krajina  regarded  of  species  (Henderson,  B . C . interior fir  regeneration  has 1982;  et  al,  with  some  southern  interior,  there  is  (Tozer,  1984).?  The  main  (Watts,  1983;  Alexander  t I n this case this term embraces a l l Picea spp.-Abies spp. combinations i n N o r t h A m e r i c a . t A l s o A . V y s e , B . C . M . O . F . , pers. c o m m . , N o v e m b e r 18, 1985.  forest  et  a  al.,  type  1984),  poor  post-logging  susceptibility  to  decay  unfounded,  example, of  species'  Crossley later  argued  (inadvertently) conditions  made  be  well-established investigators  annual  for  against  such  indicators (Hunt,  to a  and  widely  since  sizes;  true  release  in  such  fir  current  not  release  period  assessment cases,  best  on a relative  ago,  this w a s  of  growth  A s a n example,  However,  would  By  1982).  this  response  increments  delay—a  contrast, of  up  other to  Moreover,  indicator  includes  measures  34  absolute  of performance  basis  growth  other  height  of  stand  and  were  periodic a n n u a l  response.  height  the  perception  investigators  physiological  centimetres.  release  For  one of the m a i n origins of  indicator variables.  the  is not  1978; Monchak, 1 9 8 2 ;  assessments  1980; Monchak,  perhaps its  by)  aphid  T e n years  of several  differing  eleven  this  blanket judgement;  a ten-year  biased  McMinn, is  that  wooly  questionable.  modify.  data  1977),  disdain  applied, though  1983). P e r h a p s fact  the  are  1 9 8 0 ; Johnstone,  inadequate  to  While  aspects  unfairly difficult  under  eight  in  reported  increment  initial  its  most  the  with  phenomenon  regeneration,  The  in  trees  perhaps  (Herring  different  lies  downwardly  have  height  advance  seems  and M c M i n n ,  approximately  (and  1  has been  and S c h m i d t (1982) reported of  of  (Herring,  the b a l s a m  1982).  not unconditionally—by the  label  a n d also  McCaughey  yr"  some  1983; E i s a n d C r a i g d a l l i e ,  slow-growth  include  of  characteristics  1982) and to  1 9 8 2 ; Haddock,  bases  1977; H e r r i n g  increment  damage  al,  convincingly  supported—though  Bergstrom,  cm  the  performance  (1976)  (Herring,  the  (Gara,  et  the slow-growth label  the  and  (Krajina  {Adelges piceae Ratz.) entirely  form  of  trees of  are  better  1982).  second-growth  alternative  to  subalpine  fir  advance  regeneration  on  16 many  such spruce-fir sites is to attempt  these  have  not  B.C.M.O.F., well  as  floor  and  the of  been  1986a);  the  risks  very  moreover, involved  growth  as  backlog  there  in  the  (Vyse, is  will  and  be  able  future  an  effects  outlined earlier.  plantation approach present  successful  to establish spruce plantations. H o w e v e r ,  It to  1981;  and  additional cost the  is  latter  therefore  satisfy  cutover  Vyse  sites  LeLacheur,  of site  might  preparation  have  unrealistic  on to  adequately  the  in  spruce-fir  B.C.'s  1979;  the  as  forest  assume  regeneration  that needs  forests.  The  logical extension of this is that it w o u l d be silviculturally unwise to ignore totally the  potential of the  advance  regeneration  basis of traditional biases. In most cases, in  place  ESSF  to  part  of  the  second  conditions. H o w e v e r , this  circumvent in  form  these,  an  relation to the  information  decision-making. Western  Hemlock  no studies  understanding  improve  While  Martin  subalpine fir advance  already  crop,  and is  of the  is  not  fully without  species'  g r o w t h is  adapted its  post-harvest  the  confidence  (1985)  ESSF  and  investigated to  this  efficacy  such  writer's  aspects  knowledge  to  growth  of for there  zone i n B . C .  1.  general objectives of this study were  To  investigate  and  dynamic  and  describe  pattern  harvesting i n a n E S S F  of  the  forest;  the  as  follows:  magnitude,  assart  effect  harsh  duration following  to  response  desirable.  1.3 THE OBJECTIVES OF THE STUDY  The  the  the  disadvantages;  a n d earlier considerations becomes  biogeoclimatic zone,  of this type i n the  on  alternative  assart pattern  would  option—especially i f this is done  This  silvicultural the  Coastal  have  been  17 2.  To  verify  advance  the  occurrence  regeneration  in  of N the  deficiencies reported  ESSF  occur, to identify possible reasons 3.  To  harvesting  relationship to the To  the  discuss  chapters  context;  1.4  a l l fall  T H E  the  stated  above.  governed latter  the  was  subsequent  which  are  many  What  site  selection  and  the  are  general  first  I N  i n the  of  same; regeneration  forest,  and  their  and (1)  ESSF  is  to  approach  an  outline  employed i n this  other  to  to  (3)  above  for  zone.  are  developed  statements  for  a  stated  the  objectives  above.  C O N C E P T  ways  an  instance.  1982-83  Next,  approach  w h i c h were  investigation  of the  principal It  with  formative  should be  ideas  stressed  the  variables  employed tested  assumptions  are  and  and  (and their alternates)  the from  c r i t e r i a governing  relationships  presented.  which  that  period, and thus could not benefit  investigators. The  discussed.  statistical  experimental hypotheses  ESSF  specific jobjectives  formulated d u r i n g the findings b y  an  general a m b i t of the  follows  approach  in  implications  follow,  w i t h i n the  A P P R O A C H  There  for the  a s s a r t pattern;  s i l v i c u l t u r a l practices  In  i f found  describe patterns of g r o w t h of advance  following  4.  zone;  in  Finally, are  examined the  main  considered.  18 1.4.1 An Age Sequence of Uniform Sites  Ideally, place  on  any  sites  pre-disturbance level,  or  (e.g. of  the until  perhaps  Hubbard Sollins  Brook and  after  that  any  pattern  point;  One  over  different-aged constructed.  sites,  sites will  al.  pattern has  Wallace  and F r e e d m a n  There approach limitation Site  Matson  are  the  uniformity  observed  effects  of  difficulty is  a  by over  been as  area  by  use  a  by et  the al,  applied  span  sequence type  (1984),  i n various  Haskin  on  the of  in  the  such  as  resources  employment different-aged  the  assumption  measured  Martin,  on  1985;  on  sequences  forms  (and  can  with  Martin  the be  various  et al. (1981),  (1985),  these  Wallace  measurements ages  from original  used  available  variables  of  its  investigators  C o v i n g t o n (1981), L a n g  Boone  was  preclude  "point-in-time" the  reached  of  1981;  take  individually  approach and  should  Nicolson  (1985),  and  (1986).  several  i n evaluation is  and  (Lang  is,  leaf  frequently to  growth  tracked  given forest  reflected  approach  T h i s approach  (1982),  be  a  to  constraints  etc.)  within  an  1979)  Unfortunately,  That  the  Such  been  are  until  Likens,  has  objectives) by such investigators et  and  alternative  1986).  which  closure.  time,  "chronosequence"  in relation  example,  support,  time  flush  of  for  (1981).  disturbance)  Freedman,  assart  (Bormann  financial  years  the  canopy  McCorison  (i.e.  and  some until  approach.  sites—the  of  characteristics  study  personnel,  this  study  problems  associated  disturbance of  adequately  principal  attributable  effects  concern; to  natural  with  over  time.  representing it  is  difficult  between-site  using  an  age  sequence  An  immediately  mobile  nutrient  to  distinguish  variability  obvious elements.  and  between those  19 attributable latter  to the disturbance  difficulty  between-site possible  could  variability  in  their  elevation, aspect, 1981).  be  a n d time.  circumvented  minimized)  basic  physical  geographically close  the  (1978)  viewpoint in  of  Baath  such  duration.  disturbance  the  here.  only  ameliorated increases to  the  proceed (thus  at  N  (1950),  elevated  enhancing  temporarily  group  (American  included  a  group  biogeoclimatic  as  subzone,  selection criterion conceptually From  the viewpoint  it w a s desirable  was also of importance.  noted  that  (for  for  at  some  forests  ten  to have  northern  levels  might  after  net  et  disturbance forests, have  years et al.  microbiological  be s o m e w h a t  conditions  and  twenty  the  Vitousek  coniferous  where  to  A t Hubbard  of S u n d m a n  from  see  ( N O ^ -N) levels  decomposition  shorter  ai,  1979)  also  enters  nitrification c a n been  markedly  mineralization  processes,  —especially nitrifiers, etc.). I n addition, according  of plants  which  i n conjunction  Epilobium  angustifolium  Tamm  least  example,  prominent  red raspberry).  uniform  as  natural  treatments, etc.)(Covington,  procedure,  coniferous  soils under  i n b a c t e r i a l populations  Tamm  become  indicated  nitrate  I n acid  be  1979). H o w e v e r , the studies  well-documented  of increased  usually  were  in northern  appearance  of  to  (e.g.  as a site  effects  together.  (1980)  effects The  picture  the  selected  characteristics  a n d intended  (Bormann and Likens,  and  least  were  o f the age sequence sought  effects  subseqently  at  it w a s believed t h a t the  inclusion i n a n y assessment of time effects.  of logistics, available equipment,  Brook  i f sites  use of a characteristic  precluded it from  The s p a n  (or  study,  slope, h a r v e s t i n g method, post-harvest  O f course,  the sites  I n this  (1964)  he with  termed  increased  L . (fireweed)  also  a  mentioned  "nitrate-loving NO3 - N  and  flora"  availability;  Rubus  Senecio spp.  idaeus L . (ragworts  20 and groundsel)  as  the  flora"  "nitrate  concentrations Tamm  belonging to  have  (1964) a  study  Sweden  support cover  good  fpr the were  Moreover, invaders  North  (Endean 1981).  the  first a  Its  to  the  is  with  noteworthy  Gordon  and  a  Senecio spp.  cutting.  Grasses  years  at  and  least  Likens  species  following  B . C . —and  over  a  post-disturbance  elevated  1983).  Vitousek,  1981;  Moreover,  in  also dominated increased  the  in  site  sites  the  frequency  of  parts  1979; A n g o v e , in  several  McCorison,  and  McCorison  fireweed)  following  Likens,  elevations  and  Sollins  (along w i t h  and  levels  Sollins  N.  prominent  in may  range  NO3 - N  raspberry  most  Likens,  some  available  (Bormann  wide and  red  soil  as  nutrition  provided  the  of disturbed  Bormann  and  optimum  in  among  clearcutting  invader  interpreted  in A m e r i c a n  increase  was  Nevertheless,  be  (1979)  of  NO3 - N  that  1964).  long-term  1976;  Cleve,  also  can  twenty-fold  latter  (Matson  Van  (Tamm,  a  of members  indicate  site  from  Bormann  1974; L y o n s ,  association  a  noted that increases  up  three  data  presence  conclusively  on  w e l l - k n o w n prolific  and Johnstone,  (1981) study after  1974),  Brook  substantial  presence  A m e r i c a — i n c l u d i n g interior  instances 1981;  with  A  itself  Using  belief; they  Hubbard  within  by  such  supply.  (Tamm,  latter  1979). F i r e w e e d is of  N  group.  markedly  that  associated at  not  increased  believed  indicating in  does  this  two  years  clearfelling  (Tamm,  increased  NO3 - N  1950).  The  time  concentrations effect  observed  It  appearance  and  can thus be construed  is i n full  concerned.  of  operation—perhaps is  following  fully  recognized  disturbance  are  also  as at  the  duration  defining a its  that  peak the  period w h e n  where timing  site-dependent  of  to  N and a  any  availability rates large  likely to  of degree  assart  plants  is  nitrification (Vitousek  et al, 1979; of  sites  (as  picture.  Vitousek,  discussed above)  Cole  and  fluxes  can  take  fluxes  of  NO3-N  months  after  depths  such  upper  it  differences  (1968)  within  were  was  the  only  a  at not  unclear  declined.  first by  did  Sollins depth  to  soil  horizons.  Gordon  declined  subsequently  corresponding Nicolson  to  mature  However,  samples by  four  meters  (if  at  all  for  low  Contrary  values,  to  a  within  noted  following but  mere  lag  period  lower  as  years  harvesting  years  after  as  the  two cut  annual  after  NO3-N  losses  and  were  effect ten full  to  under  northern  fifteen  clearcut  retained),  this  years. (as  is  coniferous If  the  the  period would  it was  forest  intensity  case be  when more  thought  that  conditions could of disturbance advance  i n the  any last  was  and levels  than  a  increases,  for  of ten  a  years.  assart  m a x i m u m of  than  and  and  i n water  post-harvest  lower  regeneration  vicinity  high  elevated  following cutting.  observations,  the  scarification.  production  above  in  NO5 - N concentrations  T h e investigators attributed these losses to d r a m a t i c increases  the  seasonal  higher  continuing.  From  period)  years  before  significantly  much  study  h a r v e s t i n g ; the  a c t u a l l y observed  for  lesser  elapsed.  extremely  remained  N  seven  At  had  two  in  about  obvious  least  the  Increased  soil.  the  with  at  (1983)  the  months  variable  lasted  Cleve  18  increases  (1981)  in  group  enter  harvesting.  of two  to eleven months  relatively  forest.  et al (1982)  stream  nine  Van  following  until  "uniform"  greatest  McCorison  highly  NO5 - N concentrations  the  a  should not  and  when  increased  NO5 - N levels for  that  place  appearing  and  fertility  few months  take  as  While  i n inherent  demonstrated  observed  but  1981). H o w e v e r , for  the  variable  in  place  increases  levels  trends,  Ballard  logging,  Unfortunately, these  1981; Wiklander,  that  residuals In  any  of  a are  case,  22 the  period  could An  be  of m a x i m u m anywhere  age  N  from  sequence  availability a  few  spanning  as  (as  months much  at  least  assart the  adequate  flush.  ESSF  insofar  as  at  Thus,  twenty  available, a  of the was (and  preferably  possible, the  sites  had  to be  relatively  and  it w a s  close  each  the  thought  had  same  the  same  elevation,  site  from  a  a  15  similar stand  deemed  period  of  the  of sites i n  years.  In addition,  within  the  same  cover. T h e y  had  slopes  aspects.  and  meeting these  Finally,  Columbia  highly  sequence  20)  forest  mature  was  peak  age  logging.  been  sequence  close together  have  of B r i t i s h  have  and  to  for comparative purposes.  University  following  would  an  initial  and  desirable to have  harvested  of distance  have  years  ten-year  was  ten  subzone  six  commencement  required  N O 3 - N levels)  heightened  years  least  approximately  to  what  possibly  at  Further,  terms  a definition  ideally  spanning  biogeoclimatic lie  for  to  as  desirable; however, should this not be  indicated b y  ease  (U.B.C.)  to  criteria  of access in  base  was  also  a consideration.  The described  age  sequence  above,  with  a ten-year  This  sequence  with  the  main  limitations  of  sites  direct  was  considered  later  span; of the  modified  further age  one cutover a r e a was  measure  Uniformity  the  best  s p a n were found; a l l were was  same  that only  but  of sites used i n r e a l i t y fell  possible. T h e of  therefore  the had  slightly  details  sequence was effect  of  be  available. In  to  yield  be  a  dealt  final with  e x a m i n e d l a y i n three  this  each  was  variation  assumed  1982,  essentially on the  available at  between-site to  will  s o m e w h a t short of the  age  to in  on the  basis  of four  Chapter  facets.  the  cutovers  mountainside. cutovers  Two.  The  The first  was  point; thus,  prevent the  same set  in  five  no  replication  obtaining of  characteristics of p h y s i c a l  ideal  of  any  interest.  characteristics.  23 Secondly, comparable of  the  cutovers.  relevant  of  stands were  A single mature  stand  criteria—had to be used as  harvesting there  mature  was  could the  by  have  clearcut w i t h  been  density  (and  of  disturbance—though  available i n close p r o x i m i t y to  at some distance  T h e final  protection of residuals  appeared  latter  away—but  a comparison base.  retained  i n the  not  advance case  point was  a m o n g the  regeneration  these seemed  satisfying  (B.C.M.O.F.,  to be) differences  any the that  1979). T h u s , sites  and  in  terms  intensity  of  to be r e l a t i v e l y minor.  1.4.2 Indicative Variables and Relationships  The a  principal  carefully  can  be  patterns  (Sollins  sequence  the  of cutovers patterns  variables  and  emphasis  was  phenomenon  i n sites  as  far  context  McCorison, Ontario  of  in the  was  and Likens,  and  of  a  is t h a t comparisons representative  change  with  relationships  placed  on  of the the  of increased apart  1979).  various  among  mature  stand  time  derived  from  to  indicate  these  chosen  and  Indiana  et al.,  H u b b a r d Brook  of n o r t h e r n  aspects  geographically as  1981),  (Nicolson  growth  NOj - N levels  V a n c o u v e r Island, B . C . (Binkley and  study  careful consideration. Because of its o v e r w h e l m i n g importance  northwestern this  underlying this  demonstrate  Therefore,  The  observed 1983),  age  u n a v a i l a b i l i t y i n the  strong  study.  to  needed  relative a  selected  used  harvesting.  assumption  study  following  Alaska  Packee, (Matson  1982).  and  and  forms  of N  harvesting  (Gordon and  1982),  Perhaps  (Likens  and  coniferous  the  the  most  Bormann,  forests, in  has  this been  V a n Cleve,  Oregon  Vitousek,  and  Cascades  1981),  famous  and  example  1974; B o r m a n n  24 As  earlier indicated, the  dependent  on  sequence,  the  approach flush:  to  If,  observed N  to  effect  marked  an  and  site  phenomenon  have  harvested  area,  increased  remained was  at  in  factors.  crop  deficient or  tree  a  but  the  for  the  conceptually  trees  are rates  N  were  not  the  age  assart  levels  were  concentrations,  levels, it could be concluded that  trees  is  inferential  from the  NO3 - N  and  uniform  simple  benefiting  foliage weights,  critical  N O 3 - N formation  However,  mineralization  while crop  operation  t i m i n g of the  suggested  assessment of whether  a  and  beneficiaries  to  and the any  degree.  Given for  processes  NO5 - N  in  contents  assart  several  magnitude  the  foregoing considerations,  the  following  characteristics  study:  1.  Thicknesses and weights of forest  2.  Levels soil, any  3.  of  N  presence  F o r e s t floor  (K),  Height before  6.  and  upper  floor  respect  to  mineral  mineralization  and  macronutrients  [phosphorus  (P),  calcium  (Ca),  and  magnesium  (C) and  p H levels i n the  forest  (Mg)] floor  m i n e r a l soil; and m i n e r a l soil t e m p e r a t u r e  trends over the 5.  with  other  also carbon  and upper  forest  layers;  of NO5 - N ;  of  potassium  4.  the  particularly  Amounts  and  in  floor  and  growing  diameter  and after  Macronutrient  and  moisture  season;  growth  of  advance  regeneration  harvesting;  (N,  P,  K,  Ca,  and  Mg)  levels  and  were  chosen  25 needle weights of foliage 7.  On  selected  middle,  and  sites  in  oldest  of advance regeneration; and the  sites),  age  sequence  the  response  (youngest, of  advance  regeneration to N fertilizer treatments.  In the  addition, basic  assessments  mensurational  of forest  characteristics  floor  of  the  and soil  classifications  stands/cutovers  in  as  well  question  as  were  considered desirable.  Using  the  primary data generated  relationships to be investigated  by the  above,  the principal trends and  can be considered for convenience  to fall into four  basic—but overlapping—comparison groups as given below:  1.  Group I - Trends of the  following  against  time  after  harvest:  a.  Forest floor weight  b.  Forest floor  changes;  and air temperature  and  moisture  characteristics; c.  Forest  floor  availability  and  using  mineral indices  soil  N  (anaerobic  forms  incubations,  chemical extractions, and ion exchange d.  resins);  Forest floor and mineral soil macronutrient earlier listed)  and  (as  levels;  e.  Forest floor and mineral soil p H values;  f.  Forest floor and mineral soil C / N ratios;  g.  Foliar  macronutrient and  needle  weight  values;  and h.  Height  and  diameter  growth  of  advance  regeneration.  Group II - Trends of the following against height and diameter  growth  of  advance  regeneration  since  harvesting:  a.  Forest floor weight changes;  b.  Forest  floor  and  mineral  soil  N  forms  and  availability as above; c.  Height,  diameter,  and  age  of  advance  regeneration at the time of harvest; and d.  Group  Height and diameter growth prior to harvest.  III  -  Trends  of  the  following  with  fertilizer  treatment effects: a.  Forest floor weight changes;  b.  Forest floor  and  mineral soil  N mineralization  levels; and c.  Foliar  macronutrient  levels and  nutrient  status  assessments.  Group IV - Miscellaneous specific  aspects:  a.  mineralization trends  Possible refinement  of N  27 using temperature b.  and moisture  C o m p a r i s o n of soil in  moisture  light of observed  nitrification  values;  and  and  foliar  N  m i n e r a l i z a t i o n and  (if present)  levels relative  levels.  1.4.3 The Scientific Hypotheses Under Consideration  A  consideration of the overall f o r m u l a t i o n of the  examination  is  methodological the  main  necessary. issues  is  hypotheses  w h i c h follow are  A  brief  first  review  presented.  themselves.  of  This  proposed w i t h i n the  some  is  Subsidiary  scientific hypotheses of  followed  the  by  hypotheses  more  the  stated  context of these m a i n  under  important  development in  the  of  chapters  ones. Some Methodological Considerations  The  views  methodological that  any  of  K.  approaches  scientific  therefore  be  verified  (Dolby,  1982;  urged  inference"—to approach. argued  that a  to  theory  should  (1964)  aimed  rigorous  system  the  Piatt  are  considered  scientific research. must  be  at  their  Magee,  1982;  and  (1964)  multiple  dominant  of  a  since  hypotheses  Within  formal  set  approach  is  was  the  this  of  of  to  current  cannot  steps—his one  apply  truly  strictly  was  hypotheses  context,  have been a m o n g those  difficult  of  requirement  tests  1984).  hypotheses  D u n h a m (1983)  terms  falsifiable;  falsification, Bunnell,  in  H i s cornerstone  potentially  application  of  However, Quinn  that  Popper  be Piatt  "strong effective  who  have  in  many  28 ecological  situations.  appeared  to  be  For  that  against  the  Popperian  criterion—in  the  Simberloff  (1983)  of  Popper's  was  and the  single observation  repetitions  of  such  methodological hypotheses  ecological  forming  Dunham,  a  (1986). issues  which  stems  It  presented  Popperian in all  a  A  the  al,  1983).  and  The  would  et  ecology  (1983), One  Dunham,  problems  1983) were  was  the  values  measured  here Quinn  may and  to  taken  attempt  addition  that  insofar  (1964)  a  a  lack  as  be  in  (1983), to  this  Simberloff  resolution of  the  as  the  approach  prevented of  a  null  and  followed  Dunham  recent  to  (Quinn  be  the  particular  seems  is that of Connor and  Piatt's  of resources  Moreover,  be  and  be defined  of some  by  several on  models"  effects  very  study  was  of controversy  main  involved  al.  of this  followed.  constraints  consideration  extremes,  immediately;  "null  the  the c o m p l e x i t y  models m a y  may  (1983).  position be  Null  of their  succinct picture  scope  area  of whether  One  arguments  clear  (Quinn and  Another  departures  Simberloff  above.  two  community  theory  e l i m i n a t i o n of the  of H a r v e y  the  these in  (1983)  especially  H e considered that both  question  the  which  beyond  rules—and  particularly  needed.  and  alternatives.  further  were  et  Roughgarden  of m a n i p u l a t i n g t h e m dictated that refutation  a i m e d at  those  principle; however,  alternatives  moderated.  complicated  prescription  possible  that  as  Between  i n ecological research.  from  The  (1983),  is far  view  from  place  basis  gives  sciences.  event  such' as  Roughgarden  formal  an  (Harvey  1983).  publications  series  the  such  held insufficient to discredit . a  any  process  of  such  be  plane  have  investigators  natural  difficulty  those models w h i c h are  in  use  prescription should be  of communities a  matter,  rigorous  of m u t u a l  possible  was  attempted  evaluation  of  e x c l u s i v i t y of  encountered.  precise  form  of  the  hypotheses  to  be  29 tested  or  (1986),  otherwise  outlined  hypotheses, scientific precise from  links  statistical  hypotheses  are  formulations  of  clearly defined  ones  statistical  cases,  errors;  (rejection hypothesis) models  advantage more  (Toft  Simberloff,  stated,  I  case,  Type  and  1983;  null  there  effect  are  to be been  far  less  deemed  dramatic  than  to fail  to detect  Simberloff,  1986).  Furthermore,  a  worse an  degree of departure from the  Connor  under and  (Toft  notable  consideration Simberloff,  (Toft  1986).  In  Type  II  and  to  n u l l hypothesis  of  typically  be  the  kinds  Type false  1986).  Null  have  are  I  the  committed  towards  finding  Connor  and  examining  errors.  prematurely and  Shea,  can indicate Quinn  II the  and  I  null  the  of T y p e II error  of T y p e  above  a  to  in  and  two  as  1983;  (e.g.  costs  (Toft  and  errors  Shea,  jump  1983;  scientific  said  probability of T y p e  Shea,  are  reject  would  data  scientific  Simberloff, been  those  error  light  and  to  are  from  known  have  the  while  require  the  conclusions  (failure  existing effect  and  and  both  exceptions  than  i f the  In  tendency  i n basic ecological research  conclusion  effect  II  since  the  processes,  distinct  widely  Connor  is,  researchers,  experimental  quite  are  hypotheses  That  concern  scientific  S t a t i s t i c a l hypotheses  correct  and  has  the  possible  Simberloff  theories,  theories,  (scientific).  hypothesis) Shea,  are  and  i n ecology hypotheses  latter  it  and  scientific  the  by  While  of pesticides), considered  two  conservative.  any  1986).  have  scientific  theories.  that  Connor  theories  they  Popperian  concomitant  Type  of  can  of  noted  later  among  of such  therefore,  (1983)  and  Scientific  forms  truly  null  being  than  evidence  been  true  of  differences  consequences  statistical  their  often  effects  the  errors  and  the  not  (1982),  hypotheses:  verbal  testing  of a  and  Shea  and  in  Dolby  populations;  Toft and  statistical  no  the  and  hypotheses.  of  examined.  have  Otherwise to  a  false  1983; Connor error  is  strength Dunham,  considerations,  the  small, of  the  1983; use  of  30 the  null  approach  results of the  considered could  be  final  to  as  testing  accepted  as  This  has  applied. P i a t t ' s  a  fully-controlled  feasible or  or  treatment  (the  based  the  some (1964)  necessary. and  be  latter  termed  entails  "control") (Quinn and  specific  the  theories  knowledge (Connor  and  earlier  sequence  could  variables  the  tests could be  the  the  data  of  of  (see be  section  thus  study  be  as  stand's  in  for  their  the  absence  values  resulted  the from  a  other  "time  statistically using techniques  t a k i n g the  The with is  assumptions place  i n d i v i d u a l differences.  of a  of the control.  Where the  no  processes these  controlled, p r i n c i p a l l y because  different  the  and  1986).  between  hand,  that  of  Simberloff,  there  O n the  analyzed  absence  of such  lying  a  specific  consistency  and  each  ideally  spectrum,  processes;  be  elegant  from  Simberloff,  perceived as  other  be  as  character,  having  to determine  data  fully  with  other end of the  specific causal  was  would  after-the-fact  (ANOVA)—assuming  mature used  1.4.1).  perceived  could  its  steps  obtained  and  could  techniques  1983; Connor a n d  m i g h t yield in the  1986). T h i s  of these  statistical  obtained  (Connor  evaluation  operation  orientation,  of variance  met—with  and  the  values  research  be  those  Dunham,  It could not be considered as  field-sampling  analysis  with  Simberloff,  outlined  Their  or  of w h a t  two extremes. its  collection  whether  inference"  to  The  falsification.  would  compared  study.  consequences  situation, presumably  Results  non-experimental  i n this  to which this s t u d y  on  "strong  1986). H o w e v e r , m u c h ecological w o r k lies at may  adopted  on the  extent  bearing  laboratory  manipulations,  was  adequate c r i t e r i a for  methodological issue was  validly  treatments any  were  experimental.  applicable design  scientific hypothesis  testing of s t a t i s t i c a l hypotheses  n u l l hypotheses  The  to  of  problems  sites  in  the  treatment". such  as  latter A  the were  posteriori  assumptions  of  the  ANOVA  could  not  these tests could be The  ANOVA  Model  I  be  applied  designs  analyses;  reasonably  (Hollander and  envisioned  i n the  satisfied,  were  two-way  the  Wolfe,  case,  where  "mensurative"  (1984) and  the  the  only  factor  neither  does  the  contrast,  the  experiments. system them. This  at  the  considered.  latter  are  were could  feasible  it,  called therefore  that  emphasized Dunham  the  (1983)  n u l l models are postulated  and  1981).  two-way these  modifications (Gilbert, 1973;  Grieg  causal  are  also  then  view  design  noted  in  usually  the  differences  1984).  experiment  the  null  Simberloff  model  systems  beyond  of  this  (1986). the  approach.  appropriately  viewed  in  appropriate.  other  of  than further  Quinn  and  constructed  effects  such  The  scope  study  absence of the  (1986)  of a  (Hurlbert,  approaches  nature  of  among  Simberloff  include  In  exist  Connor and lie  class  properties  mensurative  questions  time  involved,  manipulative  real  or  manipulations.  considered  s y s t e m i n the  and  the  or  space  was  non-experimental  Connor  not  experiments"  therefore  employing  to describe the  process.  by  experiments—the  either  measure  techniques  pseudo-experimental of  that  which  whether  ecological  should  are  comparative  expressed  methods  types,  of  mensurative a  of  treatments  features  examine  important  The  specific  studies  termed  advisability  used  classes  significance  any  defining  be  the  many  experiments.  apply  statistical  experimentation;  controlled  Rohlf,  of  i n cells occurred  basic  of  "comparative  application of  stated  two  Tests  the  within  T h i s is i n accord w i t h latter  and  one-way  imbalance  " m a n i p u l a t i v e " . I n mensurative  investigator  points  study  which  recognized  H o w e v e r , there  These  simple  equivalents  1980; L i , 1982).  Hurlbert  is  1973; S o k a l  principally  could be legitimately a n a l y z e d u s i n g appropriate and Bjerring,  non-parametric  of  the  models  as  32 approximating  the  role  of the  control in the  non-experimental  attempts to place non-experimental data i n a n experimental  case,  and  also  as  context. The Scientific Hypotheses  The stated  scientific hypotheses  objectives  these concerns of  a  global  earlier, the  and  the  the  points  theory  conjecture  :  0  now be  raised  of the  There  harvested  was  i n the  (1982);  under  no  If  H  the  is  0  true,  mature  (see  section  assart  statistical  falsification.  Should  testing. T h e most observed; i t m i g h t failure  to  reject  time  are  hypotheses  indeed  using  the  theory null  no  effect  tests  is  is on the  approach  of  level  discussed  operational  on  the  an  therefore:  assart  where  detectable the  concerned.  derived the  effect  operational  differences  among  from fail  The this to  also  be  null  results premise  reject  instructive to hypothesis  sites  (including  soil-related variables of G r o u p s I and I V  H  of  tests  therefore 0  ^,  there  on  the  become  the  should  be  t h a t could be done would be a reporting of the  the  foremost  sites.  should be  over  1.4.2)  was  harvested  there  stand)  itself. T h i s  The  sites.  There  on the  foregoing section.  previously  test becomes:  The simplest m u t u a l l y exclusive alternate  y  considered i n light of the  assart effect  sensu Dolby  p r i n c i p a l hypothesis  H  can  speculate  (Toft  and  on the Shea,  reasons  1983).  concomitant c r i t e r i a of no  further  variable  values  u n d e r l y i n g the  Rejection  of  H  0  33 would  lead  us  characteristics next global  On step  in  benefits  to  consider  of the  and  observed  acceptance  the  context  accrue  to  idea of a n  of  stated  the  :  0  the  advance  alternate  There  :  is  true,  regeneration's Group  I  set;  growth  variable  values  become  examination  there  foliar  between  again  of of  the  of the  Here, any  also  considered.  further  also  durations,  allow  us  operational a s s a r t  objectives  no  would  be  present.  benefit  advance  to  effect,  to  In  test  from  and  proceed  other to  the  the  next  examine  similar  logical  whether  fashion  its  to  the  becomes:  the  assart  effect  regeneration.  testing;  some benefit  from  the a s s a r t  should  be  macronutrient neither  Group  timing  no  values,  should  advance  criteria  pattern. be  would  regeneration  was  There w a s  regeneration  the  magnitudes,  is:  H-i 2  0  the  relevant hypothesis under  a c c r u i n g to the  H ^  it  of the  above, the  H  If  effects;  on  conjecture.  presentation  Its  report  there  regeneration  II.  Test  for  results  falsification.  and extent  a c c r u i n g to the  effect.  detectable needle be  since on  apparent  however,  any  differences  weight  any the  of such benefits  apparent  H  kind  limitations  and  0  ^  within  magnitudes  limitations of a n y  any  statistical of  to  the  and  of  harvest  related  in  values,  indication  Rejection  noticeable limitations on the No  advance  the  advance  growth  relationship soil-related  hypotheses  would the  in  lead  once to  an  observed  assart  of such benefits  might  would such  lead us benefits  to  cease and/or  34 acceptance same  of  format  H  would  0  as  for  require  those  some  foregoing,  elucidation  the  global  of  possible  conjectures  reasons. involved  stated as:  H  ^:  0  ability  There of  was  no  advance  macronutrient  regeneration  to  limitation benefit  to  the  from  the  assart flush. H,  There  the  was  indeed  ability of advance  a macronutrient  regeneration  limitation  to  to benefit from the  assart flush. H  ^:  0  ability  There of  was  advance  no  micronutrient  regeneration  limitation  to  benefit  to  the  from  the  assart flush. H , .: There  ' 4  was  indeed  the .ability of advance  a  micronutrient  regeneration  limitation  to  to benefit from the  assart flush. H  0  ^: There  limitation  to  was the  no growing ability  of  season  soil  advance  temperature  regeneration  to  benefit from the assart flush. H , j.:  There  temperature regeneration H  0  g:  There  limitation  to  was  indeed  limitation  a  to  the  growing ability  season of  soil  advance  to benefit from the assart flush. was the  no  growing  ability  of  benefit from the assart flush.  season  advance  soil  moisture  regeneration  to  In  the  could  be  35  :  There  moisture  was  indeed  limitation  to  regeneration to benefit  It should be noted that this (mentioned a  result  earlier) was as  might  be  H  was  the  above  advance  desirable.  testing  Moreover,  testing  placed on N  of H  resources  constrained  and H g above; as indicators—thus,  the  stated earlier,  0  as  alternatives  may not result in as clear  available  0  variables  of  in this  context,  As before, the test bases should  hypotheses and tests. Rejection of each of  the.  null hypotheses would be followed by an examination and reporting of the  values  involved; regardless  hypotheses in this the null  study.  of  the  test  results  1.4.4  on  the  hypotheses be rejected, no further testing  Rather,  others,  each  of  the  null  latter group would have to be considered in turn. Should none  the  values  observed  for  the  speculation as to further causes of non-benefit  will be carried out in this  variables  would  be  discussed,  to advance regeneration  and  attempted.  The Organization of the Thesis  In was  of  soil  point at which non-exclusivity  rather than the latter two null hypotheses.  0  season  ability  encountered; therefore,  be provided by derived statistical  of  growing  from the assart flush.  is the  collection of data for possible strong emphasis  a  the  foregoing sections,  presented;  conceptual follows  has  descriptions  this  was  a background to the problem under consideration  followed  approach employed. been  organized  and  field  by  For  into  sampling  a discussion the  purpose  of the of  clarity,  11 chapters.  In  (and  layout  other)  objectives  Chapter are  the Two,  involved and  material the  presented.  which  basic  site  Observed  36 seasonal  temperature and moisture trends  few  the  of  implications  of  these  are  are  reported in Chapter Three,  discussed  as  necessary  in  but a  subsequent  chapters. Chapter Four deals with post-harvest physical aspects of the forest floor layers,  while the parallel chemical characteristics of both forest floor and mineral  soil are presented N  availability  in Chapter Five.  patterns  in  this  The perceived importance of post-harvest  study  is  reflected  in  its  separate  (Chapter Six). Having considered the environmental and soil changes, next  focussed  Seven Chapter  on the  through Nine. Seven.  is presented.  observed response  of the  Pre- and post-harvest  In Chapter  Eight  advance  growth  treatment attention  is  regeneration in Chapters  patterns  are  a consideration of post-harvest  Chapter Nine represents  soil  the  subject  in  nutrient status  an attempt to identify possible  associations  and/or relationships among observed growth characteristics and both soil variables and  foliar  implications  chemistry. is  Finally,  presented  in  a  synthesis  Chapter  Ten.  of  the  This  includes  harvest growth and nutrient dynamics in relation to E S S F forests.  cumulative  results  considerations  and  their  of  post-  silvicultural practices in the  The overall conclusions of the study are presented in Chapter 11.  CHAPTER SITE DESCRIPTIONS AND  In the  layout  study in  this  Chapter,  and  have  site  discussed.  BASIC FIELD L A Y O U T  descriptions  s a m p l i n g scheme,  been  subsequent  the  2  and  o n l y general  Further  details  field  layout  are  aspects affecting  specific to  each  presented.  For  all phases of  phase  may  be  the  found  Chapters.  2.1 T H E R E S E A R C H  AREA  2.1.1 Location  The  general  research  north-western  boundary  1983).  situated  It  is  Clearwater,  and  is  area  with  the  is  of  Tree  southern  slopes  basin  (Figures  Their  latitude  respectively. Shuswap  of S w a y b a c k  2.1a,b), and  variant  (Lloyd,  (Lloyd,  1982).  lie  lies north-east of them  at  are  Forest  Region (Watt  directly  Licence  approximately  two  1480  m  Engelmann of t h e m  a distance  of 18  the  1600  m  all lie on  Lake  and  120°  elevation  Subalpine  lie v i r t u a l l y together,  N  on its  of  Clearwater  drainage  N o r t h Thompson river 49'  its  Lloyd,  town  The sites  system. 15'  within  W the  Fir  (ESSFml)  lower  boundary  while the  mature  of a p p r o x i m a t e l y two kilometres.  37  near  1979;  of  Creek/Moira  Spruce  r e l a t i v e l y close  et al,  (TFL) No.  51°  and  Region,  north-west  Mann  being part of the  Central  cutovers  km  Ridge i n the  are  however,  Kamloops  N o r t h N e h a l l i s t o n Forest.  between  Moist  1983); The  latter  longitude  A l l sites  Highlands  the  26 Farm  T i m b e r Products, L t d . ( C T P ) i n the the  the  Cariboo F o r e s t  approximately part  in  stand  38  Figure 2.1a Location of the study area in British Columbia.  Figure 2.1b Location of the study sites in the Kamloops Forest Region.  40 A Five a  preliminary  harvested  sites  freshly-cut  mature  survey  (four  stand  mensurational  were  and  area  for  five-,  examined.  data  on the  sites.  sites  were  fertilized  at  sequence  used  was  modified  from  the  d u r i n g the  1983  field  the  carried five-,  out  seven-,  and  eleven years  old respectively b y  year-old  1983)  (in  site  p h y s i c a l characteristics  that  ten-year-old  and  (see  The  time  five-,  and  final  age  but  mature  which  retained  six,  only  eight,  included a  stand.  a  basic  investigations,  become  to  cutovers;  The  sequence  earlier set,  representative  that  1982.  provided  Eight).  final  of  freshly-cut,  main  had  fall  at  sequence  the  (which  from the  the  ten-year-old  Chapter  for  season.  are  in  In addition, the  cutovers  of these sites  and  initial  above  more  out  corresponding  seven-,  time  1983)  a  carried  This  ten-year  were  was  examination,  old), three-,  also  other  the  selected  months  was  of  and three-  The  salient  s u m m a r i z e d i n Table 2 . 1 .  2.1.2 Geology  The  study  area  lies v e r y near to the forms  part  1971;  Baker,  and  of the  features  formed by the  five  million  thousand  In  years the  metres.  between  [Holland,  regions  uplift ago)  Shuswap The  t Regional Research and J u l y , 1983.  south-eastern  D. Lloydf].  these  were  Period.  boundary  latter  1978; of  is on the  and of  the  1964;  detailed  was  given  account by  dissection i n the erosion  Highlands,  Pleistocene  the  surface land  glaciations  Ecologist, B . C . M . O . F .  interior P l a t e a u .  Quesnel and S h u s w a p  Geological  A  an  portion of the  Survey of the  Holland  of  H i g h l a n d s , but  Canada  (G.S.C.),  physiographic  (1964).  These  surface  which  earlier was  followed  (Kamloops); pers.  in  the  elevated lasted  well  history  Highlands  late Pliocene epoch (some formed  It  two  to  Tertiary over over  c o m m . October,  two one 1982  41  Table  SITE CODE  2.1 P h y s i c a l characteristics of the selected  AGE IN 1983 (yr)  YEAR OF CUT  TM  sites.  