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Radiotracer study of some aspects of the role of mosses in the biogeochemical cycle Otchere-Boateng, Jacob 1972

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tV  A RADIOTRACER STUDY OF SOME ASPECTS OF THE ROLE OF MOSSES IN THE BIOGEOCHEMICAL CYCLE by JACOB OTCHERE-BOATENG .  /  B.S.F., University of British Columbia, 1970  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of FORESTRY  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA October, 1972  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 i t 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 representative.  It is understood that copying or publi-  cation of this thesis for financial gain shall not be allowed without my written permission.  J . Otchere-Boateng  Department of Forestry University of British Columbia Vancouver 8, Canada October 6, 1972.  ABSTRACT  Some aspects of the role of mosses in the biogeochemical cycle of a coastal forest ecosystem i n B r i t i s h Columbia were studied using 137 radioisotopes.  The average concentration of  Cs from atmospheric 2  f a l l o u t in ground-dwelling mosses was 36.7 pCi/g or 6025 pCi/m .  Concen-  trations increased with p r e c i p i t a t i o n , with the highest concentrations being found in Plagiothecium undulatum (Hedw.) B.S.G. and Sphagnum squar85 134 rosum Crome.  Experiments involving a dual l a b e l l i n g with  Sr and  Cs  indicated that nutrients which are leached from stem tissues of host plants, and those in the crown washings of the overs torey trees are sources of nutrients for epiphytic mosses.  Epiphytic mosses were e f f i -  cient in f i l t e r i n g radioisotopes from s o l u t i o n , the a c t i v i t y o f throughf a l l and stemflow being reduced a f t e r passage through epiphytic mosses 85 by up to 70%.  134 Sr and  Cs concentrations in ground-dwelling mosses  under western hemlock trees (Tsuga heterophylla (Rafn.) Sarg.) followed the d i s t r i b u t i o n pattern of throughfall nutrients which decreased from close to the stem towards the crown edge.  ii  TABLE OF CONTENTS  Page ABSTRACT  . . . . . . . . . . .  TABLE OF CONTENTS  i i i i i  LIST OF TABLES  . . . . . . . . .  vi  . . . . . . . .  vii  LIST OF FIGURES ACKNOWLEDGMENT  . .  CHAPTER 1.  INTRODUCTION  CHAPTER 2.  LITERATURE REVIEW  ix 1 . . . . . . . . .  3  2.1.  Concept of ecosystem and biogeochemical cycle  .  3  2.2.  Importance of mosses i n the forest ecosystem . .  4  2.2.1.  Productivity of mosses  4  2.2.2.  Mosses and tree n u t r i t i o n  6  2.3.  2.4.  Epiphytic adaptation  6  2.3.1.  Factors c o n t r o l l i n g (moss) epiphytism. .  8  2.3.2.  Sources of nutrients f o r epiphytic mosses  10  Leaching phenomenon 2.4.1.  Patterns  11  of d i s t r i b u t i o n and the dynamics  of tree leachates on the forest f l o o r . . 2.5.  Mosses as concentrators  2.6.  Fission product isotopes: t h e i r mode of contaminating vegetation 1 ?4 85 Biological cycle of -Cs. and ° Sr ii i  2.7.  1  of toxic substances. . .  3  12 15  16 17  iv Page CHAPTER 3.  CHAPTER 4.  THE RESEARCH AREA AND THE EXPERIMENTAL PLOTS  23  3.1.  The research area  23  3.2.  Description of the experimental plots  23  METHODS  31  4.1.  Radiotracer technique  31  4.2.  Inoculation of trees on the experimental plots .  32  4.2.1.  33  4.3.  The inoculation procedure  Experimental design and sampling  34  4.3.1.  Study o f natural r a d i o a c t i v i t y of mosses  34  4.3.2.  Some nutrient sources f o r epiphytic mosses  34  4.3.2.1. 4.3.2.2. 4.3.3. 4.3.4. 4.3.5.  Leachate from stem tissues as a source of nutrients . . . .  34  Throughfall as a source o f nutrients  36  Patterns of d i s t r i b u t i o n of throughfall leachates on the forest f l o o r  38  Concentration of radionuclides by various ground mosses  38  Penetration  of radioisotopes into the  soil 4.3.6. 4.4.  CHAPTER 5.  .  . . . .  41  Sampling of the inoculated trees . . . .  41  Laboratory work  41  4.4.1.  43  The s c i n t i l l a t i o n counter  RESULTS AND DISCUSSION 137 5.1. Cs f a l l o u t a c t i v i t y levels of mosses . . . . 5.2. Primary nutrient sources f o r epiphytic mosses. . 5.2.1.  Epiphytic mosses as f i l t e r s of crownwashed nutrients  44 44 52 52  V  Page 5.2.2.  Leachates from the stem as a source of nutrients for epiphytes . 5.2.2.1. 5.2.2.2.  54  Leaching of S r and Cs from vine maple stems . . . .  54  Contamination of epiphytic mosses by stem leachates (85 and 134 )  61  8 5  S r  1 3 4  Cs  5.3.  Nutrients and epiphytic adaptation  61  5.4.  I n t e r s p e c i f i c translocation of mineral elements  63  5.5.  Nutrients in throughfall and forest f l o o r nutrient dynamics  64  5.5.1. 5.5.2.  S r and C s a c t i v i t y levels in the inoculated hemlock tree needles and twigs  64  The removal of C s and S r from the tree crowns in throughfall p r e c i p i t a t i o n  67  8 5  1 3 4  1 3 4  8 5  85 5.5.3. 5.5.4. 5.5.5.  The pattern of throughfall input of and '3^Cs to the forest f l o o r  Sr  Nutrient d i s t r i b u t i o n on the forest f l o o r 1 OA OC D i f f e r e n t i a l leaching of Cs and Sr in the forest f l o o r  CHAPTER 6. REFERENCES APPENDIX  CONCLUSIONS  69 , 73  74 . .  . .  75 77  . . . . . . . . .  92  LIST OF TABLES  Table  Page  1  Biomass of bryophytes i n nine ecosystems  2  Ecosystematic units and t h e i r d i s t r i b u t i o n i n the research s i t e  3 4 5  6 7 8  1 ^7  Cs f a l l o u t a c t i v i t y of mosses i n the UBC Forest and Endownment Lands  10  11 12  13  27  Research 45  Comparison of f a l l o u t a c t i v i t y l e v e l s of three mosses  47  Comparison of amounts of f a l l o u t a c t i v i t y i n 5 locations  48  137  Values of Cs natural f a l l o u t a c t i v i t y i n mosses from other sources  51  E f f i c i e n c y of e p i p h y t i c mosses i n f i l t e r i n g radionuclides i n throughfall and stemflow waters  53  8 5  S r and  1 3 4  C s i n stemflow waters of inoculated vine  maple trees 9  5  oc  .  .  55  1OA  Sr and Cs concentration i n tissues of l a b e l l e d maple trees OC 1 OA A Sr and Cs concentrations (uCi/10 per gm) i n e p i p h y t i c mosses and a vine maple tree at various distances (cm) from the point of i n o c u l a t i o n . . . . . R a d i o a c t i v i t y (pCi/g) of e p i p h y t i c mosses on inoculated vine maple trees . .  59  60 62  Volumes and chemical properties of throughfall water (under a s i n g l e western hemlock tree) with respect to distance from the tree stem . . . . . . . . . . . . .  70  D i f f e r e n t i a l leaching of floor  74  vi  Sr and  , J  Xs  i n the f o r e s t  LIST OF FIGURES  Fi gure 1  Page Monthly mean temperatures during the experimental period (July 1971-July 1972) .  24  Monthly p r e c i p i t a t i o n during the experimental period (July 1971-July 1972)  24  3  Location of the radioisotope experimental plots  25  4  Sampling s i t e s for  5  Plot #4 showing the inoculated vine maple trees and  2  . . . .  137  Cs f a l l o u t study . . .  35  the stemflow c o l l e c t i n g systems  37  6  Layout of the 15 throughfall c o l l e c t o r s on Plot #3 . . .  39  7  Plot #3 showing the inoculated hemlock trees and some of the throughfall c o l l e c t o r s A close view of a throughfall (or stemflow) c o l l e c t o r  40 40  8 9  10  11  12 13 14 15  85 Changes i n a c t i v i t y of Sr i n twigs and needles of inoculated hemlock trees 134 Changes i n a c t i v i t y of Cs i n twigs and needles of inoculated hemlock trees 85 Distribution patterns of Sr i n throughfall under inoculated hemlock tree canopy 134 Distribution patterns of Cs i n throughfall under inoculated hemlock tree canopy .  .  66  66  68  68  Patterns of throughfall water d i s t r i b u t i o n under hemlock tree canopy . . . . . . . .  68  Patterns of K and Ca d i s t r i b u t i o n under hemlock tree canopy . .  71  Volume of throughfall under hemlock tree canopy  vii  . . . .  71  Changes of pH i n throughfall water of hemlock tree canopy 85  134  Changes i n the a c t i v i t i e s of Sr and Cs i n twigs and needles of individual inoculated hemlock trees . . . .  ACKNOWLEDGMENT  I wish to acknowledge my gratitude to Dr. J . P. Kimmins of UBC  Faculty of Forestry for his valuable suggestions and guidance during  the course of this study.  Thanks are expressed also to the other members  of my committee, Dr. J . Worrall, Faculty of Forestry, Dr. T. M. B a l l a r d , Department of Soil Science and Faculty of Forestry, and Dr. W. B. Schof i e l d , Department of Botany for t h e i r advice and constructive c r i t i c i s m s . I am grateful to my fellow students, M. F e l l e r and M. and Mr.  Fraker,  D. Moon (laboratory a s s i s t a n t ) , f o r t h e i r help in both the f i e l d  and laboratory work; to the Director and s t a f f of the UBC  research f o r e s t  for t h e i r services; to Dr. A. Kozak and his assistants for help with the s t a t i s t i c a l analyses; to the s t a f f of McMillan Forestry/Agriculture Library; to Miss Piovesan who to many friends who  typed the f i n a l copy of the thesis and  in diverse ways made my stay here possible.  The study was  f i n a n c i a l l y supported by the Canadian Inter-  national Development Agency and the UBC  ix  Faculty of Forestry.  CHAPTER 1  INTRODUCTION The biological c y c l i n g of chemical elements i s one o f the main functional processes c o n t r o l l i n g ecosystem productivity.  Its study fur-  nishes us with information on the precise amount o f elements involved i n the  l i f e cycle of plants and animals and t h e i r subsequent fate until  return to the s o i l or water.  This i s important f o r practical recommen-  dations i n forestry and i n agriculture; for example, i n f e r t i l i z a t i o n programmes. Because of the importance of biological cycling of chemical elements, i t has been widely studied i n many forest ecosystems, and reviews and summaries of results have been published (eg. Rodin and B a z i l e v i c 1967, Ovington 1968) f o r many forest types. the  Some aspects of  cycle i n tropical areas have been studied by Richards (1952), Bartho-  lomew e t al_. (1953), Greenland and Kowal (I960), Eyre (1963), Klinge and Ohle (1964), MacArthur and Connell (1966) and Odum (1970).  Duvigneaud  and Denaeyer-de-Smet (1967, 1970) and Ovington (1962, 1965) have summarized the  dynamics of mineral cycling in the temperate deciduous forests.  Various aspects of mineral cycling within Douglas-fir (Pseudotsuga menzies i i  Franco) ecosystems i n Washington have been studied by Gessel et  al_. (1961), Heilman and Gessel (1963), Cole and Gessel (1965), Gessel and Cole (1965), Riekerk and Gessel (1965), Cole et al_. (1967) and Riekerk (1967, 1971). 1  2 None of these studies dealt e x p l i c i t l y with the role of mosses in cycling i n spite of the importance of mosses i n many forest regions. This i s a p a r t i c u l a r l y serious omission i n areas such as the P a c i f i c northwest where mosses occur extensively as carpets on the forest f l o o r , on decaying wood, or as epiphytes.  This lack of information  led to the  present study on the role of mosses i n some aspects of the biogeochemical cycle i n the west coast forest ecosystems of B r i t i s h Columbia. study i s i n three parts.  The  F i r s t l y , the a b i l i t y o f d i f f e r e n t species of  mosses to concentrate environmental pollutants, and therefore t h e i r potential as indicators of environmental p o l l u t i o n i s examined.  Secondly,  the possible primary nutrient sources o f epiphytic mosses i s investigated. The purpose here i s to t e s t , q u a l i t a t i v e l y , the hypothesis that plant bark tissues contribute nutrients to stem-flow water and at the same time demonstrate that epiphytic mosses obtain some nutrients from t h e i r hosts through leachates  from the stem tissues.  assess the contribution of throughfall leachates phytic mosses.  T h i r d l y , a study of patterns  to the n u t r i t i o n of epi-  of d i s t r i b u t i o n of leachates  i on  oc  (radionuclides  I t also attempts to  Sr,  Cs) i n throughfall, the interception of leachates  by ground-dwelling mosses, and the movement of these leachates  i n the  forest f l o o r (with ground cover and without ground cover) i s reported.  i  CHAPTER 2 LITERATURE REVIEW 2.1  Concept of ecosystem and biogeochemical cycle The term "ecosystem," meaning the total assemblage of organisms  and t h e i r environment was introduced by Tansley in 1935.  Ecosystem i s  largely synonymous with "biogeocoenose" conceived by the Russian scient i s t , Sukachev i n 1944 ( H i l l s 1960).  The importance of the ecosystem  concept in relation to forest research has been stated by Ovington (1962) as follows: Whilst the ecosystem concept has value i n relation to a number of forestry problems, i t s greatest contribution to improving forestry practice probably w i l l be. that i t provides a sound foundation f o r investigations designed to elucidate the functional processes of woodlands and to show the bearing of these processes on forest productivity on a long-term basis. Lindeman (1942) believed the concept of ecosystem to be of fundamental importance in interpreting the data of dynamic ecology. If forest research i s to be f u l l y e f f e c t i v e , i t needs to be orientated towards obtaining a better appreciation of ecosystem dynamics; p a r t i c u l a r l y in relation to quantitative studies of the biological and physical processes affecting productivity and the accumulation, transformation and flow of energy and materials (water, mineral elements, etc.) through d i f f e r e n t woodland ecosystems.  Under this concept a l l the components of the ecosystem ( s o i l s , l i v i n g organisms and environmental factors) are integrated and each has a role to play.  Even the smallest component present may be very important  in the functioning of the system.  I t may have a high turnover rate, 3  4 form part of a c r i t i c a l  pathway, or play a role i n spatial or temporal  d i s t r i b u t i o n i n the system.  Hence, to a r r i v e at a complete understanding  of the functioning of ecosystems a l l components must be investigated. The investigations may involve three main aspects; namely, energy, water and nutrient dynamics (Ovington 1968). The biogeochemical cycle (involving nutrient and other elemental dynamics) i s a more or less c y c l i c movement of chemical elements i n the biosphere.  Two major routes are recognized; namely, the biological  and geo-chemical cycle.  cycle  The former involves the uptake or absorption  of elements from the s o i l , the retention of the elements in the biomass and the return of elements to the s o i l or death of organisms.  v i a stemflow, leafwash, l i t t e r f a l l  The l a t t e r involves the input and output of  chemical elements to and from the ecosystem.  The inputs include:  c i p i t a t i o n , minerals from blown dust, weathering of parent rock.  preThe  outputs include losses through drainage (surface runoff or downward movement in groundwater).  2.2  Importance of mosses in the forest ecosystem 2.2.1.  Productivity of Mosses.  Bryophytes contribute greatly  to the plant biomass in many tundra, coniferous* temperate rainforest, and tropical rainforest ecosystems.  Forman (1969) gives the bryophyte  biomass for nine d i f f e r e n t ecosystems (Table 1). the  Wojcik (1970) found  biomass of mosses i n a dry pine forest in Poland to be 1580 kg/ha.  