AREA (ha)  ELEVAT I O N (m)  SLOPE  15.0  1595  25  %  ASPECT (deg)  SLOPE POSITION (macro)  140  upper  T3  3  1980  2.7  1580  0-2  T6  6  1977  6.2  1495  50  176  middle  T8  8  1975  9.0  1485  36  142  middle  Til  11  1972  29.4  1556  5  165  upper  upper  42 million the  years,  ending  formation  of  some  the  ten  thousand  landscapes  years  observable  ago.  at  These  present  glaciations  (Holland,  dominated  1964;  Ryder,  1978).  According fall  within  to  an area  principally  of  the  G.S.C.'s  ago)  Pre-Cambrian as  of the  area,  this  granitic  rocks  such  taken  from  identified deposits  rocks  (at  is  information, the  as  monzonite  to  frequent  of  this  form  the  third  part  form  the  be  group, t of  million  Cretaceous  quartz  being  S h u s w a p H i g h l a n d s at  500  q u a r t z - m i c a and  o v e r l a i n by  observed  materials  least  feldspathic  as  Morainal  mapped  sites  appear  to  of r a t h e r complicated geology. T h e oldest bedrock is comprised  metamorphic rocks such much  (1971)  this  principal  and  to  parent  the  years  samples  sites  were  (Holocene)  1971;  material  million  Indeed,  on  later  However, in  120  Recent  (G.S.C.,  and  schists.  prominent  complex  such elevations (Lloyd,  70  ago)  granodiorite.  and  soil  other  (ca.  and  Pleistocene  years  glacial  Ryder,  over  1978).  much  of  the  1983).  2.1.3 General Climate  Krajina  (1965)  outlined  the  major  climatic  biogeoclimatic zone i n general. I n the  southern  found  and  the  at  elevations between  North  Koppen  Thompson-Shuswap  system,  continental  1220  cold  the  ESSF  humid  t D r . E . P. Meagher, comm., M a r c h 14, 1986.  m  basin  zone  2288  its  lower  is classified  climate Professor,  with  as  cool,  Dept.  of  characteristics  of  the  ESSF  interior of B . C . , this zone m a y m. limit  Lloyd is  having a short  (1983) about  1350  that  in  In  the  m.  Dfc climate; t h a t  summers  Geological  implied  (Krajina,  Sciences,  be  U.B.C.;  is,  a  1965; pers.  43 Trewartha,  1968;  characteristics; environment  six  forested  drainage  Southern  Upper  Region's were  subzones.  basins;  zone  Hemp  The  Creek  Shuswap occurs  (Table  much  environment for  closest  1983)  Central  Some  for  Moist  the  were  also  near  the  the  climate,  Central  Lloyd  research  area  data  Cedar  represents 1983  a  and  The  upper  values  precipitation  figures.  The  seasons  should be  ESSF  zone as  bulk  i n Table and of  2.2  pers.  imply  precipitation  r e l a t i v e l y short  a whole.  and  for  the  markedly  obtained  comm.,  that  the  should with  October  research  ranges be  and  Wet  Kamloops 2.2).  available i n the  There  was  and  snow,  and  drier (and  (1965) while  of the  April  should be  lower temperatures  this  Boss M o u n t a i n  1982  sites  at  Vavenby  representative  of K r a j i n a ' s as  at  in  Northern  variant;  warmer  from  as  the  elevations  similar low-elevation station  lower temperature the  (Table  are  1985). Complete n o r m a l s  available, those  (D. L l o y d ,  the  Hemlock ( I C H m l )  Cariboo F o r e s t Region (Table 2.2) were believed most  1986).  an  Thompson-  they  for  were  i n the  conditions  as  Region  (ESSFw),  (1985)  2.2).  area's  these  zone  North  no longer operational, fell  (Lloyd,  data  Wet  long-term  available for a  of the  in  (Table  research  However,  the  of  Kamloops Forest  occur  given by  and  zone  of  increasingly wet  Interior  elevations,  some  climatic characteristics  which  Central  ESSF  these  (ESSFm),  2.2). T h i s station,  lower  than  of  whole were  station  character  zone of the  of an  climate stations  Highlands  at  a  illustrates  evident.  Four  subzones.  2.2  harsh  ESSF  i n terms  Moist  as  no operational  question.  rather  recognized the  forested  ESSF  the  Table  g r o w t h becomes  (ESSFe),  (ESSFu)  1978).  these,  for p l a n t  (1983)  Shuswap  data  from  Lloyd having  Dry  Money,  in  ESSF the  compared  17, the zone  growing to  the  Table  2.2  Climatic  characteristics  LOCATION  of  the  ESSF  biogeoclimatic  SOURCE  zone.  PRECIPITATION  (cm)  TEMPERATURE  (°C)  GROWING  FROST-FREE  DEGREE-  PERIOD  DAYS Annual  Total  Annual  Growing  Snowfall  Season -  ESSF  General  Krajina  (1965)  41  -  183  175  -  Mean  Annual  January  (May  Mean  Monthly  July Mean Monthly  Sept.)  1016  1  -  4  -18  -29  12  <  16  1000 2000'  Kamloops  Region  Lloyd  (1985)  1100  700  Atmos.  Envir.  118  782  40  U)  56  211  26  43  116  20  2  1  720'  35  ESSF Boss (1532  Mt." ESSF m)  Serv.  Hemp C k . (640  m,  ICHml)  Serv.  (4)  (-10)  (15)  (6)  (-8)  (18)  672  ]  Envir. (1982a)  Vavenby'  Atmos.  (445  Serv.  in)  12  (1982a,b)  Atmos.  6  -10  1  Envir.  1670'  (1982a,b)  'Above 6°C. !  Bclieved  unadjusted,  hence  difference  in  magnitude  from  others.  'Above 5°C. 'In  Cariboo  'Bracketed  Forest  figures  Region; derived  latitude from  52° 6'  mean  daily  'latitude  51° 55'  N, longitude  120° 3'  Latitude  51  N, longitude  119° 47'  7  1  35'  N,  longitude  normal  W; approx. W; approx.  120° 53'  W; approx.  46  km  north  of  research  area;  data  are  complete  data. 18 43  km km  north-east south-east  of of  research research  area; area;  data data  are are  30-year  adjusted  complete  30-year  normals. normals.  30-year  normals.  45  2.1.4 Soils  Basic  classifications  50 c m pits i n a l l but pits  were  lower  used  slope  sampling field.  in  Samples sampler  cm.  Temperature or  the  as  mineral  to  this  analyses  executed  in  (Bernier,  1968; K l i n k a  were  classified  upper-slope disturbed  textures  loams  (SiCL),  most  common.  rule layer  and, The  from  cm  and  carried  on  pits  out  were  of  the  texture  density  at  dug  for  the  was  these  plots.  Humo-Ferric  the  an  clayey  soils were were  i n v a r i a b l y encountered  loams  shallow not at  determined, less than  by  hand  in  the  using  down  to  the  of  a 15  50  cm  classifications  nor  such  work  mor  was  to  humus  cutover,  For  the  be  forms  1978);  metre  as  the with  an  Orthic  (C.S.S.C.),  1978].  loams  ( S L ) , silty  loams  or  clay  (SL) were  although  contact  site,  (E.DYB)  classified  sandy  all profiles  T6  Brunisol  silty  lithic  one  general  depth  Committee  (L) and  (Dumanski,  the  a  (T6)  was  loamy-skeletal;  extent,  by  and  on' a l l sites.  Dystric  Survey  by  middle,  to  floor  (O.HFP).  profile  cm  obtained  cm  However,  1977  Eluviated  Soil  to  the  Podzols  lower-slope [Canada  in  7.2  since  1981) were predominant  profiles  were  forest  profiles,  50  upper,  determined  intervals  Neither  three  covered  calculations  sampled  of two  at  sites  depth  possible.  using  of its s m a l l size, only two  internal diameter  taken  was  to a lesser  C horizon thicknesses was  bulk  (O.FHP)  ranged  Soil  considered  while  Podzol  2.2).  soil  et ai,  was  The  portions  performed  Orthic  horizons,  case.  were  detail  as  soils were  the  as  exception  profile  Ferro-Humic Soil  were  greater  the  7.5  readings  chemical  With  latter  section  of length  near  the  1980 (T3) cutover. Because  within  (see  for  core  level  the  positions  scheme  of  an  of depth.  as  a  the  general  impermeable The  depth  to  46 the  C horizon i n the profiles ranged from  least  plentiful  observed  down  down  presented  to  indicating a  past.  T h e soil  comparable in  40  this  deeper  C horizon.  to  Lake,  summary  and widespread  severe  of the sites  18, 1986).  I n the latter,  T h e depth  of  the  Podzols were  approximately  the observed  14 k m east  18 ( H e r r i n g a n d M c M i n n ,  very within  subzones-the  the trend  Ridge soils  soil  under  of the research  many  years  area  on a l l i n the  noted for  " W e t Belt"  (D. L l o y d ,  slightly  coarser  uniform  Shallow,  similar  is  the range  of penetration  sites.  were  interface  to be more  depth  roots  characteristics  w a s towards  tended  a n d absolute  Swayback  fire  well  to the C horizon  abundance  fine  at the H / m i n e r a l  fall  and E S S F w  of cases,  of these  rather  those  Humo-Ferric  A  majority  w a s observed  characteristics  soils.  i n the  2.3. Charcoal  cm). H o w e v e r , root  similar  level;  plots i n the E S S F m  litt., A p r i l  and  the  i n Table  sites,  to  12 c m to 41 c m . Roots were often at  (30 -  were  very  coarse-textured  conditions near  a n d also w i t h i n  Sock  T F L No.  1980).  2.1.5 Vegetation Original  All the  cutovers  Engelmann Monteith, R.  t  sites  Vegetation  were were  spruce  considered to be m e d i u m i n q u a l i t y . T h e original comprised  a n d subalpine  of fir  mature, trees  uneven-aged 28  m  to  District Manager, Clearwater Forest District;  Swanson,t  in litt., M a r c h  F o r m e r P l a n n i n g Forester,  38  (140 m  to  250  i n height  in litt., J u l y  stands of years) (M. E .  15, 1982; E .  15, 1984). M e r c h a n t a b l e volumes i n the vicinity of  C T P , Clearwater.  47  Table  2.3  Summary  SITE  CODE  of the  basic soil characteristics of the  SUB-GROUP TEXTURES CODE (< 2 mm) 1  2  D E P T H TO C HORIZON (cm)  sites.  ROOT P E N E T R A T I O N (cm)  Plentiful or Abundant  1  2  TM  O.HFP  SiCL, SiL, SL  31 •• 41  12 -  T3  O.HFP  SiC,  20 •• 30  5  T6  E.DYB, O.HFP, O.FHP  SiC, SiCL, SiL, L  12 ••  T8  O.HFP  SiCL, SiL, SL, L  26 •• 36  Til  O.HFP  SiC, SiL, SL, L  13 •• 17  See text for explanation S i C = silty clay; S i C L -- s a n d y loam.  SiCL  of codes. = silty clay loam; S i L  21  Fine  Roots  31 -• 41 +  33  - 20  20 -• 30 +  9 - 21 +  12 •• 21 +  26  28  26 •• 36 +  13 - 17 +  13 •• 17 +  -  silty loam; L  =  loam;  SL  48 280  m  pers.  ha"  3  1  have  been  c o m m . , September,  c o m m o n l y obtained 1983).  The "medium"  yr) o f 13 to 20 for both E n g e l m a n n spruce  Measurements Total basal area by  spruce  with  taken  (Pinus contortd D o u g l . was  comprised  relatively  3570  stems  average of  breast with  of  diameters  a n average  stand  subalpine  1983).  the above  figures.  f i r , a n d 5% by lodgepole pine  fir  averaged  4030  (Dbh).  O f this,  advance stems  Hook,  blue  huckleberry),  Rubus  Paxistima myrsinites (Pursh) N o occurrences  regeneration, ha"  subalpine  for 29 stems  with  fir accounted for  with  with  an  a n average D b h  included Rhododendron  Vaccinium membranaceum Dougl. ex pedatus S m i t h  R a f . (falsebox),  (five-leaved  as  well  creeping  as Pleurozium  of Menziesia ferruginea S m i t h (false  Gymnocarpium dryopteris (L.) N e w m .  with  of trees  1  for 4 3 1 stems  o f the m i n o r vegetation  (white-flowered rhododendron),  or  supported  index (100  1  albiflorum Hook,  schreberi (Brid.) M i t t . t .  implies a site  D b h of 4.8 c m , spruce  3 3 . 6 c m . T h e m a i n components  raspberry),  (E. R. Swanson,  h a " ; 6 8 % of this w a s accounted for  3  D b h of 30.3 c m , a n d lodgepole pine  (big or  sites  v a r . latifolia E n g e l m . ) . H o w e v e r , the understory  T h e stand  height  rating  sizes, 2 7 % b y subalpine  ex L o u d .  such  a n d subalpine fir (Watts,  mature  as 51 m  overwhelmingly  few spruce.  measurable  i n the  w a s estimated its larger  from  (oak-fern)  were  noted  azalea)  on any of the  sites.  The were poor  t  those  characteristics of a  of the major  site' w i t h  to m e d i u m soil  a  nutrient  N o m e n c l a t u r e for mosses  submesic regime  and minor soil  moisture  (trophotope)  follows C r u m  vegetation regime  mentioned (hygrotope)  i n the E S S F m l  et al. (1973).  variant  above and a (Lloyd,  49 1983). Lloyd It  T h e observed  mensurational  (in litt., A p r i l  should  quality;  values  are  18, 1986) for comparable  be noted  that  site index values  the sites  on which  place t h e m  more  within  the  ranges  Wet-Belt E S S F the latter  observed  stands  occurred  (Table 2.4).  were  i n the "good" category  by  of better  (Watts,  1983).  T h i s is reflected i n the higher b a s a l areas a n d volumes recorded. The Harvested Sites  The of  residuals  advance fall; of  present  a diameter  regeneration These  predominance  ingress  of  subalpine  thereafter)  are  litt., M a r c h  were  since  15,  oldest  obtained  cutovers  Stem  fir advance  some  Basic  The  usually  has  disturbance  observed b y H e r r i n g  m i n o r vegetation a n d time  from  than  slashing (at the time  component its original  trees, no  ( E . R . S w a n s o n , pers.  mensurational  are presented  should  protection  of subalpine fir  of the poorer-quality  be  taken  in Figure  as  a  clumped  for  2.2 a n d T a b l e O f note  only,  distribution  observed were  are  l o w rates of  indicative  spatial  comm.,  characteristics  a n d the apparently  logging ( H e r r i n g , 1977; Monchak, 1982). T h e densities portion of the range  with  d u r i n g the 1 9 8 2 p r e l i m i n a r y survey.  densities  growth  primarily  Other  the h a r v e s t  1984).  clearcuts  skidder-logged d u r i n g the s u m m e r or  of the subalpine fir component,  spruce.  from  comprised  used.  to remove  undertaken  on the three data  they  limit of 18 c m h a d been  h a d been  1 9 8 3 ; in  1979);  resulted  T h e sites h a d a l l been  logging or shortly  July,  the  (B.C.M.O.F.,  regeneration.  treatments  2.5.  stands on the cutovers  since after  i n the lower  (1977).  o n each  site  condition to  h a d no doubt  changed  1 9 8 3 . T h e species  with  mentioned  50  Table  2.4 Ranges of m e n s u r a t i o n a l values for W e t - B e l t E S S F stands on wellmoderately well-drained podzolic soils w i t h south-eastern aspects.!  CHARACTERISTIC  Age  RANGE  (yr)  166 - 300  Site index (100 yr) - subalpine fir - E n g e l m a n n spruce  18 - 26 22 - 26  Rooting depth  21 - 36  (cm)  Stems  ha"  1  500 - 2970  Mean  D b h (cm)  18 - 45  Basal  areat  Volume  (m  3  (m  ha"  2  1  44 -  )  ha" )  123 -677  1  t F r o m L l o y d (in litt., A p r i l 18, 1986). t L i m i t e d data; includes aspects between  81  9 0 ° and  270°.  and  51  600-i  500-  T6  O -C  400300  E  (D  tn  200 100 0  600 500 D JC \  E  T8  400 -  <D -•—  300  1  200  CO  100 0  JrzL  600-i  o  500-  JC  400-  V)  300  E ® CO  T11  V  200100n  0  • i  1  EZ2 Fir  1—T 1 1.2 1.4  Height C l a s s (m)  Figure  2.2 H e i g h t and diameter the oldest cutovers.  Spruce  class  ~rn 1  2  r  y  3  4  ,—,—  y y 5  6  7  8  9  10  distributions  for  D b h C l a s s (cm)  frequency  regeneration  on  52  Table 2.5 M e n s u r a t i o n a l characteristics cutovers i n 1982.  CHARACTERISTIC  of  regeneration on  1  oldest  SITE A N D SPECIES  T6  Stems h a "  the three  Til  T8  ESt  SF  ES  SF  ES  SF  52 (0)t  1638 (391)  103 (0)  2006 (745)  52 (0)  2552 (1638)  Mean  height  (m)  0.46  1.21  0.61  1.43  0.74  1.98  Mean  Dbh§  (cm)  -  2.2  -  2.4  -  3.0  area§  -  0.2  -  0.4  -  1.5  M e a n basal (m ha" ' ) 2  t E S = E n g e l m a n n spruce; S F = subalpine Fir. ^ N u m b e r s i n brackets indicate stems w i t h D b h greater § S t e m s less t h a n 1.0 c m D b h omitted.  than  1.0  cm.  53 earlier were become sites  still evident on each  very  prominent.  within  submesic  an  to  These  edatopic  mesic  comm., J u l y ,  1983). It w a s  the  medium  poor  to  changes  grid.  hygrotope  mature  2.2 FIELD L A Y O U T  AND  also  However, positions  assumed  trophotope  characteristics of the  site; however, others  they  of the  it  ESSFml  fireweed had  difficult to  2.3  (D.  stand,  to  2.7  to  the  to  Lloyd,  they  also  place  correspond  variant  mature  Figures  and harvested  SAMPLING  more  a l l appeared  that, like the  positions.  stand  made  such as  pers.  fell  illustrate  the  within various  sites.  SCHEME  2.2.1 Field Layout  along  In  the  an  open  preliminary survey traverse  were  of  used  material,  foliage  samples  from  residuals)  nearest  the  centre,  each  plot.  fertilization sample under  In  the  was  numbers  plot  cases  also  of  done.  required  conditions of r a n d o m  to  the These yield  1982, for  ten and then  twelve  each  0.01  site.  dominant  subalpine  freshly-cut,  estimates  of  c i r c u l a r plots  Single samples  mensurational  preliminary  ha  data  five-,  data the  s a m p l i n g . A f o r m u l a from  fir  allowed means Husch  of forest trees  were  and  located  (excluding  collected  ten-year-old calculation  of  selected  floor  from sites,  of  the  variables  et al. (1972)  for  an  Figure  2.3 V i e w s of the mature stand E x t e r i o r , and (b) Interior.  in summer,  1983: (a)  55  F i g u r e 2.4 The cover.)  three-year-old  cutover i n s u m m e r ,  1 9 8 3 . (Note l u s h  herbaceous  56  Figure  2.5 V i e w of the six-year-old cutover in s u m m e r , m i n o r vegetation i n the photograph is fireweed.)  1 9 8 3 . (The bulk of the  57  Figure  2.6 Subalpine 1983.  fir  advance  growth on the  eight-year-old cutover,  summer  Figure  2.7  V i e w of the  eleven-year-old cutover  in summer,  1983.  59  infinite population was used (Quesnel and Lavkulich,  n  =  t (CV) /(AE%) 2  2  1980):  2  where:  n  =  required number of sampling units; t  =  value  from  the  with  n— 1  degrees  probability (p) CV  =  Student's  =  coefficient  t distribution  of  freedom  and  0.05;  of  variation  from  the  preliminary sample; and AE%  =  allowable  sampling error in  points (10% was  The  calculated  greatly  from  number  site  represented  a  allowed  by  the  planned  (and  T8, unit  and  70  was  cutover  to  site.  compromise constraints  collected) for the  enabled  the  units  The final between of  numbers the  resources.  Fertilization was  main activities  limited to used  were  later three  separation the  given the  Thus, 100  in this  30  the  sequence  and  the  numbers  sample  units  T6, 90  Chapter,  each  The  fertilized  differed  age  for the  excavations.  of  variable  final  requirement  T M and T3 sites,  of  a  applied to  calculated  available  a composite complete  used).  required for  T i l . As explained  the remaining portion was  The  sample  for the  comprised of  activities.  of  percentage  size area  northern one-third of  for  soil of  were the  sample  the T i l  from  other  area,  while  the  otherwise.  carried  out  during  July  and August,  1983. All  60 were  restricted  represent  its  to  that  overall  continuous  condition  portion  best.  of  These  comm.,  parallel  to  the  thermometer square  July,  1983). slope  After  centimetres  above  were  installed  gravimetric period. were  Sample from at  at  these  points  were  the above  (1972), Later  400 m  floor  other  at  of the forest  four  area  A  2  the  with  areas  trends  along  well  as  their  were  over  soil  randomly  thermistor  floor o n each  out  of  each  bulbs  five  tensiometers used  the  i n the  1983 s t u d y their  centres  temperature  selected  probes  (D. L l o y d ,  centre  s a m p l i n g activities; however, as  being  w a s laid  (during A u g u s t ) ,  400 m  as  to  maximum-minimum  at  placed  moisture  points  random  Similarly,  The  confirmed  square  2  i n the season  appeared  for the E S S F m l  shade  were  which  were  section.  i n open  these  centres.  sampling  located  centres.  the F / H interface  north  of forest  the  a  regimes  centrally-located  excluded from  locate  them,  facing  Ballard  determination  to  a  the ground.  T h e y were used  on  w a s installed  area.  also  Within  site  portions  generally submesic to mesic i n their moisture pers.  each  were  sensors.  lines  radiating  randomly  located  site.  2.2.2 Sampling Scheme Field Phase  The  m a i n intent  characteristics mineral linked  soil  of a n d inter-relationships below  to the latter  comparisons  of the s a m p l i n g scheme  among  them,  among  and a n individual  w a s to allow e x a m i n a t i o n of the forest  floor  of the subalpine  two. T h i s w a s to be achieved for each sites.  Thus,  samples,  for the advance  the  related  fir advance  growth  site,  regeneration,  a  thereby  enabling  single  subalpine  61 fir  representative  orient  forest  closest  to  fulfill  formed  floor  each  the  and  basic  mineral  sample  point  was  2.  Its  height  This  tree  collections.  For  a  tree  was The  to  be  in t u r n  used  "acceptable" selected  it  to tree  had  to  4.  at  the  five  was  near line  (as  determined  from  must  been  have  [ H e r r i n g ' s (1977)  standard];  It  present  time  must  have  been  at  the  of  logging  [determined s i m i l a r l y  to (2) above, and i n consideration  of  for  the  Its  trees  than  time of h a r v e s t  three metres or less  time six  taken  years,  form  had  metres) the was  and  to  and  be  often  to as  attain much  0.30 as  m—at  seventeen  least  four  distance  from  point,  selected.  condition  the  Trees  F o r each tree, total height  Dbh,  a n d diameter  stump  height  first  were  tags.  at  had  to  warrant  its  a crop tree.  at  off-line  sample  addition, a n n u a l  trees  1983)]; and  consideration as  Sample  0.30 m or greater;  whorls a n d i n t e r n o d a l lengths)  (Watts,  the  chosen.  Its current height h a d to be  least  going  sample  1.  3.  In  soil  unit.  the following criteria:  branch  the  sample  the  (nearest  growth  sample  with  0.1  m  (Dsn) — 0.30 (as  back  to  the  time  of harvest,  latter.  In  the  fall  of  given  and,  the  apart,  acceptable  tagged  height  1983,  metres  by  where  current  and  point.  tree  a  If no  encountered  orange up  within  (less  qualifying  tree  further  flagging  to the  short  and  along  aluminum  end of 1982 growth),  m—were recorded where possible. internodal lengths) possible, year's  five  foliage  was  years of  each  recorded  previous tree  to was  62 sampled for nutrient for  analysis. S t u m p height discs were taken i n September,  the e x a m i n a t i o n of diameter g r o w t h  The sample  forest  trees.  samples  floor  and  mineral  F o r these components,  taken  from  equidistant  crown radius. This approach w a s in  such  a  (Powers, trees  1980  with  removed one  of and  can  and  crown  thicknesses removed  fashion  radii  L,  F,  and  discarded.  u s i n g 225 c m  centimetre  encountered  and  A  less  2  a  at  were  The  sub-samples  square  templates.  greater  were  At  (F  the  one  the  metre  and  then  H  layers)  and  the  fall  of  at  the  F / H interface  separately selection resins  was  were  used for  the  1983,  for  the  cation  and  from  the  near  sample  monitoring of  30  trees  exchange  sample on  N H J-N,  the  T6,  NO3 -N,  levels over a n extended period, a n d were retrieved after in situ (see  Chapter Six).  and  its  taken  used  points, L-layer  were  for the was  carefully  of a p p r o x i m a t e l y these  were  sub-sample  was  sub-sample;  case.  on  T8,  sub-  twice  was  organic  resin  trees  the  considerably  samples;  soil u n d e r l y i n g the  anion  of  the  diameters  the m i n e r a l soil was sampled to a depth of 15 c m . i n each  In  tree  corresponding m i n e r a l soil  undefined q u a n t i t y of the  of  of three  sub-sampling  Roots w i t h  excluded  up  requirements  of  recorded,  vicinity  of composite samples  intensity  m.  the  made  from  use  distance  in  was  distance  since the  0.5  relatively infrequently. The  comprised of an  a  minimum  layers  sampled  sample  sampling  than  H  were  given  taken  reduce  1984a).  patterns.  soil  points  1984  bags each  and  were site.  T i l  phosphate-P  placed Random  sites.  The  (H PO^)  a p p r o x i m a t e l y 12  2  months  63 From sites each  the above,  sample  point h a d a "sample  comprised  of a tagged,  composite  F / H forest  addition,  selected  interface.  i t should be apparent  measured floor  tree  sample,  that  i n the final  plot" associated  the foliage of which and  a  composite  "plots" h a d anion a n d cation exchange  The numbers  with  age sequence of  it. E a c h  "plot" w a s  was later  sampled, a  mineral  soil  sample.  In  resins buried at the F / H  of such "plots" per site were therefore  the same  as  those  samples  (320  of the sample points given earlier. Preparatory Laboratory Phase  The  main  composites  each  processing.  Both  available the  field  of forest the  resources  procedures  sampling floor  followed  a  yielded  and mineral  number  dictated  process  of  chemical  second  to derive  stage  a  soil,  total  of  and 320  analyses  960 foliage  samples)  for  and  constraints  of  planned  of compositing. A brief  the final  samples  description of  for a n a l y t i c a l w o r k  is given  below.  Forest which this  floor  samples  varied between step  took  several  were  20°C  air-dried i n a n environment  a n d 25°C.  months.  Because of the limited  The air-dry  used to calculate oven-dry weights of materials. A i r - d r y bulk  were  used  to  greater  than  0.25  of adherence M g m"  3  periods  samples—those  of between  which  24  seemed  of m i n e r a l particles. Samples w h i c h [near  A r m s o n ' s (1977) upper  limit]  of  available,  then  were  suspect  for  recorded,  These  because  105 °C  were  were  eliminate  at  weights  facilities  sub-samples  possibly  oven-dried  the t e m p e r a t u r e  and  small 36  hr.  densities  overly  dense,  yielded  values  were  discarded;  64 in  total,  17 samples  virtually random to  intact  were  square  samples failing  moisture  were to  original  form  was for  soil  soil  stage;  on  and  floor  floor,  Six), the  samples.  hours,  then  Original  samples  sites.  The  a  T3  samples  for  each  (F/H)  basis  from  samples  floor  the  2.0  samples of  simply then  created  this  time  i n equal  of  used i n the foliage  carefully floor  processing of the from  air-dried  the  using  after  first  the  floor  T M and for  the  yielded (F/H), T3  a  in  were  Carter  and  Lowe  from the  the T M , T i l sites.  shorter  at  process.  described  one as  70°C  exception for the for  24  as (see  forest to  36  again  analyses.  system  r e m a i n i n g sites.  above.  selections  twigs. Composites were  formed  their  sites  random  same  m i n e r a l soil,  sites  as  With  selections for subsequent  thus  material  other  but  same  oven-dried  used  samples.  analyses were the  were  a  original  sieve;  23 from  sieved  proportions.  were  retained  the  one  from  remaining  samples—29  the  least  taken  mm  related  then  stripped from  forest  while composites were created  a  at  These  were  T 8 , and  underwent  were  but  needles  each  sites.  through  had  were  T6  T M and  T 6 , 27  foliage  created according to forest  samples—135  two  total of 135 forest  the  numbers  Preparatory  these  passed  samples  sub-samples  T M and  depth-weighted  were  Samples  the  Ten  the  for  of the  were performed on these second-stage  samples  forest  Chapter  a  now a  Second-stage^ composites the  curves  second  the  analyses  from  The  the T 3 , 31 from  Mineral  for  squares  discarded.  composited  further  Mineral  F / H material.  m a n u a l l y , then  (1982a,b). There w a s 25 from  eliminated. M o s t  retention  crushed  pass  randomly  All  of  selection of such  develop  so  of  405  and  foliage  their  own  second-stage categories.  second  A key feature  was  stages, that  a  65 given second-stage Subsequent  sample in each category had its counterparts in the other two.  analyses  were  on the originals collected.  performed on these  second-stage  samples,  rather than  CHAPTER 3 SEASONAL  Climatic matter any  factors  decomposition  study  such  as  TEMPERATURE  exert and  a  the  this,  AND  tremendous growth  some  MOISTURE  TRENDS  influence on processes  of organisms  in  examination of trends  such as  ecosystems.  organic  Therefore,  of k e y climatic  variables is  highly desirable. T h e r e being no climate station i n close p r o x i m i t y to the area, site  such i n the  although  0  6  age  to  was  sequence.  somewhat  convenient H  information  out  gathered  These of  include here  data  their  in  a  are  rudimentary  presented  logical  considerations  rather  places  in  pertaining  i n this the to  main  research  fashion  chapter.  testing  for  sequence,  hypotheses  it  H  was and  0  5  3.1 REVIEW  OF ISSUES AND  Temperature the  prime  thus N  availability  Several  studies  and  controls  have  et  these.  S u c h influences m a y  i n the  ESSF  (1981),  affect  contributing  the  directly  together  decomposition  demonstrated  Cleve  forests.  of  levels,  and  with other  ( M . A l e x a n d e r , 1977; M e e n t e m e y e r ,  conditions; K r a u s e al.  CONCEPTS  moisture  forest  usually  each  In addition,  .  among  in  et  and  al.  (1978),  Weber be  these  effects  under  Soderstrom  and  Van  assumed  Cleve  substrate  quality,  are  microbial  processes,  and  1978; Swift  et al.,  various  (1979),  northern  Edmonds  (1981;1984)  are  to operate generally i n a  and/or  and  moisture  indirectly to  an  66  regimes  assart  effect.  of  given Within  coniferous  (1980), V a n examples  similar  H o w e v e r , as earlier noted, h a r v e s t i n g a n d other temperature  1979).  fashion  disturbances  sites, the  of  thereby  context  of  67 this  study,  questions  consequences While  of  any  therefore such  changes  m i c r o c l i m a t i c changes  Weetman, might  1969;  occur  important  Ballard  with  to  the  the  arise  et  have ai,  as  to  the  derived from been  noted  1977;  Black,  "incomplete"  cuts  investigation of a  harvesting  i n complete 1982),  of  possible  nature,  the  magnitudes,  of the  the  research  assart  pattern  chosen  clearcuts degree  which  was  and  sites.  (Timmer  to  area  and  and these  considered  post-harvest  tree  response.  3.1.1  Temperature  For in  relation  processes climate  study, their  well  normals 2.2]  within  the  the  to as  Table  exhibit  this  as  (direct  nutrient  [Atmospheric  indicate  that  the  annual  soil  5 ° C between  over  555 and  1110  (Weber and  advance  regeneration,  growing  degree-days  h a r v e s t i n g m i g h t have had  a  major  trees.  The  (A.E.S.), the  of between  major factor V a n Cleve, found  (base  air  modified  of  5°C the  120  (Lavkulich  M o n c h a k (1982) of  of  Service  temperature  on the  sites  is  on decomposition/mineralization  growth  5 ° C ) is between  the  layers  and  (MAST)  can be the  floor  indirect)  effects  Boss  Mountain  1982a,b;  sites  should  also  fall  2°C  and  and  180  less  days,  see  clearly  of the Cold C r y o b o r e a l class. Soils of the  cold sites, temperature forest  i n temperature  Environment  temperatures (days  and  uptake  middle to lower range  mean  over  p r i m a r y interest  influences  'growing season  days  the  latter  than and  8°C; degree-  and V a l e n t i n e , 1978). F o r such  controlling the  movement  of N i n  1984). M o r e o v e r , for subalpine fir  that  growth  temperature).  temperature  i m p a c t on microbial activity and N  regimes  was  limited  The  extent  to  of the  sites  should  have  forest  floor  availability  from  the  below  450 which  68 as  well  as  on g r o w t h .  post-harvest among  period  the  data  individual-site compared  basis.  of  in  the  the  of u p l a n d  the  20°C  the  roots  uncut  dense"  5°C  at  the  were  the  to  stand;  in  different and  cm  level  in the overall  17° C  directly  (and  mean  near  the  summer effect  of  the  fir [Abies  and  approximately.  soil  contrast,  Soil  an  whole  temperature  cover  and/or  that  by  in  of J u l y .  values intensity  thinning  prolong  (1977)  growing  winter)  -2.5  4 ° C . In  cm)  values closely  was  layers  of  those  season  for  temperature  an in  it  than  growing  stand  season  temperatures  organic  of  mean  the H / m i n e r a l  considered  Spacing  (at  to  clearcut  The  the  (L.) M i l l . ]  at  and  -5 c m level  3°C  the  cooler i n the  temperatures  control  air)  increased  Maritimes.  balsamea  a  (Mill.) B . S. P.] increased  end  to  on  i n addition, s t r i k i n g  observed  were  (but  was  as  organic l a y e r s . A t the  by  density,  comparable  w e e k l y temperature  stand;  the  differences  stem  cutovers  of vegetative  1969). Salonius et al.  forests  spaced  inevitable  post-harvest  the  (1969)  temperatures  g r o w i n g season Both  soil  all depths i n the  -5  balsam  of  conditions in  informative.  [Picea mariana  uncut  Weetman,  be  what  Weetman  an  the  be  between  conditions  for  spruce-fir  raise  average. and  indicated  at  initial  not  might nevertheless  summer  warmer  22-year-old  appeared on  11°C  ( T i m m e r and  relationships  might  m a x i m u m g r o w i n g season  was  clearcut  mean  as  differences  black spruce  soil temperatures  interface already  under  such  Because  should be indicative of change;  have  Timmer  clearcut,  August,  of  studies  expected  clearfelling summer  stand  of these enhanced  influential.  therefrom  However,  mature  disturbance.  be  duration  characteristics  a m o n g cutovers  Several be  in  the  also  obtained  to the  differences  might  should  cutovers  temperature  Similarly,  "extremely Cape  by  Breton  about  varied  2°C  between  paralleled  air  69 temperatures of  for both the  significant linear  et at,  i n B . C . have  that  quantitative  sites  affect  findings  trends  suggest  overall  even  to  the  between  which  For  the  that  observed  under  the  two  development  variables  after  shrub  with  be  bare  major  next  (Salonius  temperature  bare  ground)  also  and  least  which  disturbance.  from  Prince  George,  much  as  untreated  the  under  The  have  higher  sites.  These  sites  sites  of  this  order  a  pattern  this  of  study.  manually were  of  at  a  these modify  soil  growing  finally  season  equally  terms  were  vegetative  secondary  the  10°C  -5  cm  shrub pattern  succession  values  and might  forests level  vegetation and  of  greatest  evergreen  spruce-fir  by  tree clumps. in  they the  climate  be indicative of what  removed  between  the  temperature  In  cm  climates—perhaps  followed  whole, the  expected  1982),  (expressed  with  -50  greatly  of  pattern;  clumps,  temperatures  with  temperatures  can  highest,  (1972) might therefore  harvested  on  been  related  B . C . , g r o w i n g season  5°C  tree  Since the  term)  variations  followed  on high-elevation  subalpine  short  the  1972). T a k e n as  might  differences  single tree cover, and  diurnal  demonstrated  soil climate (Black,  the  exhibited  was  level.  decreasing  sites,  v a r i a t i o n s observed b y B a l l a r d expected  in  (1972)  cover  cm  relatively harsh  (if only  ground  -60  vegetative  applicable. I n  types;  cover  that  the  general  and  changing  these two (Ballard,  was  a  of  levels,  herbaceous  sites  disturbances  results. B a l l a r d in vegetative  at  indicative of the  might  vegetated  site between  values  on g r o w t h of the  extent  and  produced s i m i l a r  temperature  that  temperature  herbaceous  be  relationships  qualitative differences  are  effects  classification  of  and  seasonal  temperature  soil  regression  and control conditions, enabling the  1977).  Studies  the  spaced  15°C  near  were  as  than  on  on  the  70 untreated repeated both  site, and between at  the  conditions  1977).  growth Changes uptake have  been  to  7 ° C , with  have  lower  Kramer, occur  even  ranges  Rumney  approximately taken of  as  in  optimum  at  on  the  not  the  from  are  (1968)  frozen. that  (which  coniferous trees) m a y  temperature  range  coast  also  Low  so  similar  changes in  lead  activity  to  soils.  and  under  B y contrast,  growth  apparently  from  ones  (1969),  temperatures  above  growth  shoot  ceases  takes  that  7.2°C  noted  once  tend  growth  place was  to  1979;  constrain  seldom  snow  freezing  (Pritchett,  would  tree  according  cooler environments  Weetman  (1969)  context.  decomposition  Root  warmer  tree  enhanced  and  1979)  on  this  is  can such below  usually  initiation of root a c t i v i t y . The activity vital  to  also be constrained  between  McMinn,  yielded  growth  ectomycorrhizal species as  have  was  1 5 ° C ) for  and  root  vegetative  are  (Dobbs  important  forest  air  for the  ( 7 ° C to  regime  necessarily  from  and  Weetman  threshold temperature  47  those  Timmer  6 ° C . T i m m e r and  fungi  for  25°C.  than  stated  B.C.  1982). Species from  optima to  season  (Soderstrom,  coniferous  1 0 ° C to  the  microbial  temperatures  m i n i m u m range  roots  of  marked  in northern  temperatures  temperature  activity might  example,  According  vitro study  and  clipped site. The pattern  1982).  is  sub-zero  and  ectomycorrhizal  northern An  the  over  processes  (Vogt and G r i e r ,  when  lower  differences  temperature  For  optima  1983).  growth;  of  1980)  (1979),  soil freezes  with  elevations  microbial  observed  Pritchett  2 1 ° C on the  to the foregoing (Black,  growth.  (Edmonds,  but  physiological  enhancing  to  the  lower  other  and  cover  at  influence  and  level,  narrower  and results  The  cm  and  Studies  patterns  -20  1 2 ° C and  1 5 ° C and  the  efficient  functioning  by r e l a t i v e l y low by  Dennis  30°C;  (1985)  none  grew  of  temperatures. placed  their  below 5 ° C .  71 However, and  for Pacific  Grier  (1982)  1 ° C under  critical and  is also  1981).  resistances  to  temperature, spruce  Critical  spruce  Dobbs  and M c M i n n  species  water  water  natural  increased  flow  (1977)  m a y be 2 0 ° C .  b y a n d flow  of 1 ° C to 3 ° C have  environment,  7.5°C  resistance  w a s noted  suggested  that  Increased  should  McMinn  be  at  While  increase were  least  flow  significantly  greater  a general  planted  than  that  been  w a s the (Whitehead  the o p t i m u m  resistance  10° C.  observed  soil  i n Pacific below 5 ° C  i n subalpine  below  those  (1983)  that  fir, root  At  a  given  in Engelmann  to  the subalpine  fir" advance  benefit  from  temperature  for shoot  g r o w t h of  temperature  showed  that  high-elevation  low threshold temperatures—less  for b u d burst.  temperatures  spruce  able  threshold  From  their  (1977) concluded that treatments  g r o w i n g season  has shown  potentially  applied, W o r r a l l  fir c a n have  sums  study  notwithstanding, it w a s expected  is frequently  heat  uptake  increases  enhancements.  subalpine  A recent  within  1985).  above  regeneration regime  Vogt  root biomass even at  uptake  temperatures  i n its  which  1982).  these  (Sowell,  The  for  Forbes],  fir—also a n upper-elevation species—occurred a t soil temperatures et al,  low  o f reduced  below  for this  (Hinckley  of  the question  temperatures.  temperature  temperature silver  ex Loud.)  high levels of active m y c o r r h i z a l  F o r Engelmann  Jarvis,  5°C  observed  at l o w soil  observed.  fir [Abies amabilis (Dougl.  a snowpack.  There plants  silver  seedlings.  to within This  than  o w n a n d other  which  provenances  3°C—as  studies,  w e l l as  Dobbs a n d  could  increase  mean  the 10 - 2 0 ° C  bracket  would be beneficial  generalization  could  probably  be  rooting zone  applied  to  72 subalpine  fir advance  The  foregoing  increased  discussion  temperatures  completeness growth.  that  Ballard  detrimental surfaces  mechanisms  has  centered  effects  can  Ballard  et  temperatures  responsible  for  especially  al.  be  and  of  it  beneficial effects  should  Black  encountered  particular,  terms  possible  be  noted  occur—especially i n regard  (1977),  Earlier,  the  However,  also  can  this.  in  on  harvesting.  certain conditions. I n  issues,  microbial  adverse  surface  also.  through  (1972),  under  similar  regeneration  Ballard  Timmer  adverse  and  effects  (1982)  on  of  that  clearcut  explored  (1969)  high  seedling  or  (1977)  Weetman  for  all noted  exposed  et al.  to  of  the  discussed  temperatures  on  populations.  3.1.2 Moisture  As on  the  with sites  mineralization sites  was  in  the  primary  relation  processes,  nutrient  to  interest  their  uptake,  should not  supported higher  by  the  moisture Golding,  be  retention 1981).  i n spruce-fir  the  important  regeneration.  limiting  consideration  conditions most  a  and  that  capabilities  However, zones  water  for  forest than  Monchak  of the  l i m i t i n g factor  O n cutovers,  factor  in  possible tree  w i t h i n a region of higher precipitation would  moisture  and  temperature,  tree floors those  (1982)  moisture effects  growth.  on The  point towards growth of of  ESSF other  stress  was  decomposition/  cover  the  1982b). T h i s is  that  have  types  much  (Hillman  under  availability  g r o w t h of subalpine  u s u a l l y associated  of  a conclusion that  forests  observed  influences  location  (Lloyd,  K a m l o o p s Region, water  to post-harvest  regime  fir  w i t h one  certain could  be  advance or  more  73 of  (a)  growing  shallow were  season  rooting not  precipitation below  depths,  lowered  and  to be one  (Monchak, normals plausible  temporarily.  1982a)  Thus,  even  vegetation  removal), the  the  cannot  trees  be  with  encountered  (Kimmins  and  earlier has  (Potts,  been  enhanced and  drying  1985).  observed  Mahendrappa  and  the  routinely the  the  sites  Salonius (1982)  nitrification through  the  receive  stress  precipitation  250  demand  for  There  further  fine  also  roots Vogt  the  the and  that  reduction  of  stresses  on  and  d r y periods  competition  be  1982)—might  temperatures  (Whitney  speculated  (by  consideration  Grier,  m o r t a l i t y of such roots,  deficiencies  water  mycorrhizae might  and  elevated  m m , it is  conditions—if only  moisture  is  was  regeneration  Creek  than  season  stress  advance  more  (c)  stresses  growing  of g r o w i n g season  to  promote  until  Hemp  soils,  Water  Moreover, high w a t e r  moisture  1978;  addition  N  growth  post-harvest  majority of the  cause  aspects.  shortages i n the  decreased  Hawkes,  coarse-textured  southern  mm.  induce  assumed.  in  (b)  M o u n t a i n and  absence  This m i g h t to  Boss  could  complete  floors—where  350  that  effects  t h a t forest  extreme  the  mm,  good  causes of N  indicate  harvesting  permit  than  1982). Though both  that  experience  to  greater  of two major  (A.E.S.,  low-elevation  sufficiently  precipitation levels were found  (d)  250  discussed  which  in  Timmer,  turn 1983).  