This value was estimated to be seven times greater than the biomass of the  herb layer;  5  TABLE 1 Biomass of bryophytes in nine ecosystems (after Forman 1969) ,s Ecosystems  kg/ha 2 3 4 5  1695 2384 471 581 612  6 7  252 84  8 9  31 22  Alpine Krummholz Coni ferous Coniferous deciduous ecotone Northern hardwoods Oak woods  The annual biomass increase of the mosses in this forest was estimated to be one t h i r d of the total biomass (527 kg/ha), and three times the annual production of the herb layer.  Weetman and Timmer (1967) found  in a black spruce forest of the Boreal forest region in eastern Canada that the annual productivity of mosses was one t h i r d to one h a l f that of the spruce canopy and boles.  According to t h e i r data the amount of  nutrients in the moss layer represented 9 percent to 40 percent of the total nutrients contained in the above-ground part of the trees.  Annual  uptake of nitrogen, phosphorus, potassium and magnesium by moss was estimated to be 23% to 53% of the uptake of these elements by trees. Rodin and Bazilevich (1967) have stated that l i t t e r accumulation in forests with a well developed moss layer i s greater than forests with poorly developed moss cover.  6 2.2.2.  Mosses and tree n u t r i t i o n .  Mosses growing in a forest  are thought to receive t h e i r chemical elements from dust or from substances leached from the overstorey canopy by rain (Tamm 1953, 1964; Weetman and Timmer 1967).  Most of these chemical elements are retained u n t i l the  mosses decompose.  According to Weetman and Timmer's (1967) estimate,  the dead feather.moss  (Calliergon schreberi (Brid.) Grout) segments may  take from five to twelve years to decompose to the point where they are not readily distinguishable.  During decomposition, nitrogen i s mineralised  more rapidly than from decomposing spruce needles.  Hence, i n a forest  stand where available nitrogen i s d e f i c i e n t in the s o i l , the decomposition of the moss layer may be a primary source of nitrogen to the trees (Weetman 1967, Weetman and Timmer 1967), and a rapid means of entry of nitrogen contained in r a i n f a l l into the nitrogen cycle of the stand (Weetman and Timmer 1967).  The raw humus formed by mosses favours optimum mycorrhizal development i n pines (Melin 1930) and spruce (Melin T930, Weetman and Timmer 1967), probably as the result of the a v a i l a b i l i t y of this source of nitrogen. 2.3.  Epiphytic adaptation The term "epiphytic" (derived from the Greek words e p i , "upon"  and phyton, "plant") refers to a plant which grows upon another plant merely for support and which obtains no sustenance from i t s host.  This  d e f i n i t i o n i s sometimes extended to cover plants which are fastened on non-living objects l i k e rocks, buildings or telegraph wire (Silverberg  7 1967).  However, f o r the purpose o f this thesis the use o f the term  epiphyte w i l l be limited to those plants which grow above ground level on trees (trunks, branches or leaves).  Those epiphytes which i n l a t e r  stage of development grow nearer the ground and extend a i r roots soil  to the  ( i . e . , the hemiepiphytes of Ford-Robertson 1971) are not considered  in this study as true epiphytes.  The epiphytic adaptation i s found among  several great divisions of the plant kingdom and forms an important vegetative category of the forest ecosystem.  In the temperate regions  such as B r i t i s h Columbia only the lower plants such as the algae, lichens, liverworts, mosses and some ferns have developed  this adaptation. I t  is estimated (Schofield, personal comm. 1972) that about 68 species of mosses and 35 liverwort species frequently grow as epiphytes i n the province.  An additional 40 species of mosses and 23 species of l i v e r -  worts are occasionally seen as epiphytes.  The following l i s t shows the  genera of mosses and liverworts whose members are most frequently found as epiphytes i n the province.  Mosses A l s i a Mohr A n t i t r i c h i a Brid Claopodium (Lesq. & James) Ren. & Card. Dendroalsia B r i t t Homalia (Brid). B.S.G. Homalothecium B.S.G. Isotheciurn Hedw.  Neckera Hedw. Orthotrichum Hedw. Pterigynandrum Hedw. P y l a i s i e l l a Kindb Scleropodium B.S.G. biota Mohr Zygodon Hook & Taylor  Liverworts Cololejeunea (Spruce) Schiffn Douinia Buch Frullania Lophocolea Dumort  Metzgeria Raddi Porella L. P t i l i d i u m Nees Radula Dumort Scapania Dumort  8 Epiphytic adaptation  i n the tropics includes many flowering  plants i n addition to those types of plants found growing e p i p h y t i c a l l y in the temperate region.  Craighead (1963) noted that bromeliads (called  "airplants" or i n some species "wild pines"), orchids (also called " a i r plants") , Pej?pjyiQmm sppj.3,, f v g s a n d mi.sjtTetoe'cac^us--a re-epiphytic on trees in the Everglades National Park i n F l o r i d a .  For the family Orchidaceae  (Orchids).alone, Sanford (1969) found that of the total o f 400 species i d e n t i f i e d i n West A f r i c a , 239 species in 34 genera are always or often epiphytic on shrubs or trees. 2.3.1.  Factors c o n t r o l l i n g (moss) epiphytism.  The question  is raised whether or not epiphytes associate^themselves s p e c i f i c a l l y with some p a r t i c u l a r "host" species.  Evidence from R'oltturn" (1964) i n  Malaya and Sanford (1969) in Nigeria indicates that epiphytic orchids do not grow on s p e c i f i c plant hosts, but rather, they are found associated with some c h a r a c t e r i s t i c features of the "host." rough  1  These features  include  bark, large horizontal branches, and exposure, which i s controlled  by l e a f f a l l  and l e a f shading (Sanford  c h a r a c t e r i s t i c s , according  The importance o f these  to Sanford, i s pronounced when some factors  in the environment are l i m i t i n g . and rough  1969).  Thus, on favourable s i t e s both smooth  barks may carry epiphytes while i n less favourable  conditions  only rough barked hosts w i l l .  Hosokawa and associates (Hosokawa e t al_. 1964) have suggested that the d i s t r i b u t i o n of corticolous mosses and lichens on t h e i r hosts i s controlled by microclimatic factors such as l i g h t i n t e n s i t y , atmospheric  9 r e l a t i v e humidity and evaporation.  They stated that the degree of shade  tolerance o f the epiphytic plant species i s responsible f o r the lower l i m i t while the degree of drought tolerance determines the upper l i m i t of d i s t r i b u t i o n on trees. Brodo (1961) showed that the chemical composition of the bark may influence the d i s t r i b u t i o n of epiphytic plants.  I t was demonstrated  that the bark exudates of Quercus species could be injurious to some 1ichens. Grubb ejt al_. (1968) included competition in determining habitat preference  of epiphytes.  as an important factor  Grubb and co-workers  found that with more favourable water r e l a t i o n s , but less intensive shade, an hierarchy of competition  takes place.  For example, on an  extending branch, Ulota crispa (Hedw.) B r i d . (and other early  invaders)  could be suppressed by a l a t e r invader such as Hypnum cupressiforme Hedw. which i n turn i s suppressed by Dicranum scoparium Hedw.  As with other plant species, nutrient a v a i l a b i l i t y i s also a very important factor c o n t r o l l i n g the d i s t r i b u t i o n of epiphytic plants. C a r l i s l e e t al_. (1967) stated that i n addition to microclimate,  bark  texture, and bark composition, the chemical composition of stemflow waters could contribute greatly to the natural selection of epiphytic lichens and bryophytes.  Selection may be influenced by i t s nutrient  composition, pH, and transport of harmful substances to and from the epiphytes.  10 2.3.2.  Sources of nutrients ,for epiphytic mosses.  Attempts  have been made to find the possible source o f nutrients for epiphytes. Tamm (1953) has studied the growth and n u t r i t i o n of Hylocomium splendens in Sweden.  He attributed the sources of mineral  supply  for the ground  dwelling mosses as well as the epiphytic mosses to leachates  from the  tree crowns, including f o l i a r leachate, leachate o f animal excrement, l i t t e r , s a l t spray, and atmospheric dust.  According  to Tamm (1953),  the importance of dust in the n u t r i t i o n of epiphytic plants has long been recognized 1944).  (Dixon 1881,  Sernander 1912,  Rietz 1932* and Waldheim  The data related to this question have been published by Persin  (1925) and Wherry and Cooper (1928).  The atmospheric dust may be washed  down With r a i n , deposited on the mosses d i r e c t l y , or be deposited  on the  tree crown and l a t e r washed down by rain.  It was. suggested by Tamm (1953, 1964)  that mosses obtain t h e i r  nitrogen by d i r e c t f i x a t i o n from the atmosphere. may  This nitrogen source  be supplemented by ammonia and n i t r a t e i n rain and perhaps the n i t r o -  genous substances coming down from the trees.  Grubb e t a l ^ (1968) stated  that the nitrogen supply may come from nitrogenous compounds produced by nitrogen-fixing bacteria on leaves and bark of trees.  Grubb e t a]_. (1968) have discussed the type o f s o i l which forms under large epiphytic species of mosses on large branches and trunks. This s o i l  is developed mainly from bark fragments, animal d e t r i t u s ,  dust and remains of various mosses and lichens. provide nutrients to the epiphytic mosses.  This, they s a i d , may  After analysing the bark  tissue of 80-year old oak trees, C a r l i s l e et a l . (1967) suggested that the bark tissues contribute nutrients to the stemflow water which in turn provide nutrients to the epiphytic mosses.  This i s true with  calcium  which comes down in these waters in appreciable quantities. 2.4.  Leaching phenomenon The phenomenon of leaching (defined by Tukey (1970a) as loss  of inorganic and organic metabolites  from above-ground plant parts by  the action of aqueous solutions, including r a i n , mist, and dew), recognized  in about 1804  and experimentally  by Saussure (Tukey e_t al_. 1958,  demonstrated independently in 1883  von Homeyer (Tukey ejt al_. 1958). forest trees was  Mina  was  1965)  by Buchenan and  Detailed study of the phenomenon in  not undertaken until about two decades ago, however,  when Tamm showed that the p r e c i p i t a t i o n collected beneath the canopies of s i x deciduous species and two conifers in Sweden contained  greater  amounts of chemical elements than the p r e c i p i t a t i o n of the open area for the same sampling periods  (Tamm 1951,  1953).  This fact has been  confirmed by some workers in other parts of the world (Mes 1955, Nye  1959,  1961,  S t e n l i d , 1958,  Madgwick and Ovington 1959,  Greenland and Nye  1964,  C a r l i s l e 1965,  1954,  Sviridova  Egunjobi  Will 1960,  1971).  Much of this work f a i l s to quantify the phenomenon p r e c i s e l y , however, since aerosols and extraneous substances deposited  on the  vegetation  contribute to the increase of nutrients i n the p r e c i p i t a t i o n c o l l e c t e d under the f o r e s t canopy.  Thus, observed differences in the chemistry  of incident and net p r e c i p i t a t i o n are not necessarily due  to  12 leaching of nutrients from the plant tissues.  Tukey and co-workers  c l a r i f i e d this by demonstrating conclusively using radio-isotopes  that  the above-ground plant parts are susceptible to leaching of t h e i r mineral nutrients, carbohydrates, amino-acids, organic acids, and  growth-regulating  substances (Long ejt al_. 1958, Tukey e_t al_. 1958, Tukey and Tukey 1962, Tukey and Morgan 1962, Tukey et al_. 1965, Meckleburg et al_. 1966, Tukey 1970a, 1970b). The  factors c o n t r o l l i n g leaching from leaves include:  the  i n t e n s i t y , v e l o c i t y , and p e r i o d i c i t y of rain (Tukey and Tukey 1959, Voigt 1960a); the age of the leaves, with s u s c e p t i b i l i t y to leaching increasing with age (Tukey ejt al_. 1958, Tukey and Tukey 1959); type and nature o f plant; rate o f replenishment of leached materials, and the r e l a t i v e Teachability of the substance concerned (Tukey et al_. 1958). The importance of leaching i n crop management, e s p e c i a l l y i n high r a i n f a l l areas, has been stated by Tukey (1970a).  I t has influence  on y i e l d , q u a l i t y , and n u t r i t i v e value of crops, the s u s c e p t i b i l i t y o f plants to diseases, the propagation and n u t r i t i o n of plants and plant ecosystem development.  I t should also be mentioned s p e c i f i c a l l y that  these leachates have some influence on s o i l properties (Franklin et a l . 1967)  and n u t r i t i o n of epiphytes and some understorey vegetation.  Tamm  (1953) demonstrated that Hylocomium splendens (Hedw.) B.S.G. obtains i t s nutrients from leachates  2.4.1.  from overstorey  crowns.  Patterns of d i s t r i b u t i o n and the dynamics of tree  leachates on forest f l o o r .  The cycling of leachates coming down i n rain  13 from the aerial parts of plants to the ground i s an important aspect o f biogeochemical cycle studies. throughfall or i n stemflow.  Leachates may get to the f l o o r either i n Throughfall as defined by Helvey and Patric  (1965) i s that portion of the gross r a i n f a l l which reaches the forest f l o o r through spaces i n the vegetative canopy as drip from leaves, twigs and stems.  That portion of the gross r a i n f a l l which i s caught on the  canopy and reaches the l i t t e r or mineral s o i l by running down the stems is termed stemflow (Helvey and Patric 1965).  Voigt (1960a) and Mina  (1965) have demonstrated that stemflow water contains greater concentration of chemical constituents than throughfall.  Voigt (1960a) found an average  concentration of twice as much nitrogen and phosphorus  and more than  three times as much potassium and calcium i n stemflow than in canopy drips, while Mina (1965) observed an average of f i v e times as much N, K, and Mg and about twelvesttmes as much Ca i n stemflow as i n throughfall. According to Mina (1965), the contribution of p r e c i p i t a t i o n i n stemflow i s associated with the total amount o f p r e c i p i t a t i o n , the bark charact e r i s t i c s , the architecture of the crown and i t s l e a f formation, as well as the density of the stand and the wind regime during the p r e c i p i t a t i o n peri od.  Franklin e_t al_. (1967) and Gersper (1970) have shown that f a l l o u t radioisotopes i n a forest s o i l are distributed i n r a d i a l l y symmetrical patterns with respect to the tree trunks.  The quantities of  radionuclides varied with distance from the stems (usually decreasing). Tamm (1953) also reported a steady increase i n amounts of d i f f e r e n t substances i n rainwater from the opening towards the centre o f the tree  14 crown.  A s i m i l a r systematic d i s t r i b u t i o n pattern for r a i n f a l l was  by Voigt (1960b).  According to Voigt (1960b) a large  found  portion of the  p r e c i p i t a t i o n impacting the canopies of red pine (Pinus resinosa A/it), eastern hemlock (Tsuga canadensis (L) Carr.) and American beech (Fagus g r a n d i f o l i a Ehrh) was  distributed to the s o i l in a r e l a t i v e l y narrow  band around the base of the trees.  Zinke (1962) has reported that s o i l  properties under single forest trees generally exhibit radial symmetry with respect to the tree.  He attributed this symmetric pattern of s o i l  properties to the effects of bark l i t t e r , leaf l i t t e r , and to adjacent openings or neighbouring trees. It i s well documented that understorey vegetation, especially mosses and litter,} are able to intercept part of the elemental content of rain.  Thus the movement of these elements into the mineral s o i l  layer i s delayed until decomposition  and mineralization of this vege137  tation or l i t t e r occur. the forest was  Rickard (1967) showed that  Cs present in  concentrated either i n the moss carpet or in the l i t t e r . 137  However, the highest concentrations cof rather than l i t t e r (( Ri:cka\rdi 1!97T.)-. :  Cs were associated with mosses  When mosses were lacking, l i t t e r  had a higher radionuclide content than either the mineral s o i l or understorey shrubs such as snowberry (Symphoricarpos  albus (L.) Blake), mountain  huckleberry (Vaccinium membranaceum T o r r . ) , and s a l a l (Gautheria s h a l l on Pursh).  Rickard (1967) also explained that the a b i l i t y of mosses to  concentrate more radionuclides than l i t t e r , s o i l or foliage i s probably due to the i n t r i c a t e l y branched nature of the moss carpet that contributes large surface area per gram of dry weight. L i t t e r refers to the decomposing vegetative materials of the forest f l o o r .  15 2.5.  Mosses as concentrators of toxic substances It has been shown that mosses and lichens (especially the  epiphytic types) are able to absorb and tenaciously retain greater levels of elemental substances such as lead (Ruhling and Tyler 1965) and radioactive f a l l o u t substances from the atmosphere than are other plants. Shacklette (1965) found that large amounts of elements which are generally toxic to plants did not,produce t o x i c i t y symptoms in the bryophytes that contained these elements.  The e f f i c i e n c y of mosses as concentrators of  radioactive airborne debris has been demonstrated by Gorham (1959), Svensson and Liden (1965a, 1965b), Svensson  (1966), Rickard (1966,  1971), Osburn (1967), Bovard and Grauby (1966) and Odum (1970).  1967,  Bovard  and Grauby's studies indicated that mosses absorb radionuclides d i r e c t l y from the atmosphere.  This i s supported by the finding that bryophytes  concentrate the rare earth elements in t h e i r tissues even when growing on substrates in which these elements are not detected (Shacklette  1965).  The adsorbed elements show l i t t l e ( i f any) leaching from the plants (Svensson 1966, Osburn 1967).  Osburn (1967) also found a r e l i a b l e estimate  of regional f a l l o u t by means of Sphagnum moss cores, and Shacklette (1965) stated that: bryophytes may be useful in regional geochemical evaluation because of t h e i r pronounced a b i l i t y to concentrate the rare elements that may not be detected in other sampling media. This s e n s i t i v i t y to, and a b i l i t y to concentrate elemental substances from the atmosphere i s very important in a world characterized by i n d u s t r i a l i z a t i o n , rapid development  of atomic energy f o r m i l i t a r y and  peaceful purposes, and the spread of potentially dangerous into the environment.  material  16 2.6.  Fission product isotopes:  t h e i r mode of contaminating vegetation 90  Of about 200 f i s s i o n product isotopes, only  137 Sr and  Cs play  an important long term role i n contaminating man's food and body (Miettinen 1967); they become a part of mineral n u t r i t i o n in plants and animals. Miettinen (1967) explained that t h e i r harmful e f f e c t i s due to t h e i r high y i e l d in f i s s i o n products (5-6 atom percent), t h e i r long physical 90 half-lives (  137 Sr = 28 years,  Cs = 29 years) and t h e i r e f f e c t i v e absorp-  tion by l i v i n g organisms because of t h e i r chemically close s i m i l a r i t y to important bioelements (Sr to Ca, Cs to K).  High levels of a c t i v i t i e s  of these two radioactive elements have been recognized in vegetation i n the a r c t i c regions of Finland and Alaska (Salo and Miettinen 1964, Watson et a]_. 1964), and t h e i r transfer into herbivores and human beings has been established (Russel 1966, Hanson 1966, Aberg and Hungate 1966). The two radionuclides are mainly produced  (as the result of  atmospheric bomb tests) in a monoatomic state in the stratosphere (the almost weatherless part of the atmosphere).  They are transferred from  the atmosphere to the earth's surface either by rain or by gravitational settling.  Those radioactive p a r t i c l e s having a diameter of more than 1 urn  come down to the surface mainly by c o l l i s i o n with f a l l i n g raindrops (Greenf i e l d 1957).  Greenfield, (ilt957.);sahdivan dercoWesthuijze'h (1-969)• have d i s -  cussed ra 1 mode iii sfiop a -.relationship .between" tfaili],out .'deposition; air-concentriati Qnland r a i n f a l l . r  90 According to Pavlotskaya e_t al_. (1966),  Sr comes to the 137 surface of the earth mainly in water-soluble compounds while Cs i s  17 received in almost water-insoluble forms (68-93%). vegetation by these radionuclides may  Contamination of  be d i r e c t or i n d i r e c t (Russel  1966a, 1966b; Comar and Langemann 1966,  Aakrog 1969).  Direct conta-  mination occurs when the aerial parts of the vegetation (eg. the foliage) absorb the radionuclide through r a i n , gravitational s e t t l i n g , or gaseous or Brownian d i f f u s i o n to the surface (Chadwick and Chamberlain 1970). Adsorption i s often followed by absorption into the t i s s u e s . of contamination  This mode  i s described as "rate dependant" since the amount deposited  varies with the'rate at which f a l l o u t s e t t l e s . the aerial, parts of plants may  The f a l l o u t deposited on  be l o s t through radioactive decay, a c t i v i t y  removal i n p a r t i c u l a t e form from plant surfaces (eg. by atmospheric p r e c i p i t a t i o n , wind, and gravitational f o r c e s ) , translocation to the roots, v o l a t i l i z a t i o n (eg. radio-iodine in hot climates), l i t t e r  fall  (eg. leaves, needles, branches) and dying back or weathering of leaves or their surface layers ( c f . Chamberlain 1970, Indirect contamination  Aleksakhin ejt al_. 1970).  of vegetation involves d i r e c t deposition of the  radioactive aerosols into the s o i l where they are absorbed by plants through their root system.  This type of contamination  the total amount of radionuclides present i n s o i l : as "cumulative products  dependent."  hence i t i s regarded pathways of f i s s i o n  in terms of human health have been treated by Comar and Langemann  (1966) and Russel  2.7.  The detailed c r i t i c a l  i s controlled by  (1966b).  Biological cycle of  1 3 4  C s and  8 5  Sr  134 Cs, an a l k a l i metal element, i s commonly used as a tracer in b i o l o g i c a l investigations because of i t s convenient h a l f - l i f e  (2.07  18 12g years), a v a i l a b i l i t y (manufactured readily from stable cesium, or and e a s i l y measurable radiation (Davis 1963).  Ba)  Most other a l k a l i metals  have h a l f - l i v e s which are either too long or too short f o r use i n f i e l d studies.  A knowledge of radio-cesium cycling i s of practical  importance  since i t provides information on the transfer of stable and radioisotopes of cesium and related a l k a l i metal elements in natural environments and Van Amburg 1970).  (Dodd  It i s physically and chemically s i m i l a r to potassium  and behaves somewhat l i k e i t in physiological process (Davis 1963), but according to Moon and Kimmins (unpublished manuscript) there are very few cases that cesium w i l l be a physiological mimic for potassium. •I  results of t h e i r experiment indicate that  The  OC  o^l  Cs and  Rb are close mimics 42  of each other but that they are not b i o l o g i c a l l y equivalent to  K and  therefore do not provide adequate mimics of potassium i n b i o l o g i c a l  systems.  It was further indicated in the study that results which suggest a simil a r i t y between Cs or Rb and K may be due to saturation of:the membrane transport mechanism(s) which govern s e l e c t i o n . When radiocesium i s inoculated into the stem of plants, i t i s rapidly transferred to the f o l i a g e (Olson 1968), and downwards to the roots (Stenlid 1958, Waller and Olson 1964, Witkamp and Frank 1964, Olson 1965, Waller and Olson 1967) and hence to the mineral s o i l  and  associated organic matter (Witherspoon 1964, Waller and Olson 1967). In the s o i l , cesium i s strongly absorbed and bound-to i t (Amphlett and MacDonald 1956, Klechkovsky and Tselischeva 1957, Evans 1958, Nishita et al^. 1958).  The sorption of cesium i s by ion exchange absorption,  and part of the cesium absorbed i s fixed i n non-exchangeable  form making  19 i t almost unavailable to plants (Klechkovskii and Gulyakin 1957).  De-  sorption of cesium i s brought about by cations of neutral s a l t s (Gulyakin and Yudintseva 1958).  Almost a l l cesium adsorped i s bound in the organic  matter and the upper few centimetres of the mineral s o i l  (Low and Edverson  1959, Walton 1963, Franklin et a]_. 1967, Ritchie et al_, 1967, Ritchie et al_. 1970, Jordon 1970, Kline et al_. 1970).  Absorption of cesium by plants i s  inhibited by the strong sorptive forces between the cesium ion and s o i l p a r t i c l e s and only a small proportion of the adsorbed cesium i s available to plants (Davis 1963).  According to Barber (1964), uptake of cesium by  plants i s controlled by the cation exchange capacity of the s o i l matter.  organic  Calcium and magnesium concentrations have been found to influence  uptake (Shanks and DeSelm 1963).  Menzel (1954) found that cesium uptake  i s inversely proportional to the quantities of available potassium for the  plant.  Thus, i t has been demonstrated that increase in exchangeable  potassium and the clay fraction of the s o i l  (Squire and Middleton 1966),  increase i n available potassium, addition of calcium carbonate (Evans and Dekker 1966), and additional potassium chloride (Walker et al_. 1961), a l l decrease uptake of cesium by plants.  8  (half-life  ^Sr  has a h a l f - l i f e  of 64 days, i s not so hazardous as ^ S r  of 28 years), and hence i s more convenient to use in experi-  mental work than  9 0  Sr.  8 5  S r i s a member of the a l k a l i n e earth group  and i s s i m i l a r to calcium in i t s behaviour in s o i l s (Shultz 1965), plants (Collander 1941, Klechkovskii and Gulyakin 1958), and ecosystems (Alexahin and Ravikovich 1966).  Its d i s t r i b u t i o n in s o i l s , however, does not always  correlate with that of stable strontium or calcium d i s t r i b u t i o n since  20 radioactive strontium i s more soluble.  Sorption of strontium i s increased  with the r i s e of the pH; Juo and Barber (1970) found an increase i n strontium sorption between the pH range 4-8.  Under certain conditions  strontium may form insoluble compounds (Juo and Barber 1969).  Like cesium,  the bulk of strontium released to the mineral s o i l tends to accumulate i n the upper part of the s o i l p r o f i l e (Walton 1963, Kwaratskhelia et a l . 1966,  Polyakov et_ al_. 1966, Tyuryukanova ejt a]_. 1966, Gorham 1970, Jordon  1970). silicate  The bonding of strontium i n the top horizons i s attributed to their clays.  Polyakov et al_. (1966) also found that the i l l u v i a l horizons 90  are very e f f i c i e n t i n accumulating  Sr. Accumulation i n the i l l u v i a l  horizons results from the changes i n the reaction of s o i l solution moving from the upper to deeper horizons, the considerable storage o f highly dispersed clay materials and sesquioxides acting as non-isotopic c a r r i e r s , and the presence of loams which lense out into the s o i l mass and thus form a geochemical barrier to stop strontium from moving into the deeper horizons (Polyakov et aj_. 1966). Radiostrontium enters plants from the s o i l i n r e l a t i v e l y larger quantities than cesium (Romney et a l . 1957, Krieger et aJL sakhin ejt a.]. 1970).  1966, Alek-  The factors c o n t r o l l i n g mobility of strontium i n  s o i l s (eg. the intensity of p r e c i p i t a t i o n , r e l i e f and the humus content of the s o i l ) also influence plants' uptake of strontium.  In greenhouse  experiments, Kwaratskhelia e_t al_. (1966) found that nitrogen  fertilizers  (in the form of ammonium sulphate), rotted manure, and liming lead to decreasing strontium uptake from s o i l s .  Strontium uptake i s also less  intensive when Ca content of the s o i l or nutrient solution i s higher  21 (Friederiksson et al_ 1959, 1959,  B a l c a r e t a l _ . 1969).  Romney et al_ 1959,  Fowler and Christienson  Russel and MiIbourn (1957) and Comar et al_.  (1957) however, found Ca to have no influence on Sr uptake. Compared with cesium, strontium i s r e l a t i v e l y immobile in plants.  A considerable amount of cesium i s rapidly transferred to the  wood, cortex and roots between two to four weeks after tagging 1965).  (Olson  However, sixteen months a f t e r inoculation of l o b l o l l y pines  (Pinus taeda L.), Dayton (1970) found that radiostrontium concentrations below the inoculated areas were r e l a t i v e l y low, and in large roots were barely detectable.  Similar slow basipetal-transfer rates have been  reported in other plants by Bukovac and W.i!ttwerS(il>957) ley  et al_. (1967) and Handley and Babcock (1970),  acropetally into contiguous old  new  8 5  Sr  According to Handtends to move  growth and b a s i p e t a l l y into untreated  growth in about the same amounts from the s i t e of f o l i a r  contamination.  Handley and Babcock (1970) demonstrated also that cesium moves predominantly into new  growth.  Alexahin and Ravikovich  (1966), however, found  acropetal d i s t r i b u t i o n of strontium and calcium in above parts of trees. Thus the concentration of strontium and calcium in the lower parts of trees (leaves, branches and bark) i s greater than in the upper ones. The reverse i s true for the root system:  the roots in the top horizons  contain more strontium and calcium than those from lower layers.  Olson and Crossley (1963) have demonstrated that radiostrontium leaches more slowly than radiocesium  from l e a f l i t t e r .  But Jordan (1970), 85  working with tropical s o i l , showed that 33 percent of  Sr and 27 percent  134 of  Cs that were applied to the r a i n f o r e s t plots moved out of l i t t e r  a f t e r s i x months.  This discrepancy i s probably due to the differences  in the rate of decomposition and mineralization of the l i t t e r  studied.  In the same study, Jordon found that 0.57% and 0.32% of the total  8 5  Sr  134 and soil.  Cs, respectively, had moved through the f i v e - i n c h depth i n the  CHAPTER 3 THE 3.1.  RESEARCH AREA AND  The research  THE  EXPERIMENTAL PLOTS  area  The study area i s located on the University of B r i t i s h Columbia (UBC)  Research Forest, approximately 6 kilometres  (km)  (Maple Ridge Municipality) and 60 km east of Vancouver. s o i l s , topography, drainage, vegetation been described by Keser (1960).  