m i g h t contribute  for  to  NHJ-N  by  roots  limited  microbial  heterotrophs.  What activity  and  soil  growth?  a c t i v i t y i n forest minimum hyphal  and  water  content  According  values to  Bollen  soils is a p p r o x i m a t e l y  maximum  at  a c t i v i t y appears more  five  are  and  associated (1974),  the  with  optimum  for  microbial  50% of soil water-holding capacity, w i t h eighty  per  cent,  respectively.  strongly influenced by moisture  For  fluctuations  a  fungi,  than  by  74 temperature,  and  (Soderstrom,  1979).  significant;  moisture  water  matric  Alexander  some  -10 -10  MPa.  from  sources  and  do  in  with  Rosswall,  such  as  not  have  bacterial  more  et al. (1979)  exhibit almost  go  as  major  effects  populations  rainfall  1980).  Griffin  events  In  (1972),  can  be  than  terms  of  Russell  aided development of the  over  rates  at  to be  as  wide  MPa  to  capacity—usually (Griffin,  only  -0.5  within  1972; R u s s e l l ,  matric  potential  at  species  involved,  the  ammonification  can  occur  with  the  soil  (1973),  M.  generalizations  above proceed  to  within  the  fungal  growth,  -0.05  50%  permanent  a  to  wilting  generalizations under  between range  conditions  -0.1  down  M P a and  -0.01  -5.0 M P a ,  65%  for this process  narrow  of  is  50%  range,  generally  et al.,  unfavourable  to  slower  7 5 % of  from  almost  near  holding  field  capacity  1979). W h i l e  k n o w n to  clearly that  been  appears  and  fall  moisture  1977; Swift occurs  has  increasingly  between  optima  -5 M P a  range,  M P a to  at  values,  of -15 M P a ;  is between  zero  though  very  indicate  of  M P a . Ammonification  M P a - generally has  potential  range  o p t i m u m range  approximately;  range  a  range  slightly narrower  occurs  1973; M . A l e x a n d e r ,  which  a  -0.01  Nitrification  the  over  range  M P a . The  MPa  surprising  down  M P a and  as  M P a and  capacity.  can  -0.05  range  a  M P a . Their optimum  observed  below -1.5  -0.09  holding  a  over  conditions  optimum  been  between  potentials  between  moisture  -50  the  Decomposition has optimum  growth  water-logged  low as  M P a ; however,  an  vegetative  M P a . Bacterial growth  noted  zero  associated  (Clarholm  potential,  often  fluctuations  been  contents  can  genera  with  contents  follow.  principally  to  have  (1977), and S w i f t  Fungi  and  water  Short-term  increases  actual  which  high  vary  the  with  the  decomposition  and  growth  and  uptake  75 b y higher  plants.  The lower l i m i t of soil a n d limiting  is  of p r i m a r y  implied  that  plant  available water  importance  growth  optima  storage capacity  tension more  range with  which  important  permanent accepted 1969; For  of  20% the  as imposing at  forestry  moderate  the  (Black, period  below 40% of A . W . S . C .  stress  The  water  are  key  conifers water  1982;  during  southern  pines.  with  is  Brady  water  contents.  species,  and level  and the  may  the  be  the  soil-  that  the  potential)  -1.5  MPa  is the  level  is  ( B u c k m a n and  Brady,  1982; N o b e l ,  1983).  considered 1982).  volumetric  that  M o r e o v e r , while  Spittlehouse,  Spittlehouse, soil  matric  5 0 % of  found  accepted  (i.e.  (1969)  15% and  generally soil  becomes  water  as  Black  imposing  (1982)  content  also  remained  to be indicative.  within  here.  drying.  G e n e r a l l y , as  potential will converge  and  between  stress on most plants  Black  with  the  According  there is a non-linear—often potentials  Buckman  the  among  MPa  which  It  in  actual  differs  -0.2  which growth  H a s e and T i m m e r (1982)  retained  than  at  Ontario clay belt occurred w i t h i n  1979; B l a c k  the  potentials factors  context.  volume.  severe  1973; Pritchett,  stress  considered  least  contents  generally found  by  is  (P.W.P.)  applications,  are  30%  growth  point  this  i n the  water  to plant  wilting  Russell,  to  in  water  (A.W.S.C.).t  o p t i m u m growth of black spruce moisture  plant  and  their  reactions  to  Whitehead  and  Jarvis  (1981),  for  soil  (1981) dries  those of the  t A . W . S . C . is considered to be permanent wilting point (Pritchett,  the  involved  exponential—relationship between  Chaney the  plants  out  illustrated without  leaves/needles.  moisture held 1979; B a l l a r d ,  this  with  field  and  soil  data  from  its  water  replenishment,  Further  between 1981).  leaf  d r y i n g of the  soil  capacity  the  and  76 induces MPa  permanent  (Russell,  several  tree  P.W.P.,  it  within  this  species  (Ballard,  appears  what  considered  that  plant  under  course be influential species  including  transpiration subalpine  1981).  leaf  and  with  water here.  Puritch  the  gradual  The  decline  patterns were  slightly  matric MPa.  fir  steeper  be  than  that  declines  in  initial  started  the  photosynthesis.  at  its rate of  (Dougl.  A l l species  ex D .  potential  at  the  same  time,  continued  data at  -0.1 M P a , a n d definitely  under  severe  stress  soil  et al. (1982) support this view. These true  firs  tend  to  be  poorer  at but  their severe  suggest  stress  at  MPa; a  w a s attained  water  North-West,  of  rate  -0.7  moderate  Pacific  under  and  species,  well-watered  earlier  commenced  four  but  water  considerations, P u r i t c h ' s (1973)  T h e observations of H i n c k l e y  concluded  O f the  needle/twig  true fir  respiration,  i n photosynthesis,  a  w o u l d of  10% a n d 30% of their initial rates even under  considered  o f about  representatives  for four  of photosynthesis,  50% of the  path  of the earlier  might  potentials  changes  level of a p p r o x i m a t e l y 60% of the initial rate  moisture losses at between  subalpine  declines  -2.0 M P a . T r a n s p i r a t i o n losses  I n light  resistance  reached  M P a . Respiration  stresses.  flow  at  -2.9  a  fir  started  approximately  followed  subalpine  similar.  remain  1983).  might  all very  to the  usually  a l l except g r a n d fir [Abies grandis  M P a , and  approximately  values  down  1981; K r a m e r , 1983; N o b e l ,  values  show  than  process  (1973) examined such aspects  -0.9  minimum  water  A n y water  stress to  -1.2 M P a to -1.5  1983), but can be below -2.0 M P a i n  potential  fir. T h e  first  range  soil  (Chaney,  stress?  i n the  the d r y i n g  approximately  constant  occurs  Throughout  potential  increasing  fir w a s  Lindl.].  water  subalpine  decline w a s more Don)  usually  1 9 7 3 ; K r a m e r , 1 9 8 3 ; Nobel,  -0.5 M P a o f each other  At be  wilting;  that water  b y -1.5 authors drought  77 resisters  than  medium  their  tree  capability for  (Hinckley  et  strategy,  al,  drought  1982).  moisture  Relatively  harvested  sites.  undisturbed and with the a  forest  depth  and  matric potentials  vicinity  of  (Plamondon,  1972).  characteristics demonstrated  MPa)  can by  i n western  and  have  layers,  moisture  the  (1972)  having  species'  losses  the  moisture  higher  elevations  a  tolerance  drought  investigated  water  of -0.1  29%  than  concerning  avoidance  add  to  the  in  the  any  upper  Potts  a  for  a  foregoing  -1.5  layers.  little  and  lower  concluded t h a t on  harvested  presentation,  the  and  considered separately,  site  extreme  H  within  water  seven,  it contained  floor  a  drained  was  horizons  in  the  respectively  water  This  retention  was  subalpine  potential  clearly  fir  forest  (e.g.  -100  temperature  and  values  i n thickness.  influences  tree g r o w t h were it should be  an  lower portion of  A.W.S.C.  growth.  centimetres  major  The  forest  plant  one,  additional w a t e r  M P a . The  of  on  characteristics v a r i e d  s e e m i n g l y because  very  F  five  and/or  characteristics  retention  other,  significant effect  (1985)  the  retention  L , F , and H l a y e r s were  M P a and  P l a m o n d o n (1972) have  at  of decomposition of the  M o n t a n a . H e observed  were  as  growth  reported  on decomposition processes  factors  ranked  resultant  especially  in organic layers w h i c h averaged  In  two  and  was  r e l a t i v e l y low drought  respectively. The w a t e r  more  between  type  a  proportion of micropores. G e n e r a l l y ,  12%  fir  B . C . , the  i n coastal B . C . ; the  degree  H layer retained higher  floor  thick  the  and  southeastern  sensitivity,  Plamondon  nine centimetres  avoidance  studies  forest floor  Subalpine  regarded.  few  of  In  stress  disdain w i t h w h i c h it is  characteristics  associates.  noted  of  discussed. W h i l e that  their  effects  these are  78 more  often  interactive. T h e  discussed earlier was unique (by  peaks  weight)  bulk  moisture  density  highly  of  0.13  3.1.3  m"  15 is  3  cm  by  such  assumed,  interactions  study the  depth  within  the  (Swift  and  the  moisture  has  noted  -  150%  floor.  range  temperature  availability constraints  100  forest  (If  would  been  et al, 1979).  interaction between  temperatures  V a n Cleve (1985)  activity of fungi  m a i n objective of this portion of the  to  section.  questions  actually  occur  g r o w i n g season  characteristics)? regimes  sustained sites? it  contents  in  general on  the  the  N  sites?  The  sites?  a be  s h o w n to  Haskin  (1985)  and soil  moisture  on trees.  was  decided  and  retention to  the  tree  growth?  stresses  on  the  allowed only  season  as should  well  to attempt to provide  discussed  temperature  induced  provide  previous  moisture  marked  temperature likely  there  advance  as  the  any  floor air  to  some  moisture result  marked on  approach  temperatures,  temperatures valuable  in  retention  and  regeneration  rudimentary  content  changes  (including moisture  Were  a  in  and  differences  e x a m i n a t i o n of forest  characteristics,  growing  issues  harvesting  observable  available an  Had  was  i f a n y , existed i n the  and  water  that  the  study  and moisture regimes  Were  availability  resources  from  g r o w i n g season  temperature  g r o w i n g season  period  arose  W h a t differences,  among  differences  Thus,  which  Namely, what  values  peak  decreasing  Objectives and Hypotheses  answers  the  the  imposed additional N  The  the  with  10 - 1 5 ° C temperature  20% b y volume.) The  influenced  have  at  Mg  13% to  resistance  example of this. Schlentner and  ranges  concluded t h a t i n her may  flow  i n soil respiration i n the  approximately be  an  increased  in  and/or any to  of  this.  moisture  during insights.  the The  79 Boss  Mountain  were  n o r m a l l y the  the  annual  July  and  to  (A.E.S.,  only months  August  were  M a y was exclude  was therefore  The  data  growing-degree-day  precipitation; believed  climatic  hypotheses  and H g (see  Chapter  0  H  :  0  total  under  was  season  temperature  There  moisture  H  moisture  H  0  :  was  was  retention  There  t  peak  here  was  retention  There  no  was  as  in  some  major  major  change  H , ^:  was  some  g r o w i n g season  the  season  growing  harvesting.  after  change after  in  the  in  forest  floor  harvesting.  in  forest  i n the  harvesting.  the  lowest  value  was  sites.  hypotheses  floor  harvesting.  growing  season  growing  season  harvesting.  change  regime after  in  Moreover,  - A u g u s t period on the  of m a i n  growing  change  change  characteristics  no  with  The J u l y  August  1 0 ° C ; 60% of  months.  follows:  characteristics  a  two  months  subsidiaries  regime after  no  than  and  low g r o w i n g degree-day  of the  are  indeed  regime after  soil moisture  season  July  harvesting.  soil moisture  There  its  change  regime after  There  ^:  growing  One). T h e y are  There  that  greater  actual g r o w i n g season.  test  H, y  0  the  to cover the  temperature  H  air temperatures  actually lower, but the  indicated  occurred d u r i n g these  normally  it from  assumed  with  1982a,b)  H  0  o  80 H  0  : There  stresses  were  on  no  sustained  subalpine  fir  g r o w i n g season  advance  water  regeneration  after  harvesting.  H , ^:  There  stresses  were  on  sustained  subalpine  fir  growing  advance  season  water  regeneration  after  harvesting.  If  H  is true,  0  temperatures growing as  should be no differences  cutovers  compared  Coincidence or  mature  in  moisture  stand  and  generated  the  general  statistical  retention  the  at  cutover  each  ^  0  curves sites.  criteria.  might  have  of the  is  correct,  air  mature  there  constructed Statistical point  forest  stand  intervals  was no  the  forest  tests  for  differences  was  curves  accepted  relevance.  floor  during  for  it  practical  and  should be  along the  However,  no  mean  of 9 5 % confidence  common pressure  falsification  significance  If H  i n the  to those  otherwise  c r i t e r i o n of falsification.  differences  as  of the  season.  the  values  there  the  taken marked  floors  of  in  the  mean  were  accepted  that  a  Hypothesis  H  weak was  0  O  considered  in  falsification. period or  be  of the  formal  M P a . This  hypotheses  below  insights. floor  For  the  hypothesis  was  d u r i n g which therefore  concerning direct i n this  optimum  example,  temperatures  to  below  H  ^,  0  w a s likely to be true  0  g r o w i n g season  satisfactorily tested  falling  fashion  Hypothesis H  below -1.5  No  similar  study.  ranges  mean  air  soil  water  accepted  as  temperature  Nevertheless,  temperatures  a  similar  only i f there  indicated earlier  1 0 ° C (and  with  of  matric  the  was  no profound  potentials  criterion of  l i m i t a t i o n s on it w a s would less  criterion of  felt  that  provide  than  5°C  especially below 7 ° C ) could  be  were  at  falsification.  growth  could  temperatures some  valuable  and/or  forest  construed  as  81 probably i m p o s i n g some  The season  resources  only.  to w h i c h  The  limitations (direct or indirect).  available  results  limited  therefore  principal  have  to  data  be  collection  interpreted  that period could be considered c l i m a t i c a l l y  to  one  growing  i n light of the  " n o r m a l " for the  degree  sites.  3.2 METHODS  The taken  primarily  of forest that  basic  floor  site  layout  d u r i n g the  was  presented  in Chapter  J u l y - A u g u s t period  temperatures  of  Two. Measurements  1983.  for comparative purposes  Additional  were  measurements  were done i n mid-October of  year.  3.2.1 Temperature  Soil Jackson  temperature  (1965) and  measured  using  thermistor  probes  on  site.  each  approximately  Black an  four  to  seven  approximately G.  all  22).  5K  44000-C  to  Most  two  potted  metres  of the  the  The  highly  was  of the  installation was  and were  C-7  two-conductor,  epoxy.  forest  floor  depths as  of a  floors.  The  Each  was  shielded,  l e a v i n g only  Four  chosen  variable forest  Armstrong  buried,  Taylor  thermometer.  F / H interface  the  in  actual  by  temperatures  F / H interface  of B e l d e n  cable  discussed  thermistor  average  centimetres.  beads  are  (1982). F o r e s t floor  biological conditions w i t h i n  mounted  (A. W .  Model  corresponded  were  wire  and Spittlehouse  Atkins  thermistors on  methods  were r a n d o m l y installed at This  level of s t a n d a r d  measurement  stranded  approximately  82 0.30  m  exposed  for  taking  checked  for  with  precision of 0 . 2 5 ° C .  a  were  obtained  centrally  to  the  located  nearest  0.5°C,  temperature for  linearity and  the  and  at  the  taken  0.1°C.  same  as  a  Air  the  average  interval.  found  the  probes  necessary.  temperatures  forest  were  These  forest  of the  Both  the  F i s h e r mercury-in-glass  thermometers.  time as  i r r e g u l a r intervals; with  three days on the  installation,  N o calibration w a s  maximum-minimum  was  at  Before  accuracy against  nearest  measurement  measured  readings.  floor  taken  air  a few exceptions, the  readings from  the  to  the  read  temperatures.  and  all  thermometer  Probe  were  m a x i m u m and floor  were  The  minimum  mean  readings  temperatures  intervals were  were two  to  average.  3.2.2 Moisture  Samples central  area  contents 174 c m were  3  of each  were  taken  used.  The  first  A t each  distance  at  least  field  approximately  line  a  but  was  such  felt  weekly. that  taken  1965).  area.  at  pressing  were  the  one  it  site  of  previous  sites,  F / H interface  s y s t e m a t i c a l l y at  corner  was  the  (L. A . Richards,  direction. hand  from  for  Moisture  the  forest  cans  with 12  of one  Since J u l y , moisture  metre.  was could  samples  an be  were  of  1.5  325  (each  m  from  the  at  cm  relaxed  oven-dried  24 hours commencing i n the e v e n i n g of the  and  the  can)  down-slope upper  irregular  in  collection  to  of  105°C day.  leftthe  intervals,  period on  favour at  2  3  parallel  e x t r e m e l y wet  m  moisture  filling  positioned was  400  of  intervals i n the  was  Sampling  1983  sampling  The  line  the  determination  samples  approximately  subsequent  within  volumes  approximately one-metre started  floor  gravimetric  s a m p l i n g event,  Each  requirements.  of  the more for  83 Tensiometer 1982) and  were  measurements  also taken  on the  that  level  as  was  guage  graduated  in  centibars  the  T M site,  lower 400  on m  and  the  August.  frequency  events delayed  Installation  network  greatly  others  detracted  subsequently  M P a , and  sampling  and  temperature  those  of  the  T6  of the which  the  gravimetric  were lightly recharged  retention a  pressure  site  was  evaluated  the  to  curves  most  were  plate  chosen  for  extreme  differences  yielded  sites,  intact  unfeasible  exposure  site.  T6  A.  s a m p l i n g as  central  T M and  constructed  was  Its  within  the  the  entire  network's  second week of  stand  within  24 hours of  with  a  similar  measurements.  each reading.  procedure[L. It  m i n e r a l soil  after  installed  destroyed—apparently  0.001  taken  installed on  was  the  near  vacuum  were  from  installation until  were  a  thus covered the  nearest  chronologically  points  areas.  tensiometer  instruments  Corporation (n.d.)a,b].  visually  each  cut  applicable. T h e  addition, two  were  Readings were  using  the  indicate  of the  tensiometers  15 c m  or as  equipped w i t h  mature  to  Equipment  the  outside  Spittlehouse,  interface  i n the  Moisture  of  In  supply problems  was  M P a ) . Two  and  of column lengths  H/mineral  instrument  cutover.  two  the  Black  these included both of those  The instruments  portions  at  each  Secondly, four of the  installation.  Each  1965;  tensiometers  cups  (0.001  Unfortunately,  Firstly,  wildlife;  sites;  on  Richards,  Eight  their  feasible.  slope  where  area.  usefulness.  one  same  area  2  research  by  sites.  30 c m were installed w i t h  below  (S. J .  for  the  lower  forest  Richards,  1965;  Soilmoisture  to  the  most  (Bockheim  comparison possible  ten  samples  forest  floor  produce  the  within  the  were F/H  disturbed  et al.,  with  selected squares  curves  for  floor  all  [on the  basis  1975)], a n d also mature chosen  stand sequence.  randomly (see  from  Chapter  the  as  would For those Four).  84 Cylindrical extract  metal  "undisturbed"  procedure  was  the  F-layer  for  24 hours  -0.20,  rings  f-test  -1.50  and  differences between Wolfe,  1973;  System  H-layer  the  volume  placement  material above.  start of a MPa  internal  was  points  were  non-parametric  cm  were  3  on  the  pressure  in  contact  with  Samples  pressure  68  were  to  sequence.  T h e -0.01,  used  define  median  to test  were  to  plates.  The  plate,  with  the  allowed  used  imbibe  water  - 0 . 0 3 3 , -0.10,  the  curves.  used  to  The  check  for  the two curves for these points (Gibbons, 1971; H o l l a n d e r a n d  Sokal  (MIDAS)  for  (if included)  prior to the and  approximate  samples that  material  -0.40,  Students's  such  of  and  Rohlf,  statistical  1981).  The  programme  Michigan  Interactive  (Fox  and  Guire,  1976)  that  h o u r l y readings  Data at  Analysis  U.B.C.  was  used.  3.3 RESULTS AND  DISCUSSION  3.3.1 Temperature  Black  and  to  determine  of  the  presented  youngest the  advised  soil temperature  ranges  at  the  taken  in  this  rather  forest  11.6°C,  (1982)  rudimentary  indicative and  Spittlehouse  floor  approach  than  authoritative.  temperatures  on  the  i n F i g u r e 3.1. The m e a n while  those  cutovers  mature  stand,  of the  clearly but  cutovers  have  they  The  study  means  five  sites  ranged  appear  Therefore,  the  results  be  as  merely  taken  95% confidence limits  for  the  from higher to  should  necessary  and  air temperature  significantly  do not  15 c m depth.  are  differ  measurement  of a i r  period  are was  under  the  mature  stand  14.4°C  to  17.6°C.  The  three  means  than  The  mean  air  temperature  from  each  other.  85  20n  CD 0  15  0  0  t  v « r t l c o l bars o r « c o n f i d a n c * limits  t  95%  f  10  T  5  J  MATURE STAND  CUT AGE = 3  CUT AGE = 6  CUT AGE =8  CUT AGE = 11  •  For»s1 rioor (J/H)  O  Air (+5 cm)  SITE / CUTOVER  Figure 3.1 Means and 95% confidence limits for the air and forest floor temperatures of the sites, July to August 1983.  86 of  the  oldest  significantly  (Til)  from  cutover  the  is  means  intermediate,  of  either  the  and  mature  does  not  stand  or  appear the  to  differ  youngest  cutovers. The lower mean of the T i l may be related to its higher stem compared to the other cutovers and  crown closure  also  follow  are  also  (see  possible  T i l cutover  appears  The  mean forest  floor temperature  10.7°C to  14.4°C  to  differ  for the  however,  a lower level  and four degrees below).  the  2.5);  important causes.  this general pattern, but at  (between two  from  Table  than the  was  from  9.0°C  cutovers.  that  of  air  the  height  temperatures temperatures  However, in this case, even  significantly  density  increased canopy  Forest floor  two  the  mean of  mature  stand.  for the mature stand, and ranged  Unlike the  air temperatures  , the T i l  mean seems well displaced from those of the T6 and T8 sites. For both air and forest  floor temperatures,  harvesting  the  trend is  for approximately eight  toward a definite  years.  increase  Following this,  of values  temperatures  are  after likely  to decline gradually as the stand develops.  The likely  to  context mean  range of observed air temperatures be  seriously  growth was  attained.  less  might than  limiting be  July-August  period was  Climatologist,  A.E.S.;  measurement  technique  expected  20°C;  Records of the  growth  it  A.E.S. not  is  to  the  period at Boss  on  any  of  be  less  than  .unlikely  for the  that  Boss  pers.  comm.  July  the  actual  figures  Mountain  was  3,  the  this  sites.  values  from  1986).  from  station  are  that  (R.  not this  highest  this  indicate  of  in  the  than  normals  Because  that  since  greater  the  variable is  However,  optimal,  Mountain station  markedly divergent  comparable with those observed on the for  indicate that  were the  McLaren,  differences not  in  directly  research area. The mean air temperature approximately  1 2 ° C . It  can be  seen  that  87 the  observed  sites,  values  they  are  of the  similar  V a n c o u v e r Island (Black,  sites to  air  are  acceptably  close  temperatures  1982) a n d after  to  this; for  observed  after  the  harvested  clearcutting  on  spacing i n Cape B r e t o n (Salonius et  at,  1977).  Forest  floor  their  effects  as  stand  may  have  means  were  mean  temperatures  discussed been  earlier.  slightly  all apparently  provide a n  Growth  of advance  constrained  raised b y  interesting picture  by  the  regeneration  temperature.  a p p r o x i m a t e l y two to  five  degrees  10-20°C  bracket. T h u s , there should be some benefits  growth  as  well  microbial  means  fell  in  correspondingly below  the  Dennis have  less.  have  Since  temperatures limited. released  It  by  been  forest  there  has  even  exists  these  been  1984),  therefore  floor,  the  the  that on  and  highest  the  tree  air temperatures,  the  thus  growth  observed  activity  a l l the  processes given  evidence  the  a  was  mean  sites.  While  forest  floor  not  not  have  nitrifiers  substantial  b y the  might  falls  of m y c o r r h i z a l  nitrification  tree (soil)  and  can  lack  noted  roots  by  of canopy  much  the  main  zone  and  lesser  to  have  low been  the  nutrients  the  advance  closure.  fact that observations were  been  by  might  growth  processes  up  slightly  adapt  of  be  temperatures,  to a  amount  taken  low densities  tempered  may  that  would  that  Celsius to  of ectomycorrhizal fungi  sub-optimal b y  neither  possible  which  optima,  with  mature  a c c r u i n g to  decomposition/mineralization processes  above considerations m u s t be the  of  optimal growth  rendered  retarded  regeneration—especially  to  Nevertheless, as  temperature-limited  (Nakos, is  for  possibility  strongly  might  end  Interestingly,  (1985). T h e  these would have degree.  lower  lower b o u n d a r y  been  uptake  the  activity.  i n the  of  H o w e v e r , cutover  w i t h i n the  as  i n terms  of root  The  limited function.  88 Moreover,  measurements  covered  m a r k e d differences a m o n g the be  corresponding differences  into  account where  used to assess N  The for  soils  Timmer  and  increase after  forest floor in  N  portion  of  the  temperatures  mineralization  growing  season.  indicates t h a t there  rates.  l a b o r a t o r y incubation method  floor  temperatures  discussed  1977). T h e y were by  a  at  This  needs  a  constant  sites  were  to  The  should  be  taken  temperature  is  availability.  forest  mineral  a  only  earlier  slightly lower Weetman  (Dobbs  and w i t h  (1969). T h e  disturbance appeared  Finally,  the  trends  of the  parallel.  This  implies  system,  very  significant  that  observed on the  forest with  floor  a narrower  air  range  and  range  rigorous (but  still  those  of the  This  those et  al,  observed  temperature  latter  means  studies.  were  simple) d a t a  m i g h t be  g r o w i n g season.  to  Salonius  than  temperature  simple linear regressions  i n a given  1977;  to those observed i n the  and  more  between these two variables for the studies of this nature  McMinn,  magnitude  similar  a  and  similar  closely  collection  successfully developed  would  serve  to  simplify  locality.  3.3.2 Moisture  Because small  area,  of the  values  were  the  s a m p l i n g intensities  The  means  content coarse  are  and  variability  reported were  rounded  insufficient  95% confidence limits  presented  fragments  extreme  was  in  Figure  necessary  3.2. in  of soil  moisture even over  to  the  nearest  fully  reflect  to  of the It  this  was case.  forest  floor  assumed The  bulk  a  relatively  whole n u m b e r . the  observed  Further,  variability.  (F/H) volumetric water that  no  densities  adjustment used  for  for the  89  40  i Vertical b a r s are 95% confidence limits  30  H  20 H  10 H M*an Content  MATURE STAND  CUT AGE = 3  CUT AGE = 6  CUT AGE = 8  CUT AGE = 11  o-J  SITE /  Figure  CUTOVER  3.2 Means and 95% confidence limits for the forest contents of the sites, July to August 1983.  floor  moisture  90 conversion  from  1982;  Hillel,  during  another  moisture and  1982)  and  and  Black  mean  from  -0.2  as  floor (see  (F/H)  This  ranges  the  been sites  content  growth  also  (see  the  stress  in  within  later)  i n the effects  of  (the  (1982)  significantly;  they  lower portion of However,  this.  The  soil moisture growth  high  the  The  nitrification  result  over  latter.  earlier.  on  means  Black  the  the  belied  and  the  the  criteria  by  differ  discussed  differential  be  not  is  obtained  s a m p l i n g events  suggested  Black,  3.3 contains  Finally,  addition,  did  mineralization,  could  Figure  incorporated  no differences  Thus,  decomposition,  non-significance  the  potentials  there were  period.  have  tree  In  1977;  densities  T 6 sites.  individual  3.4.  (Armson, bulk  Four).  M P a values)  moisture  for  matric  the  -1.5  of  mean  T M and  Figure  (1982)  contents  27%.  floor  in  contents  Chapter  from  M P a and  water  over  processes  derived given  implies t h a t  sites  study  Spittlehouse  forest  However,  are  optimal  significance  forest  of the  20% to  broad  estimated  the  the  volumetric  ranged  the  limits  period of  volumetric w a t e r  curves developed for the  95% confidence  equivalents  to  were  phase  retention  measurement  the  gravimetric  the  lack  of  regimes of  and/or  such  were  unlikely.  within-site  variability  w i t h low s a m p l i n g intensity.  The  mean  -0.01  M P a was  could  have  estimates densities 0.14  -  value  the  due  to  likely, it could  T6  errors  retention  calculated for the 0.24  the  omitted because  been of  on  Mg  m~ )  have  3  been  retention  it was  within  r i n g samples  than from  slightly  associated  samples  might  be  curve  (Figure  3.3) corresponding  greater  than  100%  the  volume  and  with the  of both  metal sites  expected  m a t e r i a l lost i n the  for  ring.  tended mor  (101%). bulk  Indeed, to be  humus  r e m o v a l of the  to  This  density  the  bulk  higher  (range  layers.  More  samples  from  91  0.0010  20  40  60  80  100  SOIL MOISTURE CONTENT (% by volume) Figure 3.3 Moisture retention curves for the mature stand and six-year-old cutover.  60-,  0H 1  JULY 1983  Figure  1  1  1  1  1  1  1  8  15  22  29  5  12  19  r 26  AUGUST  3.4 Means and 95% confidence contents, July to August 1983.  limits for the forest floor moisture  93 the  plates  for  particularly slight  weighing and/or  after  systematic  curve—and altered  the  showed  only  (p  0.02  —  inherent  This  for  results  or  the  capabilities  in  value) Using  and  used  two  of  little  water  M P a . F o r that  of  their to  forest  floor  loss  occurred  materials.  floor  A.W.S.C.  From was  volumetric  moisture water  retention  contents  to  1.7  floor  have  The  sources  such  of  weak  of  differences.  moisture  balsam  fir  retention stands  assumed  (at  a  given  matric  volumetric  water  that  potentials was  used  to  (1981),  m i g h t be  convert  59%.  -0.01 M P a in  forest  the  forest  expected  highest A . W . S . C .  potential  cases,  lowered below  loss patterns  Ballard  which  values.  approximately were  be  potential  content  lost between  water  exhibiting the  matric  as  in  to  T M site for both  calculated  by  error  statistical  of practical  decreased  f-tests different  were  given  were  to  study  similar  times  curves forest  existence  A.W.S.C.  figures  silt loam—possibly the m i n e r a l soil texture  The  possible  procedure,  matric  observed  that  believed  degree.  a  for  being significantly  with  values  when  also be  points  not  consequential  this  was  78% of the  approximately  of  there would  is  as  almost inevitable,  data  -0.01 M P a of the  layers  representative  This  clearcutting  two  at  case,  observed  determine  -0.10 M P a . P l a m o n d o n (1972)  floor  who  curves  content  matter,  any  Together  following  subsequently  the  well.  indicating the  retention  averages  as  were  other  M P a points  (1974),  layers  losses  the  construction  as  Page  volumetric water  A.W.S.C.  Relatively -0.20  The  -1.5  curve  taken  from  same;  were the  not  in  to  respectively).  surface  Newfoundland. the  M P a and  Such  In either  present  T M curve  retention  differs  runs.  interpretations  0.04  were  result  bias  the  -0.40  and  in  virtually  upward  the  drying.  higher pressure  perhaps  significances  the  the  final  From  a  value.  calculated  values.  of  field Figure  94 3.4,  it  would  considered  appear  as  that  being  forest  stressful  stresses  occurred  particularly  extreme  for  entire  stress, one  but  d u r i n g the  which  encountered  showed in to  the  at  least  moisture give  retention  curve.  of  values  these  a  The  Campbell scale  was  the  two  relief  to  oldest  produce  were  from  to be  be  extreme  stresses  sites  such  the  only  cutovers no  all  difference  were combined  values  squares  might  sites,  Assuming  potential  least  used  some  month.  from  a  had  three  matric  (1974),  cutovers,  the  that  and  the  appeared  for data  all  site  values the  For  which  T6  July;  content  log-log  stand  in  stress  water  For  stresses  characteristics,  Following on  only.  values  encountered.  mature  week  potential  August.  the  extreme  water  indeed  during  second  retention  volumetric  were  month;  moderate  floor  for  linear  a  single  regression  an  idealized  is  somewhat  fit  moisture  retention curve (Figure 3.5). T h e equation so derived was:  ln (*)  =  11.72-3.58  (0)  ln  where:  The  r  2  because  observed sites,  9%  estimated  forest  0  forest floor  =  value of  extrapolated potential  •!» =  for  the  this  values  for  volumetric water  equation  was  transformation  (dashed  were  floor m a t r i c suction, M P a ; a n d  at  line) the  of  i n order driest  to  the  matric  T6  site,  potentials  and  13%  dependent  gain  points.  a p p r o x i m a t e l y 17% for  however,  0.91; the  some  The  the for  of -5 M P a for  content, %.  the the  variable.  idea of the  lowest  mature  this  mature  forest  volumetric  stand, T i l  The  site.  floor  was matric  contents  T 3 and  T8  corresponded  to  -6 M P a for the  T3  These  stand,  curve  water  16% for the  suspect  95  0.0011  i  i  i  1—i—i—i—i—i  1  1  1  1—  10 SOIL MOISTURE C O N T E N T (% by v o l u m e )  100  Figure 3.5 Idealized moisture retention curve and extrapolation (dashed line) for the combined sites. (See text for regression equation.)  96 and T 8 sites, -47 M P a for the  The  records  July-August  of the  period of  expected  A.E.S.  1983  might  be  more  than  normal, August  have  been  expected  contributed stress  to  provide  in  only  moisture 1982).  McLaren,  "Wet  This  limit  was  have  on  may  that  for  only  of the  Mountain  the  1.4  had  more  The  of  data  3,  times  1986).  sustained from  cutovers. I f the  of  the  to  would invalidate the  The latter  data  observed.  It  is  sampling  event values  Moreover,  interesting reported  the  i n this  study  are  accurate, only.  excessive,  so obtained  results  the  as  that  by  was  (Black  Potts was  earlier,  doubt  moisture  tensiometers  ineffective  at  soil  and Spittlehouse,  the  two  the  lower-slope  moisture  stress  H o w e v e r , it m a y causing  an  also  "irrigation"  and Spittlehouse,  less  (1985), very  extremely  than  half  the  range  similar  to  1982).  as  insulator  after  subalpine  preventing  of of  low  the  samples  variation  floors,  evaporative  loss  July  potentials  of  d r y organic from  were  taken  the  per  moisture  that one. The possibility  layers  an  no  (1985) for a drier  sites w i t h more or less intact forest  act  might  occurrence of stressful conditions from  noted  with  of Potts  t h a t on harvested might  of  what  moisture values occurring i n the forest floor  investigator noted  September.  one  organic l a y e r s  tensiometers  general finding of stressful  into  the  data  by  than times  extreme  are  the  2.5  This  surviving  Tensiometers  reached  that  precipitation  less—only 0.4  result  show  approximately  comm., July  above.  station  times  July  much  pers.  fleetingly  been. limited  recharging  which  content  had  subzone.  h a r v e s t i n g is in agreement w i t h site.  while  unexpected  Belt"  support  Boss  potentials below -0.08 M p a ( S . J . R i c h a r d s , 1965; B l a c k  levels  The  the  approximately  actually  somewhat  weak  outside  effect  (R.  a  instruments  be  had  for  normally. However,  the  levels  T 6 site, a n d -13 M P a for the T i l site.  exists surface  mineral  97 soil.  I f so,  harvest  growth as  At that  the  August earlier  imposed  H o w e v e r , nitrification Thus,  the  of moisture  been  i n the  as  Insofar  and  of microbial  floor  would on  as  important  activity,  moisture,  it can  post-  (1985).  be  safely  assumed  constraints  on decomposition/mineralization  have  slowed considerably d u r i n g  been  the  the  the  a role to p l a y i n  and that of Potts  cutovers  they depended  nutrients,  severely constrained by  bulk  have  no  situation  under temperature.  on the  m i g h t not  was indicated b y this study  availability  period.  supply  have  stress  observed levels of forest  water  processes.  a  moisture  growth  was  similar  to  on the  forest  floor  of  advance  A u g u s t stresses.  it m a y  be  that  forest floor w a s not t a k e n up b y the  the  advance  With bulk  that  no  noted  layers  regeneration such  the  for  would  constraints  of nutrients  released  regeneration.  3.4 CONCLUSIONS  Within some  general  hypotheses  levels  among suggest  by  the  can  some  3°C  to  regime  among  the  sites  the  be  of the  i n forest  change  least  employed,  of  subsidiary  terms that  the  hypothesis  temperatures eight  There  H  years.  was  should  0  temperature  were  collectively  Differences  nothing i n the  There  Hypotheses  H  appeared 0 9  and  H  to 0  „  existed data  moisture retention characteristics  harvesting.  regard.  methods  i n g r o w i n g season  floor  sites.  floor  after  i n this  at  in  indicate  forest  for  rudimentary  stated  results  and  6°C  occurred  by  indeed a  Air  regimes  that major changes  differences  now  there w a s  harvesting.  temperature  moisture  imposed  consideration. T h e  Therefore,  following  increased  limitations  conclusions  under  be rejected.  soil  the  to  and/or be  no  were  not  98 rejected. was  However,  dependent  sustained  H  on  growing  harvesting.  At  can  0  forest  floor  season  the  most  -47  M P a were  fact  that  the  organic  characteristic of the temperature  temperature advance  and  Therefore, nutrients differences  have  major  and  on  released. the  should be modified  the  sites  moisture on  the  Finally, is  regeneration  advance  stand  of the  also  moisture  growth  potentials  floors  may  after  between  cutovers.  exhibited  levels  and  low  have  -6 The  matric been  a  a n effect of harvesting. Concerning possible  demonstrated  that  fir  matric  forest  mature  advance  that these existed to  a  small  have been sub-optimal.  mineralization  i t is u n l i k e l y so  than  subalpine  estimated  floor  that  clear evidence of e x t r e m e  o n tree g r o w t h , it is likely  regeneration—even  decomposition  the  extent  was  on  in  forest  sites, r a t h e r  degree; growth m a y therefore  results  of  the  There  points,  encountered  low  to  stresses  layers  that  limitations  The  layers.  extreme  and  suggests  rejected  water  MPa  potentials  be  that  that  availability such  there  constraints  "Wet  processes  can  Belt" did  not  the  implication results  of  of  to  By be  forest  nature.  minor  g r o w t h of  so  growth utilized  laboratory  to reflect this i n studies of this  sites.  appear  the  relatively  post-harvest  ESSF  subalpine fir advance one  to  be  floor  incubation  contrast, affected. a l l of  the  temperature procedures  CHAPTER 4 POST-HARVEST FOREST FLOOR PHYSICAL CHARACTERISTICS  The after  importance  major  harvest  disturbances  physical  examined.  of the  state  Emphasis  bulk densities  and  forest  was of  was  floor  and  the  role  which  it appears  discussed i n C h a p t e r One. I n this chapter,  the  organic  placed  on  layers  humus  of  the  form  Swayback  to  play  the  post-  Ridge  sites  classifications  and  forest  decline i n forest  floor  depths  is  floor  weights.  4.1 INTRODUCTION  As weights  following  assart such  discussed i n C h a p t e r  effect  necessary section assart  to the  of the effect  the of  study  term  profile, forest a  ESSF  assessment  thus  forests  of the  to  weights  shed and  investigation  should thus  levels on a  intended  Any  of the  light on  of  logically  the  the  examine  organic  mass-per-unit-area  and  layers  basis.  dynamics  indirectly (contributions  of to  is  This the other  study).  The  comprise  of the  documented.  both directly (physical changes)  question  the  was  general  been  calculation of nutrient  The  soil  has  harvesting  Moreover, a n  phases of this  study.  disturbance  after  changes.  One, a  of  "humus to  form"  designate  floor  single  humus  form  classification is  is used  to indicate  also a  concept,  n a t u r a l l y - o c c u r r i n g , biologically  horizons.  horizon, but  The is  humus more  form  usually a  99  is  of  part  profile  importance similar  active of  to  to  this  that of  units comprised  the  composed  soil; of  it  may  successive  100 horizons  linked  recognized horizons  that  a  variety  et  al,  cover  action  faunal  agents.  dominant  four  The  poor  Bernier  (1981)  later  survey  sites—as (1968)  proportions  (thicknesses)  case  criterion. the it  v i e w has  same general can  be  indicative system  should  be  more  a  are  strongly sharply  that m o r  expressed  that in  et al.  the  into  as  the  that  as  degree  of  five  Both  (1981)  of the  than  humus  from  humus  are  (1968)  forests  use  were in  a  of  into  xeromors, relative  differentiation;  moisture  form  the  Klinka  the  for  (Watts,  in  horizons  humimors.  systems  the  main  be differentiated  and  development  the  forms  coniferous  applied  through  decomposition  groups—velomors,  humification,  coniferous  mineral  mor  two systems  Bernier's  with  1981).  a given humus  the  1978;  slower  principal basis also  Dumanski,  mites  forms  a  humus  et al.,  under  thus  Decomposition  delineated  that  (and  of  for  associated  fibri-humimors,  insofar  sensitive  1968;  been  sequence  a basis  acid, w i t h  expected  and  as  collembola, and  indicated  horizons  used  generally  forms  nutrients.  1979; K l i n k a  be  has  life  Bernier,  humimors.  i n either  been  and  differentiation  and  been  category  differences  be  might  Klinka  demonstrated of  to  had  of the  of x e r o m o r s ,  The  bases  and  generally  protozoa,  proposed  proposed  hemihumimors,  the  are  humi-fibrimors,  hemimors,  in  forms in  tend  have 1952;  1973; Pritchett,  groups—fibri-mors,  et al.  Lunt,  It  characteristics,  processes  facets  humification; they  a l l the  zone.  and  horizons  preliminary on  biological  predominant;  1968; R u s s e l l ,  The  ESSF  appears  complete  (Bernier,  soils  1978).  morphological  M o r humus  on  (Dumanski,  These  (Hoover  1981).  fungal  less  of  micro-environment).  heath  and  genetically  composition,  classification  Klinka or  the  reflect  particular form  together  deficiency  w o u l d fall  into  1983).  However,  an  layer  Klinka  H et  is  al.  (1981)  differentiating  among  101 profiles the  with  lower h u m i f i c a t i o n levels (an  reverse  believed  useful  dominant major  should to  hold  true  assess  on each  departures  for  which  those  groups  site.  This  helped  from  a  common  microbial a c t i v i t y and N  expected  with  higher  (Bernier,  to  further  trend  condition i n the  humification levels.  1968; K l i n k a characterize  would  ESSF  et al.,  the  imply  It  1981)  sites;  different  zone); was were  i n addition, conditions  of  availability.  4.2 OBJECTIVES A N D HYPOTHESES  The  main  objectives  information  on  forms),  to assess whether  and  forest  of  time since the main  floor  harvest.  hypothesis  H  and its alternate  H  0  y  :  Major  H  H  layers) bulk densities should  be  as  study  densities,  changes  One).  of  the  The  were  weights,  to  provide  and  humus  h a d occurred i n the falls  subsidiary  within  same  the  hypothesis  over  ambit of  under  test  follows:  changes  there  the  changes  characteristics  If  group  the  have  occurred i n the p h y s i c a l  forest  floor  during  the  post-  period.  post-harvest  ^ is true,  of  (bulk  major  Chapter  N o major  physical  0  any  be stated  characteristics  H,  characteristics  (see  harvest  phase  Investigation of p h y s i c a l changes  0  may  this  have of  indeed  the  forest  occurred floor  in  during  the the  period.  should be and  no  major  differences  weights of the  common  dominant  one  i n the  forest  floor  (F  sites. M o r e o v e r , a single h u m u s on  all  sites.  S t a t i s t i c a l tests  and form were  102 accepted cases.  as A  c r i t e r i a for falsification  simple  proportion form  the  of  inspection  sampled  of  points  what  was  of H mor  accepted  for  0  the  b u l k density  humus  group  as  criterion for  the  and  weight  the  largest  assessing  humus  comprised  differences.  4.3 METHODS  The Chapter nearest floor  basic  Two. 0.1  field  The  cm  layout  thicknesses  at  the  excavations  made  taken  to be the  average  used  to  determine  sampling  of  L,  middle of the per  the  sampling  of the mor  and  point.  humus  or absence of rotting wood i n the  stage F / H composite the of  corresponding the  bulk  air-  densities,  ANOVA, treatments. variation; was  and  often  weights  from each  the  associated  the  at  three  forest  thickness  were each  At  the  was  subsequently point  each  by  the  point,  the  noted.  of the  s a m p l i n g point were  used  to provide estimates of  generated sites  and  included to  p r e l i m i n a r y survey, with  layer,  to  Two)  thus  individual  recorded  in  Chapter  F / H horizons.  the  presented  of the  form w a s  oven-dry weights  of each  et al. (1981).  humus  (see  were  classification  Klinka  were  The thicknesses  oven-dry bulk densities,  R o t t i n g wood was during  and  layers  each  air- and  and  with  (1968)  oven-dry  For  group  employed  side  three readings.  presence  and  H  up-slope  of  air-  Bernier  scheme  F,  systems  The  both  and  deeper  organic  The  as  data  well  for  analyzed  the  rotting  profiles.  forest  as  a  wood  aid separation been  per-hectare  total  were  it had  as  tri-sample  floor  two-way categories  of significant  observed  Because  of  that the  weights depths, Model as  sources  its  first  I  the of  presence  imbalance  in  103 cells,  the  ANOVA  was  U.B.C.  carried  (Greig  using  available  at  GENLIN  and  ANOVA  (Fox  necessary  to achieve homogeneity of the  densities.  Natural-logarithm  MIDAS, and  a  L-layer  excluded  classification out.  The  and  Wolfe,  as  non-parametric  1973;  Sokal  4.4 RESULTS AND  1976;  and  presented  0.05) a m o n g the  tests  GENLIN  1980). they  The  met  for  were  for  test  bulk  median  procedures  and  Rohlf,  the  sites only formed the  within  its  densities  depths  MIDAS  and  since  analyses,  (Gibbons,  the  air-dry bulk  Finally,  weight  among  and  1981)  were  the  of  using  Transformations  for  and  differences  checked,  valid  total depths.  density  programme  a  a l l except  used  used for the  were  assumptions  1976).  variances  bulk  computer  data  the  Anonymous,  transformations  the  the  the  single-  were  carried  1971; Hollander programme  were  treatments.  DISCUSSION  means are  whether  from  employed; i n these cases,  variables  Bjerring,  power function was  Kruskal-Wallis  The  to  Guire,  weights, while was  and  out  means  95%  confidence  limits  i n Table 4.1. T h e r e  of  were  the  measured  and  derived  no significant differences  of a n y of the v a r i a b l e s of the  five  (p >  sites.  4.4.1 Total Depths  There [p 5.7 was  >  0.05, cm 8.6  to  were F 6.8  =  no  significant differences  1.4,  cm.  c m , whereas  degrees  The  mean  of freedom depth  i n its absence  of the  among (df)  =  the  mean  4,  308].  a l l samples mean  depth  with was  depths of the Means rotting  5.4  ranged wood  c m . The  sites from  present observed  104  Table 4.1 M e a n s and 95% confidence limits for forest floor total depths, F / H bulk densities, and weights.  ITEM  UNITS  SITE  TM  /  T3  T6  (—values rounded; figures Depth  VALUES  Til  T8  i n brackets are  95% limits—)  6.8 (8.4,5.7)  5.8 (7.1,4.9)  6.7 (7.5,6.1)  5.7 (6.4,5.2)  6.1 (7.0,5.4)  air-dry  0.16 (0.17,0.15)  0.17 (0.18,0.15)  0.15 (0.16,0.15)  0.15 (0.16,0.14)  0.16 (0.17,0.15)  oven-dry  0.14 (0.16,0.13)  0.14 (0.16,0.13)  0.13 (0.14,0.13)  0.13 (0.14,0.12)  0.14 (0.15,0.13)  90.9 (103.4,79.9)  79.7 (91.6,69.4)  87.0 (93.5,81.0)  79.4 (85.8,73.5)  78.1 (84.9,71.8)  83.0 (94.5,73.0)  72.8 (83.7,63.4)  78.6 (84.5,73.2)  71.5 (77.3,66.1)  69.7 (75.8,64.1)  Bulk Density  Weight air-dry  oven-dry  cm  Mg/m  3  Mg/ha  105 depths  are  within  the  1986)  for comparable  forest  further  reported range  for  under  et  Kingston,  lack  represents  a  organic  Piene,  1978).  decline  in  possibility  ESSF  are  forest  significant from  layers  (in  litt., A p r i l  18,  also close to those of spruce-fir  They  forests  types  Lloyd  are  much  1972; M a r t i n ,  very  of  close  the  to  lower  than  1985), but  of mor  1970;  those  within  coast/interior  those  (Wooldridge,  Following  exists  floor that  differences. the  differences the  declined  i n eastern  forest  environment, was  of  departure  clearcutting  "true"  the  values  other  1974).  by  the  transition  humus  forms  Mahendrappa  and  1980).  The  example,  of  and  (Plamondon,  within  The  observed  stands,  in B . C . (Kimmins,  1982).  variety  depths  Wet-Belt E S S F  observed  at,  a  of  B . C . coastal forests  of those  (Klinka  and  north  range  general within  spruce-fir  clearcutting depths  high  of  insufficient to trigger major  trends  discussed  three  to  forests on  within-site  nature  the  the  of  may  the  harvest  post-harvest  1974;  may  have  that  after  the  in  resulted  Chapter  Martin  of  depth  in  of  in  original  that a  sites  One.  For  spacing  et al,  (1985)  served  the  both  Salonius  33%  be  depths  years  B . C . coast,  variability  it  mean  seven  (Page,  approximately  Alternatively, partial  among  to  1977;  noted  a  depth.  The  mask  any  relatively  disturbance  cold which  declines.  4.4.2 Weights  The  calculated weights  necessarily  made  estimate  the  There  were  significant differences  no  actual  are  proportion  of  overestimates,  the  among  the  area  covered  mean  since no attempt by  F / H dry  floor weights,  was  materials. whether  106 air-dry  or oven-dry values were  =  1.8  and  2.2  ranged  from  74.2 M g ha"  ranged  from  published (1974)  69.7  observed  values  types  possible They  subalpine by  floor  in  to  1  92.8 to  1  forest of  et  this  floor  al,  study  this  In  are  the  on  .  was  in  to  forests.  values  spruce  higher  end  H o w e v e r , they  and H a s k i n  (1985)  by are  of  et al.  are  forest  may  the  far  al.  below  for B . C . coastal  little  Kimmins under  However,  be  types  said range  (1985).  et  be  floors  fir  acceptably Lang  weights  forests.  and/or  the vary  that  the  found  for  Especially  within  the  (1981)  in  the  F  counterparts to  believed high.  it  noted  for  1  general,  they  appears ESSF  4, 2 8 7 ;  mean  oven-dry  There B.C.'s  compendium of K i m m i n s  close  0.05, df =  their  M g ha"  value  1985).  1  for  56  obtaining  are  (1985)  ha"  weights  differences,  fir  , while  1  Mg  approximately  >  respectively). A i r - d r y  M g ha"  methodological also  (for both: p  cases  83.0  weights  i n the  balsam  Martin  oven-dry  Prince George;  (Kimmins  observed  comparable  on  near  and  ha"  value  forest  tremendously  range.  Mg  a  cover  of  weights  air-  information  spruce-fir  the  for  considered  weights  given latter eastern  reported  and d r y interior conditions  respectively.  Concerning the F/H it  weights,  what  should be noted  after  disturbances.  forest and  floor  authors  and  was  attributed  above  for  studies  F o r example, L a n g  (1986)  pattern  said  that other  weight w i t h  Freedman  losses  apparent lack of differences  stand  age.  pointed  out  of recovery  so  depths  have  among the  is  also  reported  et al.  (1981)  applicable here.  either  they  did  exemplified b y  their observed differences  more  slight or no  found no pattern  F o r hardwood forests that  sites i n their  not the  in Nova observe  However, differences  or trend  in  Scotia, W a l l a c e  the  H u b b a r d Brook  to changes  mean  large  weight  study.  in litter inputs  The than  107 to  decomposition  differences;  (1978)  and  weight  considerations,  have  Covington  occurred  weights  such  differences  occurred.  (1978)  was  Further,  were  argued  not  F  that  the  an  insoluble heterogeneity  in  the  L-layer  H  in  of variances)  observations  L-layer  layers  this  were  study  not  given  that  oven-dry  any  weight  no  by  losses in  could  affected. no  bulk  from  L-layer  so  that  losses  depth  densities would  tests (used  evidence  Piene  excluded  decrease  T h e non-parametric found  was  " m i s s i n g " weight  substantial  different,  been reflected i n L - l a y e r depth differences. of  the  assumption  markedly  earlier  the a  and  unlikely  on  to  study,  noticed  spacing;  event  similar  Since, i n m y  Piene after  an  materials  was  it m i g h t be  years  However,  L-layer  (1981).  there.  three  this  of such  of  have  because  differences  alone.  4.4.3 Bulk Densities  As found  among  values air0.15 Mg  with  the  the  other  mean  two  related  F / H b u l k density  were considered (for both: p  and  oven-dry cases  M g m" m"  3  to  and  3  0.14  0.17  values  they  fall  the  northerly  As  at  The  the  in  of  the  humus  range  of the  significant  sites,  whether  4, 287; F  =  a i r - d r y bulk densities  mean  oven-dry  mor  no  0.05, d f =  the  3  found  centre  spruce-fir  with  M g m" ; 3  density  >  respectively). M e a n  Mg m " .  bulk  variables,  oven-dry  values forms  observed  by  are  values very  differences air- or 1.9  and  ranged  ranged  close to  oven-dry 1.5  for  between  from the  were  0.13  general  (Pritchett,  1979).  In  addition,  Kimmins  (1974)  under  more  forests.  other  two related  v a r i a b l e s , the lack of differences  among  the  108 mean  F / H bulk  comments Three)  made  which  some  range  earlier  implied  support  disturbed the been  densities  to  represents also  by  contention  changes  of v a r i a t i o n i n the  not p l a y an important confidence  intervals  of the  very  close to that reported  from  However,  general  earlier  characteristics  were  may  not  have  retention  characteristics.  implies t h a t  sites  with  respect the  (Chapter  The  lends  sufficiently would  relatively  have  narrow  high within-site v a r i a t i o n did to a n y  greater  double t h a t of the  The  unchanged  Changes i n bulk densities  also  trend.  result  changes.  b y P l a m o n d o n (1972);  size more than  the  the  harvesting  " m a s k i n g " role w i t h  95%  4.4.4  here.  that  in  values  departure  retention  site to trigger major  accompanied  on a sample  apply  that moisture  the  a  the  "true"  differences.  The  numbers  of samples  are  latter's  i n t e r v a l was  highest in this  based  study.  Mor Humus Groups  The  velomors  Ridge  sites.  were  found  of  Klinka  Moreover, the which  et  results  corresponded  to  al. of  (1981)  did  Chapter  the  not  Three  xeromors  occur„ on  system, exception  results  hemihumimors of  points than humimors increase  are  the  T i l  are site,  h u m i m o r s . There  found on the in  presented  the  other  by  far  Table  the  hemimors was  T 3 site two  in  (Klinka  4.2.  For  dominant occupied  et al,  groups;  compared for  the  to  the  latter  others, two,  all  et  profiles  Similarly,  the  al  sites.  proportion  a noticeable decline i n the as  1981).  Klinka  on  greater  no  noted.  the  group  a  Swayback  notwithstanding,  no profiles corresponding to B e r n i e r ' s (1968) h u m i m o r s were  The  the  (1981)  With of  the  sampled  percentage of h e m i with  a  corresponding  increase  was  more  109  Table  4.2 D i s t r i b u t i o n of mor h u m u s  groups on the  GROUP  sites.  SITE/PERCENTAGES  TM (n = 3 0 t )  T3 (n = 30)  T6 (n=100)  T8 (n = 90)  Til (n = 70)  hemimors  16.7  26.7  8.0  12.2  4.3  hemihumimors  80.0  63.3  87.0  82.3  88.6  3.3  10.0  5.0  2.2  7.1  -  -  -  3.3  -  -  -  -  1.1  -  humi-fibrimors  86.7  86.7  82.0  76.7  88.6  fibri-humimors  13.3  13.3  18.0  20.0  11.4  -  -  -  2.2  -  KLINKA  et al.  humimors unclassified  BERNIER fibrimors  unclassified  IDenotes sample  size.  110 marked  in  the  hemimor  group.  This  pattern  implies  relatively  lower degree  of h u m i f i c a t i o n overall  could  explained by  the  be  felling.  If this  sequence  harvesting.  In  indicating  a  on  the  floor the  studies  this  addition,  the  if the  likely  show  Klinka  lower  be of  the  T3  site  studies).  The  et al.  differentiation  (1982)  indeed  the  (1981)  in  lesser  than  the  of  the  among  groups  of  humification sites  is  a  tests  out  that  results  the  for the  true of the  system the  are  T3  systems  scale. result  of  et al. (1981) s y s t e m to such conditions, as  as  age after  taken  of  These  such  and  involved.  indicated,  this  is  in  N  (e.g.  T i l site,  out  forest  employed is  as  though  the  T 3 cutover.  very  or  It the  may is  consistent,  T i l  sample point was  both  the  carried  microbially-affected levels  also be  one  were  individual  others  this  years be  a  with  materials.  such  humi-fibrimors comprised  fibri-humimors. O n l y  then  the  one  in  six  no  only  from  classification of The  could  had  matter  later  within  of  site  conceivably,  s a m p l i n g procedures  when  B e r n i e r (1968)  system.  dominant  the  T3  organic  pattern  T i l site  since  and/or  may  other  general  pointed  differed  same  and  the  others;  humification  by  chemical  using the  differences  end  complete  the  disappeared  the  investigator—even  at  results  The  more  from  seriously affected  up  followed b y the fibrimor.  values  without statistical support,  here appeared  The apparent  toward  the  "anomaly"  Moreover, F e d e r e r  However,  differences  to  that  can  mineralization  return  imply  subjectivity  to  of slash  the  are  data.  inputs  then  trend  observations  fresh  is true,  might  than  that  be  the  pointed out  as  seen  as  as  of  no the  group,  having a  lying  believed  sensitivity earlier.  with  dominant  classified  therefore  higher  sites  with  at  that the  the the  Klinka  Ill 4.5  CONCLUSIONS  under  Some  general  test.  From  indicate  that  changes  occurred  sites  any  harvest  subzone  to  the  in  the  constituted trigger  arise  from  rates,  both  compared  that  and  stand t h a t they  statistically)  of  six y e a r s  the  organic  this  effect  differences  there is  mature  the  form  floor  vegetation. did  not  and  to  disappeared the  should also emerge  the  in  concluded  of the  was  of  nothing  therefore  forest  the that  floor  declines noted  the  elsewhere.  the  with  increased decomposition  augmented  have  implication much  been  of the over  would  above  those  not  by  have  those  of  conclusion is  of  the  mature  litter input rates.  p h y s i c a l changes,  somewhat  within  of  A n y decline  classifications yielded some evidence (though not  a  major  p a r t i a l n a t u r e of  may  so  no  to  high within-site variation-  inputs  increase  data  layers  condition. L i t t e r  One  hypothesis  insufficient i n that biogeoclimatic  simultaneous  stand  harvest,  was  terms  it is believed that  which  forest  in  internal  to  the  following h a r v e s t i n g . I n i t i a l l y , inputs from  layers  in  a  rates  minor  made  is possible that  litter inputs  could outstrip  The humus  first  to  pioneer  decomposition  It  however,  disturbance  decreased  other  criteria,  period. It  marked  totally cut off b y  herbs  be  p h y s i c a l characteristics  a  the  now  rejected.  differences;  would  been  be  post-harvest  "true"  can  statistical  should  0  d u r i n g the  masked the  H  conclusions  lower overall  six years  forest  floor  i n the  subsequent  stage  forest felling  floor,  supported within  appeared  to  and  mineralization levels  phases of this  carry  of h u m i f i c a t i o n ; however,  of harvesting. If this is indeed the  chemistry  the  study.  of  the  case, sites  CHAPTER 5 P O S T - H A R V E S T SOIL C H E M I C A L CHARACTERISTICS  Four.  The  p h y s i c a l characteristics  We  now  occurred  in  Emphasis  both  was  and nutrient  5.1  turn  our  the  attention  forest  placed on  of the  floor  those  forest  to  and  floors were  what  examined in  post-harvest  mineral  soil  in  terms  aspects considered most  a v a i l a b i l i t y — s o i l reaction, macro-nutrient  changes of  levels and  might  their  important  Chapter  to  have  chemistry. tree  growth  C / N ratios.  INTRODUCTION  The  theory  nutrients—especially was  necessary  The  aspects  of  tree  growth  affect the  study  (N,  P,  of  the  assart  those  with  to e x a m i n e  was  the  greatest and  effect large  interest  involved  to  of N  therefore,  only  "total"  N  emphasis  was  placed  on  greatest  influence  accepted  that  their  on  and  availability  assessing  exchangeable  organic  variables  availabilities of forms.  and  i n terms  is dealt  with  For  the  For  pools  soil are  112  K, the  and  processes  most  also  it  which  phase  of  macronutrient to  of these  investigate  quantities.  i n detail i n C h a p t e r S i x ; other  forms Ca,  Thus,  mineral layers.  indirectly. T h i s  C / N ratios,  levels of those  growth.  the  organic and  directly or  assart pattern  is considered here.  tree  in  in  provide information on general  reaction,  the existence and d y n a m i c s of a n  special case  held  those  availability  intended  K , C a , M g ) levels, soil  The  fractions  basic c h e m i s t r y of the  nutrient  therefore  involves increases  and  macronutrients,  which Mg,  important  might it  is  ones  have  some the  generally for  plant  113 growth only P  (Buckman  extractable  present  variety acid  primary  soil  to  Nelson,  1975;  resin  procedure,  The  New  bulk  The chemical  organic  i n the  conversion  factors  the  other  Finally,  C/N  have  mineralization  rates.  6,  used  P  The  1977).  of  by  important.  involved  form  forms  influenced  more  a  Under  should  be  the  in  which  plants  are  (Russell,  1973;  Tisdale  and  "total" was  and  an  of available P  1986)  Krause  plant-available  in  P  situ ion-exchange resins  i n soils ( A m e r  (Professor,  indicated that  and  (1982)  This  of  frequently  have et  al,  U n i v e r s i t y of  excellent results  been  high  were  to  as be  an  index  strongly generally  their  one  in  complete related  quantity  1982).  reporting  p h y s i c a l and  closely  obtain  variation  the  Such  accepted  appears  to  to  are  Sommers,  advocated  content.  of their  importance  used  and  concomitant  strongly  many  determinations  been  Nelson  the  still  some  (C) content  matter  have  of soils influence thus  1977;  organic  ratios  is  carbon  problems  soil  the  of both  Sibbesen,  contents and  (MacDonald,  of  of  are  Therefore,  soils.  this;  measure  of the  form is  measurement  1968;  matter  Sommers  plants  requirements  Measures  comm. June  Organic  and  P  one  considered.  a cumulative index. Ion exchange  characterization.  Nelson  this  therefore  characteristics,  methodological  H POi;;  1979).  Cooke,  i n forest  mineral  by  1979).  was  B r u n s w i c k , pers.  so obtained  is  main  of their  were  uptake  reaction  Pritchett,  measure  of use and  elements  and  2  1973;  plant-available  and  long history Hislop  the  to  soil  the  ion,  Pritchett,  included.  1955;  which  conditions,  absorb  were  a  of  Russell,  nutrient  availability  orthophosphate  believed  1969;  of these  their  factors,  forest  Brady,  forms  and  of  and  of organic was  for  of  obtained, C as  employed  influencing true  from  Because  results  to  net  forest  a  here. N soils,  114 though  there  present  a  more  agricultural Ekbohm,  been  1983;  (Berg  and  Bosatta  an  study  accumulating  complex picture  soils  included as of the  has  that  Staaf,  and  important  than  evidence  initially  1981;  Berendse,  that  proposed  Bosatta  1984).  the  and  The  characteristic of both the  latter  situation  may  based  on ideas  from  Staaf,  ratios  forest  1982;  have  Berg  therefore  and been  floors a n d m i n e r a l soils  sites.  5.2 O B J E C T I V E S A N D HYPOTHESES  The  first  information and  P,  on  objective the  levels  "available" P,  ratio  values.  and  the  The  information  was  sites i n terms  to  a  phase  exchangeable  portion be  used  of to  the  part  of of the  testing  in  investigation  per-hectare  Ca,  and  were  the  whether  were  soil.  "total"  pH the  provide  and C / N  forest  floor  Secondly,  this  differences  among  chemical hypothesis  characteristics H  . Main  0  of  the  hypothesis  also  indirectly  adequately alternates  with  related; that  aspect.  m a y be stated H  0  y  however,  as  N o major  chemical  The  subsidiary  chapters  deal  hypotheses  more  under  period.  have of the  occurred i n the forest  floor  general  during  directly  test  follows:  characteristics  post-harvest  subsequent  changes  the  sites H  0  o  1  is  N  soil c h e m i s t r y .  the  of m a i n  mineral  of  to  of  finally  F / H layers  there  was  contents)  M g , and  underlying  assess  changes  the  and  K,  of interest  of  of their general post-harvest  Investigation comprises  this  (concentrations  materials cm  0-15  of  the  and  and their  115 H,  :  Major  general  chemical  d u r i n g the  H  chemical fraction  :  1  have  indeed  characteristics  occurred  of  the  in  the  forest  floor  post-harvest period.  N o major  0  H  changes  changes  characteristics  have of  occurred i n the  the  mineral  general  soil  surface  d u r i n g the post-harvest period.  Major  general  changes  chemical  have  indeed  characteristics  occurred  of  the  in  the  mineral  soil  surface fraction d u r i n g the post-harvest period.  If  H  ^ and H  0  should  be  fractions pH,  0  no  N  sites and  importance  here,  given  over  site  the  to  takes  cumulative  were for as  given  the the  hold  a  for  lower  differences falsification  representations  differences  i n terms P,  owing  assumed a  accurate  marked  of the  "total"  ^ are  C,  of the  and  to  their  short  term  the  among  C / N ratios  post-harvest  indicated  situation, there  organic  (e.g.  one  By  contrast,  emphasis  because  were  considered  sites  with  null  growing  season).  measures,  since  concentrations  of their  and  characteristics stated to  ephemeral  respect  hypotheses.  The the  of  of  greater  change same  in  mineral  earlier. T h e  be  comparatively low susceptibility to  measure.  c r i t e r i a of the  the  chemical  orthophosphate-P  a m o n g the  of the  can  a be  situ approach  exchangeable  nature.  on  Statistical  to these v a r i a b l e s were  bases tests  accepted  116  5.3  METHODS  The samples  basic field  were  detailed  fractions,  all  composites  only.  5.3.1  in  analyses  Chapter and  Two.  For  in  this  tests  and  system  both  forest  phase  of creating composite floor  and  involved  mineral  the  soil  second-stage  pH Values  A pH  layout, s a m p l i n g scheme,  r a n d o m l y selected  determinations.  mineral  soil  The  samples.  subset  same  The  of ten  samples  selections  applied  weight  organic a n d m i n e r a l subsamples. to-matrix  ratios  respectively.  of  1:8  material  1:2  taken  for on  forest  a  each site was chosen for  to  both  organic  used  was  five  Determination was  and  Readings were  of  from  done  floor  Radiometer  29  grams  i n 0.0 I M  and  and  CaCl  mineral  p H meter  for  both  in soil-  2  soil to  surface  materials  the  nearest  0.1 p H units.  The ANOVA  data  (Sokal  comparisons and  Rohlf,  violations 1976; No were  were and  of  Rohlf,  a m o n g the 1969; the  analyzed  1976)  transformations  were  u s i n g the  and  each  with  case  the  employed the  and  assumptions  Anonymous,  performed  1981)  means  Dowdy  in  Wearden, of  ANOVA  GENLIN  necessary. GENLIN  sites  a  single-classification Model  as  the  treatments.  1983). using  the  and  ANOVA  programme.  The  data MIDAS  Bjerring, and  were (Fox  I  A posteriori  S t u d e n t - N e w m a n - K e u l s method  (Greig  The  as  (Sokal  checked and  for  Guire,  1980)  programmes.  subsequent  comparisons  P a i r w i s e f-tests  (Sokal and  Rohlf,  117 1981) were values  also performed  u s i n g the M I D A S  between  the corresponding forest  floor  a n d m i n e r a l soil  programme.  5.3.2 Nitrogen and Phosphorus  "Total" colourimetric digestion which of  and  methods  procedure.  makes  and  and  data  In  these,  (Sokal samples  formed  and  available a  as  a  the  individual Tukey's  (Greig  posteriori comparisons out  using  the  assumptions  of a  programmes.  Arcsine  necessary  valid  the  ANOVA  and  with  using  Mineral the  first  Tukey's  package. w a s checked  of variances  soil  test.  Conformity using  sample  level,  the  sizes  Both  the and  ANOVA  programme  were  analyzed  the treatments.  These of  floor  while  1981; Dowdy  data  as  blue  1982).  T h e forest  statistical  sites  formation  Sommers,  unequal  and Rohlf,  and natural-log transformations  to achieve homogeneity  the  ANOVAR  1978).  I ANOVA,  GENLIN  formed  the  method,  1978; B r e m n e r  samples.  with  blue  to m o l y b d e n u m  a posteriori comparisons.  using  performed  from  Corporation,  ANOVA  (Sokal  and Osterlin,  were  reduction  floor  by  a semimicro-Kjeldahl  indophenol  1982; Olsen  sites  test  for the  performed  single-classification Model  carried  simultaneously  is determined  Instruments  two-level nested  second.  were  U.B.C.  P  and N e l s o n ,  1983) w a s employed  at  reaction;  b y the  carried out on a l l forest  1981);  the  comparisons  determined  is determined  1 9 7 1 ; Technicon  were  analyzed  Wearden,  N  1982; K e e n e y  a n d Rohlf,  were  complex a n d its subsequent  Williams,  analyses  were  concentrations  use of the Berthelot  Mulvaney,  Duplicate  P  on a Technicon A u t o A n a l y s e r following  a phosphomolybdate  (Twine  as  N  analyses  all  data  MIDAS  and  (Sokal and Rohlf,  to  A  were the  GENLIN  1981) were  i n the m i n e r a l soil N a n d P cases  118 respectively. N o transformations  The  monitoring  conjunction NO5-N  with  levels  containing organic the  g  of  oven-dry  of selected  latter  S i x ) . In equivalent  sample  trees  for - assessing  the  fall  of  of  Fisher  placed  at  on each  changes  1983,  Rexyn  the  resins in  NHJ-N  and  nylon  mesh  bags  201  (OH)  strong  base  F / H interface  interference sites in  were  with  resins  solution after  The  kept  performed. by  in  30-50  P  their  minutes, then cold  of  Resin data  anomaly  in  were  bags  in  Bartlett's  test  according  to  a  storage  were  were  left  then  to  cm  from  T M and  discussed the  tests  (Sokal Layard's  above. for and  T3  homogeneity.  test  with  for  1.7°C)  until  1981),  (Layard,  months 2 M KC1  fashion data  variances  but  weakly  1973;  Greig  were  hours.  Extracts could  be  colourimetrically Corporation,  to the  mineral  exhibited a  slight  homogeneous  heterogeneous and  24  paper.  Instruments  transformed  The  ml  analyses  concentrations  (Technicon  the  100  W h a t m a n N o . 41  2  microbial  resin exchange  approximately  statistically in similar  However,  prevent  were shaken i n the solution for  H PO«  AutoAnalyser  Rohlf,  was  approximately 12  extracted  equilibrate  (approximately  processed  sites  per cent of the  retrieved after  gravity-filtered t h r o u g h  Technicon  data  five  (1984). T h e bags  then  other  m e r c u r i c chloride solution to  Aliquots were used to determine  means  1971a). soil  30  solution was  were  T h e bags  H a r t and B i n k l e y  approximately  a  collected ions; a p p r o x i m a t e l y  so saturated.  situ. T h e  with  on  in  30  site. A l l "plots" of the  placement  was  16 and  treated  resin  exchange  selection among sample "plots". T h e m e s h size of the beads was between were  for  ion  random  A l l bags  selections  were  by  data.  by  50.  resins;  the  beads  for the forest floor  availability  2  Chapter  anion exchange  had  H PO«  use  (see  11  bases  sites  the  of  were necessary  Bjerring,  (p  = 1980).  by 0.02) To  119 circumvent ANOVA  any  and  weak  heterogeneity,  subsequent  the c u s t o m a r y p =  the  comparisons  nominal  was  taken  significance to  be  at  threshold =  p  0.01  for  the  instead  if  0.05.  5.3.3 Carbon and C/N Ratios Carbon  A stage  subsample  composite  was  ground;  subsamples  material  through  approximating used i n the  On C,  the  of between ground were  the  obtained  0.5  assumption  mm  was  that  determined  high-temperature  induction  0.75  and  1.50  KOH  to  employed  a  0.5  by  sieve.  mm  Of  Mineral  subsampled  floor  soils  approximately  these  floor  of each forest  sieve.  passing  was  condition  system  the  g  iron  five  second-  were  not  grams  of  fractions,  weights  a n d m i n e r a l soil respectively were  before  systematically  20  chosen  samples  could  u s i n g total C procedures (Nelson  and were  the  generated;  C0  2  based.  each  run.  Blanks In  added  be  with  Sommers,  accelerators  volumetrically  samples were included at the approximately  a l l C i n the  furnace  absorb  concentrations  of  pass  0.05 g and 0.2 g of forest  the  tin  to  three g r a m s  C determinations.  latter  g  two a n d  to  a  LECO  1982). each  thus,  LECO  only)  20% of each  Duplicate run,  analyses  plus on a n y  were samples  521  Approximately The  measure were  one-gram  beginning a n d end of each run—each  samples.  Model  sample.  the  (accelerators  addition,  considered organic  unit  of  C  used  to  standard  r u n consisting  performed yielding  on  a  apparently  120 unusual  readings.  readings  were  instrument, the  In  taken  and  cases  as  the  of  noticeable  data.  Readings were  a correction for  atmospheric  calculation of C concentrations.  analyses,  so  that  unusual  or  discrepancies, taken  on the  temperature  T h i s calculation was  anomalous  averages  readings  1.0  and  the  at  easily  two  g scale of  pressure  done  were  of  the  applied i n  the  time  of  the  and  immediately  checked.  T h e forest  floor  single-classification employed  for  necessary  to  ANOVA  with  acceptably sufficed  to  provide  sites  as  the  carrying  out  study,  the  believed Wolfe,  a  Hollander  give  a  of  be  found  (1984). jackknife  Detailed in  Sokal  homogeneity  of  (1974).  the  conflict within  1973;  the  confidence  intervals  acceptable  result  was  in  using this  a  was  transformation  was  assumptions  The  no  data  were  tests  with  and median the  of  samples,  methodology  non-parametric and  as  test  soil  regarding  Sokal  Tukey's  variances.  Kruskal-Wallis  some  programme)  the  mineral  95%  Rohlf  power  variances;  Wolfe,  discussions  limits  the for  Rohlf,  of  framework  1981).  In  this  T u k e y ' s jackknife  was  respect  (Hollander  and  t h a t m a r k e d departures from n o r m a l i t y existed i n of  the  jackknife  (1981),  Efron  F o r this i n v e s t i g a t i o n , a computer confidence  A  However,  is  GENLIN  treatments.  and  reasonably  and  among  comparisons  1973), since it appeared  data.  as  means.  non-parametric  There  posteriori  construction  to  the  Wold  treatments.  (using the  sites  among  met.  analyzed u s i n g the  1971;  the  homogeneity  therefore  (Gibbons,  analyzed  comparisons  achieve  transformation  were  ANOVA  the  were  data  written  and  its  and  Gong  programme  on  the  basis  various  applications  (1983),  and  Gregoire  for calculation of the of  the  formulae  may  Tukey  given  by  121 Carbon:Nitrogen Ratios  C/N ratios were calculated for each second-stage composite the  N  and  average  C concentration  values  obtained.  For the  organic  sample  using  materials,  the  N value from the duplicate analyses was applied. The data for forest  floor and mineral soil were analyzed statistically  in the same way  as outlined  above for C, with the exception that no transformations were necessary  for the  forest floor ratios.  5.3.4 Potassium, Calcium, and Magnesium  Exchangeable K, Ca, and Mg were determined by an ammonium acetate (NH„ OAc) extraction method followed and Suhr, 1982; Knudsen et al, From each forest placed  in  60  by atomic absorption spectrometry  1982; Lanyon and Heald, 1982; Thomas, 1982).  floor and mineral soil sample,  ml  of  (Baker  approximately  IM  five  NH„ OAc  grams  of material were  solution  with  a  pH  of  approximately 7.0. These were then shaken mechanically for one hour, then left standing Whatman  for at least one No.  41  paper  more into  a  hour. The solution was 100  ml  volumetric  then  flask.  filtered through  The  material and  container were then rinsed with a further 40 ml of N H OAc in 20-ml aliquots; a  the leachates were filtered into the same flask. The filtrate was made up to 100 ml with fresh NH„ OAc, then placed in cold storage (1.7°C) to await analysis. Two blanks  (NH OAc 4  only)  were included with  each  set.  The extracts  analyzed using a Perkin Elmer Model 4000 atomic absorption  were  spectrophotometer.  An air-acetylene flame was used for all three elements (Allen et al., 1974; Baker  122 and  Suhr,  1982;  The  Lanyon and Heald,  forest  floor  K , C a , and M g data  ANOVA,  and no transformation was  analysed  using  construction above  of  (Section  classification  the  Tukey jackknife  of  variances.  statistical  did not  analyses  soil  the  and median  assumptions this.  data  as  described  Power  posteriori comparisons  were  performed using  necessary  were the  done  MIDAS  analyzed  by  problems, with the individual sites as the treatments. were  successfully  followed  single-  C a and Mg data  were  They were  tests,  limits—in similar fashion  of  as  the A  confidence  Mineral  fulfill  found which could achieve  non-parametric Kruskal-Wallis  ANOVA  transformations of  the  1982).  to  by  achieve  Tukey's  homogeneity method.  and G E N L I N  The  programmes  as earlier discussed.  5.3.5 Unit-Area Elemental Weights  In estimated were  mean  multiplied  foregoing Chapter from  order to  the  soil  estimates  weights of forest by  Sections. Four.  obtain  of elemental  floor  and mineral soil  the  mean  concentration  The  forest  floor  Mean profile  bulk  densities  samples  were applied to an assumed  data  weights of  contents  the  collected  for  of  soil volume of 1500  (to  obtained the  sites  mineral soil that  on  3  ha"  unit-area  a depth of as  described  were  fraction  purpose m  a  dealt were  (Chapter 1  for the  basis, 15  cm)  in  the  with  in  calculated  Two). 0-15  These  cm. soil  layer.  Since corresponding 95% confidence  limits were also calculated, the  method  123 used  to  derive  the  unit-area  weights  needs  of the  form:  be derived b y simple functions  u  =  some  elaboration.  The  weights  would  xy  where:  According estimator errors  of  u  =  derived elemental m e a n  x  =  mean  weight per hectare of soil fraction;  y  =  mean  elemental  to  Black  of the the  error of the  (1984),  resulting  the  components  in  are  derived q u a n t i t y  Au  mean  the  above  normally  square  /[(Ax)  distributed.  +  2  (R.M.S.)  function,  m a y be calculated as  =  hectare;  concentration.  root  error  weight per  on  For  error  the  a  good  assumption  this  (Black,  is  case,  that  the  R.M.S.  quantities  used i n  1984):  (Ay) ] 2  where:  Au  =  relative error of the derived m e a n  weight;  Ax  =  relative e r r o r of the  weight;  Ay  =  relative error of the elemental  Calculated 95% confidence limits were the  weight  derivations.  expressed  as  expression  of relative  i n t e r v a l of the  a  The  percentage error.  variable.  The  the  concentration.  available for each of the  difference of  soil fraction's  between  the  corresponding  resultant  R.M.S.  upper mean,  error  was  and was used  lower used as  limits, as  the  the  95%  124  5.4 RESULTS A N D DISCUSSION  In because  the  absence of declines i n forest  of the  placed  on the  method  used  to  concentration  derive  data  floor  weights (Chapter  unit-area  for interpretive  Four),  and  also  weight estimates,  emphasis  was  purposes.  soil  Mineral  weight estimates  h a d r e l a t i v e l y wide confidence intervals associated  doubt  due  this  samples  was  to  the  low  number  and  variability  of  elemental  with  the  them;  bulk  no  density  taken.  5.4.1 pH Values  The sequence among mineral soil:  p  trends are  the  means The  the  mean  ranged soil,  of  both:  0.001, F (p  <  than  approximately approximately between  forest  =  floor  the  4,  6.9).  In  mature  4.3 floor  to  the  soil  There  were  different  the  forest  mean  was 4.1  mineral  45; forest  themselves pH  5.1.  the  higher  except  4.0  for  =  0.05)  and  Figure  df  approximately  a l l cutovers  values  in  cutovers  forest  from  floor  p H values  (for  significantly  forest  presented  mean  soil <  of  did  sites  floor:  to  4.3  values  not  differ  T3  had  stand.  The  each,  while  4.4.  Within  of  of  for  (p  the  <  the  sites,  =  and  T8  stand. each  For  the  T3  had The  other.  stand,  higher  cutovers  very  the  mature  and  floor  4.1; m i n e r a l  from  0.05)  age  differences  mature  sites.  TM  remaining  individual  F  significantly  the  forest  except  the  harvested  means  the  0.01,  than  3.9  significantly  those the  the  i n both <  across  significant  a l l cutovers  pH  for  values  very  p  floor,  approximately  pH  and  mineral  mean  pH  sites  were  ranged  from  significant  differences  a n d m i n e r a l soil m e a n p H values were found on the  T 3 and  125  V e r t i c a l b a r s are 9 5 % c o n f i d e n c e limifs  4.8  -i  4.8n  3.8 H  3.6  J  3  4  Y E A R S  55  T  6  AFTER  7 7 8 89  10  11  l 12  H A R V E S T  Figure 5.1 Means and 95% confidence limits of the pH values across the age sequence.  126 T 8 sites only. mineral  soil  F o r the  (p  <  T 3 site, the  forest  floor  0.01); however, the reverse  had  a higher m e a n  w a s true for the  p H than  the  T 8 cutover (p  <  0.05).  The a  clear  mineral  above  increase soil  disturbance the  i n the  temporary  pH  viewed apply (T3)  with  values. as  appeared  but  lagged to between  eleven year  forest  was  case.  only one its  near that  floor  sequence values  between  higher  disturbance  a  at  which  the  p H values  organic  the  H o w e v e r , data  changes  and  p H values  ESSF than  therefore  the be  and  in minor  floor  overlying  viewed  as  within constant for  the  is  not  vegetation  values  at  this  the  can does  three-year  be not  point  p H value w a s n u m e r i c a l l y reported  Lloyd  mineral  the  supported by  however,  be and  of  point  forest  u n d e r l y i n g m i n e r a l soil  forests  floor  six years  mineral  changes;  (1974)  from  to  years  eight-year  idea is s o m e w h a t  Kimmins than  three  sustained  the  with  mean forest  forest  and  A v e r y interesting observation is t h a t  Kamloops  may  T3  the  three  be  appeared  e x a m i n e d . T h e reason  at  m i n e r a l soil  m i n e r a l counterpart.  the  to  possibly associated  l a g i n the  P r i n c e George. in  of both  to occur w i t h i n  generally appeared  difference  consistently higher  the  point.  