north of Haney The geology,  and climate of the forest have  The area is characterized as equable  (marine) mesothermal humid to rainy climate (Krajina 1969).  January,  with a mean monthly temperature of 1.1°C, i s the coldest month, while July and August (the hottest months) have a mean of 16.6°C. annual p r e c i p i t a t i o n i s about 2280 mm. in November, December and January. August.  The weather recorded  The  total  Most of the p r e c i p i t a t i o n occurs  The d r i e s t months are June, July and  (at the D.O.T. Station nearest to the  experimental plots) during the study period i s shown below (Figure 1 and Figure 2).  3.2.  Description of the experimental plots Four experimental plots were selected in the south portion of  the UBC  Research Forest (Figure 3) i n a 40-year old secondary forest  characterized by a co-dominance of Coastal Western Hemlock and Western Red  Cedar.  Klinka (personnal  communication 1972) 23  has designated  the  Figure 1.  Monthly mean temperatures during the experimental period (July 1971-July 1972).  Figure 2.  Monthly p r e c i p i t a t i o n during the experimental period (July 1971-July 1972).  Figure 3.  Location of the radioisotope experimental Legend:L Plot #1 2, Plot #2 3, Plot #3 4 , Plot #4 OT-) Orthic Polystichum  BfiBlechnum-Rubus \ T Vacci ni um-Lysi chi turn  plots,  2 o m  26 area as belonging to the Orthic Polystichum ecosystem type, although some portions of the Degraded Polystichum type may  be found.  The characteris-  t i c s of these ecosystem types are summarized below (Table 2). The of 1970.  f i r s t three plots were selected and fenced in the summer  A wooden cat-walk was  constructed  of the forest f l o o r during sampling. summer of 1971  on each plot to reduce tramping  These plots were l e f t until  to allow the forest f l o o r to recover from any damage  incurred during fencing and the construction of the cat-walks. plot was  located and The  the  fenced during the summer of  The  fourth  1971.  f i r s t plot (hereinafter referred to as Plot 1) was  about  161 square metres in area.  The  tree layer consisted mainly of western  hemlock (Tsuga heterophylla  (Rafn.) (Sarg.), western red cedar (Thuja  p l i c a t a Donn), clusters of vine maple (Acer circinatum Pursh) and paper birch (Betula papyrifera Marsh.). vegetatively. (Polystichum  The  The ground vegetation  ground was  not completely covered  consisted Of western sword-fern  muni turn (Kaulf. Presl.)) and mosses (Dicranum scoparium)  Hedw., PIagiomnium insigne (Mitt.) Koponen, Rhytridiadelphus (Hedw.) Warnst., Leucolepsis  menziesii  (Hook.) Steere, Hylocomium splendens  (Hedw.) B.S.G.) which grow mainly on decaying logs. Hook., Isotheciurn stoloniferum  1oreus  Neckera douglasii  (Hook.) Brid and Scapania bolanderi  are epiphytic on the vine maple trees.  Plot 1 was  Aust.  selected because of  the abundance of the epiphytic mosses on the stems of the vine maple trees which were growing underneath a dominant western hemlock The main objective on this plot was  overstorey.  to study whether the epiphytic mosses  receive nutrients from throughfall p r e c i p i t a t i o n coming from the hemlock tree crown.  27 TABLE 2 E cosy sterna t i c units and t h e i r d i s t r i b u t i o n in the research s i t e ( a f t e r Klinka's preliminary draft 1972)  Eocystem Type Characteristi cs  Orthic Polystichum  Degraded Polystichum  Blechnum Rubus  Dry  Subzone  Land Type  Glacial  Vaccinium Lysichitum More or less both dry and wet  Drift  General Grouping  Hygrophytic species combination, concave r e l i e f . Presence of seepage, deep s o i l s . High productivity.  Spring water, swamp formation, outwash terraces  Land Form  Lower slope. Outwash terraces 130365 m. Seepage permanent and moving depending upon slope, fast on slopes.  Depressions gently sloping. Seepage at s o i l surface 48305 m.  Soil S e r i e s  1  Lower slopes 140-530 m Seepage temporary  Lower slopes terraces, valley bottoms seepage slow  Capilano (CP), Bose (BO), Boosey (BY)  Boosey (BY) Jackman (JM) Judson (JN)  Continued  28 TABLE 2 - Continued  Characteristics o f the s o i l  series:  CP:  Parent material - G l a c i o f l u v i a l (outwash and ice contact); Texture - Gravelly loamy sand, well s t r a t i f i e d ; C l a s s i f i c a t i o n - Orthic Humo-ferric Podzol; Drainage - w e l l ; Slope - 5 to 20%; Coarse fragments - 0 to 5%  BO:  Parent material - G l a c i o f l u v i a l <150 cm over glaciomarine; C l a s s i f i c a t i o n - Mini Humo-ferric Podzol; Drainage - well to moderately w e l l ; Slope - 5 to 20%.  BY:  Parent material - G l a c i o f l u v i a l <150 cm over glaciomarine; C l a s s i f i c a t i o n - Gleyed Mini Humo-ferric Podzol; Drainage - imperfect; Slope - 0 to 20.  JN:  Parent material - organic; C l a s s i f i c a t i o n - T e r r i c Mesisol; Drainage - very poor; Slope - 0 to 2%  JM:- Parent material - G l a c i o f l u v i a l <150 cm over glaciomarine; C l a s s i f i c a t i o n - Rego Humic Gleysol; Drainage - Poor; Slope - 0 to 5%.  29 The second plot (Plot 2) had an area of about 79 square metres. The vegetative cover was  s i m i l a r to that of Plot 1 except that paper  birch was  lacking and s a l a l (Gaultheria shallon Pursh) was  There was  also a r e l a t i v e l y large carpet of Hy1ocomiurn splendens under  one of the hemlock trees.  The selection of this s i t e was  i t s s i m i l a r i t y to Plot 1, for which i t represents Plot 3 was 116 square metres.  present.  based upon  a replicate.  situated in an opening and had an area of about The ground was  covered almost completely with mosses.  The moss species i d e n t i f i e d were PIagiomnium insigne (occupying  the;greatest  portion of the forest f l o o r area), Hylocomium splendens (mainly around the base of t r e e s ) , Eurynchium oreganum ( S u l l . ) Jaeg. & Sauerb., mengte^i&can^  Maikeiethe':ro.ther- p'tots ;al:l'-the mosses r  seemed to grow on decaying wood.  There were also some sword fern, deer  fern (Blechnum spicant (L.) Roth.) and s a l a l .  The tree layer consisted  mainly of western hemlock and some paper b i r c h . of the study was  Leucolepsis  On this p l o t the  aim  to find the probable d i s t r i b u t i o n of nutrients in through-  f a l l p r e c i p i t a t i o n on the forest f l o o r , the concentration  of radionuclides  by various ground mosses, and the penetration of radioisotopes into the s o i l beneath various species of moss and i n the absence of moss.  Plot 4 was was  situated immediately adjacent to Plot 3.  not completely vegetated, being occupied  The tree layer was  The ground  i n part by mosses and ferns.  again, western red cedar, western hemlock, paper birch  and thickets of prostrate vine maples which were hosting the Isothecium stoloniferum.  This p l o t was  epiphyte,  selected on the basis of the  30 prostrate vine maples in order to study whether the bark tissues c o n t r i bute nutrients to stemflow waters and also whether the epiphytes obtain nutrients from this source.  CHAPTER 4 METHODS 4.1.  Radiotracer technique 134 A tracer technique, involving a double l a b e l l i n g with  Cs  QC  and  Sr, was used i n the study.  The radioisotope tracer technqiue has  been used as an aid i n finding solutions to d i f f i c u l t and complex problems in ecosystem studies.  Applications of this technique i n the plant and  s o i l sciences and i n several aspects of forestry research have been reviewed by Spikes (1963) and Fraser and Gaertner (1966), respectively. In investigations involving biogeochemical cycles, known quantities of an isotope (or isotopes) are introduced into one part (or compartment) of an ecosystem and subsequent sampling provides an estimate of d i s t r i bution and accumulation within the various compartments of the total ecosystem.  For this study, the isotopes were introduced into the eco-  system through the stem of trees. Tagging of plants can be accomplished by a variety of techniques which have been reviewed by Fraser (1956, 1958), Sudia and Li nek (1963) and Olson (1968).  Radionuclides i n solution can be introduced into the  aerial portions of a plant by one o f the following methods:  l i q u i d drop  applications, spray application, leaf flap methods, stem-well methods, stem injections and wick methods.  Radionuclides may also be applied 31:  32 to plants through the root system (Sudia and  Linck 1963).  For a f u l l -  size tree, inoculation can be achieved by methods involving d r i l l i n g of holes into the wood,.foliar spraying, wrapping of gauze around branches of trees, or the stem-well technique.  In this study a technique involving  s t e m - d r i l l i n g and the use of transfusion bottles was was  adopted.  The  technique  f i r s t used by Petty and Williams (1965) and l a t e r modified by Dayton  (1970); some modifications 4.2.  Inoculation On J u %  have also been made in this study.  of trees on the experimental plots 16, 1971,  two dominant western hemlock trees (one each 85  on Plots 1 and 2) were each inoculated with 8 m i l l i c u r i e s (mc) (in 0.5  N HCl)  and 4 m i l l i c u r i e s (mc)  in 300 m i l l i l i t r e s was  99+  (ml) of water.  of  The  1 3 4  CsCl  (in 0.5  nic/mg, respectively.  The  Sr and  in diameter breast height (dbh)  metres (m)  in height.  The  tall.  hemlock trees of s i m i l a r s i z e (24.5  diluted isotope  Cs were  tree on Plot 2 was  27.7  and about  10.0  26.5  cm dbh and about 28 m  cm dbh  and about 26 m in  height) on Plot 3 were each inoculated on July 22, 1971 amounts of isotopes  SrClg  tagged tree on Plot 1 measured  25.65 centimetres (cm)  Two  N HC1)  radiometric purity of each 85 134  percent while the s p e c i f i c a c t i v i t i e s of  m'c/mg and 49.0  of  with the same  as used for the trees on Plots 1 and 2.  Labelling  of f i v e prostrate vine maple stems (with diameters ranging from 4.6-6.9 cm)  on Plot 4 was  done on July 30, 1971.  of them, which were single 134 stems, were each inoculated with 1.0 mc Sr and 0.3 mc Cs dissolved in 75 ml H^O. The remaining three were in a group which was l a b e l l e d with a single application of 3.0  mc  85  Two  Sr and 0.9  mc  Cs in 225 ml  FLO.  33 4.2.1.  The inoculation procedure.  Plexiglas spouts were  constructed consisting of 7.5 cm square plates of 0.25 cm thickness which we.re bent to conform to the diameter of the tree being l a b e l l e d and which had a 1.5 cm (outside diameter) plexiglas pipe angled upwards at about 45°.  Four spouts were used on each hemlock tree, one on each cardinal  direction at a height of about 2.5 m.  The bark was smoothed and the spout  made secure with Dow Corning s i l i c o n e sealant and screws.  The tube was  f i l l e d with water and a hole of 8 cm i n depth was made (through the tube) into the sapwood of the tree by means of a long-bit power d r i l l . hole was flushed with water to remove chippings.  The  The four spouts were  connected by small bore p l a s t i c tubing to a 500 ml transfusion (saline) bottle which was suspended 1 m above the spouts.  The entire system was  set up free of a i r bubbles, and a f t e r checking for leaks and s a t i s f a c t o r y uptake of water, the transfusion bottle was exchanged for one containing the isotope i n 300 ml of water. q  The isotopes were introduced into the transfusion bottles i n  breakseal ampules enclosed i n p l a s t i c gauze bags, broken with a steel rod and the water added. retained by the p l a s t i c gauze bags.  the ampules were  A l l glass fragments were  This method was found to be rapid,  safe and resulted i n minimum external contamination. A l l handling of ampules were performed using long-handled tongs and the use of lead and water shielding.  After complete uptake of the radionuclide s o l u t i o n ,  the inoculation bottle was removed, rinsed with 500 ml of water and returned to i t s position on the tree for further uptake.  34 A s i m i l a r technique was  used for the inoculation of the vine  maple trees on Plot 4 except that each stem was side.  inoculated only on  The inoculation bottles were rinsed with 100 ml of H 0  per 1.3  2  85 a c t i v i t y of  one mc  134 Sr and  Cs used f o r the inoculation.  Uptake of the isotopes by the hemlock trees was occurring in less than 12 hours.  very  fast,  On the other hand, the movement of the  isotopes into the vine maple trees was  slow, ranging from about four days  to approximately one week. 4.3.  Experimental Design and Sampling 4.3.1.  Study of natural r a d i o a c t i v i t y of mosses.  One-quarter  metre square quadrats of mosses were taken between trees in d i f f e r e n t areas at the UBC  Research Forest and the UBC  Endownment Lands (Figure 4)  in August 1971.  Each quadrat of moss c o l l e c t e d was  bag and taken to the radioisotope laboratory (at UBC  put into a p l a s t i c Faculty of Forestry,  137 Vancouver) for radioassay 4.3.2.  Cs.  Somer,nutrient sources forsepiphytic mosses  4.3.2.1. This study was  of  Leachate from stem tissues as a source of nutrient.  conducted on P l o t 4.  A s p i r a l flow gauge was  fitted,  before inoculation, to each of the five inoculated prostrate vine maple stems and one other unlabelled stem (30 cm from the group of the labelled stems) by a method s i m i l a r to that of Cole and Gessel A piece of weather s t r i p p i n g was stem by using rubber cement.  three  (1968).  attached to a smoothed portion of each  The lower end of the s t r i p p i n g was  directed  Figure 4.  Sampling sites f o r Legend:  Cs f a l l o u t study.  1.) UBC Endownment Lands 2) Y-Camp 3) Kimmins study area (also research area f o r the main study, c f . Figure 3) 4) Mark Wier 5) Blaney Lake 6) Eunice Lake  36 into a p l a s t i c container which led into an ion exchange resin column to c o l l e c t radionuclides i n the stemflow water (Figure 5).  The exchange  columns were s p e c i a l l y designed to f i t the standard t e s t tubes (25 mm diameter x 150 mm length) used in the s c i n t i l l a t i o n counter. also be cleaned with 2 M HC1 after sampling and re-used.  They could  Each c o l l e c t o r  was set up so that the part of the stem below i t received neither stemflow or throughfall from the upper part of the inoculated trees.  In May  1972,  the stemflow c o l l e c t i n g systems on three of the inoculated stems were modified to c o l l e c t leached radioisotopes and total volume of stemflow waters from s p e c i f i c surface areas of the stems.  Samples of epiphytic  mosses were taken from the areas below the stemflow c o l l a r s and away from the zones of inoculation from September through November 1971 and in July 1972.  Resin columns were c o l l e c t e d and replaced i n October and  November 1971 and in March and July of 1972.  4.3.2.2.  Throughfall as a source of nutrients.  Mosses  were sampled on the stems of the vine maple trees growing under the canopy of the inoculated hemlock trees on Plots 1 and 2 between September and November 1971. 1972.  Three vine maple stems on Plot 1 were selected in May  A l l the epiphytic mosses on each stem were removed except those  growing on a length of about 30 cm ( i n the lower h a l f of the stem).  A  stemflow c o l l e c t o r was constructed below each zone of the remaining epiphytic mosses to c o l l e c t the total volume of water and radioisotopes after passing through the mosses.  The moss portions on the stems were harvested  85 in June 1972 to assay f o r  134 Sr and  Cs a c t i v i t y .  