the  of the  T8  the  consistently of  The  part  than  show  floor,  h a r v e s t i n g there  in p H values  increase  least over the in  units  following  concomitant litter input quality. T h i s  was  stands  0.3  effect  obvious. It  to the  higher  The  decline  immediately  T8  about  forest  soil.  one, l a s t i n g at  the  of  indicate that  materials. The  mineral  and  results  (in soil  forest  surface  18,  horizons  layers. The  around  layers  i n spruce-fir  litt., A p r i l  floor  strongest  floor  the  1986) have impact  three-year  127 Comparison literature  should be  example, 18,  the  1986)  and  within  observed  the  context  as opposed to ranging from  respectively  For  values  L F H value  3.6  of  study  and  methodological  to  4.4  and 4.1  mature  in  (4.9),  this  calcium chloride). Lloyd  under  determined  in  ESSF  of  the  differences  (for  (in  study  water,  Kimmins  litt., April  5.1  stands;  of this  with the  to  those  for organic these  were  fell entirely within the (1974)  observed  a  underlying Ae ranging from 4.0  units. Since the latter should be slightly higher than values determined in chloride  terms  of  noticed  were  post-harvest  based  after  values  harvesting  on very in the  Wallace  p H values  the  differences.  disturbances  sites,  1982),  in  with those of Kimmins  p H changes  (1985)  hardwood  (McLean,  in agreement  conclusions  fir  of water  constant  sufficiently  among  viewed  layers  ranges.  calcium  Martin  p H values  in calcium chloride. The values  remarkably to 4.6  the  reported values  determined  In  use  mineral  latter  of  and  with stand  in Newfoundland, Page  in  However,  this  of site  Freedman age.  B . C . , neither Martin  felt  Haskin  (1985)  similarly  noted  that  sites  preparation treatments.  By contrast,  to  (1985)  cautioned  Haskin's (1985)  (1986)  be  nor his  all had  On eastern  no  differences  following clearcutting of balsam  an increase  of approximately 0.5 p H  units in surface organic and mineral layers. There was  a subsequent decline past  approximately increased  five  pH  phenomenon—for  to  levels  (1974) observed  are  (1974) for comparable fractions.  limited sampling. form  study  seven  years  following  example,  after  harvesting  possibly  limited  similar to those of the E S S F moist subzones  cutting. may to  site  Therefore, be  a  and  in this study.  it  may  broadly disturbance  be  that  site-specific conditions  128 5.4.2  Nitrogen Concentrations  Patterns  of N concentrations in the forest floor and mineral soil materials  are illustrated in Figure 5.2. There were highly significant differences among the means =  of the sites for both organic and mineral fractions (both: p <  4, 130; forest floor: F =  the other  T3 site  had  sites;  none  a  13.5; mineral soil: F  significantly  of the  (p <  0.05)  remaining means  =  25.3). In the forest  greater  was  N  cutovers  had  significantly  1.11% to 1.28%. For the (p  other sites, but did not differ remaining sites  <  0.01)  from  different  from  the any  1.53%, while those of the  mineral soil, the T6 and T8  lower mean  significantly  floor,  concentration than  significantly  other. The mean N concentration of the T3 site was other sites ranged from  0.001, df  N  concentrations  than  one another. The means  ( T M , T3, T i l ) were not significantly  different  from  the  of the  each other.  The mean N concentrations of the T6 and T8 cutovers were 0.11% and 0.09% respectively; those of the other sites were between 0.16% and 0.17%.  From the above result, it would appear that there was an actual increase in forest floor N concentration within the first three years after harvesting. The increase may be due  to fresh inputs from  slash  and  fine roots—especially the  finer materials, and also to a subsequent change in the quality of litter with the invasion  of  herbaceous  pioneer  vegetation.  The  increase  was  temporary,  disappearing by the sixth year following disturbance; moreover, between the sixth and eleventh year there may have been a tendency  (non-significant) towards  the  development of even lower concentrations than those of the mature stand (Figure 5.2). In the absence of significant forest floor weight losses, this would imply the  129  0  J  0.25-1  MINERAL SOIL (0-15 c m )  0.20-  0.15-  ."o 0.10-  0.05-  1  | 0  1 1  1 2  1 3  1 4  Y E A R S  1  1 5  6  AFTER  1 7  8  1 9  1  1 10  1 11  1 12  H A R V E S T  Figure 5.2 Means and 95% confidence limits of the N concentrations of forest floor and mineral soil materials across the age sequence.  130 possibility  of v e r y minor temporary  part  of the  time  sequence.  the  mineral  soil  fraction.  m a t e r i a l inputs noted pattern  of  than  inputs  changes  the  pool of N  year  N  (mature  mature  concentrations mineral  soil  values  observed  in  values  from  values  in  (1974).  in this N  forest  may  ignition.  floor  (1985) on the  forest  as  study  a  floor  N  have  been  B y contrast,  is  very  layers. With there  and  by  have  to  data  the  benefit  to be  far  more  influences  definite  fractions  of The  from  declines i n  fraction. H o w e v e r , by the  m i n e r a l soil  from  mark.  but  no direct major  latter  the  three-year  similar  appeared  m i n e r a l soil  fall  two in  pattern  and  to  appeared  of  of organic  with the  age  litt., A p r i l  is  eleventh to  return  ESSF  zone  had  forest  floor  and  1986).  The  18,  ranges.  Compared  1974),  lower; however,  greater after very  (1981)  than  those  harvesting, close  to  that  for  to  organic  mineral  soil  of  Kimmins  the  increase/  observed  by  observed no significant change sites.  However,  c o m p a r i s o n variable employed; he  expressed  matter,  for  these  are  concentrations here  for  (Kimmins,  times  Covington  (1974)  in  within  study  Kamloops  0.06-0.29%  stands  three  N  the  (Lloyd,  of this  B . C . coast.  in  squarely  observed  because  sites  spruce-fir  value  were  Page  three  respectively  concentration  percentage  the  1.07-1.96%  study  C o n s i d e r i n g changes  decrease Martin  this  from  T3  extent  organic l a y e r s at  comparable  northerly  the  not  N levels i n the  levels.  horizons this  some  to  cover,  organic  stands,  more  a l l but  floor  to  floor  appear  year  surface  stand)  ranging  surface  materials  forest  the  did  surface  after  the  levels of both  Under  latter  i n vegetative  within  to pre-harvest  N  for the  for the  is supported  The  concentrations  pronounced and  This  declines i n forest  the  reported  eastern  latter  hardwood  being  decreases  determined  in N  as  concentrations  loss  on  within  131 approximately  seven  concentrations coniferous marked  mean  of  In  following  addition,  Cascades,  concentrations  evident  among  Matson  of forest  those  eastern  of the  spruce-fir  wave-form  and  floor  Boone  materials  stands;  diebacks (1984)  among  m i n e r a l soil fractions  of  noted  sites.  No  ( M a t s o n and  1984).  The  trends  those  of the  11.16, df  5.16,  of  floor  df  4,  mean =  4,  130).  <  mean  was  forest  floor  mean  other  values  fell  0.05)  significantly P  only.  In addition, the mean 0.07%,  Finally,  were  138)  lower  mean  all  others  in Figure  0.11%,  <  5.3. T h e forest (p <  were  0.05)  that  the  T6  the  rest  were  of the  r e s i n - P concentrations  (p  of the  <  T6  site  only.  T8  the  T8  all  0.001, F  the  0.001, sites  T8  The  T6 The  means  of  T i l site  were  approximately F  =  =  The  T3 mean.  sites  F  was  0.12%.  those of the  than  and  significant differences  site  floor  observed  mean.  m i n e r a l soil,  higher  the  T8  T3  higher than  of  <  and  0.001,  also  of the  the  of the  and  In  mean  except  significantly  of  concentrations,  among sites  the  that  0.14%.  (p  was  those  highly  case,  was and  P  m i n e r a l soil fraction (p  (lower) from  concentrations  also  mean  significant differences  floor  than  0.13%  while  soil  presented  i n the  forest  T8 mean  among the  are  highly  significantly  P  approximately there  the  different  between  T 6 and T 8 were  soil  Similar  concentration  sites  mineral  In  mineral  significant differences  P concentrations 130).  (p  and  resin-collected P ,  =  significantly  4,  forest  P values exhibited h i g h l y  a m o n g the  =  Oregon  clearcutting  Phosphorus Concentrations  also  =  the  in N  seemed  of  thereafter.  in  differences  Boone,  5.4.3  increased  forests  differences  years  The both  0.06%. 6.0,  (Figure 5.3).  df The  132  Vertical bars are 9 5 % confidence limits 0.16-1  ± O  0.14  H  0.12  A  0.10  H  0.08  FOREST FLOOR (F+H)  J  0.10-1  MINERAL SOIL ( 0 - 1 5 cm)  0.08-  O !o  0.06-1  0.04  J  16-i  "a> O  14-  <°  12-  |* ^Q_ c '(/) <D #  ANION RESIN (at F/H)  10864_| 2  J  I  I  I  0  1  2  I  3  I  4  Y E A R S  Figure  I  I  5  6  I  7  A F T E R  I  I  8  9  I  I  I  10  11  12  H A R V E S T  5.3 M e a n s and 9 5 % confidence l i m i t s o f the forest P concentrations, including r e s i n - P concentrations.  floor and  mineral  soil  133 Til  mean was  significantly  not  significantly  were  not  sites.  Assuming  significantly  concentration from  noted  relatively  concentrations regeneration. of  an  years.  The  which  the  This  point  lowest pool  by  is  any  the  of  in  eight, forest  floor  m a r g i n a l d o w n w a r d movement This  movement  peak  of this  seemed  movement  resin-P data (1982),  mechanisms  for  the  such  results  pattern  T M and the  as  resin  around  mean  P  to  that  the  fraction  some  of  the  years sixth  in  terms  there  a  slight,  was after  (or  the  point,  Although  not  clearly  a  even  lower)  a  three  following  towards  following and  well  as  in  is  useful  measuring  in  marginal  eighth  levels.  temporary  the  years.  The  The  availability.  root  and  years.  harvest.  approximating  phosphate  P  advance  sites, spread over two to three  three  between  in  interpreted  was  pre-harvest  differences  growth  six-year  levels.  evident,  changes  organic layers  pre-harvest  return  method  T3  ranged  been  of these  small  can be  implies  occurred its  ranges  significance for  the  of P on the  occurred  means  of others  a n d m i n e r a l soil patterns i m p l y  initiated  T8  involved,  . Those  1  and  trend  gives some support to this conclusion. According to O l s e n the  P,  of  was  and  i n the  a  T6  site P variables have  whether  m i n e r a l soil  then  bag"  pool of P  to  the  mg  practical  floor  this  those  species  magnitudes  notwithstanding, forest  or  The  .  1  debatable  restored  trend  4.3  those of the T 6 and T 8 , but  means.  other  a m o n g the  It  point  year  together,  Sommers  was  absolute  had  T3  ionic  2  the  The  was  the  each  H PO4  i m p o v e r i s h m e n t of the  enrichment  of the  from  the  have  pattern.  demonstrated,  Taken  small.  lower t h a n  T M and  10.7 m g bag"  that  could  assart  temporary  the  significant differences  should be  were  0.01)  T i l cutover to  1  from  only  the  6.6 m g bag"  <  different  that  on  While it  different  (p  and  uptake  While  the  134 earlier  portion  of the sequence  resin-P implies a rise the of  forest  floor  logging. forest  This  floor  P were  increase  were  1986)  included  direct  comparisons.  this  used  ESSF only;  the trend well  three  a n d eight  mobilization  of  levels  years  of P  %  with  i t c a n be concluded t h a t  through  those  those  than  of  those  not  a n y major  observe  they  (1974)  observed  have  after  from  its  with  soil  variable t h a n  However,  floor  the m i n e r a l  soil  Wooldridge  (1970)  for  soil  Morash  (1985).  published  their  forest  several  were  have  Concerning data.  differences  with  values  unfortunately, P  levels  concentrations sites,  softwood  Lang  of  of  (1974) for  P concentrations  under  in  actual  concentrations  coniferous  two P  are are but cover times  following  et al. (1981) d i d  age a m o n g  were  been  no reported  approximately  comparable  floor  resins  floor  a n d M o r a s h (1985)  concentrations  precluded  those of K i m m i n s  T h e forest  of F r e e d m a n  differences  almost  study;  T h e forest  (in litt., A p r i l 18,  the  been  w a s one such  P concentration that  although  there  dealing  Lloyd  study.  w a s little  noted  from  of the latter  and  there  sources  methodological  resin-P,  not published.  Mineral  Freedman  Data  moreover,  (1986)  forests.  literature  forests.  extractions,  et al.  disturbance,  Page  soils  were  Canada.  of  However,  principally  few available  under  spruce-fir  to  higher  Eastern  those  Thus,  slightly between  are v e r y close to b u t more  similar  slightly in  Hart  to three times  also  increased  i n laboratory  northerly  two  patterns.  F o r ion exchange  concentrations  study  more  soil  relatively  mineral  situ applications. resin-P  differences,  i n plant-available P coinciding e x t r e m e l y  occurred  P concentrations  frequently  no significant  pool.  There "total"  a n d fall  and mineral  plant-available  exhibited  generally  decreases i n "available" P of 20-50%, followed  their very  stands. high.  b y recovery,  135 in surface  5.4.4  organic l a y e r s ; m i n e r a l soil levels varied little.  Exchangeable Potassium, Calcium, and Magnesium  Figure forest  floor  5.4  and  significant  In  <  0.001)  among  significant  differences  130, p  0.001; F  the  =  those  other  sites.  themselves.  A s stated  forest  mean  means  ranged  concentrations 95%  significantly  were  sites  me  than  T8  respectively.  The  >  the  0.05)  the  was  K  highly Ca  floor M g  differences  there  the  and  forest  were  were highly  (both: df  no  was  0.8  to  1  1.4  significant  (100g)"  me  me  (100g)"  (100g)"  significantly  stand.  fell  me  In  1  and  1  =  4,  mean  K  ; the  1  1  these  differences  other  . Mineral  forest  the  T 8 values. T h e  between  lower  no differences.  higher  me  floor  than among  The  forest soil  T6  mean  mean  (100g)"  1  extremes  floor  mean  for  forest the  (Figure  T8 floor  . F o r C a , according to  addition,  20.0  forest  significantly  m i n e r a l fraction showed  (100g)"  others  around  exhibited  T M , T 3 , and  me  floor  for the  However,  concentration  latter  mature  11.3  (p  detected  C a and M g concentrations  intervals  showed  the  forest  0.01) differences  a l l a p p r o x i m a t e l y 0.2  the  for  tests  M g for  10.1 for C a and M g respectively).  (100g)"  sites  sites  significant  mean  the  The  above,  1.1  than  were  no  concentration  all  higher  concentrations T6  from  intervals,  concentrations  K  <  K , C a , and  non-parametric  among  confidence  that  The  concentrations.  18.3 and  95%  indicated  floor  K  a m o n g the  jackknife  the  fraction,  mean  concentrations of  differences  mineral  observed  The  patterns of exchangeable  and v e r y significant (p  the  <  the  m i n e r a l soil components.  (p  concentrations, values.  illustrates  K the  mean appeared floor  Ca  T M and 5.4).  The  136  V e r t i c a l b a r s are 9 5 % c o n f i d e n c e limits  FOREST FLOOR  0 1 2 3 4 5 6 7 8 9  10 1112  YEARS AFTER  MINERAL SOIL  0 1 2 3 4 5 6 7 8 9  10 11 12  HARVEST  Figure 5.4 Means and 95% confidence limits of the forest floor and mineral soil exchangeable K, Ca, and Mg concentrations.  137 mineral  soil  Ca  significantly However, the  (p  and  3.6  me  that  the  forest  than  those  concentrations  than  and  the  were  of  mean T6  of  the  T6  sites,  Finally,  mean  T M , T3,  and  T8  were  the  were  with  of  the  T3,  T8,  and  and  2.2  me  (100g)"  exchangeable  from  viewed  within  exchangeable  bases  within of  a l l but  of the  these  and the  T3  me  site  of  fractions  are  concentrations value.  these  limitations. T h e  data  levels c u l m i n a t i n g around the  soil  the  P  case  earlier, this  components—though  T3  (100g)"  the  earlier,  site  had  The and  1  apart  0.5  quite even  comments  0.05) a  mean greater  significantly of the  me  (100g)~  the  Ca  short  which  to  for  the  this,  the  term  follow  detracts  should  gradual  eighth y e a r  and  recovering by  suggested  differences  are  1  trends,  and  is  T3  these values.  Added  the  Mg  slight  trend  a  floor  encountered  small.  were  The  means  from  differences  imply  values  suggested  forest  (p <  1  significantly  respectively.  1  T i l site.  over  The  (100g)"  site  was  mean  sites falling between  ranges  other  those of  significant differences  T i l  the  the  concentrations  interpretive  K  0.3 other  their  Unlike  mineral  B y contrast,  than  phosphorus  magnitudes  nature  further  eleventh.  sites.  approximately  the means  the  absolute  transitory  other  1.4  was  values.  higher t h a n  the j a c k k n i f e 9 5 % limits  The  2.1,  T6  with  T 8 and T i l sites. N o other  2.7,  The  C a concentrations  M g concentration  M g concentration  sites  As  and  pattern.  also significantly  control and  means.  a l l the  respectively, w i t h  the  was  (Figure 5.4).  of the  those  m i n e r a l soil  the  mean  this  soil M g concentration of the T 6 site w a s significantly  those  lower  floor  among  mineral  Mean  these two  than  T i l mean  for  1  paralleled  greater  the  sites.  (100g)"  between  apparent  0.01) case,  T3  lying  higher  <  i n this  T M and  concentrations  i n both  be  decline i n  forest  non-significant  in  the floor the  138 latter of  instance.  the three  soil  bases  fractions  beyond  levels  of the time  three  years,  T h e M g data  of this  element  sequence. then  appeared  returning  to pre-harvest  readily  apparent.  I n a n y case,  except  exchangeable  tree  results cation here  T h e C a result  of K l i n k a  et al. (1980).  therefore  suggests  (albeit  somewhat  fraction's up to a  A clear  i n the forest  is itself  extremely  I n the latter  not v e r y  a post-harvest  floor  well)  with  increase  usefulness. 1986) this  are slightly  ESSF higher  o v e r l a p p i n g those  concentrations ranges. generally  data  with  those  o f other  soils  under  mature  i n general,  of L l o y d .  exchangeable  With  exchangeable  (Lloyd,  base  in litt., A p r i l  concentrations,  but with  of this  year s i x  trend  is not  i n light  have  of the  C a w a s the  growth)  very  limited  (in litt., A p r i l 18,  cover.  T h e K values of floor  concentration  of m i n e r a l soil  M g , the  i n the middle of L l o y d ' s those  Compared floor  in all  possibly beyond.  the forest  overlap w i t h  a l l the forest  at  productivity. T h e result  of Lloyd  fall  floor  i n the latter  the changes  studies  the exception  18, 1986).  Forest  q u a l i t y (for forest  forest  cation fractions  T h e m i n e r a l soil M g concentrations lower  those  lasted  h a d a n y m a r k e d impact  forest  o f other  T h e values compare f a v o u r a b l y w i t h  for comparable  study  ranges  o f these  maximum  exchangeable  i n site  and m i n e r a l  M g declined w i t h i n the  interesting  study,  the clearest  C a ; this  slightly  explanation  w h i c h lasted for the period covered b y the sequence—and  Comparisons  floor  inconclusive.  to decline  to increase  C a concentrations  correlated  forest  it is open to question whether  growth.  best  were  appeared  levels.  be considered  levels o f exchangeable  T h e m i n e r a l soil  before  on  might  h a r v e s t i n g , both  exhibited increased  the eleventh y e a r .  portion  i n C a concentrations  examined. F o l l o w i n g  generally  exchangeable  first  T h e trend  of L l o y d , to K i m m i n s  values  as  well  b u t are (1974) as the  139 mineral soil Mg concentrations of this study are much lower. Mineral soil K and Ca  values  are  similar to  those of the  latter  study.  The mineral soil cation  concentrations of this study fall well within the ranges observed by Van Ryswyk (1969) in subalpine and alpine soils further south disturbance  patterns,  although  there  were  in B.C. In terms of post-  analytical  differences,  these  results  agree very well with those of Covington (1981) for the Hubbard Brook sites. He found no major trends with stand age in K or Mg concentrations; however, there appeared to be a significant increase in Ca concentrations in the earlier portions of  his  age  sequence  (Covington,  1981).  In  the  main  Hubbard  Brook  study  (Bormann and Likens, 1979), stream-water concentrations of K, Ca, and Mg were dramatically increased (as much as  11-fold)  losses commenced within weeks of the  within the first three years. These  disturbance. In this  study,  revegetation  was not suppressed as at Hubbard Brook; however, the possibility exists that the cation fractions with increased levels after harvesting may have experienced losses in stream-water. Where Ca is concerned, the results of this study are similar to those of Page  (1974); however,  subsequent  declines  were  noted  in the  latter  study. The trend of Mg values in the mineral soil are also similar to those of Page (1974). The pattern of K values and forest floor Mg concentrations do not follow those of Page (1974).  5.4.5 Carbon Concentrations and Carbon:Nitrogen Ratios  Patterns of C concentrations and C/N ratios in the organic and mineral fractions  are  presented  in  Figure  5.5.  Forest  floor  mean  C  concentrations  exhibited no significant differences among themselves (p >0.05, F =  0.9, df =  140 V e r t i c a l b a r s a r e 95% c o n f i d e n c e limits  4 5 -i  FOREST  FLOOR  MINERAL SOIL  6-i  5-  404(_>  35-  30  H  35  35-i  30-  30-  25-  25-1  20  20  q "5  15  J  I—I—i—I—l—I—l—I—l—l—I—l I 0 1 2 3 4 5 6 7 8 9 10 1112  15  YEARS AFTER  r~l—I—r—r~l—I—i—I—i—i—I—I 0 1 2 3 4 5 6 7 8 9 10 1112  HARVEST  Figure 5.5 Means and 95% confidence limits of the forest floor and mineral soil C concentrations and C/N ratios.  141 4,  130).  0.001)  B y contrast,  differences  jackknife  95%  the  among  of the  those  T M and  different;  however,  the  T i l site.  For  the  and  in  fractions  (both: p  T3  sites.  T6  and  floor  the  T8  <  addition, the  T6  The T8  significantly  between indicated  the  T M and  that  all  lower  than  that  mean  ratio  was  the under  T i l  significant differences  from  19.8 on the site h a d the  The  C  concentrations mineral  soil  mineral  <  =  29.6 on the  the  other Forest  floor  of  forest  there  was  data  floor a  indicate  mean  T 8 site. F o r the  organic  noticeable  that  matter  there after  decline; this  the  were  the  forest  a l l others; T M but  were  detected  95%  limits  significantly  sites,  the  latter  exhibited  C / N ratios  T i l  ranged  m i n e r a l fraction,  the  lowest (24.7).  no  major  disturbance. reached  were  the  were  cutover  cutovers;  39.9%.  m i n e r a l soil  jackknife  highest mean ratio (31.1) a n d the T i l the  concentration  and  than  C / N ratios  Among  the  The  of  T M (4.8%)  130). I n  higher  that  to  0.05) lower t h a n  ratios.  mean  among themselves.  4,  than  differences  significant differences  mean  stand.  i n the  floor  C  significantly  37.2%  significant  2 0 . 5 , df  soil  from  forest  lower  not  < The  mean  lower t h a n  highest  significantly  lower t h a n  T 3 site to  were  (p  values.  soil  were  ranged  =  T i l . No floor  mineral  significantly  both  were  fraction  means  for  F  significant (p  a l l significantly  Highly  significantly  mature  significantly  T3  were  soil  the  were  T M and  floor:  forest  the  cutovers  values  the  cutover  that  (2.3%).  means  from  mineral  C concentrations  0.001; forest  different  indicated highly  C concentrations  site  T8  the  means  materials  and  for  T5  mean  C / N ratio  tests  indicated  case, the T 3 m e a n ratio was  not  TM  the  the  among  no  limits  T 3 , T 4 , and  Forest  detected  in  groups  m i n e r a l fraction, mean  lowest  floor  the  confidence  concentration of the  non-parametric  its  changes  However,  m a x i m u m at  in  in the  about  142 eight  years  after  logging,  organic  matter  levels  values.  Given  the  (Chapter floor  mineral  pool  materials. arisen  acceptable if  true,  activity. a  is  not  downward  would i m p l y  changes  more  from  sequence.  the  organic then  matter  outstripped  The organic values quickly ratios  ratio  mineral  soil  pre-harvest  continued concepts  been  the  affect  decline  this  i n the  (Chapter mineral matter  extent  have  that  the floor  m i n e r a l soil could  have  would  reflect could  the  be  more  floor  materials;  this  increased  have  come  from  sampling  zone.  This  0-15 c m fraction were  i n the  required  inputs  the  in  forest  declines  pool above  forest  recovery  than  should  of  sequence  levels i n the  o v e r l y i n g forest  outside  point,  pre-harvest  the  explanation  outputs from the floor  to  and  more  i n the  Six) soil  ll^year  across  matter  activity. This  would  patterns  w i t h i n three years to  forest  of  the  returned  layers  i n organic  occurred  matter  yet  F/H  pattern  microbial  recovery to  of  At  a  from  first h a l f  of the  slowing i n above  first  the  not time  rate  balanced  of and  losses.  C/N  and  developed have  output  the  not  concentrations  organic  organic  initiated.  had  impacts  indices  of  balanced b y inputs Further,  The  p l a u s i b l y , the  movement that the  soil  change  had  availability  was  weights  matter  increased  if similar  Perhaps  in  assart  organic  greatly  N  mineral  surprising.  implies t h a t  the  recovery  lack of major  Decreased  from  the  similarity  F o u r ) , the  materials  in  then  a  components, after  levels gradual  of the  questioned  in  present  the  and  an there  harvest. even  decline  interesting was Forest  definite  floor  s l i g h t l y higher. over  time.  control of C / N ratios recent  a  times.  As  over N  However,  picture.  ratios  For  decrease returned  B y contrast, noted  both  earlier,  in  as  the  ratio  relatively  mineral  soil  previously  availability i n forest  insofar  the  C/N  soils ratios  143 influenced the  decomposition  three-year  processes) would  might  have  remained first  mark  and  suggests  have  been  three years  been  quickly  i n effect  N  that  N  greatest  arrested  i n the are  m i n e r a l i z a t i o n processes, availability  within  in  the  the  forest  entirely i n consonance  (and  first floor  m i n e r a l fraction. T h e  the  perhaps  three  what  but  of both  to  initial  ratio  values  is probably  a  result  m i n o r vegetation and litter inputs. B y contrast, mineral  soil—buffered at  changes—is  unexpected  concentrations stand.  The  studies  must  data C  1.6%  to  my  the  study  are  this  ratio  values  of  how  the  validity  phase  from  of  the  the  the  study  results  compare  in  the  expected forest  d y n a m i c s of trend  effects  encountered—especially  above  have  of the  post-harvest  it is likely t h a t  stages  of comparisons. L l o y d  were  and  23  mature  between  to  27  oxidation procedures  In  light  within  of  stands  28.7%  (in  of  in  the  vegetative  after  logging.  was  the  low  under  the  mature  with  i n the  and  46.7%,  litt., A p r i l Kamloops while  m i n e r a l soil, C concentration and  (op. cit.) would  study.  of  C/N  41. F o r the  7.1%  dichromate Lloyd  result  comparable E S S F  24 to  initial  would  those  of  C  other  now be considered. It should be noted that methodological differences  concentrations  from  in  and question  affect from  i n the  trend  fractions  a n indication of w h a t m i g h t occur without revegetation  One  would  least  This  m i g h t have been  of the  at  decomposition  w i t h disturbance and additions of organic m a t e r i a l . The r a p i d r e t u r n floor  decrease  years.  materials,  patterns  with  sharp  respectively. (Nelson  have been this,  Lloyd's  it  somewhat  can  ranges,  and  be  but  seen lie  18,  Region.  its  Sommers,  1982), the  towards  the  it  for the C  their  was  one  concentrations lower  were of  recovery method  ends.  floor  ranged  C / N ratio ranges  that  that  Forest  C / N ratios  Assuming  lower t h a n  1986) provided  the rates  used i n of  The  this C/N  144 ratios  observed  are  somewhat  comparable fractions. K i m m i n s Prince as  George; the  his. The  higher  (1974)  floor  those  of  but  used  C concentrations Kimmins  approximately  one  order  Concomitantly,  C / N ratios  (1974);  of  forest  of this  study  however,  the  higher  floors  those  those  The  of m i n e r a l soil  are  v e r y close to  soils the  those  in B . C . Finally, same  (Klinka  range et  observed  as  al, in  implication  (see  organic  It  can  study  is t h a t  by  are the  studies  entirely  be  safely  same slightly  values latter  were study.  the  and  C / N ratios  two times  C / N ratios  i n high-elevation  of the  acceptable.  m i g h t have  soil the  the  but  for near  a p p r o x i m a t e l y two  (1969)  forests  be indicative of a  than  in  are  were  forest within  coast/interior t r a n s i t i o n  concluded One  generally low C / N ratio  may  mineral  m i n e r a l fraction  therefore  close to  C concentrations  V a n Ryswyk and  are  virtually  comparable between  of this study  observed i n E S S F  and N a v a i l a b i l i t y  that  the  extremely  values  of the  m u c h greater  values  interesting  ESSF  forests  level of m i c r o b i a l  been expected from  accepted  concepts  C h a p t e r One).  In  terms  disturbance, on  those  this  in this and other activity  observed  both  1982).  here  ranges  ranges  spruce-fir forests  than  were  m i n e r a l soil  other.  Lloyd's  ranges from  studies, but for the of the  with  i n m y study were  magnitude  of the  overlap  reported  a n a l y t i c a l methods  forest  than  lower,  the  of  reported  nature  and  in  results extent  The  study  i n general agreement  (1981),  and  Matson  of  C  have  conditions. are  lack  trends  of  concentrations been the  differences  and  Boone  C / N ratios  over  predictably variable, depending disturbance  in  with  and  the  data  (1984).  forest  floor  presented The  and  general C  site  time  {inter alia) and  concentrations  cover of  by Piene (1978), L a n g  existence  of  after  differences  this et al.  in  the  145 mineral Boone  soil  concentrations  (1984); however,  reported i n the latter age  the  above mentioned  studies.  (1984)  that  age  observed  study.  i n m i n e r a l fractions.  implied  with  Lang  Trends  are  similar  have  been  of  not  the  data  significantly  mineral  not  increased may  forest  regard.  (1974) with  floor  support  C / N ratios  be analogous to M a t s o n  circumstances this  did  for  of  disturbance  The ratio  any  of  and  this  ages  after  organic m a t e r i a l ; those  those of the latter  differences study  at  of  in  involved  of the  any  and  of  trends  that with  directly b y  Matson  and  the  Boone  C / N ratios  in  the  of old-growth stands. the  eight  ratios years  preclude  h a r v e s t i n g are  Matson  opposite  reported  a n d Boone's (1984) increases;  patterns  of  the  higher  w i t h r e g r o w t h compared to those  data  is  were  forest floors of stands soil  result  et al. (1981) did not observe  i n C / N ratios  may  the  direction of change  H o w e v e r , inspection  there  to  very  with after  The  age.  The  disturbance  however, the  differing  concrete  statements  close to  those  m i n e r a l fraction  are  not  in  of  in  Page  agreement  study.  5.4.6 Unit-Area Elemental Weights  The organic For  estimated  and  weights  m i n e r a l fractions  completeness,  the  data  They  et are  elevations  al.  (1982)  for  are  unit  within  the  i n the  dry  interior  those observed by K i m m i n s  of  the  various  in Tables  densities  5.1a  elements  and  and weights of the  b  range  depths for  (Haskin,  in  soils  the  same  1985).  The  under depths values  are  the  respectively.  within  mature in  in  m i n e r a l fraction  of b u l k density values lies squarely  comparable  also  area  presented  on b u l k  have been included. T h e range Klinka  per  ESSF  podzols much  that of  at  lower  cover. high than  (1974) for comparable horizons i n spruce-fir forests  to  146  Table 5.1a M e a n s and 9 5 % confidence limits of the elemental u n i t - a r e a for the forest floor fraction.  FRACTION VARIABLE  /  SITE /  TM  T3  (values rounded;  FOREST  VALUES  T6 figures  weights  T8  i n brackets are  T i l 9 5 % limits)  FLOOR  Total N t  Total P  1045 (1197,893)  1116 (1285,947)  927 (1018,836)  796 (882,710)  895 (993,797)  109 (124,94)  101 (116,86)  87 (95,79)  84 (92,76)  92 (102,82)  42 (48,36)  38 (44,32)  35 (38,32)  23 (26,20)  33 (38,28)  Exch.  K  Exch.  Ca  189 (222,156)  221 (248,194)  315 (353,277)  217 (238,196)  243 (275,211)  Exch.  Mg  25 (29,21)  24 (29,19)  22 (24,20)  19 (21,17)  18 (20,16)  31.4 (35.7,27.0)  27.1 (31.4,22.9)  30.5 (33.1,27.8)  27.1 (29.8,24.5)  27.8 (30.5,25.1)  Total C,  Mg/ha  tUnless  otherwise  stated, units  are k g h a "  147  Table 5.1b M e a n s a n d 9 5 % confidence limits of the for the m i n e r a l soil fraction.  FRACTION VARIABLE  /  SITE  TM  /  T3  elemental u n i t - a r e a  weights  VALUES  T6  T8  Til  (values rounded; figures i n brackets are  9 5 % limits)  UNERAL SOIL B u l k density, Mg/m  0.77 (0.99,0.54)  0.71 (0.72,0.70)  0.84 (1.16,0.53)  0.98 (1.34,0.64)  0.68 (1.05,0.32)  Weight,  1152 (1491,813)  1070 (1084,1056)  1266 (1732,800)  1478 (2003,953)  1022 (1570,474)  1843 1819 (2412,1274) (2035,1603)  1393 (1921,865)  1330 (1851,809)  1737 (2692,782)  3  Mg/ha  Total  Nt  Total  P  Exch.  Exch  703 (917,489)  621 (675,567)  823 (1135,511)  1049 (1432,666)  562 (868,256)  K  89 (117,61)  85 (94,76)  97 (134,60)  97 (133,61)  73 (113,33)  Ca  323 (454,192)  287 (374,200)  919 (1326,512)  590 (857,323)  602 (970,234)  50 (66,34)  35 (39,31)  74 (103,45)  63 (87,39)  40 (62,18)  46.6 (50.4,42.9)  35.8 (49.7,30.0)  34.3 (46.7,21.9)  37.3 (57.4,17.3)  Exch. M g  Total  C, Mg/ha  55.7 - (72.5,38.9)  t U n l e s s otherwise stated, units are  kg ha  148 the  north;  higher 0.5  the  than  Mg  those  m" ).  elemental  they  mineral  the  C a l c u l a t e d forest based  concentrations  on  are  the  from  (Williams,  made  to quantify  is, as  opposed  As  data  instructive  intervals  were in  concentrations.  bulk  density  definite  derived  semblance  contents of  the  fine  fractions  (<  2  the  finer fractions  Moreover, as  actual coverage  are  noted of the  interpretative  priority  change  likely  to  only.  by forest  taken mean  as  a n indicative basis  unit-area  Nevertheless,  elemental  some  was  has  no  floor  with  been  Ca  while shown  levels  than  attempt  was  materials  accorded  extent  i n this  regard.  it w a s  derived  (that  at  differences  in  95%  those  apparent.  elemental  considered  A s m i g h t be  paralleled were  the  possible  The  minor differences  soil  etc.).  occurred.  contents  be with  fractions,  Four,  and have  It  to  overestimates;  m u c h higher N  where might  was  be  F/H  examine contents  thus  of m i n e r a l  foregoing. Nevertheless, what  (0.3  estimates  i n the  to  much  associated  in Chapter sites  soils may  of  mm)  are  intervals  entire  can have  forest  estimates  confidence  compare  elemental  Brown  considered to  elemental  trends  Alpine  weights  earlier,  absolute  the  for  wide  to  H o w e v e r , they  3  to rock outcrops, exposed m i n e r a l soil,  stated  concentration least  the  the  M g m" .  mean  the  1983a).  1.83  mean  only  floor  that i n organic m a t e r i a l s others  soil  attempts  Here,  to  (1969)  Nevertheless,  constrained  contents.  are  1.22  of V a n R y s w y k  acceptable.  severely  values.  range w a s  The  3  considered them  latter  of  confidence expected, the  mean  149 Nitrogen  Mean 796  and  and  b). I n  than  N  the  decline  tempting  direction  at  are  also greater  forest  near  values  are indeed  forest  floors  (Kimmins  eight  studies.  respectively  1  i n concentrations,  moreover,  years  floor  However,  weights  the estimate  George  of almost  between  (Tables 5.1a  there  the T 8 value  w a s no  suggested  250 k g N  ha"  given  the  lack  a n d concentrations,  floor  of  N  an less  1  of the derived 9 5 % limits,  it is  contents  change  in  this  it is believed best  Abies  forests;  the ranges et al., 1985).  of values  reported  1974).  This  H o w e v e r , higher either  a n d spruce-fir  and Rapp,  et al. (1985) the forest floor N  of 8 4 2 k g N h a "  (Kimmins,  overestimates.  i n spruce  within  mark;  end of the range  Prince  of  trend  ranged  to  result.  than  layers  are  the  fractions  as indicating a n a c t u a l decline i n forest  other  the higher  (Cole  at  mineral  1843 k g h a "  on the review b y K i m m i n s  are  Europe  content  this  reject this anomalous  observed  unlike  and  values. I n light of the w i d t h  in  i n both  Based  and 1330 to floor,  in N  to accept as  1  floor  at the three-year  stand  time,  for forest  forest  increase  mature  over  contents  1116 k g h a "  suggested absolute  Content  1981; K i m m i n s  of values for s i m i l a r  They  for spruce-fir forest  floor  values or  i n eastern et al.,  for Abies forests.  supports  equivalent  types  1  contents  have  higher  Canada,  1985).  depths under  the  belief  been values  that  the  reported for have  been  the U . S. A . , and  The mineral spruce  soil  and/or  values  fir types  150 Phosphorus Content  The  ranges of m e a n P contents  floor  l a y e r s a n d from  5.1a  a n d b). T h e forest floor trends  a  significant  while  the  content  data  suggests  point  approximately  to  the  N  general  encountered content  by  other are  detract  Kimmins  et al.  from  1  also  ranges;  stand  other  For to  estimates  (1985), the  mineral  concentration data  i n that  are  of  suggested. about  minimum  magnitude  year P  of  However, six,  levels.  the  the Both  latter  is  levels.  P  values  similar  reasons  be  point  reported The  nevertheless,  given  values,  are  or  what  somewhat  higher  earlier,  overestimates.  was  said  higher  than  have  been  values the  However,  of decline given  forest this  earlier. F r o m  the  floor  should  P not  review of  soil P values compare favourably w i t h  similar  spruce and/or spruce-fir forests i n v a r i o u s locations. Exchangeable Potassium, Calcium,  were  the  forest (Tables  decline at  suggested  mature  workers.  the  is  for  1  soil fraction  organic l a y e r P  the  with  109 k g h a "  mineral  to the  maximum  eight  84 to  for the  1  similar  applies here.  believed  from  a  decline;  comparisons  reported  values  from  are  implied year  some  contents  seriously  data  that  25 k g h a "  Concerning for  1049 k g h a "  decline and recovery i n the  concentration d a t a  measures  earlier  562 to  were from  In  the  23  to  forest 42  floor,  kg  respectively. I n the  ha"  1  mean ,  189  and Magnesium Contents  exchangeable to  315  kg  K, ha"  same order, m i n e r a l soil m e a n  Ca, 1  ,  and  and  18  M g content to  25  kg  values ranged between  ranges ha"  1  73 a n d  151 97 k g h a " forest  1  , 287  floor  with  trends  lessened  Declines and  and  a l l supported  sensitivities  i n forest  seven  reasons  919 k g h a "  kg  floor  ha"  similar  to  exchangeable  C a , the  year  six of  126  596  kg ha"  1  k g ha"  i n that  other  studies  that  the  similarly, range the  from  are  floor  within  the  soil  fraction—the were  the  forest  suggested  . Mineral  obtained  mineral  soil  wide  19 k g ha" was  i n forest  suggested  in which  an  though  95%  limits. for  1  rejected  contents  increase  also  case  N  earlier,  derived  M g decline  floor  an  data  only  limited  above  value.  for are  the  As  K for  earlier. floor  For  levels by  increase,  but of  significant differences  cation data  with  organic  probably  in  N  and  fraction  acceptable  with P,  were  within  it  results  of  is believed  overestimates; the  very  wide  point-in-time samples. It is interesting that w h e n compared to (1974),  the  exchangeable  m i n e r a l soil fractions (1974)  range  data  suggested.  contents  Kimmins  and  Kimmins  1  relatively  respectively. The  1  levels of a p p r o x i m a t e l y  for  data  concentration  suggested;  given  of extremely  values  of  the  the  74 k g h a "  earlier, comparisons of exchangeable  possible from  results  forest  the  stated  to  M g were  content  m i n e r a l fraction contents  As  of  owing  those  35 a n d  those  exchangeable  for  1  , and  1  for  observed  acceptability of the  i n this  exchangeable in  results.  this  Ca  study.  K  study contents  These  and  are  M g contents  of  m u c h lower. The  of both  observations  both values  fractions  lie easily  support  somewhat  152 Carbon Contents  As Mg ha"  ha"  given i n the  1  i n the  1  i n Tables  mineral  appeared  to  floor  content.  C  fraction  C  forest  be  floor  soil  fraction.  Unlike  contents since  the  statistical  differences) content  and  the  overall  pattern  that  evidence  of  may  in  the  contents 34.3  related  differences  concentration no  C  between  A s with  showed  differences  mean  and  of any  its  to  b,  layers,  no indication  However,  marked  5.1a  over  this  been  due  age  and  1  pattern  changes  data,  the  mainly  to  of  forest mineral  the  (though  wide  sites. without  apparent  the  there  in  among  similar  27.1  55.7 M g  sequence  the  was  concentration  have  the  marked case  M g ha"  between  concentration data,  counterpart, of  ranged  lack  of  confidence  limits.  For floor few is  horizons  are  discussed likely  to  58%  C,  comparisons  forests.  M g ha"  1  horizons  1985), in  be  can  The range  the  estimates  overestimates.  and  Alaska  difficult markedly  to  under  compare among  with  data  (Cole  than and  with  those  studies.  Their  survey  in  those Rapp,  of other range  the  forest yielded  assumption that organic  matter  from  various  spruce  and/or  (1974)  for  The  studies  the  the range  Scotia  entire  overlaps  of the  of  study is higher t h a n  Nova  1981).  contents  literature  However,  for  C  of this  of K i m m i n s  stands  of  values  of F / H C contents  coniferous  Europe  made  A  O n the  spruce-fir stands.  v e r y m u c h lower and  be  calculated from  of more n o r t h e r l y m a t u r e F/H  earlier,  studies w i t h directly comparable d a t a .  spruce-fir 20  reasons  floors  mineral  with  is w i t h i n  (Freedman  forest  since  total forest  soil  and  that  of  Morash,  the  cover  are  s a m p l i n g depths C  floor  that of  of spruce data  the  more  differed contents  153 observed  in  the  0-15  cm  fraction  menziesii (Mirb.) F r a n c o v a r .  5.5  hypotheses major  the H  forest  beyond  the  H  results, should  0  pH  levels  and  ratios  K,  declined  temporary  The  plant  values  over  a  to  the  downward years  after  also  rejected.  et al,  1985).  of  noted  i n total  P  concentrations values  M o r e o v e r , for growing same.  logging,  season  T a k e n as of P  and  was  have been  suggest  the  the  Ca  a  of  evidence  that  the  post-harvest  floor  In  the  i n the  of  not be of major  over  bases,  the  M g , and  in  importance  P  data  suggest  from  temporarily  total  ephemeral  the  some  also i n  P  and  practical significance  on  this  remainder,  appeared  changes  total P ,  fraction, C / N  F o r . the  K and  m i n e r a l soil  profile;  a  mineral  mark.  N , exchangeable  limits  appeared  decreases occurred in the  11-year  may  period. I n both,  T e m p o r a r y increases i n forest  fraction.  derived p r i n c i p a l l y  occurrence  clear  subsidiary  last  whole, the  spread  both  to  exchangeable  the  was  concentrations  magnitudes  places  through  and  d u r i n g the  this  beyond  There  that  general chemical characteristics of both  noted; t e m p o r a r y  to  absolute  movement  available P m a y data  Total  concluded  sequence.  K and M g concentrations  growth.  attached  age  C / N ratios  consistently  concentrations.  exchangeable  C  and  declines were  increased.  be  was  exchangeable  11-year span of the  exchangeable  it  and m i n e r a l soil fractions  total N and available P were  to  Douglas-fir [Pseudotsuga  menziesii] stands i n Oregon ( K i m m i n s  h a d indeed occurred i n the  floor in  foregoing and  0  changes  increases  C  different-aged  CONCLUSIONS  From  the  under  started  three  or  the  forest  nature of  which  that  can  there w a s  approximately more floor  years.  be a  three Plant-  fraction. T h e  slight d o w n w a r d movement  of organic  154 matter. and  Unlike  was  Finally,  P , this appears  not the  have  been  have  been  initially  general  by  a  higher  level  of  occurred more  inputs  from  as  seen  the  results  from  the  and fractions the  may  under  can  to have  be  associated  was stand  be  after  23%  the  occurred.  virtually  interpreted  as  availability  for  mineral  a l l except  and  of the by the  by  year  six-year The  were  soil  the  profile,  horizons.  there than  may might  C contents.  principal by  the  elemental  of  kg ha" the  Forest  1  floor  P  approximately  point  in  age  (31%  of T M value)  ,  sequence. by  year  be  eleventh year  after  be  overestimates;  the  Ca  values  of that  approximately No  of the 45%  changes by  the  E x c h a n g e a b l e " M g contents 11. B y contrast,  forest  years—and  that  in  which  chemical  change  disturbance.  the  fraction.  occurred 1  limits  The the  of  latter mature  i n forest  floor  , approximately  Exchangeable K T M value,  they  estimation  185% over  by  declined by floor  The  nevertheless,  25 k g ha"  sequence. of  period of  The wide confidence  prevented  decreased  19  1  eight  to  of  contents  sequence.  year  ha"  pattern,  principal  three to eight  of changes.  , or  the  manifestations  believed to  T M value, by kg  assart  v a r i e d according to  as  mark—appeared  exchangeable  600  six  of an  trends  period from  indications of magnitudes  with  value,  declined  organic  i n general  i n terms  h a r v e s t i n g emerged  disappeared  increased by nearly  total N  N  mineral  consideration. H o w e v e r , it m a y be concluded that i n  elemental contents used  changes  around  change  unit-area  that  and  foregoing discussion that  first eight years  mainly  maximum seemed  the  overlying  imply  activity  importance i n this context. W i t h i n this, the possibly  the  observed  microbial  within  expected.  can be  elements  balanced  relatively low C / N values  Insofar it  to have  contents  the 7  exchangeable  kg Ca  same ha"  1  was  155 increased year  by  126  six of the  kg  ha"  sequence.  1  ,  approximately  67%  of the  mature  stand  value,  by  CHAPTER POST-HARVEST  In N  Chapter  i n the  that  forest  total  plants.  Thus,  and  and are  a more  was  given to  m i n e r a l soil fractions. often  explicit  in this  have  availability the  Heal  poor  post-harvest  patterns  of  H o w e v e r , it is generally  indicators  examination  PATTERNS  of  the  availability  of post-harvest  N  of  total  accepted  soil  availability  N  to  trends  is  chapter.  been  in  problem of N al.  (1982),  (1984a).  As  noted  lies i n the been  net  numerous  forested  et  many  earlier,  the  of a  determination  the  and Recent  forest  Tamm  key  the  of that  i n both  reviews  trees  (1982), to  publications dealing w i t h  which  have  A similar  but The  element.  used,  much general  1971; K e e n e y ,  1980 and  156  of  For  classifying t h e m  more  recent  consensus N  in  Powers  forms  reasons,  of  has  circles i n  the  summarized  either  chemical  r e v i e w of approaches was  an  that  the  unknown  N  there  (1965) as  facets (1980),  and  inorganic  N . Bremner  cycling  of K e e n e y  (1984),  such  N  various  forestry-oriented  ( M N ) i n a laboratory 1982).  Gosz  availability  indication of plant-available  of mineralizable N  include those  agriculture- and  been  concerning  (1982),  reliable index of plant-available  approaches  for  to  m i n e r a l i z a t i o n level  out by K e e n e y (1982).  procedure  Hesse,  ecosystems.  Robertson  or biological methods. carried  studies  availability  long-standing interest  development the  consideration  AVAILABILITY  INTRODUCTION  There  of  floor  measures  now presented  6.1  Five,  NITROGEN  6  most  soil  is  incubation ( B r e m n e r ,  was  reliable by  the  1965;  157 The basic principles of m i n e r a l i z a t i o n studies documented soils are  are  elsewhere.  too  aspects  anaerobic  lengthy will  be  procedure  and  pioneered  highly recommended  1980  and  1982).  40°C  has  emerged  can  be  Waring  and  between  the  referred and  to  calculated  preas  "net  1984b),  in  considered—the  Regardless several  1960;  is  Bremner,  W h e n forest more  acute  or  Waring  repeated For  and  available  detail.  index  anaerobic  (Keeney,  in  which  MN  is  is  the  that  of  post-incubation  the  at  this,  the  method  of  the  N H J -N; by  basic  incubation  With  as  NHJ-N  the  become  original  proposed  involved  1971; Keeney,  1982).  calculated  concentrations is  has  one-week  first  way  (1964)  forest  Nevertheless,  applications,  (Hesse,  The  the  here  in  issues  availability  ways.  only  The  many  two  second  writer, t  Bremner  form of the  incubation approach  have  served  possible effects  1965; K e e n e y under  bring  and  to  of  or method  make  the  of sample  w e l l - k n o w n effect  soils are  be  this  briefly.  post-incubation  of w h i c h  the  to  well  difference  this  will  Powers  be  (1980  concentration  is  is employed, there  are  M N " measure.  difficulties w h i c h  here  in  which  problems include the note  best  M N " . The  "gross  by  some  (1964),  and  elsewhere  been  problems—especially where  biological index of N  the  Bremner  and  very  by  Specifically, as  methods  complex  highlighted  most  results  general  involved—were e x a m i n e d  much  some  The  by incubation have  and  re-wetting  1966; Hesse,  consideration, additional factors  further  imperfect  collection, handling, and  drying  Bremner,  index a n  complications.  These  one.  storage;  (Birch,  1959  1971; S a l o n i u s , often  include  Such  render stocking  of and  1978).  problems levels,  t T h i s was done i n a n unpublished report prepared for F o r e s t r y 512 (Dr. T . M . Ballard—Professor), F a c u l t y of F o r e s t r y , U . B . C . Copies are available from the author.  158 management  practices,  and  One  1980).  floor—the  and  of  internal  the  most  1979).  should  excluded (in p a r t  of  be  a  single  Powers, for  investigator  1984a,  many  Opinions  b). T h e r e  reasons,  nutrition  studies, 1969;  Youngberg,  1978;  studies.  of  Bhure,  their  effects.  samples  reported  from  sample  effects  Among  were  in to  a be  also  methods  skepticism  by  around  difficulty  simulating Forest  or  three  some  on  Research  whether  pattern,  and  in  part  of some  field  Project  of  the  (1984b)  standard  (R.F.N.R.P.),  layers  i n the  mind  and  1980;  tree  1963; T a m m  and  Hawkes, and  in  N  1978;  Van  presented  a  Cleve, succinct  mineralization seasonal,  and  reference  gross  by  depth,  composite  M N measure.  This  problems  McNabb  procedure main  [Hase 1984].  has  criticisms to and It  accept  it  As  regarded  seems as  last  deriving  (1984).  been  and  avoidance of  1984b). V a r i a b i l i t y problems  researchers  conditions  forest  M N and  1981; Weber  fashion  anaerobic  to  and  overcoming intractable  similar  One  (Viro,  standardization  the  a  indicating that  variation—spatial,  storage (Powers,  the  is crucial  encountered  at  1978  floor  1978  of evidence  Kimmins  Powers  aimed  forest  (Keeney,  layers  of  of  M N studies—even  et al.,  of a  in  actual  to  1975;  types  Keeney,  soils from a g r i c u l t u r a l ones  time  variation  useful  general,  the  presence  ecosystems  use  investigators.  reflecting  Nutrition  of  the  and  discussed in  forest  proposals  extremely  floor  1982).  main  was  as  in  V a n Cleve  triangular  pre-treatments  incubation  a  points  Lamb,  sources  these  the  is  whole) from  of forest  1979;  several  1975;  o v e r w h e l m i n g amount  Salonius,  major  made  taken  was  and  identified  analytical—and  an  1970;  Tamm,  the  He  a  different  consideration  Mahendrappa  summary  as  divided  especially i n northern  Pettersson,  1981;  been  or  is  factors  (Lamb,  differentiating forested  have  at  patterns  important  principal characteristic  (Pritchett,  cycling  to  and for with  revolve  adequately  Timmer,  1982; Regional  has  suggested  been  that  159 at  least  in  (Myrold,  coniferous  1985).  The  soils  above  strongly  recommended  Powers,  1980  and  forest  for  standard  use  Smith,  1984;  1984b;  A n attempt was  differences  the  Given  the  as  well  as  of  promising  (Keeney, 1980 acid  or  other  and  in  distillation  western  statistical for  study.  form  of  Keeney,  Several  to refine  1982;  anaerobic soils  situ  buried  include  1984), the  procedure  applications 1984).  This  it on the  use  1982;  to  Carski and  1980;  employed  investigation of this  been  Sparks,  Bremner,  an  urged.  Examples  N  method (Keeney,  (Keeney,  1985),  1985).  1980),  and  alkaline  Powers  (1980),  overall best choice, observed  was  actually  were  the  considered  indicated  (Powers  too  best  for  was a  studies —either been et  al,  choice  variable  method  preferences  mineralization  containers  (Keeney,  of temperature  acid chromate  and  incubations. There have  soil-filled  been  chloride-autoclave  1980). A K C l - e x t r a c t i o n have  has  hot-water-extractable  of hot  Gianello  its - results  researchers  primarily  study  basis  continued  calcium  1980),  KCl-extractable N  approach  a  incubation as  however,  N  Three).  Mahendrappa,  (Keeney,  with laboratory of  soil  R.F.N.R.P.,  made  microbial  anaerobic  incubation approach,  applications (Powers,  in  conjunction use  the  standpoint;  this  the  1982;  (Keeney,  forest  routine  the  i n forest  Chapter  methods  1982; R . F . N . R . P . ,  while p r e f e r r i n g  measures  indices—mainly chemical extractions—has  alkaline KMnO<,  steam  (see  of the  laboratory  1980  and  sites  flaws  method  notwithstanding,  such a procedure. among  the  from  in  general  to  separately  1978;  a  employed i n  return  noteworthy  that  some or  in  innovations i n  Bonneau,  1980;  1980).  One  recent  and  exciting  alternative  to  the  direct  involvement  of  soil  160 materials  has been  Chapter  Five),  availability N  such  resins  to plants.  (Binkley  Cromack has  and Binkley,  sample  changes).  that  their  makes  differences are  et al.,  noted  of soil  i n laboratory  useful  is  for  i n microbial  very  and Matson,  i o n mobility  N  Binkley  availability  to  (Binkley,  1984). T h e r e  (1984)  tree  remains  the  currently  recovery  Nevertheless, under  a  is of m u c h less  common  method  in water  flow  increases that  this  of N O i - N . the  availability  (Binkley,  over  (Hart to resin  Moreover,  emphasize  anion resins  role  were  degree  of  used  a period, thereby  and B i n k l e y , bags  he felt  This  to reflect  ion  importance  nitrification  1984).  of  last  i n comparative  in  indicating points  method-dependent.  studies (1984)  noted  that  N H J - N capture  more  than  Binkley  mobility resin  point is of great  relative differences  advantages.  sites  the greater determining  (Binkley,  among  1984).  m a y increase  that  is  uptake  disadvantage  On  the  this  Moreover,  a n d plant  g i v e n the potential  side,  has shown  roots.  1984). H o w e v e r , this is a relatively m i n o r setback analytical  i n the use  a n d transport;  that such a n index c a n only be used for c o m p a r a t i v e purposes  the  approach  of indicating the  competition for N , m i n e r a l i z a t i o n rates,  also reflected b y the method  and co-  a n d microbiological  the advantage  sensitive  an  inherent  chemical  1984).  assessing  of P  1 9 8 3 ; B i n k l e y , 1984;  (R.F.N.R.P., to  studies  I n t u i t i v e l y , such  effects, have  earlier (see  for the e x a m i n a t i o n of  of the difficulties  that the resins  conditions  A s noted  recently b y D . B i n k l e y  1986).  (e.g. pre-treatment  ion collection  them  employed  of c i r c u m v e n t i n g m a n y  materials  effects  been  1982; B i n k l e y  1984; H a r t  It h a s been  integrated  long  h a s been largely pioneered  a n d Packee,  the advantage soil  have  resins.  H o w e v e r , the in situ use of resins  (and P) a v a i l a b i l i t y  workers  of  the in situ use of ion exchange  bag  of N O ^ - N  would  estimates  of N  importance  to this  study;  i n N O 3 - N levels cumulative  of m a x i m u m (or otherwise)  N availability  161 across  the  have  age  studied  Elsewhere, initiated i n the  6.2  (in  and  1982)  main  to  phase  patterns  Matson  United  and  after  Packee  (1982)  harvesting  using  (unpubl.) incorporated the  long-term study  OBJECTIVES  changes  In B . C . , B i n k l e y  availability  southeastern  attempt This  N  Vitousek  The any  sequence.  of the  effects  and the  Martin resin  method  of disturbance  N  in N  the  concerns  of  this  phase  of the  study  had occurred on the  findings  to  the  m a i n hypothesis  H  overall  sites  to  examine  indirectly  and  a  and their  alternates  lesser  involved.  m a y be stated  y  from  extent  No the  major forest  as  changes floor  an  m a i n hypothesis  assart H  from  : Major the  changes  forest  floor  The  s u b s i d i a r y hypotheses  follows: occurred  in  N  materials d u r i n g the  availability post-harvest  indeed occurred  in N  materials d u r i n g the  availability post-harvest  period.  H  0  from period.  No the  major  changes  m i n e r a l soil  to  effect. is  also  under  test  0  o  period.  H,  whether  since harvesting, and  investigation of  directly;  0  was  X  0  dynamics  States.  availability  relate  H  recently-  A N D HYPOTHESES  objective  to  approach.  in a  on  (1985)  occurred  in  N  fraction d u r i n g the  availability post-harvest  162  H,  : Major  from  the  changes  mineral  indeed  soil  occurred  fraction  during  in N  availability  the  post-harvest  period.  If  H  0  ^ and  H  mineralization sites.  0  ^  are  and  there should be  inorganic N  S t a t i s t i c a l tests  falsification  true,  for  levels observed  such differences  c r i t e r i a of the  null  no  marked i n the  among  differences  relevant  the  sites  among  fractions  were  the  from  accepted  as  N the the  hypotheses.  6.3 METHODS  The  basic  field  samples  for  analysis  mineral  soil  fractions,  stage  composites  were  exception  fractions  of  presented  Three  studies,  the  s a m p l i n g scheme,  all analyses  only.  employed—incubation the  layout,  in and  and  both  floor  tests  in  this  of  N  availability  and  ion exchange  resins.  both  organic  and  mineral  mineral  soil  samples  were  i n a v a r i e t y of w a y s . These  composite  Two. For  categories  data  of creating  Chapter  chemical extractions,  resins,  system  obtained  are  for  phase  forest  involved  the  and  second-  indices  were With  discussed below.  6.3.1 Incubation Studies  Incubations of  each  employed. placed  site.  In  For  the  with  24  were all  carried out cases,  organic  m l distilled  the  samples, water  on  the  forest  seven-day, three in a  grams  20  X  floor 40 ° C  and  anaerobic  of sieved, 125  mm  technique  was  air-dry m a t e r i a l  were  borosilicate glass  culture  163 tube.  The  sample  trial  and  error)  absorption, Each  but  tube  weights such  yet  that  allowed  was  (approximately  13  mm  treated  same  volume of water. of  a  vortex  Scientific only) the  similarly,  Model  were  included  preparation  mercury-in-glass  volumes  water  by  a  and  a  except  that  five  gravity  phenolic  a  batch  of  thermometer;  (by p r e l i m i n a r y  tubes  of cap.  incubator;  soil  thread soil  two  blanks  in  tape  samples  used  was  batches  sample  a l l samples.  were  in  was  for  Mineral  materials  placed  after  Teflon  of a i r - d r y  Incubation  was  chosen the  of sample  then  samples.  this  screw  grams  were  batch.  filled  combination  convection  each  were  volume to be used  Complete s a t u r a t i o n Samples  used  virtually water  wide)  with  of  the  sealed  mixer. 4EG  water  a constant  tightly  were  use  and  in  the  ensured  by  a  Precision  (distilled  water  initiated i m m e d i a t e l y  Temperature  was  checked twice d a i l y  monitored d u r i n g the  after  using  a  incubation  period.  After storage  bottles  material was  were  rinsed  filtered  (1.7°C)  NO^-N Section).  For  taken both  the  24  the  in  light  No. of  organic  the and  the  each  41  2 M KC1 in  Concentrations  by  m i n e r a l fractions, traditional net  temperature  12  and The  the  among  leachate in  the  sample  extracts  Technicon  data  sample  placed  of  allowed newer the  cold  AutoAnalyzer NHJ-N  2 M K C 1 extractions these  into  then  concentrations  M N and  differences  in  a  tube  aliquots.  were  on  gravity-filtered  The  ml  of N H J - N  Initial  obtained  were  paper.  which  procedure  1973).  values  tube  filter  containers,  Corporation,  to be  of  of  indophenol blue  m i n e r a l i z a t i o n indices—the  addition,  ml  same  analysis.  Instruments  were  contents  Whatman  into  by  the  with  until  determined  (Technicon  two  through  were  also  storage  incubation,  (see the  gross sites  and next  use  of  M N . In  and  their  164 implications mean  (see  forest  floor  assuming  Q,  Adjusted  MN  discount  Chapter  temperatures  =  0  Three),  2 for  levels  formula  N  were  these  indices  observed.  This  were was  m i n e r a l i z a t i o n (Stanford obtained  (Chapman  and  by  done  1947)  to  on  et al,  incorporating  Meyer,  adjusted  according a  per-sample  latter the  in  the basis  1973; Powers,  the  yield  to  1980).  the  general  following calculation  formula:  AMN  =  T  M N  /{2**[(40-T)/10]}  where:  AMN T  =  T  =  M N level adjusted  relevant  mean  to temperature  forest  floor  "T";  temperature  (Chapter  Three); MN  Mineral  soil  fraction's floor for  and  mean  Powers  For  and  M N level at  adjusted  would  in  be  is  four  and  each  anaerobic  using 2°C  T = 40.  the  lower  simple than  assumption  the  indices of potential N  Matson  case.  results  Burger  adjustments  four indices, the d a t a  appear  to the  and  by  to  i n each instance  0  that  and  [sensu  adjusted  been values;  (1984)  forest  1986). T h u s ,  mineralization  temperature  aerobic N  18,  have  Pritchett  that  corresponding  (1985)] —unadjusted  There  incubation  noteworthy.  and moisture  the  were  Vitousek  levels  adjust  (1984a)  temperature  were  fraction there  MN to  unadjusted  temperatures  (1984a)  attempts  =  ( M . N o v a k , Professor, U . B . C ; pers. c o m m . M a r c h  each soil  gross  Q  M N values  means  Powers  4  very that  applied  net few by both  procedure.  were analyzed as  a single-  165 classification  Model  comparisons u s i n g the  1980). Conformity  of  1976;  Some  a  valid  ANOVA  Anonymous, in  all  sufficed  1976)  cases for  to  was  checked  and  GENLIN  achieve  a l l net  estimate—however  unit-area  regression  could  be  variety  it  would  be  was at  least  base  of  new  set  data  found  on  that  the was  to  total  N  soil the  which  variances.  Power  the  From  values  over  observed  from  level  chosen.  observed be  a  laboratory  Chapter  in  were  Five)  of  the  a  expressed  as  a  sample;  a  each  analyzed statistically i n  homogeneity allowed  of the  the  variances.  forest  floor  No data  N  were  mineralization similar  necessary  transformations to  this  for  were  achieve  in  field  these d a t a  transformations  period  incubations  fraction  Arcsine  and  the  that  anaerobic  Therefore,  observable  not  showed  12-month  during  N  (1984a),  each  above.  same  does  Powers  incubation values  concentrations  (see  technique  for  to  have  might  these  generated  data  could  MN  concentrations  original  which  laboratory  field  measurement  samples,  (Fox  Transformations  fractions;  anaerobic  quantities.  temperature  the  cases  of such  and  However,  thereby  The  concentrations  those  year.  F o r m i n e r a l soil to  the  equal one  the  MIDAS  to  r e s u l t i n g potentially m i n e r a l i z a b l e  desirable.  conditions  than  assumed  of  fashion  forest  depending  percentage  index.  of  both  out  for a l l gross M N measures.  derivations field  the  of  carried  of a l l d a t a  programmes.  in  A posteriori  were  u s i n g both  M N measures  believed  analyses  homogeneity  crude—of the  between  m u c h higher  study,  nominal  was  to direct  equation  incubations,  these  basis  lend itself  a  treatments.  (Greig and B j e r r i n g ,  true of natural-log transformations  under  the  package  transformations  readily  as  GENLIN  necessary  a  sites  These  Guire,  a  the  u s i n g T u k e y ' s test.  and  on  with  performed  assumptions  was  ANOVA,  were  the  were  I  conform  in  were to  the  166 assumptions parametric 1973; of  and Rohlf,  nature  Tukey's  ANOVA.  Therefore,  Kruskal-Wallis  Sokal  this  and  median  1981)  (Chapter  within  Five),  the  the  as  of M N and  their  associated  presented  all  for  programme. of  95%  by  the  non-  the  total  confidence  limits  earlier (Chapter Five) i n v o l v i n g R . M . S .  using  Per-hectare  limits  were  derived  data,  and  the  N  Wolfe,  A s in- earlier cases  a posteriori comparisons.  9 5 % confidence  data,  analyzed  (Gibbons, 1971; H o l l a n d e r a n d  MIDAS  basis  concentration  were  construction  used  per-cent-of-total  a  these tests  jackknife w a s  estimates the  for  using  approach  error calculations.  6.3.2 Chemical Extractions  In equilibrium floor  and  extraction w i t h  in 50  ml  The  were  then  samples  gravity-filtered  into  place  storage  in  cold  extracts  were  NO3 - N  were  (Technicon  non-parametric  Thus,  grams  until  and  an  Whatman  analysis. those  1971b).  and  "absolute" Tukey  not  No.  i n the  None  hour.  extracts  were  paper,  then  NHJ-N  in  the  incubations. Concentrations of  on  a  of the  Technicon data  AutoAnalyzer  conformed  to  were found w h i c h  K C 1 extraction data 95%  shaken  one  filter of  by  forest  were  than)  The  41  Concentrations  no transformations  jackknife  less  additional hour.  colourimetrically  Corporation, ANOVA,  for  to  1982). F o r both  of sieved, air-dry m a t e r i a l  through  similarly  Nelson,  a p p r o x i m a t e l y (but  settle  bottles  (1.7°C)  a l l such  methods  analyses  to  determined  for a v a l i d  this.  left  determined also  five  2 M K C 1 for  storage  Instruments  assumptions  Separate  2 M K C 1 (Keeney a n d  mineral materials,  mechanically  achieve  of N H J - N and N O 3 - N were determined  each sample, concentrations  intervals  were as  the could  analyzed u s i n g  described  were done for N H J - N , N O ^ - N , and their s u m (IN).  earlier.  167 Weights estimated  of  KCl-extractable  using the  Observed  sample  same  approach  concentrations  respective  total N levels, thereby  exception  of  parametric these  forest  tests  data  fraction's with  not  sites  the  were  using the  necessary  to  GENLIN  achieve  derived using the  A  as  MIDAS  error  were  of  a  limits  earlier  were  as  ANOVA.  were  values. their  non-  outlined;  I  organic ANOVA,  performed as  using  described  transformation  Per-hectare  presented  the  the  The  c a r r i e d out  A power  variances.  calculations as  were  of  using  single-classification M o d e l  analysis  the  percentage  performed  valid  programmes.  of  unit-area  sets for a n a l y s i s . W i t h  confidence  a  checking and  and  a  posteriori comparisons  homogeneity  R.M.S.  95%  analyzed  test. Statistical d a t a  earlier  analyses  per  for M N unit-area  as  new data  requirements  treatments.  earlier  expressed  generating all  NO3 - N  and  described  were  NO5 - N ,  fulfill  as  as  Tukey jackknife  NO3" - N data  the  Tukey's  did  floor  and  NHJ-N  was  estimates  were  earlier.  6.3.3 Ion Exchange Resins  Ion  exchange  NO I -N  levels  separate  but  resins  trees  containing (H)  paired  were  sample  over  resins an  at  on  each  17 g and  strong  acid  exchange  beads.  employed  a  11  organic  polystyrene  the  monitor relative changes Cations  fall  F / H interface,  site.  Each  g  oven-dry  cation  mesh  to  period.  lots. I n  the  The  used  extended  resin  placed  were  lot  and  size  of  1983,  30-50  cm  consisted  of  equivalent Rexyn  was  and  were  lots  of cation  30  from  the  the  16  and  collected  bases  separate  nylon  of F i s h e r  (OH) strong  between  divinylbenzene m a t r i x ;  anions  respectively  201  i n N H J - N and  base  50.  cation resins  and of  by  anion  selected  mesh Rexyn  bags 101  organic  anion  resin  types  Both were  sulphonated  168 and  i n the  hydrogen  quaternary mercuric  amines  "plots" other  of  was  200  used. left  to  used  bags  filtered  through  (1.7°C)  until  Instruments  per  cent  five and  T3  in  for  bag.  treatments.  A  posteriori  The  GENLIN  and  MIDAS  a n a l y z e d as  analyses—including  transformation  variances.  No.  1971b  as  a  anion  was  a  24  paper.  were  used  on  a  and  checks  for for  were  conformity  both  were  the  the  the  30  to  resins,  extractant  kept  then  in  NHJ-N  the  using to  ANOVA however,  achieve  was  minutes,  were  cation  referred  N H J - N data;  transformation  on  in situ.  cation  then  gravity-  cold  storage  and  NO3-N  AutoAnalyzer  performed  to  placement  volume of  solutions  determine  programmes  saturated. A l l  months  (Technicon  and  single-classification Model I A N O V A ,  statistical  natural-logarithm  For  approximately  Extracts  In  so  a  ions;  m l of 2 M K C 1 solution  The  to  12  the  Technicon  1973).  comparisons  necessary  but  100  hours.  with  "plots".  (1984),  case  alkyl  collected  resin  approximately  solution for  41  Aliquots  data  required  the the  for  with  treated  with  were  K C 1 solutions.  Binkley  in  were  sites  selections  sample  and  approximately  Corporation,  resins;  with  aminated  interference  exchange  after  bags  In  shaken  the  for  had  colourimetrically  were  of the  were  A l l bags  microbial  retrieved  Hart  Whatman  form.  selection among  their  after  were  sites  were  analysis.  concentrations  hydroxyl  to  each  equilibrate  anion exchangers  prevent  lots  m l for  The  the  the  to  extracted  KC1 was  in  by r a n d o m  resin  were  while  solution  TM  was  The  IM  two  the  sites  Resins  and  chloride  approximately  form,  anion with  the  Tukey's earlier  cases,  method.  were  assumptions. the  NO5 - N  homogeneity  sites  of  used No data the  169  6.4 RESULTS AND DISCUSSION  6.4.1 Incubation Studies  The  trends  of forest  floor  and mineral  soil  N mineralization  levels according to the various indices are presented  concentration  i n F i g u r e 6.1. Forest Floor Materials  130)  There  were  among  the  (NUMN). than  of the  thus  significant  means  T h e means  those  groups  highly  of  the  T M , T 3 , and  formed, there  were  The T 6 a n d T 8 means  those  of the other was  predictably GUMN  repeated  means  comparisons data, mg  N (kg soil)"  (kg  soil)"  .  <  yielded  1  The  same basic pattern  <  data  in  were  0.001,  from  F  the  0.001,  F  the  were =  level.  net  gross  (p <  of the  M N data  significant df  groupings  =  4,  two  different  of the  member  respectively;  1  (kg soil)"  differences  of means  0.05) lower  (GUMN),  130). as  4,  M N procedure  a m o n g the means  highly 34.8,  same  respectively, while unadjusted  each  9.7, d f =  net  636 and 746 m g N  unadjusted  There  significance  within  =  482 a n d 503 m g N (kg soil)"  between  the  exactly  T i l sites;  no differences  ranged  values.  (p  at the same  1  sites  higher  unadjusted  (p  of the T 6 a n d T 8 sites were significantly  sites.  pattern  differences  The  1  .  This  but  among  at the  a posteriori  did the  NUMN  T h e T 6 and T 8 means  were  the others  9 6 3 to 993 m g N  and  gross  ranged  from  M N procedures  of N a v a i l a b i l i t y levels across the age  both  sequence.  5 4 3 and 5 6 9  indicated  the  170  Vertical bars are 95% confidence limits FOREST FLOOR 9  ^  0  0  MINERAL SOIL  20-i  "1  800-  15-  |> 700-  10-  ^  600-  ^  500-  5-  400_ 120 - i  02.5  Z  2-  100  1.5  E  1-  80H  0.5-  < 60-  Z  0  1  ~v  12001  O) 1100\ 1000D> 900E, 800700600500o 400-  25-  140-1  2.5-  2015-  z  1053  1  |» 120H  ^  100 H  <  8060-  2 1.51l  I  I I I l  l  I l  l  I  I I  0 1 2 3 4 5 6 7 8 9 10 1112  0.5-  I  I  I  I I—I I  I ! 1—I—I—I  0 1 2 3 4 5 6 7 8 9 10 1112  YEARS AFTER HARVEST  Figure  6.1 M e a n s a n d 9 5 % confidence l i m i t s of the N m i n e r a l i z a t i o n concentrations given b y the four m e a s u r e s . (See text for abbreviations.)  The  adjusted  moreover, those  the  of the  differences Til  adjusted  <  presented  gross  adjusted  (p  mean  data  net  =  N  95 m g N  (kg soil)"  130)  were  was  .  means  Highly  (p  not  significantly  (kg s o i l )  observed  significantly it  1  <  82  change following  greater  those  97  those  of the  mg N  the  mineralization  and  rates  this  then recovered w i t h i n  the  three subsequent  counterparts. no first  real  They  increase  eight y e a r s .  conflicts The  to  with  GAMN  the trend  be  more  present or  point,  reflective conflicting  decrease  However, trends agreed  the  a  in  of the  T M and  T6  those  71 (T6) and  0.001,  of both with  the  the  and  data. the  the  df  The  T6  mean  field  mean  N  until for  GAMN  other  sites  the next  that third  and G A M N  trends  their  data  unadjusted  pattern  occurred  that  year years,  than  indices a n d  no  five  the a  implied  during  indicated by y e a r  indices i n  was  similarly  suggest  the  NAMN  was  4,  which  and T 8  after  mineralization  unadjusted  unadjusted  data  conditions  increase  from  was  of the  The N A M N  The  site,  =  .  GUMN  declined  89 (T3) m g  16.6,  The T 6  1  NAMN  =  T8  T8  place  years.  pictures.  significant  F  respectively; those  rates  potential  significant  than  T i l sites.  took  of  very  to  The  GAMN  T3  NUMN  were  trend  means.  141 (T3) m g N (kg soil)"  both  different  above;  NAMN  <  addition,  At  assumed  (p  In  1  the  a m o n g the  of a l l except  (kg soil)"  to  were evident. T h e T i l m e a n  of the  disturbance.  were  130)  There  ranged between  means  different.  from  i n potential N  0.05)  than  115 ( T M ) and  trends  4,  differences  the  lower  than  =  patterns  exhibited a  (Figure 6.1).  . The others  1  among  and  <  significant  0.05)  lower  ranged between  The  -  (p  different  values  among the means  significantly  were  4.0, df  significantly  sites; no other differences was  M N (GAMN)  M N (NAMN)  0.01, F  was  somewhat  GAMN  the  11. This values.  definite decline  172 and  recovery  extremely but  pattern  "increase"  m a r g i n s defining  and  have drop  Five).  appears  that  post-harvest  entirely  the  GAMN  trend  m i n e r a l i z a t i o n by  the  different  from  increases  in  the  organic  materials  at  possibility,  and  may  more  a  situation  One  the  results  the  The  T M mean  the  N  that  point  floor  (see  above,  representation  forest  three  concentrations  presented  accurate  in  year.  m i n e r a l i z a t i o n by y e a r  of the  be  eleven.  third  light  in  availability  and  indices indicated a non-significant  i n potential N  possible i n observed  N  N  three  than  of  the  it the  other  indices considered for that fraction.  forest  Haskin  few published studies  floor  materials.  (1985)  were  examining  mature  ESSF  disturbance  effects  i n other  (1982) (1984)  times)  than  reported  a  observed  approximately. between values  employed  levels observed  three  219 of  this  al.  (1982),  net  Haskin 540  study  the  gross  stands;  MN  the  reported  M N level was  (1985)  were  Matson  index.  other  two  in  the  of 239  observed N  (kg  so  much  40 a  soil)"  .  higher  the  net  et  al.  studies  forests.  Both  than  were  investigating  much  higher  (two  studies.  The  (1982)  and  three  of  M N measure,  NUMN  latter  and  and  the  are  (kg soil)"  (1984),  were  study  range 1  Boone  of this  mg N  between  incubation technique  and  Klinka  high-elevation western  those  mg  anaerobic  first two used  i n organic materials  range  and  et  applied the  three such studies; the  third  GUMN  have  Klinka  while , the  to  years  not being significantly  Considering this  potential  Very to  between  potential  A n increase  C / N ratios  Chapter  MN  narrow.  been  in  in  this point as  extremely  would  indicated  interesting point is that both adjusted  noticeable  were  was  Klinka  et  al.  ; Matson  and  Boone's  225  mg  (kg  soil)"  gross  M N concentrations  reasons those  1  why of  the  N  the  forest  others  are  1  of  floor not  173 immediately were  obvious.  entirely  analytical  Given  comparable  bias  is  suspected.  so m a r k e d l y higher t h a n  Comparisons  her  (1985)  study.  F  after  (increase 1984). ratios  Matson may  01  horizon.  this  study.  and  to  therefore  imply  floor  Boone  That  to  the  is,  decrease  expectations that  for to  of the  a  see  study  (see  next  given  area  Section)  technique,  w h y the  should have  based  the  in  a  on  unadjusted  M N trends study  decrease  also  be  similar  the  for  N  reasons  of  an  indices of forest  opposite  trend  ( M a t s o n and Boone,  materials  and  high C / N  mineralization in for decreased  m i n e r a l i z a t i o n (and concept  N mineralization  The  horizon  woody  potential  been  potential  availability)  assart  floor  N  effect.  and  Gadgil,  suppression would  be  extracted  of a  from  an  1975 and  indirect consequence 1978; B e r g  decomposition—presumably build-up  in  the  pool  such materials would  of  and  of the  Lindberg,  highest potentially  undergo  a  on  would This  1980). W i t h mature  mineralizable  release  from  run might  m i n e r a l i z a t i o n were  so-called " G a d g i l  the  the  levels in  viewed  as  to  some  trends (Gadgil  been  made.  sensitive to the on-site conditions i n this study. A l t e r n a t i v e l y ,  be  N  inconclusive in  strikingly  indicated. 02  that  the  the  were  are  in  were  i n the  theorized  N  can  not sufficiently may  no  potential  O l horizon—a m i x t u r e of L and  noted  decrease  disturbance  this  recovery  was  (1984)  of  were unlikely to have  direct  others  gross  trends  subsequent  operated  These  contrary  GUMN  b y decrease)  have  A  forest  1979).  with  followed  the  M N values  of M N levels after  Boone (1984) for  (Pritchett,  disturbance  of  organic m a t e r i a l s  that  H o w e v e r , the  materials  those  soil  H o w e v e r , it is difficult  of trends  and  mineral  elsewhere.  reported  that of M a t s o n  the  with  m i n e r a l i z a t i o n levels of the  Haskin  that  the  N.  such effect"  mycorrhizal stand—there A  sample  suppression,  and  174 thereby level.  exhibit On  initially; of  would  samples  would  be  taken  from  With  increasing  allow  decreased  reflect  major  of  the  of  Matson  an  initially  high rate  the  the  more  recalcitrant  fractions  development,  its control. Therefore, the  "true"  situation  factor—especially  the  in  and  conjectures.  Boone  (1984)  Unfortunately,  this  might  have  no  for  floor some  m y c o r r h i z a l suppression to the materials  There values  (NAMN  indicated unadjusted applicable the  were  "true"  trends  no  and  GAMN)  are  counterparts. here.  available data  Thus,  trends of N  more  could in  Nevertheless, the  may  horizon  as  well  do  data  M N values.  as  not  suppression one.  By  more indicative  roots. fit  The  the  given  to  would  may  this  be  not  were  samples  phenomenon  of m y c o r r h i z a l  speculation  the  in  results  foregoing the  latter  importance  of  involved.  which  with the  m i n e r a l soil  encountered;  such  case  mineralization  mycorrhizal  the  magnitudes  directly compared.  line  N  decline i n their  studies  depth  with  be  are  where  study  02  decreased  incubation techniques  i n horizons  the  availability  greatly  for  suppression  laboratory  numbers  forest  allowed  this  comparative  lower  potential  the  m i n e r a l soil incubations of this  be  N  of mineralization—as i n the  progressed,  (tree)  spurious  should  time  " t r u e " . trends —assuming  study;  suppression  As  canopy  adequately  extension,  as  mycorrhizal  such m a t e r i a l would correctly reflect  reassert  a  sites,  above.  gradually  is  relatively high M N value—indicating a  harvested  this  the  a  theoretical  As  noted  expectations  criticisms outlined above values  availability across the  may age  of the  again  sequence.  be  adjusted  earlier,  their  than  their  should also  more  reflective  be of  175 Mineral Soil Materials  130)  There  were  highly  among  the  means  (NUMN) (p  <  0.05)  higher  than  different  groups  the  member  sites.  Unlike  the  observed and  sites;  T 8 . There  but  the  in  net  addition,  dissimilar  increased  potential  followed  by  a  Highly  (p  gross  <  mean  were  (T8)  sharp  to  was  N  at  and  stand  manifestation  means  of  (kg soil)"  repeated  9.2,  df  than  in  were  =  4,  greater  1  .  the  indeed  136).  those  1  The  of the T M  than  among  that  the  of  GUMN  20 m g N (kg soil)" ~ respectively;  stand  1  are  closure. the  N  (kg  sites.  six-year levels  apparently  of  the  of the  six m g N (kg soil)"  significantly  the  availabilities  4,  procedure  each  14 m g N  greater  a m o n g the  mature  Actual  a  0.005)  =  indicated  decline  was  F  within  among  =  significantly  differences  both  harvest.  increase  significant  MN  were  fully  M N procedures  after  secondary  not  mg  mineralization  cover  and  (T3)  m i n e r a l i z a t i o n levels  vegetative  five  14  potential  increasing  sites;  and  10.8, df  net  significant differences  individual differences N  T8  was  16 a n d  to  curiously, the  <  the  12  0.001,  (p  no other  T i l means  and  between  =  T i l cutovers  were  (GUMN).  T3  for  no differences  pattern  the  10  were  this  to be  from  T 6 and  fell  means  0.001, F  T M , T 3 , and  there  sites  <  data  T i l means  case,  GUMN  appeared  with  of the  were significantly  ranged  unadjusted  other  (p  unadjusted  of the  and  M N data  T h e T 6 and  others  T6  floor  T i l means  T8  means. the  gross among  those  of the  forest  unadjusted  the  the  thus formed, The  respectively; those  and  of  (Figure 6.1). The means  two  T6  significant differences  the  is  basic  more  was  after  year  to  Thus,  same  mark  increased  It  .  1  The trend  by  unlikely  soil)"  eight.  again have  by  the trend,  that of  harvesting, Somewhat 11  years  increased  plausible  "potential-measuring"  with  that  the  nature  of  176 incubation year a  methods.  N  concentrations  in  eight then recovered (Chapter Five); the  reflection  of  Total  the  of this. I n s u m , then,  mineral  sharp  decline  fraction to  was  it w a s  increased  pre-disturbance  the  mineral  a  levels  declined  to  secondary increase is believed to be  concluded that  to  fraction  peak  at  occurred  by  the  N  supplying  six years year  after  eight.  power  logging;  A  a  secondary  increase i n N availability is not believed to have occurred.  The above,  adjusted  but  at  data  reinforced the  m u c h lower  magnitudes.  basic The  exhibited a different trend to that of the There  were  among  the  result  as  were  highly  significant  NAMN in  the  means. unadjusted  significantly  differences. soil)"  1  soil)'  1  also  <  . Highly  differences exception greater  among  of than  that  greater  and  mature  soil)"  1  soil)"  1  T8  than stand  of  the  Thus,  the  means to  mean, the  that  those all  of the  main  gross  net  interpretations M N (GAMN)  M N (NAMN)  0.001, F  =  instance—the  than  {p  <  0.001, F the  for  their  ranged of  (TM) and =  GAMN  In  were  were  no  T 8 means from GAMN  1.7 (T8)  differences 1.1  1.8 • (T3)  to  data  here  2.2  that  (kg were  the  <  0.05)  was  once  the  T8  mg N  (kg  ( T i l ) mg  was  N  With  (p  1.5  (kg  individual  between  and  N  130)  However,  T i l mean  means  apparent  mg  4,  significantly  were  125) same  mg  counterparts.  addition, the  4,  other  10.8, df =  unadjusted  means  0.8  data.  =  T i l site  and  of  stand.  and  a p p r o x i m a t e l y 1.6 0.5  rest,  pattern  exactly the  no  T 8 . There  feature  the  T6  noted  (Figure 6.1).  