At the same time  the resin columns were replaced with another s e t , and the volume of water  F i g u r e 5.  P l o t #4 showing the i n o c u l a t e d v i n e mapfte t r e e s and stemflow c o l l e c t i n g systems.  37  38 collected was measured.  Another c o l l e c t i o n of resin columns and water  were made i n July 1972 to measure the concentrations of the radionuclides per unit volume (in absence of the mosses). 4.3.3. the forest f l o o r .  Patterns of d i s t r i b u t i o n of throughfall leachates on The experiments reported here were carried out i n Plot 85  3.  To determine the patterns of d i s t r i b u t i o n of  134 Sr and  Cs leachates  in throughfall, f i f t e e n collectors were i n s t a l l e d p r i o r to the tagging o f trees under and at the margins of the canopies  of the two inoculated  western hemlock trees i n the patterns shown i n Figure 6.  Each c o l l e c t o r  consisted of a 12.5 cm diameter p l a s t i c funnel (with a nylon-wool connected to an ion-exchange resin column.  filter)  The c o l l e c t o r was held one  metre above the ground level by means of a metal support (Figures 7 and 8). Monthly samples were taken from September to November 1971 and i n March 1972.  No samples were taken between December and February because of the  low winter temperatures.  The low temperatures made the r e l i a b i l i t y of  March samples questionable since the resin columns were frozen.  In late  April 1972, the resin columns were replaced with p l a s t i c containers to measure the throughfall volumes.  This was done to test the relationship  between total leached a c t i v i t y i n throughfall and the volumes of throughfall  at the same sampling spots.  Throughfall volumes were measured for  four individual storm fronts from May to July 1972. 4.3.4J The understorey  Concentration  of radionuclides by various ground mosses.  vegetation (mainly mosses) on Plot 3 was sampled at the  same time as the resin columns. positions of the resin-column  Samples were taken very close to the  collectors so that comparisons could be  Figure 6.  Layout of the 15 throughfall c o l l e c t o r s on Plot #3. Legend:  Inoculated  hemlock trees  ©  Positions f o r c o l l e c t o r s  •  39  F i g u r e 7.  P l o t #3-showing the i n o c u l a t e d the t h r o u g h f a l l c o l l e c t o r s .  F i g u r e 8.  A throughfall  hemlock t r e e s  ( o r stemflow) c o l l e c t o r .  and some o f  made between the amounts of radionuclides intercepted by the vegetation and the total a c t i v i t i e s i n the throughfall. 4.3.5.  Penetration of radioisotopes into the s o i l .  P r i o r to  2 the inoculation of the treesj 0.06 m  quadrats of ground-dwelling mosses  were taken from Plot 3 and counted to give a measure o f pre-inoculation background  activity.  In April  1972, s o i l cores (5 cm i n diameter and  15 cm i n depth) were taken at s p e c i f i c distances from the trunk of the inoculated trees on the plot to study the d i s t r i b u t i o n of radionuclides in the undisturbed condition and i n the absence of mosses. 4.3.6.  Sampling of the inoculated trees.  Small branches  from the inoculated hemlock trees were sampled p e r i o d i c a l l y (using a r i f l e ) i n the middle crown areas.  Stem cores were taken from the inocu-  lated vine maples on Plot 4. 4.4.  Laboratory Work The samples of epiphytic mosses and the understorey vegetation  were a i r - d r i e d i n the laboratory and c a r e f u l l y separated from l i t t e r , s o i l and other extraneous substances. species.  This was not easy i n some moss  For example, i n PIagiomnium insigne, i t was not possible to  separate the "root system" completely from humus.  The needles of the  small branches from the hemlock trees were detached by air-drying i n p l a s t i c bags for about a week or by oven-drying i n paper bags f o r a few hours.  The twigs were separated from the needles and cut into small pieces.  Samples of twigs and needles were taken from each l o t . The stem cores from the vine maple stems were a i r - d r i e d .  42 Each s o i l core was analysed as follows: Moss (where applicable) LF - mixture of f r e s h l y - f a l l e n l i t t e r layer and the fermentation layer H  - humus substance layer  Mineral s o i l layer (top 3 cm) For  the, humus and the mineral s o i l  centimetre of depth.  layers, samples were taken at every  Mean values were then calculated to represent  either the humus or the mineral s o i l layer. counted in special v i a l s with a s c i n t i l l a t i o n 85 for the  A l l the above samples were counter (described below)  134 Sr and  Cs using the appropriate window settings.  Samples from  s o i l cores were counted for 90 minutes with 60-minutes background  counts while the vegetative samples were counted f o r 60-minutes with 30-minutes background counts. in each vial was measured.  After counting, the height of the sample  Samples were then over-dried (105°C) f o r 24  hours and weighed. The moss quadrats sampled f o r studying natural  radioactivity  were oven-dried for about 72 hours a f t e r removal of extraneous material. They were ground to a homogeneous powder and counted i n standard t e s t 137 tubes (25 x 150 cm) f o r count.  Cs for 90 minutes with a 60-minute background  The weight and the level of each sample in the test tube were  measured. The heights and weights were used f o r geometry and weight correction respectively.  The counts f o r the samples were also corrected  for radioactive decay, background counts and machine e f f i c i e n c y .  Activity  .43 of the s o i l and the vegetative samples were expressed as microcuries per gram. 4.4.1. used was  The S c i n t i l l a t i o n Counter.  The s c i n t i l l a t i o n  counter  a Picker Nuclear Autowell II (with an automatic 100 capacity  sample changer) with a Twinscaler II (Model 644-125). 3D x 3 in (7.62D x 7.62  cm) Nal(Tl) crystal with 1 1/8D  5.08 cm) w e l l , with a 3-inch lead s h i e l d .  The detector was x 2 i n . (2.86D x  Since autowell has a 2-channel  analyser i t can simultaneously measure two radioisotopes in a single sample.  CHAPTER 5 RESULTS AND  DISCUSSIONS  137 5.1.  Cs f a l l o u t a c t i v i t y levels of mosses 137 The biomass and  Cs a c t i v i t y levels of mosses at the UBC Re-  search Forest and the UBC Endownment Lands presented i n Table 3 show high biomass values (dry wt/0.06m ) f o r Sphagnum squarrosum Crome and Rhytidiadelphus loreus, and the highest a c t i v i t i e s (pCi/g dry wt) i n p r a c t i c a l l y a l l cases, f o r Plagiothecium undulatum.  A c t i v i t y levels of the three  mosses (Mnium glabrescens, P. undulatum and j*. loreus) which were present in a l l f i v e of the locations were analysed using Analysis of Variance and Duncan's New Multiple Range Test.  On a per graiiin basis, there were  no s i g n i f i c a n t differences i n the levels of a c t i v i t y of the mosses i n the four locations at the research forest.  The a c t i v i t y levels i n each  of the research forest locations were, however, s i g n i f i c a n t l y d i f f e r e n t (at the 5% level) from those of the Endownment Lands. 137 the mean concentration of  Differences i n  Cs f o r a l l s i t e s between P_. undulatum and  M, glabrescens were i n s i g n i f i c a n t (at the 5% level) but the mean of either M. glabrescens or P. undulatum d i f f e r e d s i g n i f i c a n t l y (at the 5% level) from that f o r JR. loreus. These results are presented on Tables 137 2 4 and 5. The amount of Cs deposited per unit area (m ) of moss was less than that which was deposited i n each of the areas of the research forest (Table 3 and 5), though, the biomass values of mosses per unit area were higher at the Endownment Lands than at the research forest (Table 3).  44  TABLE 3 1 37  Cs f a l l o u t a c t i v i t y of mosses in the UBC Research Forest and Endownment Lands (based on 2 single quadrats for each moss). Sampling date: August 1970.  Location  A l t i tude (m)  Estimated mean annual precipitation (mm)  Moss species  Biomass^ q/0.06m^  C s a c t i v i t y level pCi/g pCi/m^ 0 7  46  2110  £. oreganum I_. stoloniferum M. glabrescens P. undulatum JR. loreus  8.5 7.9 8.6 6.0 14.5  0.1 1.6 1.7 T 0.8  19 38 40 58 27  + + + +  0.7 8.5 3.2 1.8 + 1.1  2576 4832 5440 5552 6240  Mark Wier  152  2286  E. oreganum H_. splendens I. stoloniferum M. glabrescens P_. undulatum R. loreus S_. squarrosum  6.7 7.0 6.4 4.3 8.9 9.1 8.5  + 0.6 T 0.3 + 1.4 T 0.8 + 1.9 + 1.0 + 1.4  36 28 21 59 26 22 10  + + + + + + +  6.0 4.6 2.1 4.6 5.0 1.8 0.7  3808 3088 2160 4048 3696 3120 1360  Kimmins Study Area  168  2286  £. oreganum H_. splendens M. glabrescens P_. undulatum R. loreus  10.1 + 0.6 9.7 T 0.8 9.0 T 0.2 9.9 + 0.1 14.7 + 0.5  33 27 43 61 43  + 2.8 + 0.7  5328 4192 6080 9536 10112  Y Camp  + + + +  1 37  ^.3f  1  -T 1.1 + 0.4 + 8.5  continued  TABLE 3 - continued  Location  Altitude (m)  Estimated mean annual precipi tation (mm)  1 "37  Moss species  Biomass q/0.06m  ?  Cs a c t i v i t y level  Blaney Lake  343  2670  H. M. P. R. *S. S.  splendens glabrescens undulatum^ loreusl bolanderi -j squarrosum  9.3 + 0.9 NA 4.3 9.4 10.1 + 1.0 30.0  pCi/g 28 + 0.4 38 + 0.4 86 31 33 + 3.5 62  Eunice Lake  482  3050  H. I. M. P. R. S.  splendens stoloniferum glabrescens undulatum loreus squarrosum  NA NA 9.8 + 7.3 + 9.0 + 17.6 +  0.7 2.0 1.3 2.3  24 +.1.1 32 + 4.6 43 + 0.4 75 + 0.7 26+1.8 54+1.8  NA NA 6742 8760 3744 15206  8.0 + 1.3 9.2 + 1.0 17.8 + 0.5  15 + 1.4 19+1.8 16 + 1.4  1920 2797 4557  36.7  6025  Endownment Lands  30  Average a c t i v i t y ( a l l locations) single sample *liverwort NA - not available f - standard error  1475  M. glabrescens P. undulatum R. loreus  pCi/m 4166 NA 5917 4662 5333 29760  2  TABLE 4 Comparison o f f a l l o u t a c t i v i t y levels of three mosses (mean of 5 locations) 137 Moss  Biomass g/0.06m  Cs a c t i v i t y  level  ?  pCi/g dry wt  pCi/m  P_. undulatum  8.2 + 0.3^  48 +.2*  6298  M. gl abrescens  7.9 + 0.3  40 + 2*  5056  27+1  5616  38.3  5657  R. loreus  13.0 + 0.4  Average a c t i v i t y  f - Standard error * - Homogeneous samples according to Duncan/s New Multiple Range Test  48  TABLE 5 Comparison of amounts of f a l l o u t a c t i v i t y i n 5 locations (mean of P_. undulatum, NL gl abrescens  and R. loreusT  Biomass g/0.06iT)  Location  ?  UBC Endownment Lands Y Camp Mark Wier Kimmins' Study Area Eunice Lake  Estimated mean annual precipi tation (mm)  137  Cs a c t i v i t y level  pCi/g dry wt  11.6 + 0.8^  1475  17 + 0  9.7 + 0.7  2110  41+2  3155 6363 i  7.4 + 0.5  2286  35 +.3 **  11.2+0.5  2286  49 + 2**  8.7 + 0.4  3050  Average a c t i v i t y  i i  ** 48 + 4 38.0  f - standard error ** - Homogenous samples according to Duncan's New Multiple Range Test  pCi/m^  4144  8781 6682 5825  49 P r e c i p i t a t i o n has more influence on radionuclide f a l l o u t deposition (van der Westhuizen 1969,  Ritchie et a K 1970) than any other  factor, though p r e c i p i t a t i o n , l a t i t u d e and elevation, being correlated, i n t e r a c t to control the amount of f a l l o u t radionuclide that i s deposited in an area.  The concentration  of f a l l o u t radionuclides i n plants, however,  depends on species and the growth habits of plants (Gorham 1959, 1970)&and i s said to show a general  decrease with decreasing  Kline  latitude  (Lockhart e t al_. 1965, Kline and Odum 1970), elevation (Kline and Odum 1970,  Ritchie et al_. 1970) and amount of r a i n f a l l  ( P e l l e t i e r et al_. 1965, 137  Roser and Cullen 1965,  Kline and Odum, 1970).  Comparison of  activity  2 levels (uCi/g and yCi/m ) of the 3 moss species from the study areas (Table 3 and 5) supports the e x i s t i n g evidence i n the l i t e r a t u r e that 137 p r e c i p i t a t i o n i s an important factor c o n t r o l l i n g the amount of deposited.  Since the annual p r e c i p i t a t i o n of the research  Cs  f o r e s t where  samples were taken was greater than that of the Endownment Lands (table 3), 137 the lower levels of expected.  Cs a c t i v i t y of the Endownment Lands samples are  The unexpected non-significant differences between the sample  means of the locations within the research  forest may be due to the small  number o f samples taken r e l a t i v e to the great v a r i a b i l i t y of input of chemicals to the forest f l o o r i n throughfall p r e c i p i t a t i o n (Kimmins, unpublished manuscript). 137 The  Cs concentration  values reported by Kline and Odum (1970)  in Puerto Rico (Table 6) are greater than those obtained i n the present study due possibly to differences i n p r e c i p i t a t i o n and the growth habit of the moss species involved (Tables 3 and 6).  Kline and Odum (1970)  50 sampled epiphytic mosses (filamentous hanging mosses) which are known to have a much greater a b i l i t y to absorb radionuclides than ground dwelling species (Odum ejt aj_. 1970, of the sampling  Kline and Odum 1970) which were the subject  in the present study.  We should, therefore, expect higher  levels of a c t i v i t y with epiphytic mosses in B r i t i s h Columbia than those reported in Tables 3, 4 and 5 f o r the ground-dwelling mosses. The values for the ground dwelling species of the present study (36.7 pCi/g dry wt) are s i m i l a r to those (35.8 +3.7 for ground-dwelling  pCi/g dry wt) obtained  mosses (mostly Hylocomiurn spp. and Rhytidiopsis spp.)  of a cedar-hemlock stand in Washington (Rickard 1971,  Table 6), although  Rickard had e a r l i e r (1966) reported a mean value of about 60 pCi/g dry wt for mosses (mainly Rhytidiopsis robusta) in the same v i c i n i t y .  From this  data, i t could be inferred that Rhytidiopsis sp. intercept more f a l l o u t than Hylocomium sp.  Lower levels of a c t i v i t y found in Hylocomiurn sp.  (24-28 pCi/g dry wt) in this study are probably due to rapid loss of the intercepted radionuclides from the decomposing older segments of the moss.  These older segments have higher concentrations of a l l elements  except K as compared with the younger segments (Tamm 1953, Tyler 1970). through  Riihling and  This probably indicates rapid K loss from these segments  leaching and or translocation into the new segments.  Since Cs  or K leaches out of plants more rapidly than most elements and even more so in older tissues, leaching would probably be the cause of the low Cs or K concentrations in the older moss segments.  i  TABLE 6 Values of  137  . . Cs natural f a l l o u t a c t i v i t y in mosses from other sources Acti vi ty  Elevation Location E f f i n Forest (Puerto Rico) Cascade Mountain of Washington Packwood v i c i n i t y La Wis Wis  Lati tude 18°N  48°N  48°N  Summit Creek  48°N  Ogotoruk Creek Valley, Alaska  68°N  _JlD)  Precipitation (mm)  Moss type  (pCi/g dry wt)  Source  5080  Epiphytic mosses  61.7 - 210  Kline and Odum (1970)  1472  Mainly Rhytidiopsis robusta  60  Rickard (1966)  454  1472  Mainly Hylo- 35.8 + 3.7 comiurn spp. and Rhytidiops i s spp.  Ri ckard (1971)  600  1472  Mainly Hylo- 33.7 + 2.8 comi urn spp. and Rhytidiops i s spp.  Rickard (1971)  Sphagnum spp. 19.1  Rickard et a l . 7J965)  914  457  203  +4.1  52 5.2.  Primary nutrient sources f o r epiphytes  5.2.1.  Epiphytic mosses as f i l t e r s of crown-washed nutrients.  The results obtained  from the experiment conducted to show that epiphytic  mosses are e f f i c i e n t at sorbing chemicals from throughfall are shown in Table 7.  I t i s apparent from these results that mosses are indeed  highly e f f i c i e n t concentrators  of leachate chemicals.  But whether these  nutrients enter into the tissues of the epiphytic mosses or are merely adsorbed on t h e i r surfaces i s another question.  Leaching studies made  with Spanish moss ( T i l l a n d s i a usneoides L.),^ an epiphyte, by Elder and Moore (1965) showed that various degrees of washings with water or  0.5  137 N KC1  did not remove  Cs and other radionuclides from this plant.  They concluded that Spanish moss actively binds and incorporates into i t s tissue the elements i t adsorbs on i t s surface.  Riihling and Tyler  (1970) have demonstrated with Hylocomium splendens that elements which are sorbed by i t are retained in i t s tissue.  From this evidence we  may  assume that the nutrients which the epiphytes f i l t e r from throughfall or stemflow are retained and u t i l i z e d by them. Tamm (1953, 1964)  has claimed  that some ground-dwelling mosses  and a l l epiphytes depend for t h e i r nutrients on substances that are leached  out of tree crowns.  However, observations  have shown that some  epiphytes can thrive without the influence of tree canopies. to Benzing and  Renfrew (1971) dwarf cypress  (L.) Rich.) supporting  According  trees (Taxodium distichum  large colonies of twisted a i r plant ( T i l l a n d s i a  ^Spanish moss i s an epiphyte, not a true moss. plant belonging to the family Bromeliaceae.  I t i s a flowering  TABLE 7 E f f i c i e n c y of epiphytic mosses in f i l t e r i n g radionuclides i n throughf a l l and stemflow waters  Biomass of moss (g)  Calculated surface area occupied by moss (sq cm)  Total a c t i v i t y washed through moss (pCi/10 ) 5  85  Sr  134 Cs  Total a c t i v i t y picked by moss (yCi/105) 85  Sr  134 Cs  Expected a c t i v i t y picked by 1 sq cm of moss (uCi/10 )  Filtering e f f i ci ency of moss [%)  85  85  5  Sr  134 Cs  Sr  134  Cs  Tree 1 moss  5.42  1020  11100  699  7308  369  7.17  0.36  66.4  52.8  Tree 2 moss  7.03  1530  14732  880  7892  110  5.16  0.07  53.6  12.5  Tree 3 moss  4.50  22560  2214  16680  1574  1.64  73.9  71.1  962  17.34  cn CO  54 c i r c i n a t a Schlecht.) in Florida have very sparse f o l i a g e which are present only in the growing season, and that there are many epiphytes in the forest which have no l i v i n g branches above them at a l l .  This contradicts the  idea that tree crowns are the main source of nutrients for a l l  epiphytes.  85 Reference to Table 7 shows that  Sr was sorbed by the epiphytes 134  involved in the present study in r e l a t i v e l y larger quantities than  Cs.  This i s in agreement with Bell's (1959) finding that l i v i n g Sphagnum moss shows preferential absorption of ions of higher valencies from solutions resembling natural waters in composition.  According to Bell  (1959), and Ruhling and Tyler (1970), d i f f e r e n t species of Sphagnum have been demonstrated (by Williams and Thompson (1936), Anschutz and Gessner (1954) and Puustjarvi (1955)) to act as ion exchangers.  The manner in  which the epiphytic mosses sorb elements from water i s probably s i m i l a r to that o f Sphagnum moss. 5.2.2.  Leachates from the stem as a source of nutrients f o r epiphytes oc  5.2.2.1.  Leaching of  I  Sr and  on Cs from vine maple stems.  C a r l i s l e e_t al_. (1967) have provided data for the quantities of nutrients which are added to stemflow waters of a s e s s i l e oak (Quercus patraea (Mattuschka) Liebl.) woodland.  The amounts of Ca and K added annually  to these waters were stated to be 1.90 kg/ha and 1.46 kg/ha respectively. The o r i g i n of the nutrients i s doubtful, although i t was said that leaching of elements from the bark tissue could possibly account f o r some of the nutrients in these waters.  Table 8 presents the results of the experiment  TABLE 8 8 5  S r and  k5 A c t i v i t y , yCj'/HO  Tree #, Sampling date  85 Sr  134  Cs  1 3 4  C s i n stemflow waters of inoculated vine maple trees  Sr/ Cs (1:1 inoculum) assumed) 8 5  1 3 4  Volume of ;S temf 1 ow water (ml)  Activity/ml uCi/10 5 85 Sr  134  Cs  Expected a c t i v i t y 1 sq cm of sterrir surface (yCi/ltr)  Stemfl ow collection area (sq.cm)  85 Sr  160 320 520  21.2 2.6 38.0  134  Cs  October 26, 1971 43 67 134  68 169 262  0.19 0.12 0.16  NA  290 19 2143  288 22 2142  0.31 0.26 0.30  NA  513 190 2472  128 22 1285  0.22 2.62* 0.58  NA  3172 821 19774  426 93 2857  2.26 2.68 2.10  #2 #4 #5 November 29. 1971 #2 #4 #5  March 3, 1972 #2 #4 #5 July 5, 1972 #2 #4 #5  275 935 1000  11.6 0.9 19.8  1.5 0.1 2.9  2.7 0.3 5.5  Continued  TABLE 8 - Continued  Expected a c t i v i t y  Tree #, Sampling date  55  A c t i v i t y , yCi'/WO 85  Sr  134  Cs  Sr/ Cs (1:1 inoculum assumed) 8 5  1 3 4  Volume of stemflow water (ml)  Acti vi ty/ml yCi/10* 5  8 5  Sr  1 3 4  Cs  Stemflow collection area (sq cm)  1 sq cm of steirir  surface (yCi/10 ) 85  Sr  134  Cs  July 15, 1972 #2 #4 #5  1223 828 26928  214 137 5653  NA = not available  1.73 1.82 1.44  1300 1500 4000  0.9 0.6 6.7  0.2 0.1  1.4  160 320 520  7.6 2.6 51.8  1.3 0.4 10.9  * = the r e l a t i v e l y high ratio i s , probably, due to machine error  cn  57 performed to test the hypothesis that the bark tissue contributes 85 rients to the stemflow waters.  Both  nut-  134 Sr and  Cs were detected  in the  stemflow waters which were c o l l e c t e d from the inoculated vine maple stems, suggesting  that for vine maples of the p a r t i c u l a r age under study,  leaching of the stem may  constitute a s i g n i f i c a n t source of nutrient  loss. 85 Initially,  Sr was  leached out in r e l a t i v e l y smaller quan-  134 t i t i e s than  Cs.  This trend was  reversed during the l a t t e r part of  the study, however, due probably to the d i f f e r e n t rates of mobility s u s c e p t i b i l i t y to leaching of the two elements.  and  Cs (or K) i s said to  move more " f r e e l y " in the plant than Sr or Ca (Levi 1968)  since Cs (or  K) i s not strongly bound to exchange s i t e s in the xylem as i s Sr (or Ca). Sr (or Ca) movement in the xylem i s therefore r e s t r i c t e d because other bound cations are more readily replaced (Bell and Biddulph 1963). According  to Tukey et al_. (1965) and Mecklenburg et al_. (1966),  cations such as K, Rb, Sr, and Ca are leached  from the plant by a process  of ion exchange and d i f f u s i o n involving exchange s i t e s .  Leaching of  cations from f o l i a g e (and probably, the stem) i s primarily a passive process, although some metabolites through active process.  may  be deposited  upon plant surfaces  Carbonic acid i s f i r s t formed from CC^ from  a i r and water on the plant's surface.  Dissociation of the acid takes  place and the released hydrogen ions exchange with cations on the c u t i c l e (or bark) and c e l l wall exchange s i t e s to form alkaline carbonates. The alkaline carbonates are either precipitated onto the surface of the plant or remain i n the leaching solution and are washed o f f the surface by p r e c i p i t a t i o n .  58 Ca has been demonstrated to be immobilized i n the phloem as oxalate c r y s t a l s (Fraser 1958) after i t s transfer from the xylem (Fraser 1958, Zimmermann 1960, Thomas 1967a).  Samples of bark, wood, twigs,  leaves and mosses were taken in July of 1972 from the vine maple stems to study the d i s t r i b u t i o n of the radioisotopes therein.  The purpose  was to determine the concentration of radionuclides i n the bark tissue in order to establish the relationship between bark concentrations and 134 bark leaching.  The r e s u l t s , which are given on Table 9 show that 85  was present i n a l l the components studied while  Sr was present only  in the leaves and some of the moss and twig samples. 8  Cs  The detection of  ^ S r i n stemflow waters (which were sampled at the same time as the  above vegetative samples) and i t s absence from the bark led to a further investigation.  Samples were taken a t various distances from the point  of inoculation along one of the labelled vine maple stems to study the 85  134 Sr and Cs i n the plant. Table 10 presents the 134 r e s u l t s . Whereas Cs was again detected i n every stem component, the presence of ^ S r was i r r e g u l a r . Two samples taken at adjacent points  d i s t r i b u t i o n of 8  may or may not contain  85  Sr, which indicates that  85 Sr was very unevenly  d i s t r i b u t e d i n the plant. or  The reason f o r the observed patchy d i s t r i b u t i o n of components i s not known.  Sr i n stem  I t may be suggested, however, that this was 85  due to l i t t l e tangential translocation of  Sr from the ascent pathway.  59 TABLE 9 oc  1OA  Sr and Cs concentration in tissues o f labelled vine maple trees (sampling date July 5, 1972)  A c t i v i t y per gram (uCi x 10 8 5  Sr  9145 29483  1 3 4  Cs  5475 7083  Tree 11  Moss Moss  Tree 2  Moss Moss Xylem Bark  Tree 3  Moss Moss Xylem Bark Foliage Twi gs  263 U U U 121 4  71 28 101 524 166 T  Tree 4  Moss Moss Xylem Bark Foliage Twig  56 9 U U 541 U  39 35 295 837 1088 5  Tree 5 5  Moss Moss Xylem Bark Foliage Twi g  745 276 U U 2525 1354  165 469 660 2386 1824 487  . Moss Moss Xylem Bark Foliage Twi g  35 U U U 19 U  6 40 1 3 12 T  *  Tree 6  U = undetected T = trace  U 2482 U U  2292 1218' 209 640  -4 /g)  TABLE 10 Sr and Cs concentrations (yCi/10 per gm) in epiphytic mosses and a vine maple tree at various distances (cm) from the point of inoculation. (Sampling date: August 22, 1972.)  **  *  10 85 Sr Xyl en| Bark^  Living twigs  *  100*  *  1000*  994 1268  971 1105  347 511  1235 903  255 332  357 426  187 115  9 12  3 5  8030 U  3578 5476  762 7463  2300 2319  3083 4302  1258 1396  1529 1950  689 730  26 U  13 16  52  1366  757  190  195  U  42  27  767 1158  451 424  Sr  S r  U  1 3 4  Cs  2008  85  S r  1 3 4  U  Cs  85  S r  1 3 4  Cs  8 5  Sr  1 3 4  2 11  r  Dead ' twi gs  Cs  8 5  1 1  1  5  1  1  = cm distance above point of inoculation  U = undetected  UN = unlabelled stem  **  Sr  1 3 4  Cs  U 11  3 2  13  14  8 5  Sr  1 3 4  1 2  Old foliage  *  100*UN  1150  3720 U  106  Moss  60  85  8 5  1 3 4  *  134  CS  c  30  10  = cm distance below point of inoculation f = duplicate samples o  Cs  61 5.2.2.2. leachates  ( S r and 8 5  1 3 4  Contamination of. epiphytic mosses by stem  C s ) . Nutrients  leached  from stems may  source of nutrients f o r stem dwelling epiphytes.  be a major  Table 11 shows that  the epiphytes taken from the incoculated vine maple stems were contaminated by the radionuclides, and there was O f mosses from September of 1971  a general  to July 1972.  increase of r a d i o a c t i v i t y pr-  Sr levels were i n i t i a l l y  very low or undetected in the mosses but increased over the course of 134 the experiment.  Cs, on the other hand, was  detected  from the  sampling date and increased steadily throughout the study. increase in the moss a c t i v i t y indicates that there was  The  first general  a continuous supply  of radionuclides to the mosses and can be interpreted as indicating that the mosses were able to retain the radionuclides e f f i c i e n t l y .  Losses  of radionuclides from the mosses by leaching were not determined but the l i t e r a t u r e would suggest that such losses were probably small and Moore 1965, 5.3.  Svensson 1966).  Nutrients and epiphytic  adaptation  From a consideration of the data presented in the sections, i t may  previous  be said that epiphytic mosses and probably other epi-  phytes u t i l i z e nutrients leached plant.  (Elder  from the bark tissue of the  "host"  Rain, f o l i a r leachates or dust w i l l provide an additional source  of nutrients for these plants.  The r e l a t i v e importance of each nutrient  source to the epiphytes w i l l depend upon the morphology of the epiphytes and the a v a i l a b i l i t y of the nutrient source which i s influenced by conditions such as the nature and the presence of overstorey  trees, and  the  TABLE 11 Radioactivity (pCi/g) of epiphytic mosses on inoculated vine maple trees  Sept. 16, 1971  Oct. 26, 1971  85  85  S r  1 3 4  Cs  S r  1 3 4  Cs  ..Nov. 29, 1971^* 8 5  Sr  :  1 3 4  Cs  Jan. 28, 1972  July 5, 1972^  85  85  Sr c  1 3 4  Cs  Sr c  1 3 4  Cs  Tree # 1 mosses  113  235  U  1289  119 U  3633 116687  15691  71805  914478 2948270  547548 708327  Tree # 2 mosses  24  259  307  1992  369 2  4101 2335  39560  20062  248169 U  121757 229199  Tree # 3 mosses  U  1755  U  2096  959 U  4907 1085784  9097  26932  26304 U  7101 2817  Tree # 4 mosses  U  418  18  1055  338 U  305 98731  2406  2260  5598 892  3855 3517  Tree # 5 mosses  32  226  U  2712  274 U  861 91592  1732  23509  27625 .74492  46852 16499  62  118  124  361  480  703  1273  171  U 3504  1246 599  Tree #  ** 6  **  f = two samples taken from d i f f e r e n t portions of the stem = tree was found to be dead on this date; increased in a c t i v i t y attributed to death of stem tissues.  U = undetected  = unlabelled stem  63 s u s c e p t i b i l i t y of the host to leaching.  Epiphytes such as mosses which  form mats close to the stem may u t i l i z e nutrients leached  from the stem  tissues as t h e i r primary source of n u t r i t i o n .  In terms of the nutrient c y c l e , epiphytes may play an important role by holding up nutrients obtained at l e a s t temporarily.  from the host (and other  sources),  Thus nutrients which may be l o s t to other compart-  ments of the ecosystem through leaching from the host tissue are retained in d i r e c t contact to the host by the epiphyte.  For green stems (such as  those of vine maple i n this study) there i s a p o s s i b i l i t y that these nutrients would be reabsorbed through the bark of the host a f t e r release 85 by the epiphyte.  Absorption  of  134 Sr and  Cs through the green vine  maple stems was not determined, but Riekerk (1967) reported a study by Kiseler using radio-phosphorus which showed that elements are absorbed through the bark, and Tukey et al_. (1958) have claimed that any part of the plant which can lose nutrients can also absorb nutrients.  Thus,  there may be a mutual nutrient exchange between the green stem tissue and the epiphytes, with the rate o f the cycle depending upon the rates of elemental leaching and absorption by the host and the epiphytes. 5.4.  I n t e r s p e c i f i c translocation of elements From Tables 9 and 11 we may deduce that the uninoculated  stem  in the clump of inoculated vine maples received some radionuclides from the inoculated trees.  This i s i n agreement with the findings o f Woods 45  and Brock (1964) and Woods (1970) which showed transfers of  Ca and  32 P from red maple (Acer rubrum L.) donors (Woods and Brock 1964) and  64 32  P,  4 5  Ca,  86  R b and S from sand hickory (Carya p a l l i d a (Ashe) Engl. & 3 5  Graebn.) and blackjack oak (Quercus mari1andica Muenchh.) donors (Woods 1970)  to other species.  Transfer was said to be achieved  through exu-  dation from the donor and absorption by the receptor species, through mutually shared mycorrhizal  fungi, or through root grafts (Woods and  Brock 1964). 85 The transfer of  134  Sr and  Cs to the uninoculated  stem and  the presence o f these isotopes i n samples taken 10 cm below the inoculation point (Table 11) indicate that the isotopes can move b a s i p e t a l l y .  