11.2, d f  with  between  cutover  mature  others  <  were  values. The T M and  respectively; the .  fell  differences  dissimilar  the  (NUMN) greater  others  significant  were  net  T i l means  respectively; the  {p  and  a posteriori comparisons yielded  0.05)  T h e T 6 and  observed  again  (p  adjusted  adjusted  differences  The  patterns  N  (kg  increased  177  mineralization was indicated earlier—at the three-year point—than for the others.  The The  NAMN  trends of both the NUMN and GAMN  trends  and GUMN data were discussed earlier.  were  assumed  conditions; the reasoning used in the NUMN here. The NAMN indices.  and GUMN cases is also applicable  GAMN  pattern suggested that potential N mineralization  levels were increased as early as  three years  found  as  expectations,  the  trends,  supports  more indicative  of field  and GAMN trends strongly supported those of the unadjusted  Moreover, the  in  to be more reflective  (than  as  the  well  their  argument that  those of the  harvesting. The unanimity  concordance  the  forest  after  with  the  theoretical  mineral soil MN trends may be  floor)  of the  "true" situation  which  obtained on the sites.  The  mean NUMN  and GUMN values observed in this study compare well  with others found in the literature for comparable techniques and conditions. The range of the NUMN  means is below that noted by Klinka et al. (1982) under  mature ESSF stands, but above that of Matson and Boone (1984) in the Oregon Cascades. The range of the Haskin  (1985),  and  well  within  1984a). However, it was similar  technique  and  GUMN  below  soil  means  the  is very similar to those noted by  ranges  reported  by  Powers  (1980  and  that observed by McNabb et al. (1986) for a  fraction  in  the  Oregon Cascades.  These  favourable  comparisons lend support to the idea that the mineral fraction MN values may present floor  a more accurate  counterparts.  The  picture of the indicated  post-harvest  patterns  of  situation than their  potential  N  availability  forest after  disturbance also compare reasonably well with the findings of other studies which  178 employed  anaerobic incubation techniques.  the  eight years  first  after  The pattern  harvesting is similar  of the  NUMN  values for  to that of Matson and Boone  (1984) for a sequence of disturbed sites; however, the seeming secondary increase (after  the  trends  eight-year  point) was  of this study  the apparent  are  not  apparent  strikingly  secondary increase  similar  in the  to those  latter  in mineralization levels. For her  the secondary increase was at year  this  study  respective changes  and noted  "true" as  rather  earlier.  13—beyond the range  artifacts  Unfortunately,  of cutover ages  representations  of the  Haskin  (1985) also  the dual peaks  indeed accurate  than  first  logging respectively, while  question of whether  in hers were  situations,  discussed  the  GUMN  sites, the  12. Interestingly enough, Haskin  noted a later (secondary) decline by year used in this study. This raises  The  of Haskin (1985)—including  peak and decline occurred at eight and ten years after  in  study.  method  (1985)  did  implied of their  and not  total  N  include  a  consideration of total N values.  As which  with their forest floor counterparts,  the  magnitudes  directly  compared.  perhaps  refine)  of the  As noted the  adjusted earlier,  trends  values  they  indicated  there were no available data (NAMN  reinforce  by  the  and  (and,  in the  unadjusted  unanimously pointed toward a trend of increased post-harvest the three-  and before the eight-year points, with a peak  after  harvesting.  have  occurred  accordance increase  in  with  Moreover, the  at  the  the  forest  three-year  forest  floor  GAMN  floor  total  N  point GAMN at  data or  suggested even  trends,  three  years  a as  could  GAMN  values.  little well  case, four  N availability  after  the  with  six years  increase  earlier. as  be  The  occurring at that  after  GAMN)  with  This the  logging (Chapter  could is  in  seeming Five).  179 Therefore,  this  indicated  a  index  secondary  W h i l e this was the in  rather this  well  increase  Unit-Area  a  again  interval  data  among  not be for  6.1.  concentration  the  of  GAMN)  The  data  sequence.  comparisons  the  that  site  extremely  by  weight  one.  between  the  The  eight  results  and  11  also years.  a secondary decline),  phenomenon  The  excluded  (NUMN  unadjusted  L-layer from  interest  was  earlier, but  values  value.  The  close to the  materials  and forest  far  a  more  four  an  artifact  <  0.001)  sets.  These  floor  might  the  adjusted N  the  assumption basis are  reflection  of  and  forest  ha"  on  floor  an  are  soil  1  .  data  However,  values  closer  1983b).  Since  support  the  to  that  view  parallel  across  absolute  calculated by M c N a b b  mineral  presented  the  methodological differences,  literature  kg  and  stated  the  better  basis  (NAMN  mineralization estimate  17  values  data  less indicated differences  from  annual  GUMN)  close  (p  in obtaining m e a n  Under  involved  below those  (Williams,  s a m p l i n g , this  was  with  phenomena  with  are  differences  of the  estimates.  (1983b) —approximately  ranges  i n each  maintained  of the data  significantly  of M N levels on a per-hectare  patterns  reasonably  unadjusted  means  unit-area  limited  Williams  highly  since  presented  of these  are  range. from  taken  discussed,  Because  m i n e r a l soil data The  "accurate"  availability  per-cent-of-total-N basis,  will  Table  given  N  position w a s  earlier, the r e s u l t i n g estimates  are  in  most  Weights  found  differences  site  the  noted b y a n earlier investigation (along w i t h  conservative  On  in  be  study.  were  may  for  the  and humus  adjusted  et al. (1986). fit  the  latter  the  values  observable  layer  was  specifically  that  the  adjusted  indices  180  Table 6.1 M e a n s and 9 5 % confidence limits of the estimated u n i t - a r e a weights of mineralized N given b y the four measures. (See text for abbreviations.)  FRACTION / VARIABLE  SITE  TM  T3  /  VALUES  T6  T8  (values rounded; figures i n brackets are  T i l 9 5 % limits)  FOREST FLOOR NUMN  56t (65,47)  . 58 (71,45)  40 (45,35)  38 (43,33)  56 (65,47)  GUMN  84 (98,70)  79 (95,63)  44 (49,39)  42 (48,36)  . 70 (80,60)  NAMN  6 (7,5)  8 (10,6)  6 (7,5)  6 (7,5)  7 (8,6)  GAMN  10 (12,8)  11 (13,9)  7 (8,6)  7 (8,6)  9 (10,8)  NUMN  6 (9,3)  7 (9,5)  15 (21,9)  8 (12,4)  15 (24,6)  GUMN  13 (18,8)  17 (20,14)  21 (29,13)  15 (21,9)  21 (33,9)  NAMN  0.6 (0.9,0.3)  0.3 (0.4,0.2)  0.3 (0.4,0.2)  1.1 (1.6,0.6)  1.7 (2.7,0.7)  GAMN  1.4 (1.9,0.9)  2.1 (2.5,1.7)  2.8 (3.9,1.7)  2.2 (3.1,1.3)  2.4 (3.8,1.0)  (INERAL SOIL  f All  units are  kg ha"  1  181 give a more representative absolute  magnitudes  of  picture. Insofar as this is true, it may be stated that  MN  sequence. The main change increase six years  of approximately after  levels  did  not  change  drastically  across  the  site  from mature stand levels appeared to be a maximum 1.4  kg ha"  1  from  the mineral fractions  approximately  harvesting.  6.4.2 Chemical Extractions  sums  The trends  of concentrations  (referred  as  to  TIN—total  of KCl-extractable NHJ - N , N O i - N , and their  inorganic  N)  are  given  in  Figure  6.2  0.001)  among  each  for  the  of  the  organic and mineral fractions. Forest Floor Materials  There NHJ -N, limits  were highly  indicated  that  and T8 means  N  other.  (kg soil)"  the  were  1  on the For the  concentration  of the  In  the  addition, each  NHJ-N  (p  values  <  of the  concentrations  sites. of  The jackknife  the  T6, T8,  95%  and T i l  lower than that of the mature stand. In addition, the T6 lower  than  N H J - N concentrations  the  others,  but  ranged from  not  different  mg  mg N  on  T M site down to approximately 51  T3 site appeared to be significantly remaining  however,  of  cutover these  means only  the  were T8  from  approximately 346 (kg soil)"  NO3" - N data, with the exception of the T6 site, the  three  other;  mean  significantly  The mean  the T6 site.  from  differences  NO5 - N , and T I N concentration  sites were significantly  each  significant  higher not and  than  the  significantly Til  1  mean others.  different  means  were  182  Vertical bars are 95% confidence limits FOREST FLOOR  MINERAL SOIL  YEARS AFTER HARVEST Figure 6.2 Means and 95% confidence limits of the inorganic N concentrations given by KC1 extraction. (TIN = total of N H J - N and NO5-N.)  183 significantly or  different  otherwise  i n the  from  that of the  last  three  N O 3 - N concentration  mean others  fell  exactly  between  the  The inorganic similar  compared  was  and  3.3  mg  N  pattern  of differences  above  results  indicate that  on  all  that  sites.  Its  indicated b y  to  stand.  the  approximately  same  N  to  1.2  mature  trend  the  as  T M were 13  (kg  soil)  the  T h e m a r g i n s for significance  -  mg  N  .  The  1  across  the  site  incubation d a t a  indicated decline can be considered i n s i m i l a r  earlier;  that  is, the  resistant values  fractions are  probably  environmental provide  and  limited  extractable  were  seriously  support  NO 3-N  trends  of nitrification  elevated  slightly  result  during than It  the  is  even  N  possible  might  above  the are  which mature  more  have  - 1  that  been  the  of  in  by  fall  in the  fall  at  the  of  sampling  N O ^ - N levels  was  least  point of m a x i m u m N  at  was  ,  while  the  exhibited  the  However,  that  three-year  the  NHJ -N  they  constraints.  they  reflect  point,  and  of the  the  fact  that  1982  had  indicated negligible  because year  availability  a  of  of do The  some  possibly  rest  floor  more  incorporation  these  in  GUMN  to those outlined  proceeded  of  of  surprisingly and  availability,  lack  highlighted  sampling  increased  time  within  interest  of  1  (NUMN  processes.  levels i n forest  Markedly one  the  and  view  -  T3  d o m i n a n t form  terms  of N  levels for the  events. at  as  results  highest  stand  summer  missed  by  extreme  was  that  index  incubation  NO3-N  (kg s o i l ) ]  an  conditions  exciting  preliminary survey  1.0 m g  is  for  As  fact  constrained  microbiological  measure  This  encountered.  the  the  sequence  The  reflect  soil)  T I N means  by far  earlier).  extractions  (kg  narrow. The  N H J - N concentrations.  N H J - N was  unadjusted  very  period considered. chemical  materials NO3 - N  would  across  the  presence  that  precipitation  imply  age  [less  on a l l sites.  intervening  three  extraction  that  that  sequence.  The  184 resin d a t a  should therefore  shed further  N H J - N and  N O ] - N extraction  the  data  total  That the  N  is,  there  harvest;  (Chapter  appeared This  organic reported this  in  result  lower  accords  1985;  in  and  clearcuts  as  observed  among  Freedman  s a m p l i n g for  precipitation  studies.  The  NO5 - N  between  to It  levels  at  for  of  this  higher  are  not  between  following  and  data.  eight,  but  are  NHJ-N  accumulations  s a m p l i n g dates.  harvesting  have  in  data  might As  been  those  Morash,  were  available  forest  harvesting, floors  of  i n N O ] - N were  study have  noted  to  the  and  following the  latter  those  apparent;  comparable  differences  t h a t i n the  than  the  H o w e v e r , both  (Freedman  of trends  no  higher  in  immediately  earlier.  Canada  stands;  noted  such that  first  following  observed  magnitude  noted  Eastern  of mature  should be  by  years  three  of N O 3 - N values  noted  at  the  incubation  three  concentrations  order  M N values  in  hinted  adjusted  years  materials. In terms  (1986)  occurred  the  1986). N o directly comparable  floor  those  patterns  availability  NHJ-N  one  range  T a k e n together,  11.  reasons  materials  N O i - N was  events  declined  high  Freedman,  sites.  subsequently N  are  respect.  the  increased  study  general  floor  opposed  and  level by y e a r  the  elevation forest  Wallace  increased  this  the  forest  substantiate  KCl-extractable  with  W a l l a c e and  for higher  be  literature.  N H J - N and  observed  of  of  the  to  stand  maximum  materials  Five)  availability  recovered its m a t u r e  The  data  light in this  in  the  frequency  been  missed i f  Chapter  documented  by  One,  several  185 Mineral Soil Materials  As were of  with  apparent  the  mean  site  was  For  was  the  significantly of  between  (T6)  3.9  means  of the  stand.  The the  0.5 soil)"  1  mean from  floor  other  mean.  (T6) to  closer  together  year  data,  The  but there  95%  a l l others;  in  T M mean  10.1  (TM) m g  N  mg  N  than  (kg  soil)" .  fell only  of the  sequence. than  latter,  in  For  forest  N H J-N,  the  was  evident  was  implication  limits  soil)" ;  1.8  the of  the  NHJ -N  others  ranged  mean  the  was  and  1  mature greater  6.7 was  was  (T3) m g N  (kg  that  T3  of the  ranged  .  complement the  trends  case.  of  all  three  year  subsequently.  Considered movement  values  patterns  three;  temporarily  for the  variables  observed  went  downward  results  NO5 - N mean  The  levels b y  decline  the  T M materials  (T6) and  T6  mean  that of the  T3  the  N O 3 - N data,  the  than  of  T M , T 6 , a n d T 8 sites. The means  floor  of a  the  1  For  values  indicated that  addition, that  significant difference  the  a l l inorganic N  recovery the  that  Moreover, N H J - N and  i n the  T I N concentration  greater  was  between  both parallel  the  1  N O 3 - N concentration  others  those  (kg  0.001)  {p <  concentration. The  a l l significantly  mean  ; the  1  results  increase six.  was  and  jackknife  significant difference  Unlike  age  significant  6.4  than  significant differences  NO3 -N,  16.7 (T3) m g N (kg soil)'  above  the  site  T I N values, the  materials.  levels,  and  being greater  across  by  T3  (kg soil)"  The  highly  the  the  cutover sites were  . F o r the  5.7  higher  lower than  the  only  T6  mg N  materials,  N H J - N data,  significantly  concentration  than  organic  among each of the N H J - N ,  sites.  T3  the  are  forest similar  were  much  indicated  a  levels h a d declined below  with  mature the  forest  of N H J - N from  stand floor the  186 organic  horizons  to  the  upper  mineral  pattern  observed  in  the  forest  floor  reasons  given  suggested  by the  The literature. values  earlier.  obtained  Taking  (true  was  similar  While soil  fir  those  and  other)  to  et al., 1983) accepted  the  ideas.  documented those  as  and  of  this  patterns  sampling  of  Powers  cover  narrower  believed  Martin  elevated  Freedman  concentrations concentrations this  (1985)  (1985)  study.  supported  the  interesting  for  supported  (1980)  stands.  than  The  those  (Lee  the  trends  Morash  in  in  coastal  across were  the  from  mature  (1985).  For  are  B.C. Martin  (1985)  noted  his  observed  age  sequence;  by year  four—a  however, result  but no  values (1985).  i n acid  forest Lee  accords well  with  agree w i t h previously somewhat  higher t h a n  States,  TIN  1982;  involving  United  the  high-elevation  Morash  rare  stand  were  southeastern  mean  Robertson,  cutovers  sites  and as  1978;  of N O 5 - N values  in  of N H J - N mean  not be  Stewart,  the  western  of F r e e d m a n may  reported  account,  range  NO5 - N levels i n the  The range  and  and  those  into  N O 3 - N value of the  low m e a n  observations.  Matson  data  extremely  with  depth  ranges of values for inorganic N i n this study and  is  generally  favourably  evidence t h a t nitrification  once  The  in  to  there is some  conditions  compare  differences  similar  coniferous very  fraction;  observed  NO 3-N  The  incubation data.  data  are  The  soil.  lower  than  disturbance,  the  those  lower  than  differences increases  supported  by  of Vitousek  in in  the  those  of  NHJ -N NO5 - N  findings of  187 Unit-Area Weights  Highly  significant differences  values  of  each  stated  earlier,  of  the  these  three  inorganic N  6.2. A s m i g h t  be  earlier. even  The  more  apparent,  forest the  floor  fact  eastern The  of into  trends  of  forest  change  floors are  are  the  the  B . C . coast.  inorganic N contents  basis  those  are  the  true  similar of  for  reasons  closeness  stated  (Freedman  importance  than  comparable to those  values  are  trends  materials  in Chapter  of change  are also v e r y s i m i l a r  to  with  data  became  Five,  and the  T h i s is supported b y  and  than  of other in  those time  those  Morash,  absolute  t a k i n g differences comparable  of  of N H J - N  generally m u c h higher  depths  more  As  in Table  concentration  floor  likely to be overestimates. are  site  N-basis.  presented  of the  same  study  the  discussed. The resulting estimates  reflected  is  among  per-cent-of-total  per-hectare  Nevertheless,  The  a  forest  not directly  m i n e r a l soil  on  observed  of NO3" - N i n the  of  thus  methodological differences. account,  be  m i n e r a l soil. F o r the  values of this  soil values  (1985) on the  the  softwood  Mineral  the  unit-area weights are  that  not  trends  contents  0.001) were  categories  will  the  while  of the  <  levels on a  expected,  low overall  N O 5 - N contents  data  differences  KCl-extractable  (p  sampling noted  to those of M a r t i n  1985).  magnitudes.  studies  after  of  by  because depths Martin  harvesting  of  (1985).  6.4.3 Ion Exchange Resins  A  total of six cation and seven anion r e s i n bags  damage—presumably N O 3 - N concentrations  by  soil  fauna.  adsorbed  The  onto the  patterns  were excluded because of  of change  r e m a i n i n g resins  i n the  after  NHJ-N  and  a p p r o x i m a t e l y one  188  Table 6.2 Means and 95% confidence limits of the estimated unit-area weights of inorganic N given by KC1 extraction. (TIN = total of N H ; -N and NO5 -N.)  FRACTION / VARIABLE  SITE /  TM  T3  VALUES  T6  T8  Til  (values rounded; figures in brackets are 95% limits) FOREST  FLOOR  NHJ-N  4 (5,3)  4 (5,3)  14 (17,11)  0.6 (0.8,0.4)  0.1 (0.2,0.1)  0.2 (0.2,0.1)  0.1 (0.2,0.1)  29 (34,24)  21 (27,15)  4 (5,3)  4 (5,3)  14 (17,11)  N H J -N  8 (11,5)  11 (13,9)  6 (9,3)  7 (10,4)  6 (9,3)  NO5-N  0.6 (0.9,0.2)  7 (10,4)  3 (4,1)  4 (7,2)  4 (7,1)  8 (11,6)  18 (22,13)  8 (12,5)  11 (16,6)  10 (16,3)  NOi-N  TIN  UNERAL  TIN  29t (34,24)  20 (26,14)  0.1 (0.1,0.1)  .  SOIL  t A l l units are kg h a  - 1  189 year  in situ are mean  presented  i n F i g u r e 6.3.  in  the  4,  139). T h e means ranged  highly  mature  1.2  =  4,  others;  The  The  the  similar  differences  documented to  reflection  the  the  N  variability to  N  may  have  the  second  the  "true"  and  exist. masked  findings  one.  The  To  some  third  F  =  than  all  of  the  that  that  the  sites.  of the  T i l  m g bag"  1  .  incubations a n d K C 1 First,  Binkley  (1985)  study,  it  is  possible  a  possibility this is  run  the  to the  more  to  any  earlier,  lack of resin  differences  possibility  to is  presented  that  that  as  than  similar  no  contrary  result  no  result  noted  well  resins  that is  a  who  the  (1984),  noted  such  as  that  suggested  possibility  would  cation  =  were  0.001,  among  (1986),  is  the  differences;  fourth  df  there  than  extent,  H o w e v e r , it  of  0.6,  greater  and 1.6  observed  situation; that is, there were  onto  measures  "true"  and  possibility  adsorption  The  ,  - 1  indices of this  second  other  bag  Freedman  harvesting.  =  <  0.05)  apparent  1.3  F  (p  those of the  availability.  The  <  possibilities exist:  i n addition, M a r t i n  where  indeed  support  availability  The  mg  between  Wallace  governing  were  were  . B y contrast,  1  significantly lower  2.1  main  reflect  phenomena.  view;  was  Four  of  availability.  latter  did  other  factors  differences  availability  related  assart  of  NHJ -N  of the  was  0.05,  N O ^ - N values  differences  NHJ-N  that  mg bag'  >  significantly (p  do not  i n ammonification after  evidence  support  to  in  (p  was  m e a n s ranged  accurately  differences  3.9  sites  mean  concentration  earlier.  the  the  significant  . The other  1  resin data  be  related  NO3-N  considered  post-harvest  the  other  to  T i l mean  resin N H J - N results  extractions  would  No  mean -  3.0  among  i n addition, the  mg bag  among  138). The T 3 m e a n  stand.  T3  that  from  significant differences  10.5, df the  N H J - N concentrations  N o significant differences  high  in  N  within-site  may  also  be  resin  bags  all  190  0  J  0  1  2  3  4  5  6  7 78  i  9  n 10  i 11  1  12  YEARS AFTER HARVEST Figure 6.3 Means and 95% confidence limits of the inorganic N adsorbed by the ion exchange resins.  concentrations  191 became  saturated  NHJ -N;  this  the  cation  recovered  over  the  period  is believed most  resins by  (3.3 meq  extraction.  in  situ, thus  unlikely, g"  and  other  results  of  conclusion t h a t  reflect  situation;  are  post-harvest  believed to have  In anion  contrast  resins  supported  many  they  represented  data  strongly  the  seventh  levels  by  noted  a  year peak  respectively. magnitudes  above,  an  of  an  second  the  during  12.  and This  NO5 - N  a  the  fourth  apparently is  decline  While  significant  differences  when  compared  times  the  level  (1985) reported  to  to  that  other  of the  of the  similar  mature  case of the latter  Considering  mature  studies.  stand;  very much larger  at  concentrations  and  the  above  accurately  possibilities listed  strongly were  above  resin  increases —up to  time.  The  formation—hence  N  this  had  below  Martin  in  increase  (1985),  after this  here  and P a c k e e  subsided  pre-harvest  study,  was  (1982)  who  harvesting  N O 3 - N levels  30 times  were that  years  observed  peak  both B i n k l e y  of  eight  stand's  concrete  slightly  that  and  (and  the  in  harvesting;  to  were  The  more  onto  conditions over  declined to  five  adsorbed  supported  NO3-N  after  comparable  subsequent  for  capacity of  did not  concentrations  in  year had  low  study  third  They  peak  and  relative  and  expression of the  that  result  this  reading  exchange  relatively  indications, but  and  rated  same  regard.  picture.  earlier  integration  year,  the  exciting  indicated  availability—occurred by  the  presented  by)  the  the  resin N H 4 - N d a t a  the  been effective i n this  to  high  weight)  considerations led to the the  the  dry  1  The  given  giving  their  were  low  only  1.3  and  Martin  control levels i n  the  study.  the  KC1 extraction  and  r e s i n results  together,  it would  appear  192 that neither  KC1 N H J - N  the  cation resin N H 4 - N adsorption  extraction nor the  methods could yield conclusive results when applied to or in the organic materials under consideration. The mineral soil KC1 data all gave consistent results.  The  informative conditions  anion  result, over  NO5 - N  resin but  went  time.  In  procedure  further  general,  in  that  all data  also it  yielded  a  represented  obtained  and instructive consistent  an  integration  NO3 - N  from  of  assessments  pointed toward the conclusion that levels of that anion were generally after  and  increased  harvesting.  6.5 CONCLUSIONS  The  results  hypotheses  H  from  forest  both  during  the  discussed  and  0  H  floor  post-harvest  in  the  should be  0  and  mineral  period.  foregoing rejected. soil  The  suggest  Major  changes  materials  several  that  appeared  measures  the  subsidiary  in N  availability  to  used  have  differed  occurred in  their  apparent efficacy and indications given. The "potential" nature of the incubation measures needed to be borne in mind in examining the results. Moreover, in the case of the organic materials it is believed that influences of the needed consideration. For the mineral fraction, changes N  appeared  to influence  the  results  in the  latter  in concentrations  portion of the  For reasons given earlier, the  mineral soil incubation results  more  post-harvest  reflective  adjusted unadjusted are  of the  incubation  measures  counterparts.  limited by  their  "true"  The  are value  believed and  situation; to  be  are  similarly, more  interpretation  point-in-time character;  "Gadgil  age  of total sequence.  believed to be  the  temperature-  indicative  than  of KC1 extraction  in addition, they  effect"  do not  their results  take  any  193  direct  account  secondary  (support)  concerned,  the  constrained considered yielded  of m i c r o b i a l l y measures  efficacy  by  inconclusive.  The  procedures  were  floor  clear from years;  there  adjusted peak  indeed the to  a  peak  Though went thus  the  below  a  case.  fairly  thus  appeared  its  far  more  the  the  be  anion  than  were  therefore  resin N  the  as  heavily  were  post-harvest  useful  more  resins  to  results  that  concerning  be  during "better"  the  concerning the  three  the  years  overall  results  availability cation  decline i n N six  of  the  there w a s  three  to  forest or  four;  floor  four  sequence.  resins  as  m i n e r a l i z a t i o n , the two  the  was  then  result and  from  What  supported  increase kg ha"  1  . The  the  first  the  decline  suggested resin)  organic  three  this  to  by  the  was  increase year  t h a t the  refuted  this.  six.  decline It  was  levels only,  indicative of actual  materials  m i n e r a l soil  less  idea of a  appeared  incubations were  from  was  concluded that  to  forest  direction i n  six went d o w n to pre-harvest  adjusted  general incubation  i n the  i n this  availability  years,  NO5 - N (KC1  decline at y e a r  it  some  availability  a n y increase  N  incubation ( G A M N ) the  above,  indications. T h e  non-significant) trend  three  levels,  small—less t h a n  stated  KC1 and resin NO5 - N d a t a  first  Insofar  a  and  whether  (though  adjusted  pre-harvest  limitations  i n suggesting  years  at  and  Therefore, i n the  and remained there.  been  Both  availability  in N  made  strong  concluded that the  changes  may  method  believed  information  incubations w a s  was  is  considered  Where  adsorption;  it  were  purposes.  resin  ion  contrast,  unanimous  M N data.  in N  be  between  the  By  assumptions  now  materials  cation  These  w h i c h involve r e l a t i v e l y long in situ placements.  the  can  the  processes.  interpretive  governing  method  for s i m i l a r studies  statements  for  qualitative  latter  Under  of  factors  important  trends.  mediated  results  would  have  support  the  194 view  of  increased  duration  appeared  increase  would  post-harvest to  have  be  until  been  the  N  mineralization  year  eight  same  as  in  by  this  for the  case.  forest  also suggested  a d o w n w a r d movement of N H , - N from  fraction  perhaps  (and  beyond).  approximately  25  kg  ha"  1  approximately  3  kg  ha"  1  fractions  Viewed  i n terms  eight  years  of  were  at  peak  sustained changes  forest  0-15  cm  the  increases  in  soil  the  sequence around  peak  (to y e a r were  of a n  also  six.  above.  1  that  These  the  year  magnitude  the  of  any  T h e K C 1 extractions  organic to the  mineral  NHJ-N  content  declined  by  fraction  had  increase  of  Both  it can  increased  of the  floors.  however,  forest  an  floor  these  and  were  mineral less  than  the  first  respectively.  three-to-four-year at  three;  The  N O 3 - N contents;  pattern,  witnessed  occurred  six) t h a n  stated  m u t u a l l y supportive.  the  assart  floor mineral  year  and a p p r o x i m a t e l y six k g ha"  1  a  the at  exhibited apparent  one k g h a "  mineral  ;  The  year  levels mark  three,  forest  be  floor.  conclusions and  concluded t h a t of N  for  but The those  the may  availability. forest have  These  floor. been  The more  possible magnitudes of of  Chapter  Five  are  CHAPTER 7 PRE- AND POST-HARVEST TREE GROWTH  In  the  foregoing  chemical characteristics a  similar  Chapters, following  e x a m i n a t i o n of the  their height a n d diameter  consideration  the  harvest.  subalpine  fir  growth before  was  given  W e now t u r n  advance  and after  to  soil  our  attention  towards  I n this  Chapter,  regeneration.  physical  and  logging are considered.  7.1 INTRODUCTION  The assart with the  effect a  next  0  of  between  step  was  phases  three to  regeneration  2 stated  the  and  examine  present;  p r e v i o u s l y . It  was  C o n s i d e r i n g two extremes,  was The  after  from  noted, major period  of  yields—especially and M u r r a y to  over  release  the  by  assart  benefits response where  give excellent g r o w t h ,  is  flush.  were  an  sequence  delay  is fir  of is  be  shorter  195  (Chapter accruing  that  main  of of  provide  assumed full  have  great  firs  earlier  and  pre-  they  immediate  accrued to the  One), to  the  and in  postthis  i n annual were  not  response  regeneration. second-growth  Chapter  One). H a r r i n g t o n  c a n recover from  e a r l y suppression  than  (see  to  an  hypothesis  insights  that  importance  of  harvesting,  exhibited no increase  concerned  that while true remain  to  after  benefits  would  it m i g h t  assumed  years  examination  Conversely, if a  could be  they  eight  therefore  that  provided evidence  discussed  i f regeneration  logging,  subalpine  (1982) noted  site  As there  context  the  first  years.  believed  respect.  benefiting  patterns  the  previously  the  whether  growth  rates  within six  harvest  growth  considered  o c c u r r i n g principally  peak  advance H  results  trees  of the  same  age  that  196 emerged  more r a p i d l y from  Several both  for  Stettler and  studies  logging (1958),  Alberta,  have  examined  residuals  Herring  Bergstrom  the juvenile  (1983).  and  and M c C a u g h e y  the  advance  (197.7), Others  Herring include  periods  first  years  was  the  period  of  between  ten  and  fifteen  years  were  noted  height  growth  Johnstone, to be a  suggest  is  the  years.  usually  rapid  and  that  response  the  to other  Standiford,  The  which  first  Those  in  and  release  For  McMinn  two  to  and  adaptation; after  five  Schmidt,  pronounced  western  delay true  firs  a  were  and  United  of  of  while  regeneration,  the  after  period  for  well  that  height  height  (Gordon,  Monchak  (1982),  Stettler  in  (1958) The  response  declines i n g r o w t h response  delay  (Herring, response  growth.  appears  Other  noted  1973; Seidel,  in  1977;  radial growth  growth  other  (1978)  maximum  1982); r a d i a l g r o w t h  than  include  fir residuals.  logging  noted  fir,  B.C.  States.  subalpine period  subalpine  Johnstone  harvesting,  years  response  as  (1980),  (1976)  response  advance  gave  studies  above  is  1980; H e l m s  aspects of the  response  discussed by Ferguson and A d a m s (1980) and H e l m s and  (1985).  question of w h a t  a n n u a l growth rate  occurred is of importance. There  The  regeneration.  1985). T h e physiological origins and  delay phenomenon Standiford  of  ( H e r r i n g , 1977). Crossley (1976)  consistent  applicable  has  20  in  1978; M c C a u g h e y  more  more  and  after  growth  and Schmidt (1982) i n the  three  occurred  post-harvest  Crossley  recognized five  phase.  would  occurred  be  by  comparison  historically  both  are of  at  least  observed  before  indicates  and  that a  two w a y s current after  response  of approaching  growth the  release  rates  to  harvest—the  this. those latter  197 presumably more  in  r e l a t i v e l y constant tune  assessment growth". the  of  the  Where  southern  as  with  15 c m y r "  true  fir  Adams,  1980; 1980  efforts  is  total  suggested  no  taller  the  height measure  McCaughey  and  1985;  are  of  germane  argument  yet  other  release  of release  is  of  this  and  Adams,  height  some  influence  g r o w t h m a y be  (Johnstone, Helms  1986).  Detailed  study.  can  it  the  and  be  in  taken  the  occur  in  McCaughey  indirect i n absolute  Ferguson  their  some  the  general  response  1985;  of  these  of  their  consensus  growth.  What results  effects  are.  Some  taller  trees  compared  trees and  cases.  growth  and  earlier—highlight  1978); Seidel  shorter  varying  Standiford,  mentioned  release  response  of  consideration  appears  what  that  1978;  Nevertheless,  studies  rates  more  "acceptable  employed models  1973; Johnstone,  on  is  simple  regeneration  standard  (1982) m a y be included i n the were  as  advance  1982;  affects  1980;  a  of predicting g r o w t h  these  Firstly,  implied  involve  defined  minimum  issue  precisely  response  studies  and M o n c h a k  exert  al,  1958; Gordon,  (Ferguson  of  et  of logging  initial  the  success  here.  fir  approach  1986b).  non-predictive  of  (Stettler,  the  second  would  rate  subalpine  Schmidt,  scope  area  (1977)  may  the  on  of  Ferguson  those  higher  of  The  it  pre-set  regeneration;  degrees  time  effect;  effects  advance  varying  which  that  ones  Herring  other)  with  a  concerned,  focussed  at  ones  such  have  of  achieve  1985; B . C . M . O . F . ,  height  an  shorter  growth  outside  points  remains  height  and  results—along  that  current  studies  regeneration.  management;  to  with  Seidel,  three  forest  taken  (Ivanco,  1  advance  time  (and  complexity  practical  interior of B . C . is  Several of  for  (1980)  noted  better  than  1982).  Both  respond Schmidt,  last category, The  suggests  to  fact that  that a  though initial relative  suitable. T h e second issue highlighted is  198 that  growth  useful  in  the  predictor  Schmidt, useful  1982;  patterns.  release  on  implied  that  growth  Helms  Standiford,  and  The  final  age  at  1976;  H o w e v e r , Stettler age  western  true  believed  useful  has firs  been  to  include  was  found  to  and a  is  that  simple  of have  1978;  it  might  either response  Monchak,  a  be  age  at  concluded  or  subalpine  1982).  This  interior of B . C . at  response  of  of  of  view for the  Seidel,  assessment  effect  southern  opposite  1980;  Thus,  the  growth  growth  Adams,  found  1980; M c C a u g h e y and  1985).  i n the  affect  been  to provide comparative historical  Johnstone,  of the  has  same  inversely  1985).  It  in  was  possible "effects  species. other  therefore  of  age  on  AND HYPOTHESES  primary pre-  and  p a r t i a l l y to  enhanced  by  the  should have on  subsidiary  objectives  assart  extent  sites.  hypotheses  phase  height  noted  A s noted  and  earlier.  differences the  will  made  soil in  were  diameter  of advance  in Chapter  Unlike be  this  growth  pattern  been no detectable  the  of  post-harvest  what  g is involved here.  time  Seidel,  investigators  i n practice  (1958)  Adams,  directly affect  1977;  view  (Ferguson  OBJECTIVES  concerning  0  dominant  interest  harvest  growth.  The  H  the  and  1985;  Several  Herring,  present.  Moreover,  the  of  logging does not  to be  assess  (Ferguson  point  growth.  appears  7.2  preceding  of response  subsequent  (Crossley,  release  period  to include this growth period i n that used  growth  fir  five-year  to  provide  growth  regeneration  A s stated  One, i f this  earlier,  considerations, this  case.  patterns,  no  Rather,  and  m i g h t have main  hypothesis  i n g r o w t h of advance  information  been  hypothesis  is true,  there  regeneration  formal  statement  conclusions  to  over of  concerning  199 the  above  patterns.  main  hypothesis  Additional  also presented  will  be  investigations  in Chapter  drawn of  from  the  a  simple inspection of the  veracity  of  main  hypothesis  H  data  0  are  Chapter  Two.  Eight.  7.3 METHODS  The This  basic  layout  included the  and  procedure  1983. F u r t h e r details are  sampling used  scheme  in the  were  discussed  measurement  in  of a n n u a l height g r o w t h i n  provided below.  7.3.1 Height growth  All  data  termination trees to  was  the  were  of 1982 estimated  year  were  height  growth  height  increment  as  and  by  logging  the  could  within  a  Only in  the  cutover, the  data  for  at this  MIDAS  point,  the  successive  yielding  calculated  also be  mature  each  trees  height  the  starting  subtracting  denominator  applied to the  each  as  ( R H G ) was  1  For  by  retained  c m c m " , but  were  growth  of logging.  centimetres  numerator  processed  set.  A  relative  release.  The  each same  calculation; the  stand's advance  i n other  used  as  at  release  measured  height  year's  growth  back  than each  absolute  were  R H G figures terms.  of  the  of cutover  greater  measure  units  Using  used  were  zero year's  annual in  the  expressed  N o R H G calculations  regeneration.  period c o m m e n c i n g at  and ending i n 1982 was  year's  release  dividing  considered  height  a  by  programme.  a basis  five  years  before  the  for establishing absolute  year  of  annual  200 height  growth  exhibited RHG  by  the  values  mature  trends.  rather  mature  were  stand  These  stand's  plotted  values.  trends  For  in  were  advance  similar  assart  periodic  years  a  increment  applied  to both  case  of  was  assessed.  of  the  absolute  mean the  five  absolute  growth,  time  rate  years  annual  the  but  comparisons,  growth  of  not  prior  taken  the  to and  to  for  graphically the  without period  taken  growth  time  compared  regeneration  fashion,  a r b i t r a r i l y considered to be the  consecutive  also  same  any  the  two  year  of  the  15  The  delay  sustain times  two mean  This  was  addition, i n  cm  yr  -  to was  for  the  harvest.  R H G values. I n  achieve  period.  of response  than  those  comparisons  to achieve and less  to  the  standard  1  7.3.2 Diameter Growth and Age  (0.30  Diameter  growth patterns  m)  taken  growth, a  Parker  Instruments  to  with  number  an  Apple  extremely  fall  age  of  Absolute  data  1984.  Three  rings;  diameter  growth  measurement;  idealized. The stump  in  above  a  this  Starting  height diameters  Many  of  the  the  on each  discs  were  the as  machine  asymmetrical, the  growth  ages at  MIDAS two data  release  1984  disc u s i n g  measuring  giving  of  maximum  wider portion of the  calculated  (Dsh) and  stump-height  ring  path  within  diameter  the  termination  performed  chosen on the  was  from  the  growth  processed  year  sense,  were  at  measurement  were  i n each  determined  annual  microcomputer.  narrow  obtained  were  measurements  Model He  age  of rings perpendicular to it w a s  The  growth  i n the  r a d i a l growth and  coupled and  discs  and  times  disc.  programme. the  radial  are  somewhat  were  determined  201 by the  same  to  age  the  been a  as  measure  data.  and  as  data  order  with  time  taken  year's were  to  at release  was  the  grouped  examined height the  the  degree  growth  year  and  of the  of harvest.  The  R E S U L T S  A N D  T h e patterns in  Figures  the  7.1  R H G and  Figures  have  A  summary  It  was  increase  explained  by  the  was  influenced by  that  the  T3  of  could  have  1983). I n addition, also calculated i n  approach  whether  as  there  with  the  were  any  growth, simple correlation a n a l y s i s three  age  growth  annual  oldest cutovers. at  for  release  the  and  five-year  t h a t any  height  respectively. F i g u r e s  kept  This  analysis  both  the  period  influence of age  total  following should be  to changed conditions.  the  obvious  in  growth  fact  that  the  understory  and diameter 7.3  respectively. T h e same  so  indicated response  immediately  noticeable  same  idea  period of adaptation  R D G measures  of the  of the  (Watts,  This  ( R D G ) was  u s i n g the the  height.  applied  D I S C U S S I O N  7.2  been  growth  between  diameter  of absolute  and  years  and release  data  N o corrections were  stump  seventeen  rationale here w a s  most pronounced d u r i n g the  7.4  attain  simply  association total  to  diameter  examine  age  on  height data.  examined  associations between carried out  the  h i g h as  of each  The  In  used  for  four  fashion.  height  as  estimates  low as  relative  similar  approach  that  as  responded  of the  delay  estimates  is presented  was  even  before  the  year  the  relatively s m a l l  large  the  that  of harvest.  neighbouring T i l site. It  increased  availability  them.  i n Table  anomalous;  of  of two  between  result  on  trends latter  T3  of the to  vertical scales  comparisons  growth  presented  illustrate the  facilitate  understory  harvesting  7.4  to  the  occurred  and  g r o w t h are  7.1.  is,  a  This  is  T3  area  appears  light.  It  is  202  = Advonce regeneration in mature stand (or same period  Cut  1980  T3  V • —  •-  24-  * - 21I t—  18-  occ  15-  t— I  12-  oUJ X Z  < 2  1  1512-  UJ  9-  z <  5 -  2  3-  T8  /  21-  X  UJ  1975  i-  18-  X  Cut  T6  6-  o cc o  1977  9-  24  X  Cut  • —  •TV  24-  o X  21-  Cut  18-  o  Q.  15-  t— X  12-  O  o  UJ  9-  z  6 -  2  J-  X  <  -6  1972 T11  -5  -4  -3  -2  -1  0  1  2  3  4  5  6  7  8  9  10  11  Y E A R S BEFORE/AFTER H A R V E S T  Figure  7.1  Patterns  of absolute  a n n u a l height g r o w t h of advance  regeneration.  203  Advance regeneration in mature stand for some period  :  Cut  1930  T3  y  •  —  • —  •  —  Cut  1977  Cut  1975  Cut  1972  \  T6  18  «  Til  /  °i -6  i  i  i  -5  -4  -3  i -2  i -1  i  i  i—i  0  1  2  3  i—i—i—~i—i—i—i—i—i 4  5  6  7  8  9  10  11  12  YEARS BEFORE/AFTER HARVEST  Figure 7.2 P a t t e r n s  of absolute  annual  diameter  g r o w t h of advance  regeneration.  1-]  E E  0.80.6-  RH  o  0.4-  <  0.2-  Cut  1980  L1 _ • LJ 1  01-.  0.8-  E  0.6-  RH  o  0.4-  <  0.2-  Cut  1977  \  1 * i I 1  1  0-  1-i 0.8-  £  0.6-  o a:  0.4-  <  0.2-  Cut  1975  ll - . LJ I  0-  1-i  £ ^  £  0.6H  o £  z  0.8-j  < UJ  1972  Cut  0.4 H  0.2  0  -6  -5  -4  -3  -2  -1  0  1 1  ' 2  ' 3  i 4  i  r - — i1  5  6  7  8  1 9  1 10  YEARS BEFORE/AFTER HARVEST Figure 7.3 Patterns of relative height growth of advance regeneration  i 11  I-i  IT  0.8-  E 0.6-  /\  Cut 1972  RD  o  0.4-  <  0.2-  1 . 