However  the a c t i v i t i e s below and above the inoculation zone show that downward translocation was comparatively  slower than upward movement.  also shows that there was a general  Table 11  decrease of a c t i v i t y levels with  distance from the inoculation point. 5.5.  Nutrients i n throughfall and forest f l o o r nutrient dynamics  85 134 Sr and Cs a c t i v i t y levels i n the inoculated hemlock 85 1^4 -4 tree needles.and twigs. The Sr and Cs a c t i v i t y per gram (pCix 10 /g) 5.5.1.  of the needles and twigs from the inoculated hemlock trees are i l l u s t r a t e d 134 in Figures 9 and 10 respectively.  The scale used on the  pc  Cs axis i s  pc  double that of Sr f o r convenience i n comparing the a c t i v i t i e s of Sr 134 134 and Cs, since the amount of Cs used f o r the inoculation was h a l f that of  8 5  Sr. 134 The peak a c t i v i t y of  Cs i n both needles and twigs occurred  between January and March 1972 (241 days a f t e r inoculation) and dropped  65 till  the l a s t sampling date (July 15, 1972).  The rates of radiocesium  movement have been studied by Witherspoon (1963, 1964), Auerbach et a l . (1964) and Kimmins (1970) in white oak (Quercus alba L.), yellow poplar (Liriodendron t u l i p i f e r a L.) and red pine (Pinus resinosa A i t ) , tively.  respec-  In a l l these studies peak Cs a c t i v i t y in foliage was obtained  within 40 days from the time of inoculation but the samples taken a month a f t e r inoculation in the present study showed low a c t i v i t i e s .  Since no  samples were taken between the middle of August 1971 and January 28, 1972, i t i s possible that the peak a c t i v i t y may actually have occurred during this period, si Dargen''amounts 'of = 1  Cs'were-leached in-through f a l l  6fuT.97T. thanotniea'nycoth^ictfllJec'tiJo'n  in October  >p6i9iwd (-Figure'oVl^'f-^HoweVer h i g h total  throughfall a c t i v i t y over a period of several weeks may not necessarily 134 r e f l e c t peak  Cs a c t i v i t y in foliage since throughfall leaching i s not  solely dependent upon f o l i a r concentration. of  The duration and frequency  rain storms i s of greater significance than total p r e c i p i t a t i o n for  the  period.  We should also not over rule the fact that the l i f e span of  the  foliage can a f f e c t the time f o r f o l i a r peak a c t i v i t y .  The leaves  of the t u l i p trees and the white oaks, respectively used by Auerbach et aj_.  (1964) and Witherspoon (1964), being deciduous, have a shorter  l i f e span and hence accumulate nutrients and gain weight early in spring whereas non-deciduous leaves achieve these throughout most of t h e i r year of growth.  first  For example, whereas Thomas (1967b) found 73% + 6 of  45 the  total  Ca inoculated into dogwood trees (Cornus f l o r i d a L.) i n the  foliage of the trees one month a f t e r inoculation, Dayton (1970) did not detect the peak f o l i a r a c t i v i t y of radiostrontium (an analog of Ca) i n l o b l o l l y pines (Pinus taeda L.) until 13 months after inoculation.  Figure 9. Changes in activity of Sr in twigs and needles of inoculated hemlock trees (mean of 3 trees).  Figure 10. Changes in activity of Cs in twigs and needles of inoculated hemlock trees (mean of 3 trees).  67 QC  The highest  Sr a c t i v i t y in the twigs was observed in July 1 OA  pc  1972.  There were decreases in  and twig samples i n May  Sr (and  Cs) a c t i v i t i e s of the foliage  1972 from the values obtained in April  1972.  These may be attributed to heavy leaching of the radionuclides from the crowns by the high r a i n f a l l in May of 1972, or as Kimmins (1972) suggested, to the d i l u t i o n e f f e c t of shoot and needle expansion. Kimmins 134 (1970) also found that greater quantities of Cs accrued in twigs than in the needles of red pine due, probably, to the greater s u s c e p t i b i l i t y of leaves to leaching.  While the samples of August 1971  and July  1972  85 had more  Sr i n the twigs than in the leaves, the opposite was  the other sampling periods (January 28-Apri<l> 18, 1972).  true for  I t would appear  pc  that  Sr moves from the twigs to the needles during the f i r s t part of  the growing season and with the loss of the older needles and possibly through leaching, the a c t i v i t y of the foliage drops. 134 85 5.5.2.  The removal of  throughfall p r e c i p i t a t i o n .  Cs and  Sr from.the tree crowns in  The data for the removal of the radioisotopes  in throughfall from the time of inoculation to the end of November 1971 are presented graphically in Figures 11 and 12. During this period about 134 85 0.6% of Cs and 0.025% of Sr used f o r the inoculation were removed to the forest f l o o r by f o l i a r leaching. These figures are lower than 134 those reported by Witherspoon (1964) and Kimmins (1970) for Cs, and 89 that by Dayton (1970) for  Sr.  The lower values of the present study  may be due to differences in duration of sampling or may be an evidence for resistance to leaching by trees in areas of high r a i n f a l l  since  the r a i n f a l l i n the study area i s higher than those areas of Witherspoon (1964), Kimmins (1970) and Dayton (1970).  Figure 11.  Distribution patterns of Sr i n throughfall under inoculated hemlock tree canopy.  Figure 12.  Distribution patterns of Cs i n throughfall under inoculated hemlock tree canopy.  Figure 13.  Patterns of throughfall water d i s t r i b u t i o n under hemlock tree canopy.  69 OC  5.5.3.  The pattern of throughfall input of  "I  Sr and pc  to the forest f l o o r .  The d i s t r i b u t i o n o f throughfall  collected i n r e l a t i o n to distances pc  Figures 11 and 12. Both  OA Cs  "i 04 Sr and  Cs  from the tree stem i s presented i n "I  Sr and  nuclide a c t i v i t i e s increased  Cs show the same pattern.  The radio-  from about 0.25m from the stem to a peak  at about 0.05m and then dropped with further distance from the stem. The depressions i n the curves at 1.25m are due to the r e l a t i v e l y open nature of the crown above the sample location f o r this distance.  The  mean throughfall volumes collected a t the sampling spots are presented in Figure 13. In general,  the throughfall volumes increase with  away from the stem, although the small considerable  distance  number of samples results i n  variance.  The pattern of throughfall nutrient d i s t r i b u t i o n was further investigated i n August 1972 by c o l l e c t i n g throughfall water a t equal intervals along two radii out from the stem under a 50-year old hemlock tree, s i m i l a r i n crown form to the l a b e l l e d trees.  The throughfall water  samples were analysed f o r Ca, K, Na and Mg by means of atomic absorption spectrophotometry. The results of these analyses given i n Table 13 and Figures  14 to 16 show that the s p a t i a l d i s t r i b u t i o n of each of the elements 85  was s i m i l a r to that of  134 Sr and  Cs, and that the pH, conductivity and  throughfall volume increased with distance from the stem. The spatial pattern of the throughfall nutrients observed i n this study i s s i m i l a r to that reported elements i n surface mineral s o i l .  by Zinke (1962) f o r chemical  These results are consistent with  the throughfall d i s t r i b u t i o n inferred from s o i l  moisture data by Voigt(1960b).  TABLE 12 Volumes and chemical properties of throughfall water (under a single western hemlock tree) with respect to distance from the tree stem. Na Distance from the tree stem (m)  K  Mg  ppm  total mg  ppm  total mg  ppm  1075  3.08  0.30  42.0  4.12  5.90  0.58  27.8  2.72  4.0  584  1.65  0.45  17.0  4.59  2.50  0.68  11.8  3.19  365  4.2  360  0.96  0.35  8.2  2.99  1.26  0.46  4.7  1.72  2.5  360  4.7  236  0.64  0.23  8.6  3.10  1.29  0.46  4.0  1.44  3.0  440  5.7  133  0.36  0.16  5.6  2.46  1.06  0.46  2.1  0.92  3.5  520  5.6  107  0.32  0.17  3.4  1.77  0.78  0.41  1.6  0.83  pH  0.5  98  4.1  1.5  270  2.0  :  Ca : total mg  Volume (ml)-  Conductivity, mmho/cm (25°C) .  ppm  total mg  Figure 14.  Patterns of K and Ca d i s t r i b u t i o n under hemlock tree canopy.  Figure 15.  Throughfall water d i s t r i b u t i o n under hemlock tree canopy.  Figure 16.  Changes of pH in throughfall water of hemlock tree canopy.  71  Distance from  tree  stem(m)  2 | 60*3} ou  8. 4) 400J  E  o >  |20QJ 3 O  1  1 Disiance  2 from tree  3 stem(m)  72 Zinke (1962) attributed the pattern mainly to the differences between the e f f e c t s of bark l i t t e r and the absence of l i t t e r in the opening between trees.  According to Zinke (1962), the bark l i t t e r i s usually  very acid, low in bases, nitrogen with l e a f l i t t e r . in pH,  and carbon, while the opposite i s true  As a r e s u l t , the s o i l close to the tree stem i s lower  lower in bases and nitrogen  than the s o i l  under l e a f l i t t e r farther  away from the stem, while in adjacent openings, without l e a f l i t t e r , soil  i s lower in exchangeable bases and nitrogen.  Gersper (1970) and  the  Gersper et al_. (1967),  Gersper and Holowaychuk (1971), however, related  the  differences in pattern of f a l l o u t radionuclide d i s t r i b u t i o n under single trees to the magnitude of the stemflow.  Only throughfall d i s t r i b u t i o n  patterns were investigated in the present study, but the s i m i l a r i t y of the results to the published work on s o i l  properties  indicates some  important influence of throughfall on s o i l s under the canopy of trees.  A further explanation  i s therefore needed for the v a r i a b i l i t y  of nutrients on the forest f l o o r .  For any  given rainstorm, the concen-  tration of throughfall w i l l be a function of the biomass of branches and foliage contacted by the descending water.  The structure of the  crowns of the trees used to obtain the data in Table 12, and 12 and 14 was  Figures  such that the v e r t i c a l column of crown biomass decreased  towards the crown edge.  However, r e d i s t r i b u t i o n of throughfall to stemflow  and canopy-edge drip resulted in a very low throughfall volume at (Table 12 and  11,  Figure 15) from the stem.  The combination of the two  0.5m patterns  of volume and concentration  resulted in the observed patterns  throughfall chemistry.  low pH close to the stem indicates the higher  The  a c i d i t y of the bark tissues of the larger branches.  of total  73 5.5.4.  Nutrient d i s t r i b u t i o n on the forest f l o o r .  The return  of nutrients from the aerial portions of trees to the forest f l o o r i n fluences the chemical properties of s o i l s .  The v a r i a b i l i t y o f chemical  properties may be attributed to factors such as the throughfall quantity, throughfall chemical composition, and d i s t r i b u t i o n patterns of crown washings and l i t t e r , as well as the rate of s o i l 1964)  leaching.  Tamm (1953,  observed that the annual y i e l d of Hylocomium as well as the nutrient  concentration  in the l i v i n g moss vary inversely with l i g h t i n t e n s i t y  under the tree canopy, and that outside the canopy, the moss y i e l d decreases  regularly with distance until the moss i s replaced by other  species.  I t may be inferred from these findings that the growth of  these mosses (and probably other ground f l o r a ) depends on the tree canopy and that the productivity of these plants i s proportional to the amounts of nutrients released by the crown;  In the present study, the radionuclide a c t i v i t i e s i n the mosses growing under the inoculated trees followed the patterns of the nutrient input to the f o r e s t f l o o r , so that mosses which were growing i n areas receiving the greatest input of radionuclides contained nuclide concentrations of radionuclides.  greater radio-  than those growing i n areas receiving lesser inputs  I t was therefore not possible i n this study to d i f f e r e n -  t i a t e the r e l a t i v e interception a b i l i t i e s of the d i f f e r e n t species of moss.  Such comparisons could only be made by spraying the various  of mosses with equivalent amounts of radionuclides.  We may suppose,  however, that since mosses are said to depend on nutrients leached the crown canopy (Tamm 1953, 1964), the observed  species  Cs and  from  Sr a c t i v i t i e s  74  of the mosses r e l a t i v e to the total isotope inputs indicate t h e i r nutrient requirements or t h e i r dependence on crown leachates.  H_. splendens and  L. menziesii which were growing close to the stems of the inoculated hemlock trees were found to e x h i b i t high  activities.  TABLE 13 . pc  1 on  D i f f e r e n t i a l leaching of Sr and Cs in the forest f l o o r (based on 8 single samples for each layer) 8 5  Sr/  1 3 4  Cs  and  Layers  1:1  (data corrected to equal 134cs  Soil core without moss  Moss  .54  LF  .86  1.20  H  .55  1.97  2.23  3.63  5.5.5.  floor.  8 5  Sr/  in Table 1 3 .  1 3 4  Sr  inoculation)  Soil core with moss  Mineral s o i l (top 3 cm)  8 5  D i f f e r e n t i a l leaching of  Cs and  Sr i n the forest  C s ratios i n the f o r e s t f l o o r components are  presented  The increase of the ratios from the top layers to the 85  mineral  s o i l layer indicates that 1 ^4  deeper layers than (1970).  Cs.  Sr leaches more rapidly into the  This i s s i m i l a r to what was  reported by Jordan  CHAPTER 6 CONCLUSIONS The  findings of this study (in relation to the main objectives)  are that: 137 1.  Cs f a l l o u t deposition in mosses i s related to the mean annual 137  r a i n f a l l and that  Cs concentration  d i f f e r s from species to species.  Of the ground-dwelling mosses studied, Plagiothecium squarrosum showed the highest a c t i v i t y l e v e l s .  undulatum and Sphagnum  Since epiphytes are better  interceptors of air-borne materials than ground-dwelling plants, i t i s suggested that studies be made with epiphytic mosses (such as Neckera douglasii and Isothecium stoloniferum) to find the best i n d i c a t o r of 137 f a l l o u t materials.  The a c t i v i t y of  Cs in the mosses show that mosses  can obtain nutrients from the a i r . 2. The amount of nutrients removed from the crown to the f o r e s t f l o o r increases outwards from the stem to a peak value a short distance out from the stem and  then drops s t e a d i l y towards the crown edge.  As a r e s u l t , 134  ground-dwelling mosses close to the stem were found to have higher  Cs  85 and Sr a c t i v i t i e s than at any other point beneath the crown. The mosses (eg. hL splendens and J^. menziesii) which were found to accumulate the 134 85 greatest quantities of leachates  Cs and  Sr may  be assumed to depend on crown  as t h e i r major source of nutrients. 75  76 3. Epiphytic mosses may obtain t h e i r nutrients from the stem tissues (of the host) or from the enriched  rainwater from the overstorey  It was found that about 70% of the nutrients from the overstorey  crowns. canopy  could be f i l t e r e d by the epiphytic mosses and that these epiphytes showed 85 a preferential absorption  of  134 Sr over  Cs.  Nutrients were found to  be leached from green stem tissues, thus contributing to the stemflow chemical load and absorbed by the epiphytic mosses growing on the stem. 4. Though the contribution of substrates  to the n u t r i t i o n of ground-  dwelling mosses was not investigated, i t i s speculated (such as humus) may provide nutrients to such mosses.  