1 l_l_J  2 - 6 - 5 - 4 - 3 - 2 - 1 0  1  ~i 2  i 3  i 4 4  i 5  6  r  7  8  1  1  9  10  1 1 11  12  YEARS BEFORE/AFTER HARVEST Figure 7.4 Patterns of relative diameter growth of advance regeneration.  206  Table  7.1  S u m m a r y of response  delay  VARIABLE  DIAMETER  SITE  /  VALUES  T6  T8  T i l  2t  1  3  GROWTH  absolute relative HEIGHT  estimates.  1  1  1  GROWTH  absolute  4  5  5  relative  2  4  3  5  6  10  to  15 c m y r  fAll  _  1  units are  years.  207 unlikely  that  this  characteristics patterns  in  effect  the  prompted  extended  unharvested  their  to  T3  exclusion  from  any  site. the  soil  This bulk  or  nutrient  anomaly  of the  in  availability  the  T3  growth  discussion w h i c h  follows  below.  7.4.1 Height Growth  Considering the three oldest cutovers, pre-harvest consonance  with  (Figure  7.1).  growth.  This  Only  were  from  4.3  were between  height  that  the  the of the  be  of a  envisioned.  the  cm  assumption  oldest  yr"  appeared that  cutovers,  (T6) to  1  to  6.1  the  five-year cm yr"  was  stage,  consistently  rates  a  response  relative rates was well  with  relative measure trees.  l a g between  results  diameter  importantly  in  be  and this  a  The  growth  averages  R H G trends  five-year  averages  (T8).  1  period indicated by  that  from  delay  better  pre-harvest  delay  two to four values  may  I f so, the  than  7.3).  regeneration  similar  (T8). P r e - h a r v e s t  1  (Figure  response  greater  indicated  agrees  More  the  had  to be i n  marginally  pre-harvest  (T6) and 0.09 c m c m "  post-harvest  uniform  advance  exhibited  cutovers  cm c m '  1  stand's  have  0.06  indication  reaction less  site  less  growth  However,  T8  mature  somewhat  indicated b y  delay  obtained i n the  but  growth  Absolute  the  For  similar  In  which  reinforced the  characteristics. ranged  that  g r o w t h appeared  of  the  four  relative  to  five  absolute measure.  years,  while  years  (Table  7.1).  The  absolute  from  other  studies  as  noted  earlier.  more  sensitive reflection of the  suggest height study,  that  for  growth the  subalpine  responses  shorter  delay  fir than of  there  "true" may  previously the  RHG  208 measure  indicates  was at by a  its peak;  about  that  delay of five the  T8  site;  up  to  cm  height  yr"  yet  he  for  rates  growth; unknown.  7.2  considered  and  7.4), this  Assuming  regeneration  these  was  temporary  study.  below  20  Herring  cm yr"  was  a  serious  post-harvest  height  is capable. The  highest  cm  yr" a  1  (1977)  , but  1  so,  the it  This at or  regarded  reported  to  valid,  benefit  by  to  the  have been constrained throughout  post-  serious  post-harvest  mean  the  current  growth  levelling  appear  assart the  may  that  diameter  diameter  i t would  from  as  unlikely  subsequent  only  range  sites. It is recognized  somewhat  a  a  periodic  of  the  contrast,  , with  1  of m a x i m u m  supported  applied  By  these  (1980)  period  .  1  noted  estimate  least  be  yr"  better  seems is  h a r v e s t i n g on  cm yr"  g r o w t h on scarified  considerations to able  effect  there  represents  after  g r o w t h of 21  sites.  indicated  potentially  , seven y e a r s  1  phases,  Even  assart  standard,  1  the  species  McMinn  achieved.  which  nevertheless  considered by this  be  was  and  (1958)  achieved. will  cm  delay,  the  maxima  in advance  1  Stettler's  above  44  Herring  been  whether  growth m a y  achieved. T h i s  response  24  the  m i g h t have been missed  was  release  of 16 to  peak  15 c m y r "  of w h i c h  comparable  of 34 c m y r "  have  (Figures  the  ,  when  management.  the  all had  respond  of the  22 c m y r "  average  increments  according to  higher  cutovers  1  of  to  that the  this  below those  performance.  increments  not  well  length  observed  underestimates;  that,  the  other  (1982)  growth  years before  rate observed was  25  harvest  of  fell  the  Monchak  able  viewpoint of practical forest  rates  post-harvest  were  Considered i n terms  to ten  Regardless growth  trees  absolute growth suggests  one y e a r .  l a g from  the  the data  off of  growth  is  that  while  release,  such  post-harvest  period  209 7.4.2  Diameter  Once diameter  year T6  again  growth  obtained the  Growth  i n the  considering appeared  advance  very  pre-harvest  regeneration  sites  growth  averages  respectively).  It  the  average.  H o w e v e r , since  is  differences  and  fairly  0.05  cm cm" .  cannot  uniform  (Figure  marginally  mature  from  somewhat  7.4).  cutovers,  stand  to  interesting  not  0.06  which  As  with  uniformity.  cm  the  yr"  (T8  1  and which  the lowest diameter  growth  performed,  T8  Five-  site,  Pre-harvest  five-year  that  (Figure 7.2).  that  possessed  were  here.  Their  0.03  pre-harvest  below  a s s u m p t i o n of pre-harvest  ranged  assessed  oldest  but  of the  statistical tests be  three  to  highest height growth average,  any  the  significance of  R D G trends  averages  fell  were  between  similar  0.04  and  1  In  the  post-harvest  phase,  indicated consistently greater Absolute  growth  measure  suggested  indicated a  accord well w i t h those of  growth  a  suggests relatively the  relative  response.  steeper  that  the  similar  height g r o w t h , this reinforced the  exhibited  use  mainly  than  It  those  a  of  measure  did  is perhaps of  one  with  the  of  one  in a  to  year  growth,  three  absolute  growth  relative diameter  growth.  years,  throughout  while  (Table  the  7.1).  relative  The  delays  the l i t e r a t u r e . It would appear  that  improve  diameter  indeed  noteworthy  that  R H G measure  response  position to benefit  delay  the  radially  levels  estimates  for  R D G patterns  (Figures  were concentrated  growth  height  delay periods t h a n  noted earlier from  diameter  trees were  delay  period  t h a t g r o w t h efforts quick  response  as  7.3  and  rather  further  are  7.4); than  support  i n whole or i n part  this  somewhat possibly  vertically. the from  the  The  argument the  peak  210 of the  assart  flush.  There of  subalpine  growth 0.07 yr"  appears  fir  ranged  and  advance  cm  from  to  0.25  0.10  yr"  1  ;  cm  1  (1978)  . The  with, these  values.  They  (1985)  for  other  released  growth  generally  suffered  height  growth.  The  immediately  obvious;  physiological  cost  to  ranges are  none  site  trees  site,  mean  ;  that  of the  1  range  this  growth study  to  the  ranges  Thus,  it  generating  0.07  to  diameter  fell to  0.35  primary  as  by  that on  release  are  not  in  the  differences to  Seidel  diameter  result  opposed  from  favourably  observed  appears  possible  cm  subalpine  compare  conflicting  between  ranging  seemingly operating  apparently related  T8  rates  this  growth  absolute  was  in  firs.  diameter  (Dbh inside bark)  diameter  constraints  be  of  T6  the  close  true  of the  may  on post-harvest  five-centimetre  very  for  yr"  observed  western  reasons  the  cm  T i l for  the  post-harvest  also  they  For  0.39  the  suggested  yr"  published data  and  for  Johnstone  logging residuals  0.08  little  regeneration.  between  0.50  . Data  1  fir  to be  secondary  growth.  7.4.3 Tree Age Considerations  The advance values the  mean  regeneration are  values  =  on  release the  generally s i m i l a r .  mature  limit  ages at  103  stand yr,  observed  had  a  and  cutover  are  presented  B y c o m p a r i s o n , the  subalpine  mean  age  lower 9 5 % l i m i t were  148  corresponding 95% confidence limits  and  32  in = yr  sites  1984 81  of 92  yr). The  years  in  Table  fir advance (n  =  for  7.2.  the  Their  growth i n  30; upper  95%  T M m a x i m u m and m i n i m u m  respectively i n  1984. T h e  ages of  mature  211  Table  7.2 M e a n release  ages for advance  regeneration  on the  cutovers.  SITE  nt  AGE? (yr)  T3  28  35  49  21  T6  100  31  35  27  T8  90  42  48  36  Til  70  48  56  40  tDenotes sample size. t V a l u e s are rounded means.  95% L I M I T S Upper Lower  212 stand as  advance  88,  85,  83, and  corresponding This  regeneration  cutover  implies  eliminated.  80  that  This  the  Chapter  Two). H e r r i n g  are fir;  correlation 0.05).  It  does not indeed was  be  they  are  height was is  the  reflective  <  note  the  of  negative  that  seemingly  constrained diameter  than  were  of  advance such  the  observed  larger  these.  somehow  applied  (see  were  very  are  more  trees  release observed  by  under  The  harvesting  growth  ages at  reported  such height growth.  r  =  a  Herring similar  (1977)  in for  conditions  -0.36,  to  df  age =  diameter  at  at  231). growth  correlation  on  age  post-harvest  values. earlier;  association  growth,  but  This  supports  the  view  total  significant  variable  this  idea  that  might  growth  which  counter  is  the age  >  variables  to  extremely  significant for  (p  result  runs it  very  non-significant  and  between  however,  appeared  was  No  height  This  there  release  relationship. Nevertheless,  discussed  an  on growth response,  significant  influence  indirectly) as  of age  corresponding  a causal  concepts  to  sites  result  correlation between  that  to  interesting  The  range  those  0.01,  point  or  to  negative  (p  a  larger  moreover,  possible effects  acknowledged  (directly  accepted  general  lower  slashing treatments  s m a l l e r ones.  close  observed . w i t h  fully  the  estimated  1977).  weak  growth  necessarily  unconstrained  the  unintentional  that  can be  definitely  harvested  post-harvest  noted  very  respect to  related  currently  b y the  within  v e r y significant but  five-year  an  harvested  T i l sites respectively.  been  the  representatives;  Sock L a k e ( H e r r i n g ,  With a  well  have on  been  (1977) older  to  stems  have  sites were  T 3 , T 6 , T 8 , and  to logging damage t h a n  study  nearby  the  other  appear  effected  generally speaking the  subalpine  for  the  older  could  or otherwise  this  yr  values  process,  susceptible  when  for  the  seemingly might  have  213 played  a  direct  Monchak  (1982)  response the  greater  remained  than  role  in  convinced  conceded  (release)  age  that  of a  stump  height  study  were  affirmation height  as  ten  would  years  be  60  yr.  The  all  well  below  this  that  age  played  a  response.  nevertheless,  Such  the  of this aspect  a  results  might be  growth.  direct  age  was  usually  at  the  ages The  (direct can  at  release  foregoing or  at  supporting it at  equivalent  least  be  1983)  in  where  that age"  trees  only  indicate t h a t further  to at  in  this  tempt  an  constraining  accepted  was  (Achuff  and  "threshold the  on  height  considerations  indirect)  best  lower  of 30 y r  for  While  effects  breast  1982; B e r g s t r o m ,  1983),  value.  conclusion  height  to grow to breast height  mean  role  no  regeneration  Murray,  (Watts,  were  performance  advance  time  release  there  growth  L a R o i , 1977; H a r r i n g t o n and height  influencing that  the  80 y r . A s s u m i n g  stump  7.5  indirect  growth, he  average  and  or  release  tentatively; investigations  desirable.  CONCLUSIONS  Some  general  objectives  of  this  pertaining  to  pre-  Absolute  height  measures  for  release  which  statements phase  growth  the  and  post-harvest  growth  response  both  height  would  be that i n situations height  of  can  have  and  was  these  application of relative measures  there  within  details  and  diameter  four  to  growth the  five  the  of  indicated  patterns  years,  peak  of a  context  growth  indicated  assart  is less  previously appeared  made  The  height  diameter  than  be  study.  coincided w i t h  such as  responses  now  an  noted  by  the  to improve interpretations  relative  response  earlier.  lag between  values  presented.  the  earlier  stated  and  were but  of  It  may  diameter  literature. of both  to  and The  height  214 and  diameter  measure within yr"  1  indicated one  year  level,  represent  position  conclusive)  absolute that  of h a r v e s t i n g . was  a  to  in  benefit support the  for  a  course  constrained  by  There  evidence  conditions  occurred  to  the  changed  respect  to  the  achievement  the  lag  associated  viewpoint of the  forest  is  thus  rejection of m a i n hypothesis  H  of  assart  a  more  effect.  concrete  However,  which  seemed that  even at  the  examination  release not age  height  to  limit  of the  of  the  this.  This  partial  of  validity  the  growth diameter advance  in  (but  will  the r e l a t i v e l y low release  cm  could  potentially  . This  0  15  manager.  There  the  regeneration  with  least  suggesting  played a role here,  relative  at  Eight).  influences  g r o w t h , the  response  ten-year  the  F o r diameter  was  from  (Chapter  was  that  measures.  With  five-  concluded  hypothesis  have  the  consistently  there  was to  later  over  a serious problem from  It  to  data  be  not.  referred of  appeared growth  a  to  this be  response.  regeneration  ages observed.  might  CHAPTER 8 POST-HARVEST FOLIAR CHEMISTRY  have  The  results  been  some  consideration  to  chemistry  the  of  consequences the  such  advance  of the  to  in  post-harvest one  possibility  importance  discussed  assart  the  limitations  possibility.  In  regeneration  is  patterns  of  nutrient  tree  growth,  previous  noted  limitations the  main  Chapter  suggested  on  growth,  and  this  Chapter,  the  considered—both i n the  to  soil  growth.  emphasis  gave  and  placed  may  preliminary  terms  Because  was  there  post-harvest  in  data,  that  of  on  of  foliar possible  also  i n light of  its  established  patterns  of  foliar  N.  8.1 INTRODUCTION  Many soils a  (see  method  body  of  include  Stone  the  Chapter  reviews  literature  (1968)  on  of  (1984),  noted  Six) logically  of assessing  those  Lambert  of  nutrient this  (1973),  Timmer  and  dealing  included some availability  subject.  Leaf  earlier  to forest  Morrison  N  availability  consideration of foliar  Noteworthy  Morrow  with  trees.  efforts  (1974a),  (1984),  not  van  and  There  in  analysis  is a  Ballard  mentioned  Driessche and  (1974),  Carter  (1986).  also considered microelement nutrition of forest  trees i n some  Conceptually,  two  be  the  of nutrient  diagnosis  stimulus Other  (Morrison,  general  purposes  of foliar  deficiency and  1974a;  a n a l y t i c a l approaches  van  den  the  analysis  prediction of tree  Driessche,  do exist; however,  215  may  1974; the  Ballard  consensus  stated;  detail.  these  response and  to  Carter,  appears  as  substantial  previously  den  forest  to be  are some  1986). that  216 foliar tree  analysis nutrient  Ballard  and  predictive  is by status  concentrations; in m a n y  of  Ballard  Ballard  nutrient  1974a;  clearly  foliar  contents  van  available diagnostic den  Driessche,  coupled w i t h  established  ratios  tool for  1974;  assessing  Powers,  1984a;  fertilizer treatments,  (Morrison,  of  different  1974a;  Timmer  its and  Timmer  and  predicting  graphical  Still  the  diagnostic  co-workers  and  to give a  response method  r a p i d , low-cost method response  methods  During  Timmer  fertilizer  for  nutrients  nutrient  interesting  I n B . C . , this  potential  weights  have  them  examined  have  become  the  been  one  1984a; B a l l a r d  also  within  also  been  plants  other  researchers  levels  (Morrison,  nutrient included  most  widely  and  Carter,  employed, (van  have  den  in  Driessche,  preferred  1974a;  part  the  Powers,  use  1984a;  1986).  to v a r y i n g degrees.  1974a;  needle  usually  1974a; Powers,  between  1986).  balanced  very  (Morrison,  (Morrison,  Carter,  and C a r t e r ,  unit  have  of critical levels has  antagonisms  and  a  analysis and  T h e concept  interpretations  presented  a  been  and/or  Several  1984).  currently  Moreover, when  involving  of possible  optimum  above  has  However,  because 1974;  1986).  instances.  in data  1986).  best  1984).  Studies  used  the  (Morrison,  Carter,  value  Morrow,  far  to  been  Stone,  for  1978).  and  fertilizer treatments  was  which later  combine  fertilizer  later  Stone,  1978;  responses  modified  Timmer  (Weetman  and  by  status  and  a mini-plot technique  stands for their  the  D . Heinsdorf,  of evaluating nutrient  coupled with  of screening forest  examining  This  r a p i d method  been  developed  1960s, H . K r a u s s , and  technique  (Timmer has  have  V. and  Morrow, to  yield  nutrient  status  and  Fournier,  1982  and  217 1984).  T.  Ballard  and  co-workers  have  developed  diagnosis, interpretation,  and prescription of fertilizer  species.  is  The  system  accommodate and  both  Carter,  Zinke  and  based  macro-  1986).  A  and  very  co-workers;  it  on  critical  micronutrient  interesting  entails  the  a  comprehensive  treatments for major  and  optimum  evaluations  diagnostic comparison  of  1979;  system yet  to be  circles—the  Diagnosis  (1973). T h e  Zinke,  applied to  system  and uses  of directly comparable may  be  Lambert  included. (1980),  Porada  (1986)  solution  to  serious may In  are  most  data  addition,  the  critical  analysis to  the  few  has  as  affecting  to  Powers  problems  in  forestry.  in  the  levels  were  and was  ratios  but the  Ballard by  P.  non-linear  data  (Zinke  and  comprehensive  (DRIS)  its objective  of  Beaufils  the calculation  yield; non-nutritional applications; (1985),  (1984a), Its  establishment above,  a  can  developed i n a g r i c u l t u r a l  System  forestry  probability method  of  principal  and  presents  a  difficulty—and  a  to a  this  criticism  lesser  variables  applied on selected cutover  and  Zasoski  DRIS  norms;  perhaps  Truman  and  main  factors  extent.  used.  In  sites.  HYPOTHESES  The objective of this of  and  According  be  the screening technique  status  Integrated  factors  been  was  and  developed  most  for  western  1984;  against  the  and K i m (1981), H o c k m a n et al.  examples.  8.2 OBJECTIVES AND  nutrient  ratios,  have  perceived  also a p p l y to study,  nutrient  was  benchmark  perhaps  problems  Recommendation  There  foliar  Finally,  such forestry  indices for the  Leech  one—was  this  1986).  ratios,  (Ballard,  technique  (Weibull) fit of c u m u l a t i v e probabilities developed from Stangenberger,  system  phase of the  advance  study  regeneration.  was  The  to  main  ascertain aspects  the  post-harvest  of interest  were  218 the  post-harvest  assart  patterns  harvest  growth  hypotheses well  patterns  as  change  H  those  mineralization  earlier;  were  apparent.  0  of  i n the  f  . , and H  foliar  and  also,  0  deficiencies.  processes  have  been  levels  those  noted  i n the  This  in  fell  any  extent  these  nutrient  within  the  ambit  of  If  should  H ^  is  0  the  Also,  soil.  true,  there  supply of w h i c h for  such  A  valid  H  have  of  implies  the  to  post-  of  main  of toxic levels as  neither  trends  0  tests  been  depended  elements,  post-harvest  paralleled  limitations  effects  between  the  what  . L i m i t a t i o n s include the  soil.  evident  to  whether  levels of nutrients  parallelism and  change,  noted  , H  0  of  mainly should  change  that  little  for  in  the  on any  foliar macro-  o nutrients  no  have been latter  arises.  ratios  evident i n the  applies to H  The  Mg,  levels or  foliar  Five  boron  of  which  hypothesis H  m i c r o n u t r i e n t s were  (B), copper  specific 0  (Cu), iron  and  frequently  for  between Al  can  toxic  conditions should similar  could  0  be  taken  chosen; those  as  noted  reduce  the  of N , P , K , C a ,  g—including a screening approach involving N  considered appropriate; (Fe), and  Pendias, plants  Kabata-Pendias A l and  to  diagnostic  manganese  these  were  (Mn). The  not been confirmed;  a l u m i n i u m (Al),  general essentiality  while it is a common  of a l l plants, its physiological functions have not been clearly  (Kabata-Pendias  1979;  nutrients  , N levels were  of A l beyond certain p l a n t groups has constituent  deficient or  macronutrient values. A n a r g u m e n t  a n d S were used i n testing H  only.  either  and micronutrients.  0  question  For main  indicating  1984).  growing  and  However,  on acid  Pendias,  cation uptake,  and  toxicity  soil—including  1984).  some macronutrients which  Al  Moreover,  forest there  influence uptake  also hamper  effects  of the  m e t a b o l i s m of P  have  trees are  identified been  (Pritchett, interactions  latter;  excess  (Kabata-Pendias  219 and  Pendias,  1984;  the  basis  of  recent  B  levels  that  low  growth  after  of toxicity.  growing  in on  this valid  absence  of  1  .  foliage (T.  unresolved; high  test and  the  true  1960;  1968;  firs  true  the  i n the  fir  Vosges region Powers  to  in (e.g.  the  3,  of the  mg  of  viewpoint  from research  The  with  concept  with  seedlings has  fallen  kg"  also  He  1  apparent  that  greater)  to  be the  traced  to  above  300  mg  observed  effect  nutrient  in  refute  in  on  of M n toxicity  apparent  1986).  be  been  adverse  to  concept  often  have  3,  tended  reported  can  question  or  March  concentrations  other 1  comm.  in  growth may  be  limitations,  slow-growing trees  respect.  above  considerations,  alternates can now be  t Professor, F a c u l t y of F o r e s t r y M a r c h 3, 1986.  mg  The  kg"  old-  plantations,  from the  believed the  growth  foliar  any  1986).  absence  2000  at  1000  B . C . without  noted  hampering  i n spruce  has  (1979)  fir  consideration i n this  their  pers.  poor  up  was  e x h i b i t v e r y h i g h M n levels without  Ballard,  occurred  included on  It  associated  1967).  limitations,  March  context  was  elevations.  of  problems  stemmed  high  latter  in  comm.  firs  it  were  Ballard.t  of M n was  Vallee,  T.  Fe  observed  at  levels  levels  the  France;  T.  main  inclusion  tree species  (Stone,  nevertheless, foliar  forest  nutrient  Mn  pers.  Within  the  levels were  1983). Nevertheless,  subalpine  might w a r r a n t  under  with  effects;  However, of  B , C u , and  B . C . by  among  of  (Rousseau,  western  other  Ballard,  very  mulls  work  Mn  been  region  since m a n y  some  inhibiting kg"  Vosges  (Drapier,  for  interior  L o w C u and F e  i l l effects  recent idea  have  in  1986).  idea of M n toxicity appears to have  acid  apparent  More  may  the  into disfavour, any  Carter,  slashburning. Finally,  The  firs  and  observations  spruce-stands.  especially  true  Ballard  and  Dept.  the  subsidiary  hypotheses  stated: of Soil  Science, U . B . C . ;  pers.  comm.  H  :  0  No  levels  major  changes  occurred  of advance  regeneration  There  indeed  in  during  the  the  foliar  N  post-harvest  period.  H, y N  levels  were  of  advance  major  changes  regeneration  in  during  the  foliar  the  post-  h a r v e s t period.  H  :  0  There  between  was  post-harvest  regeneration harvest  Hi 2  no  N  and  marked foliar  that  similarities N  levels  previously  of  described  for  post-  availability.  post-harvest  foliar  N  levels  regeneration  and that for post-harvest  H  detectable  :  pattern advance  There were indeed m a r k e d s i m i l a r i t i e s i n  :  between  0  in  No  deficiencies  occurred  N  or  i n the  N  of  advance  availability.  other  advance  pattern  macronutrient  regeneration  after  harvesting.  g:  Detectable  the  advance  H  • Neither  in  0  any  of  regeneration  macronutrient  regeneration  after  toxicities of  B , C u , and after  deficiencies harvesting.  A l or  Fe  harvesting.  occurred i n  Mn  occurred  nor in  deficiencies the  advance  221  H,  : Toxicity  in  one  or  advance  There is  should have  true.  criteria.  The  examination H  0  g  and  toxicities  H as  0  are  the  for  B,  micronutrient data  for  falsification;  Cu,  after  such  data  and  H  from  before,  Fe  i n foliar  statistical  deficiencies  occurred  in  the  N  levels among  the  were  consisted  0  tests  l e v e l s . or  sites.  and/or  harvesting.  should not  the  and  statistical  critical be)  Mn  differences  judging  true,  and  where  for  case m a y  as  of  no differences  tests  plotted  ^  of A l or  regeneration  criteria of  more  been  Statistical  effects  of for  ratios  have  accepted a  the  indicative  been  identifying  0  of  among  of  visual  sites.  deficiencies  evident i n the thus  if H ^  falsification  combination  differences  S u c h comparisons tests  as  sites  If (or  foliar  macro-  formed the  criteria  differences  were  included  necessary.  8.3 METHODS  T h e basic samples the  study  Carter for  were are  (1986)  presented  layout,  s a m p l i n g scheme,  in Chapter  given below. F i e l d  analyses.  and  S was  and  Two. Further  done  after  are (and  system  details  s a m p l i n g followed  i n principle. A l t h o u g h they  micronutrients  nutrient  field  the  specific to this  composite phase of  guidelines of B a l l a r d  considered on the  of creating  together  basis  of)  below,  the  main  and  analysis macro-  222  8.3.1  Main Foliage Analysis  Sampling taken  from  branches shoots in  the  were  upper  twigs  storage  and  grouping needle  stored  the  twig  second-stage et  al.  before  counting,  before.  Because not  determined duplicate  Lanyon  obtained as  1000  et  for  by al,  in  al,  1974;  on  bags  at  was  twigs  the  were  uppermost  Total for  200  each)  have  N  and  from  on application of weights  into  fairly  to  of  cold  P  at  60°C)  storage  low, the  affected  in  after  1982;  dry  substantially  this  ashing  Knudsen  as  samples  concentrations  samples;  the  samples  were  instance,  Concentrations of K , C a ,  spectrometry Suhr,  Random  re-dried (six hours  soil  a l l samples.  and  of  envelopes  the  point. E s t i m a t e s of  lots  was  samples  removed from  this  needle  were  unlikely  Five  laboratory,  temperature.  based  to  sample  1978).  at  were  paper  the  room  (five  Two)  terminal  carefully  done  used  is  In  then  per  absorption Baker  done.  needles  in  this  Chapter  performed  tree;  current  were  Samples  placed  et  atomic  be  Chapter  of foliage  (Salonius  were  and Heald,  Analyses  paper  (see  analysis;  described  obtained (Allen  amount  before  analyses  were  digestion  the  ground  results  could  composites  afterwards  each  Ten  placed  p r e l i m i n a r y survey. and  of  sites.  placed i n plastic bags. T h e twigs were  from  formula  crown  all  lateral  composite; The numbers  (1972)  on  and  in  obtained  1983  consisted of the  24 hours; needles  temporarily  were  of live  drying  to provide second-stage  d u r i n g the  Mg  fall  of  until  6 0 ° C for  taken  the  the  third  (1.7°C)  weights  Husch  were  in  excluded. E a c h  dried at  each  done  on that branch; these were  cold  were  was  et  and al,  and HC1  1982;  1982).  micronutrients  and  S  were  carried  out  on  a  subset  of  the  223 samples,  after  was  restricted  less  g  needles)"  and  S  apparently  sub-samples found  colourimetric  amounts  were  determined by  were  site  the  For  S,  60°C),  analyzed  at  analyses. S u b - s a m p l i n g  exhibited needle of  1.35%  "worst  was  weights of five  or greater. T h u s ,  case"  development  or  micro-  which  was  comprised of four r a n d o m l y chosen  T 8 . In  the  latter  a  following  U.B.C.  available,  total  sulphuric  were  total  above  case,  no  samples  were  c r i t e r i a . T o t a l B w a s analyzed by d r y a s h i n g and  absorption  for  the  S  using  in a  azomethine-H  A l , C u , Fe,  acid-hydrogen  a  method  ( A n o n y m o u s , 1984). Because  spectrometry ground  the  (A.  mill,  Model  Mn  peroxide  Gammell,t  Wiley  Fisher  and  in  re-dried  475  as  of  the  concentrations  digest  procedure  litt., J u n e (three  analyzer  16,  hours  (Guthrie  at and  1984).  Data GENLIN nutrient  were  processed  programmes contents  per  1000  needles  applied  here.  N o content  critical  levels  (1982)  for  needle  of B a l l a r d  for N  earlier. were  a n d P , the  used  weights  and  Carter  for N  using  the  For  the  determined  average  calculations were  ratios  and  analyzed  outlined  data;  and  and  as  concentration  t  the  principally  employing  samples  for  subset  except  material  atomic  which  examined  stated  from  concentrations  by N . The  each  of  1986).  those  obtained  Pedology l a b o r a t o r y  small  Lowe,  N  determinations,  i n the  followed  and  1  limited  fulfilled  been  foliage samples  effects  from  which  applied  had  to those  (1000  nutrient not  results  of the  done  interpretation  for  ANOVAR,  macronutrients  u s i n g the  and  except  needle  S,  weight  and  duplicate measurements the  were  levels of subalpine  MIDAS,  was  micronutrients or S. those  given  by  fir regeneration,  (1986). T o t a l N concentration and content  The  Monchak  as  well  data  L a b o r a t o r y Supervisor, Woodlands Services D i v i s i o n , M a c M i l l a n Bloedel, L t d .  as  were  224 analyzed Rohlf, the  as  a  1981); the  second.  was  two-level nested  analyzed  as  treatments: contents,  individual sites  Tukey's  employed  ANOVA  for  test the  formed the  (Sokal  a  and  N/S  while logarithmic transformations  data.  In  A l and  existed i n the detected  by  spite  this  of  allowed an  condition  the  (see  and  were very  Results  content  was  was  ratios,  necessary  and  and  formed  Wearden, were  with  1983)  separately  the  sites  and for  all  the  and  micronutrient  Ca  concentration  A l , B , N / S , and K / C a  heterogeneity  1974). data  true  section),  for  non-parametric  No  for P the  median  the  analyses  transformations and  as  C a concentrations  applied to the slight  samples  following  contents,  (Sokal  of  variances  still  N e v e r t h e l e s s , since no significant differences  (Lindeman,  same  using the  a  data.  ANOVA  concentration  analyzed  cases,  transformed  the  ANOVA;  B  and  sizes  the  problems,  K/Ca  transformation  Dowdy  The  ANOVA  and  data,  the  1981;  concentrations  concentrations, A n arcsine  I  sample  level, while  posteriori comparisons.  Needle weights, K  concentrations.  unequal  first  Rohlf,  single-classification M o d e l  S  with  M g to be  were  accepted  were  found  validly  Ca/Mg  ratio data.  These  and  Kruskal-Wallis  were  tests  which  analyzed  were  in  by  therefore  i n conjunction  w i t h T u k e y jackknife 95% confidence i n t e r v a l s as described earlier.  8.3.2 Screening Trial Approach  During  the  1982  five-,  and  ten-year-old  Two).  The  latter  of  the  traverse  final on  cutovers  two sites  sequence. each  preliminary survey,  site.  were  of  what  T w e l v e 0.01 The  the  ha  distances  urea  initial became  was  applied to  sequence the  investigated  T 6 and  c i r c u l a r plots were between  plots  the  were  (see  T i l sites located  freshly  Chapter  respectively  along a n  variable;  cut,  plot  open  centres  225 were of  chosen  the  in such  cutover  treatments  as  were 0,  respectively.  A  pair  The  the  off-centre  centre  tree  fertilizer  was  T i l case  which  other  ensure  that  other  of  300  of sample  was  trees  with  original the  N  fertilized  an  of  The  as  NO, N I ,  to  i n an  and the  N2  (excluding  Fournier, centre  1982).  tree.  Each  a l u m i n i u m identification tag. cyclone seeder.  separate  the  T6  case,  care  cutover  were  excluded  the  The  Unfortunately,  entirely  In  of  and  dominants  (Weetman  three  treatments  re-located in 1983. A s noted  place.  areas  each  plots.  the  nearest  of  portion  area  earlier, i n to  was  that  on  taken  to  from  any  s a m p l i n g activities.  the 1983,  N  to  the  number  of plots  m i n e r a l i z a t i o n studies  samples  were  taken  each r e m a i n i n g plot u s i n g the  same  scheme  as  The  60°C  for  removed the  from  were  dried  the  twigs,  samples  were  at  counted,  ground  and  nutrient  manner.  Graphical  contents  24  forest  floor  (see  Chapter  from  the  One).  two  discussed i n the  hours;  weighed  as  needles  In  selected  change the  fall  trees  on  previous Section.  were  described  weight  then  carefully  previously. In  this  i n a W i l e y m i l l for analysis. Concentrations of N ,  P , K , C a , and M g were determined Section;  the  attempted  were  samples  of c u r r e n t  lost, neither  growth  case,  from  plot u s i n g a  were  12  , designated  1  dominant  each  took  the  trees  flagging and  "representative"  replicates  selected  off-centre  plots  four  ha"  36 plots could be  fertilized  identifiable  site,  was  largest  m u c h of the  among  kg  and  the  marked  each  allocated  and  plot-centre  cover as  On  s a m p l i n g activities  Owing nor  to  applied throughout  only 26 of the the  150,  tree  was  as  randomly  to  as  way  possible.  corresponded  residuals)  a  per  representations  1000  u s i n g the needles  of the  data  procedures  outlined i n the  were  also  calculated  were  constructed  in  previous the  same  and interpreted  in  226 terms  o f observable  1982).  T h e needle  separately the  two-way,  weight  Model  treatments. and  site  as  a  I ANOVA,  1978; Weetman  concentration a n d content  from  with  data  a n d Stone,  single-classification,  and N data  A s before,  GENLIN  (Timmer  weight, n u t r i e n t  for each  needle  shifts  Model  data  and Fournier, were  I ANOVA.  a l l sites  were  pooled  the individual  sites  and N  analyzed  I n addition,  and analyzed  as a  applications as the  processing a n d analysis w a s done  u s i n g the M I D A S  programmes.  8.4 RESULTS AND DISCUSSION  8.4.1 Main Foliage Analysis  The  post-harvest  trends  values across the age sequence those  for concentrations  while  N / P , K / C a , and C a / M g  of needle  weight, N concentration, a n d N  are presented  a n d contents ratio  in Figure  of the other trends  after  content  8.1. Figure  8.2 illustrates  macronutrients  (S excepted),  harvesting  are  presented  in  F i g u r e 8.3. Needle weights and Nitrogen  There needle all:  df  weights, =  concentration, all  were  4,  highly  mean  significant  N concentrations,  130; F  =  a n d N content  significantly  greater  differences  {p <  (p  and mean  20.4, 24.2, and  <  0.001)  N contents  needle  respectively). T h e cutover m e a n  needle  that  of the m a t u r e  the  mean  o f the sites (for  for  0.01) t h a n  22.3  among  stand;  weights, weights  N  were  i n addition,  227  Vertical bars are 95% confidence limits  3  0  i  0  1  1  1  2  1  3  1  4  1  5  1  6  1  7  8  1  9  1  1  1  10 11  YEARS AFTER HARVEST  Figure 8.1 Means and 95% confidence limits of the foliar needle weights, N concentrations, and N contents.  228  Vertical bars are 95% confidence limits  CONCENTRATION (%)  CONTENT (mg/1000 needles) 18-,  0.27-i  0.24 CL  0.21-  6  0.18-  70  1.3 —| 1.2-  60-  1.1 1-  50-  0.940-  0.80.50  30-  0.45 H  D O  0.40  25-  0.35-  20-  0.30-  15-  0.25-  10  0.18-j  10  0.16-  cn  8-  0.146  0.12-  4  0.100.08-  n—I—I—l—I—I—I—l—l—I—I  1 2 3 4 5 6 7 8 9  10 11  2-  i—I—I—I—l—l—I—\—l—I—l—l  0 1 2 3 4 5 6 7 8 9  10 11  YEARS AFTER HARVEST  Figure 8.2 Means and 95% confidence limits of the foliar P, K, Ca, and concentrations and contents.  Mg  229  1  J  | 0  1  1  1  1  2  3  1  1  4  5  1  6  1  7  1  8  1  9  1  I  10  11  Y E A R S AFTER H A R V E S T Figure 8.3 Means and 95% confidence limits of the foliar N/P, K/Ca, and Ca/Mg ratios.  230 the  T 6 mean  differences  was  among  significantly  greater  than  the  weight  means  weight i n the  mature  were between  5.07  the  sites;  were  apparent.  respectively; mean that  than  those and  others  T i l mean  other  means  ranged  of the  cutovers  contents  T3  the  (1982)  for  stand;  and  were  between  needle weights, N  those  mature  T i l means  within  two sub-groups and  of the  47.1  84.0  and  released  the  range  than  those  after  logging.  of those  reported Martin  were highest i n the  The  by  regeneration  54%  the  first  0.05)  were  No  mg (T6)  mg  contents by  Husted  Monchak (1982)  increased  six years  weight their  after  of the  a m o n g the  means  1.64%  1.56%  (T6).  Finally,  (p  0.05)  greater  <  significantly  were  needles)"  individual  harvesting.  apparent.  et  needles)" .  The  1  al.  (1965)  1974b). T h e  N  grown" N  (Figure needle Sizes  and  are  are  Pacific  are  The  mean well  Monchak  slightly  contents  are  above well  m u c h higher  silver  N concentrations age  lower  respectively; the  1  concentrations  "well  trends  and  observed i n this study  e a r l y portion of his post-harvest  needle  those  (1982); however, they  for  cutovers  1.32%  was  (1000  Beaton  (Morrison,  than  were  differences  subalpine fir. T h e  from  greater  mean  (1000  needle  . F o r N concentrations,  ( T M ) to  T8  other  86.9  implied  1  a l l significantly the  mean  1  differences  1.21%  (1985) also noted that foliar  post-harvest  advance in  from  78.8  observed i n y o u n g b a l s a m fir  within  <  The  significant  " ; those of the  concentrations  moreover,  (TM) and  or  (p  N  T i l sites.  reported  y o u n g or  detected.  no further  concentrations, and N  ranges  were  T 3 . N o other  (T6) g (1000 needles)"  were significantly  these  of the  fell  5.98  The T3  the  N  than  T3  (T3) and  within  of the  stand was 3.89 g (1000 needles)  T 3 and T i l means  other  the  needle  that  (and  fir  trees  contents)  sequence.  8.1) weights  remained  suggest by  that  the  approximately  constant  thereafter  231 implying  that  physiological  maximum  size  Monchak  (1982)  subalpine  fir.  conflicting  pictures.  post-harvest one of  peak  N  even  deficiencies  to  the  suggest  it  been  data  tested  interpretations. increase  in  taken  as  a  1964;  Jones  the  the  of  the  by  the  itself  For  example, weight  trees  were  manifestation Eck,  of  1973;  the  in  their  adequate  The  trend  1974a).  a  By  may  data  of  the N  experienced  N  harvesting. I f the  variable presents  the  two, concentration Timmer  is  may  Stone  (i.e.  status)  has  complicate  with  growth  and  based  a  (Figure  it  N  immediately after  factors  Thus,  of  the  after  this  or  any  have  However,  six  marked  concentration  contrast,  and  effect"  to  stand.  concentration  three  "Steenbjerg  Morrison,  eight. T h e  reflection of nutrient  decline i n N years  least  on  Other  the  at  N-deficient  which  degree.  present  indications  picture? O f the  on  by  8.1)  increased  N-limited  use.  given  represent  to y e a r  Seven). W h i c h  assumption  between  to  (and possibly beyond)  widespread  the  differ  regeneration  more  substantial  up  mature  post-harvest  is an  (Figure  appeared  not  1  the  N levels did occur in  standards.  "true"  implicit  trends  generally  was  advance  that  of the  any  and  (1982)  needles)"  even  l i m i t i n g g r o w t h of released  i n foliar  variables  However,  (1000  be  content  delay period (Chapter  to  needle  two  understory  t r a d i t i o n a l l y found  concentration  may  uptake  regeneration  mean  representation  that  N  Monchak's  that  would  closest  noted  that  six and eight years  g r o w t h response  (1978)  and  mg  declined thereafter  The  advance  in  N  completed.  three-year-mark  values  harvesting.  between  true,  has  7.5  suggests  height  data  the  below  indicate that changes  change;  the  trends  is  well  concentration  Both  according  sites—not  been  level below w h i c h  N  contents  that  content  the  The  following  indicate  is  had  period. M o r e o v e r , the  deficiency  this  as  of such  mean  degree  attained  adjustment  that not such  simultaneous  8.1)  could  be  dilution  (Tamm,  be  in  that  this  232 case n u t r i e n t be the  content  more legitimate indicator of n u t r i e n t  There extent of  are  is yet another  the  subalpine  advance  of  (1982)  data  indicated that  equalled or  components) spruces  al.  as  (Ballard  well  as  1974;  (1965)  the  latter  the  regeneration  as  concentration  is  part a  for  this  view.  may  expected  and C a r t e r ,  of its  valid  for  this  white at  and  foliar  of  concentration  respectively of  published  standards  growth.  However,  advance levels  (foliar than  Data  and  its  from  other  companion a  study  by  comparisons  Engelmann)  spruce;  the  same  shade-tolerant  reproductive  indicator w i t h i n  strategy. this  species  heterophylla which  Therefore,  context,  1.4  in  1986). T h i s is also a p p r o x i m a t e l y the [Tsuga  below  can  1.5%  hemlock  levels  this  being too low. Other  assumption,  (or  needle  Examination  50%  other  1978).  fir  to  western  1986), another  no  nutrient  Under  and/or  .  1  weight  assailed as  Hawkes,  noted  be  needle  nutrient-demanding  and  subalpine  less)  needles)"  released  higher  more  Kimmins  applied to  and Carter,  none  be  released  status  considered N-deficient;  (1000  be  To w h a t  indicators of N  (or  be  apparently  standards  1974a; B a l l a r d be  can  are  have  to  support  deficiency  might  to  1.2%  may  mg  valid  criteria,  of  90  above arguments:  a p p r o x i m a t e l y 40% and  there  reputed  against  N  study,  is as  et  (Morrison, level  of  exceeded b y  trees—definitely  (Kimmins,  made  latter,  content  fir  fir  his  less)  points. The concentration level  subalpine  be  By  (or  1  N  subalpine  Beaton  needles)"  the  (1982)  concentrations  foliar  M o n c h a k ' s (1982)  for  N  affects  Monchak  a  were  data  by  regeneration?  exhibiting (1000  status.  question w h i c h  given  advance  g  to  Monchak's  than  fir  7.5  corresponds  levels  standards  growth  weights  his  (an expression of both needle weight and concentration) may-  it m a y  (Raf.)  produces  to  the  be  more  Sarg.] advance  extent  that  logical  to  233 increase of  the  assumed  departure;  Regarding  25%  the  current  foliage  needles)"  1  (Husted,  ;  of  75  observed  same  species  lower  N  of  values  content  concentration  w e i g h t standard u