that the substrates  REFERENCES  Aarkrog, A. 1969. On the d i r e c t contamination of rye, barley, wheat and oats with 85s r , 134cs, 54Mn and 134ce. Radiation Bot. 9:357366. Aberg, B. and F. P. Hungate (eds.). 1966. Radioecological concentration processes. Proc. o f Inter. Symp. Stockholm. Pergamon Press, London  (1967).  Alexahin, R. M. and M. M. Ravikovich. 1966. On behaviour o f a l k a l i n e earth elements - calcium, magnesium and strontium - i n a forest biogeocoenosis (ecosystem). Iri.: B. Aberg and F. P. Hungate (eds.), Radioecological concentration processes. Proc. Intern. Symp. Stockholm. Pergamon Press, London (1967). Aleksakhin, R. M., F. A. Tikhomirov and N. V. Kulikov. 1970. Status and problems of forest radioecology. (Trans1.) Ekologiya 1:27-38. Amplett, C. B. and L. A. McDonald. 1956. Equilibrium studies on natural ion-exchange minerals. I. Cesium and strontium. J_. Inorganic Chem. 2:403-414. Auerbach, S. I., J . S. Olson and H. D. Waller. 1964. Landscape investigations using caesium-137. Nature (London) 201(4921):761-764. Balcar, J . , A. Brezinova-Doskarova and J . Eder. 1969. Dependence of radiostrontium uptake by pea and lupin on the content of calcium in the nutrient solution. Biologia Plantarum (Praha) 11(1):34-40. Barber, D. A. 1964. Influence of s o i l organic matter on the entry o f caesium-137 into plants. Nature 204:1326-1327. Bartholomew, W.V., J . Meyer and H. Landelout. 1953. Mineral Nutrient immobilization under forest and grass fallow i n the Yangambi (Belgian Congo) Region. Pub!. Inst. Nat. Etude Agron. Congo Beige Ser. S c i . , No. 57. B e l l , P. R. 1959. The a b i l i t y of Sphagnum to absorb cations preferent i a l l y from d i l u t e solutions resembling natural waters. J_. Ecol.  47:351-55.  B e l l , C. W. and 0. Biddulph. 1963. Translocation of calcium. versus mass flow. Plant Physiol. 38:610-14.  77  Exchange  78 Benzing, D. H. and A. Renfrow.  1971.  Amer. Jour. Bot. 58(9):867-873.  Biddulph, 0., F. S. Nakayama and R. Cory. 1961. Transpiration stream and ascension of calcium. Plant Physiol. 36:429-36. Bovard, P. and A. Grauby. 1966. The f i x a t i o n of radionuclides from atmospheric f a l l o u t in peat-bog Sphagnum sp., Polytrichum, and Myriophyllum. In: B. Aberg and F. P. Hungate (eds.), Radioecological concentration processes. Proc. Intern. Symp. Stockholm. Pergamon Press, London (1967). Brodo, I. M. 1961. Transplant experiments with corticolous lichens using a new technique. Ecol• 42:838-41. Bukovac, M. J. and S. H. Wittwer. 1957. Absorption applied nutrients. Plant Physiol. 32:428-435.  and mobility of f o l i a r  C a r l i s l e , A. 1965. Carbohydrates in the p r e c i p i t a t i o n beneath a s e s s i l e oak Quercus petraea (Mattushka) L i e b l . canopy. Plant Soil 22:399. , A.H.F. Brown and E. J . White. 1967. The nutrient content of tree stem flow and ground f l o r a l i t t e r and leachates in a s e s s i l e oak (Quercus petraea) woodland. J_. Ecol. 55:615-627. Chadwick, R. S. and A. C. Chamberlain. 1970. F i e l d loss of radionuclides from grass. Atmospheric Environment 4:51-56. Chamberlain, A. C. 1970. Interception and retention of radioactive aerosols by vegetation. Atmospheric Environment 4:57-78. Cole, D. W. and S. P. Gessel. 1968. Cedar River research - A program for studying pathways, rates, and processes of elemental cycling in a f o r e s t ecosystem. Forest Resources Monograph Contribution No. 4. Univ. Washington, Seattle, 54 pp. , and S. F. Dice. 1967. Distribution and cycling of nitrogen, phosphorus, potassium, and calcium in a second-growth Douglas-fir ecosystem. Jjni^: H. E. Young (ed.), Symposium on primary productivity and mineral c y c l i n q in natural ecosystems. "New York City. ______ and E. E. Held. 1961. Tension lysimeter studies of ion and moisture movement in g l a c i a l t i l l and coral attol s o i l s . Soil S c i . Soc. Am. Proc., 25:321-325. Collander, R. 1941. Selective absorption of cations by higher plants. Plant Physiol. 16:691 -720. Comar, C. L., S. R. Scott and R. H. Wasserman. 1957. movement from s o i l to man. Science 126:485-495.  Strontium-calcium  79 Comar, C. L. and F. W. Langemann. 1966. General principles of the d i s t r i bution and movement of a r t i f i c i a l f a l l o u t through the biosphere to man. ITK B. Aberg and F. P. Hungate (eds.), Radioecological concentration processes. Proc. of Intern. Symp. Stockholm. Pergamon Press, London (1967). Craighead, F. C. 1963. Orchids and other a i r plants of the Everglades National Park. Univ. of Miami Press, Coral Gables, Florida. Davis, J . J . 1963. Cesium and i t s relationships to potassium in ecology. In: P. L. Schultz and F. B. Klement (eds.), Radioecology. Reinhold Publ. Corp., New York. Dayton, B. R. 1970. Slow accumulation and transfer of radiostrontiurn by young l o b l o l l y pines (Pinus taeda L.). Ecology 51:204-216.  1^4 Dodd, J . D. and G. L. Van Amburg. 1970. Distribution of Cs ° in Andropogon scoparius Michx. clones in two native habitats. Ecology 51: 685-689. Duvigneaud, P. and S. Denaeyer-DeSmet. 1967. Biomass, productivity and mineral cycling in deciduous mixed forests in Belgium. J_n: H. E. Young (ed.), -Symposiurn on primary producti vity and mineral cycling in natural ecosystems. New York City. and . 1970. Biological Cycling of Minerals in Temperate Deciduous Forests. I_n: D. E. Reichle (ed.), Analysis of Temperate Forest Ecosystems - Ecological Studies, Vol. 1_~ N.Y. x i i + 304 pp. Egunjobi, J . K. 1971. Ecosystem processes i n a stand of Ulex europaeus L. II. The cycling of chemical elements in the ecosystem. J. Ecol. 59: 669-678. Elder, R. L. and W. Moore, J r . 1965. Comparison of cesium-137 binding c h a r a c t e r i s t i c s in pangola hay and Spanish moss. Radiol. Health Data 6(10) :586-589. Evans, E. J . 1958. Chemical investigations of the movement of f i s s i o n products in s o i l . Atomic Energy of Canada Limited, Chalk River Project Research and Development, Chalk River, Ontario CRER-792. 24 pp. and A. J . Dekker. 1966. Fixation and release of Cs-137 in s o i l s and s o i l separates. Can. J_. Soil S c i . 46:217-222. Eyre, S. R. 1968. Vegetation and S o i l s (2nd ed.). Chicago, xvi + 328 pp.  Aldine Publ. Co.,  Forman, R.T.T. 1969. Comparison of coverage, biomass and energy as measures of standing crop of bryophytes in various ecosystems. B u l l . Torr. Bot. Club. 96:582-591.  80 Fowler, E. B. and C. W. Christensen. 1959. Effect of s o i l nutrients on plant uptake o f f a l l o u t . Science 130:1689-1693. Franklin, R. E., P. L. Gersper and N. Holowaychuk. 1967. Analysis of gamma-ray spectra from s o i l s and plants: I I . E f f e c t of trees on the d i s t r i b u t i o n of f a l l o u t . Soil S c i . Soc. Proc. 31:43-45. Fraser, D. A. 1958. The translocation of rubidium and calcium in trees. Jj^. K. V. Thimann: The physiology of f o r e s t trees. Ronald Press Co., N.Y., pp. 19-37. , and E. E. Gaertner. 1966. U t i l i z a t i o n of radioisotopes i n forestry research. JJX? Sexto Congreso Forestal Mundial. Madrid. Frederikson, L., B. Eriksson, B. Rasmuson, B. Gahne, K. Edvardson and K. Low. 1958. Studies on soil-plant-animal i n t e r r e l a t i o n s h i p s with respect to f i s s i o n products. Irr. Proc. U.N. Intern. Conf. Peaceful Uses Atomic Energy P/177:470. Geneva. Gersper, P. L. 1970. Effects of American beech trees on the gamma radioa c t i v i t y of s o i l s . Soil S c i . Soc. Amer. Proc. 34:318-323. and N. Holowaychuk. canopy trees on chemical  1971. Some effects of stem flow from forest properties of s o i l s . Ecology 52:691-702.  Gessel, S. P. and D. W. Cole. 1965. Influence of removal of f o r e s t cover on movement of water and associated elements through s o i l . J_. Am. Water Works Assoc., 57:1301-1310. , R. B. Walker and P. G. Haddock. 1951. Preliminary report on mineral d e f i c i e n c i e s i n Douglas-fir and Western Red Cedar. Soil S c i . Soc. Am. Proc. 15:364-369. '  and . 1956. Height growth response of Douglas-fir to nitrogen f e r t i l i s e r . Soi1 S c i . Soc. Am. Proc. 20:97-100.  Gorham, E. 1959. A comparison of lower and higher plants as accumulators of radioactive f a l l - o u t . Can. J . Bot. 37:327-329. . 1963. A comparison of natural and f a l l o u t r a d i o a c t i v i t y in Ontario s o i l s under pine. Can. J . Bot. 41:1309-1318. Greenfield, S. M. 1957. Rain scavenging of radioactive p a r t i c u l a t e matter from the atmosphere. J . Met. 14:115-125. Greenland,.D. J . and M. Kowal. 1960. forest. Plant S o i l . 12:154-174.  Nutrient content of moist tropical  , and P. H. Nye. 1964. Organic matter and nutrient cycles under moist tropical forests. In: Proc. 10th Intern. Bot. Congr. Edinburgh Univ. Press, Edinburgh.  81 Grubb, P. J.,,0. P. F l i n t and S. C. Gregory. 1968. Preliminary observations on the mineral n u t r i t i o n of epiphytic mosses. Trans. B r i t . Bryol. Soc. 5_: 802-817. Gulyakin, I. V. and E. V. Yudintseva. 1958. Uptake of strontium, caesium and some other f i s s i o n products by plants and t h e i r accumulation i n crops. I_n: Proc. 2nd Intern. Conf. Peaceful Uses Atomic Energy. United Nations, Geneva, 18;475-485. pr  Handley, R. and K. L. Babcock. 1970. ^'Cs-and R u in woody plants.  Translocation of c a r r i e r - f r e e Radiot. Bot. 10:577-583.  1 0 6  Sr,  and R. Overstreet. 1 9 6 1 . E f f e c t of various cations upon absorption of c a r r i e r - f r e e cesium. Plant Physiol. 3 6 : 6 6 - 6 9 . and reticulata.  . 1 9 6 8 . Uptake of c a r r i e r - f r e e Plant Physiol. 4 3 : 1 4 0 1 - 1 4 0 5 .  137  Cs by Ramalina  _, R. K. Schulz, H. Marschner, R. Overstreet and W. M. Longhurst. 1 9 6 7 . Translocation of c a r r i e r - f r e e 8 5 s r applied to the foliage of wwoddy plants. Radiot. Bot. 7_:9]-95. Hanson, W. C. 1966. Radioecological concentration processes characterizing A r c t i c ecosystems. In: B. Aberg and F. P. Hungate (eds.), Radioecological concentration processes. Proc. of Inter. Symp. Stockholm. Pergamon Press, London (1967). Heilman, P. E. and S. P. Gessel. 1963. Nitrogen requirements and the b i o l o g i c a l cycling of nitrogen in Douglas-fir stands in relationship to the effects of nitrogen f e r t i l i z a t i o n . Plant Soil 8(3):386-402. Helvey, J . D. and J . H. P a t r i c . 1965. Canopy and l i t t e r interception of r a i n f a l l by hardwoods of eastern United States. Water Resources Res. 1:193-206. H i l l s , G. A. 1960. The Total S i t e C l a s s i f i c a t i o n of Forest Productivity. Research Branch Paper. Ontario Dept. of Lands and Forests. 61 pp. Holttum, R. E. 1964. A Revised Flora of Malaya, I. ment Printing Office. Jenny, H. 1941. 281 pp.  Factors of s o i l formation. 85  Singapore:  McGraw H i l l , N.Y.,  Governxii +  134  Jordan, C. F. 1970. Movement of Sr and Cs by s o i l water of a tropical rain forest. In_: H. T. Odum (ed.), A Tropical Rain Forest. USAEC. Juo, A.S.R. and S. A. Barber. Soil Science 108:89-94.  1969.  Reaction of Sr with humic acid.  and . 1970. The retention of strontium by s o i l s as influenced by pH, organic matter and saturation cations. Soil Science 109:143-148.  i  82  Keser, N. 1 9 6 0 . A study o f s o i l s as related to s i t e index of Douglas f i r at Haney, B r i t i s h Columbia. MF t h e s i s , Univ. of B r i t . Col. Kimmins, 07 P. 1 9 7 0 . C y c l i c fluctuations i n herbivore populations i n northern ecosystems. A general hypothesis. Ph.D. t h e s i s , Yale University. . 1 9 7 2 . The r e l a t i v e contribution of leaching, l i t t e r f a l l , and d e f o l i a t i o n by Neodiprion s e r t i f e r (Geoffr.) (Hymenoptera: Diprionidae) to the removal of cesium-134 from 15-year-old red pine trees (Pinus resinosa Ait.) Oikos 2 3 : 2 2 6 - 2 3 4 . _. 1 9 7 2 . Sampling throughfall p r e c i p i t a t i o n i n nutrient c y c l i n g studies i n B r i t i s h Columbian coastal f o r e s t s . Unpublished manuscript submitted to Ecology, 1 9 7 2 . Klechkovsky, V. M. and I. V. Gulyakin. 1 9 5 8 . The behavior i n s o i l s and plants of traces of strontium, cesium, ruthenium and zirconium. Soviet S o i l Science 1 9 5 8 ( 3 ) : 2 1 9 - 2 3 0 . and G. N. Tselishcheva. 1 9 5 7 . The behavior o f radioactive f i s s i o n products. In_: V. M. Klechkovsky (ed.), On the behavior o f f i s s i o n product i n s o i 1 , t h e i r absorption by plants and t h e i r accumul a t i o n i n crops. U.S.A.E.C. translation series AEC-tr-2867, pp. 7-102.  Kline, J . R. and H. T. Odum. 1 9 7 0 . Comparisons of the amounts of f a l l o u t radionuclides i n tropical f o r e s t s . In_: H. T. Odum (ed.), A Tropical Rain Forest. U.S.A.E.C. , and J . C. Bugher. 1 9 7 0 . E f f e c t of gamma radiation on leaching o f 1 3 7 c s and 5 4 m from t r o p i c a l forest f o l i a g e and l i t t e r . In: H. T. Odum (ed.), A Tropical Rain Forest. U.S.A.E.C. n  Klinge, H. and W. Ohle. 1 9 6 4 . Chemical properties o f r i v e r s i n the Amazonian area i n r e l a t i o n to s o i l conditions. Verh. i n t . Verein. theor. angew. Limnol 1 5 : 1 0 6 7 - 1 0 7 6 . Klinka, K. 1 9 7 2 . Ecosystematic units and t h e i r d i s t r i b u t i o n i n UBC Research Forest - Preliminary d r a f t . Krajina, V. J . 1 9 6 9 . Ecology o f f o r e s t trees i n B r i t i s h Columbia. In: V. J . Krajina (ed.), Ecology o f Western North America 2 ( 1 ) : 1-147.  Kramer, P. J . and T. T. Kozlowski. H i l l Book Co., N. Y. 642»pp.  1960.  Physiology  of trees.  McGraw-  Krieger, H. L., B. Kahn and S. Cummings. 1 9 6 6 . Deposition and uptake of 9 0 s r and 1 3 7 r j - j established pasture. ITK B. Aberg and F. P. Hungate (eds.), Radioecological Concentration Processes. Proc. Intern. Symp. Stockholm. Pergamon Press, London ( 1 9 6 7 ) . s  a n  n  83 Kwaratskhelia, N. T., G. G. Glonty, T. N. Arnautov and E. K. Gamazova. 1966. The influence of some natural factors on the behaviour of radioactive strontium i n s o i l s . J J K B. Aberg and F. P. Hungate (eds.), Radioecological Concentration Processes. Proc. Intern. Symp. Stockholm. Pergamon Press, London (1967). Levi, E. 1968. The d i s t r i b u t i o n of mineral elements following leaf and root uptake. Physiologia Plantarum 21:213-226. Lockhart, L. B., J r . , R. L. Patterson, J r . , A. W. Saunders, J r . , and R. W. Black. 1964. Atmospheric r a d i o a c t i v i t y along the 80th Meridian (West). In_: A. W. Klement, J r . (ed.), Radioactive Fallout from Nuclear Weapons Tests. Germantown, Md. AEC Symposium Series. No. 5. CONF - 765. Long, W. G., D. V. Sweet and H. B. Tukey. 1956. The loss of nutrients from plant foliage by leaching as indicated by radioisotopes. Science 123:1039-1040. Low,  K. and K. Edvarson. 1959. Cesium-137 i n Swedish milk and s o i l . Nature 183(4668).-1104-1106.  MacArthur,: R. and J . Connell. 1966. Wiley and Sons, Inc., N. Y.  The Biology of Populations.  John  Madgwick, H.A.I, and J . D. Ovington. 1959. The chemical composition of p r e c i p i t a t i o n in adjacent forest and open plots. Forestry 32:14-22. Mecklenburg, R. A., H. B. Tukey, J r . i and J . V. Morgan. 1966. A mechanism for the leaching of calcium from f o l i a g e . Plant Physiol. 41:610-613. Mel i n , E. 1930. Investigations of the significance of tree mycorrhiza: an ecological-physiological study. (Trans!. S t i c k e l , P. W.) U.S.D.A. For. Ser. Northeastern For. Exp. Sta., Amherst, Mass. Menzel, R. G. 1954. Competitive uptake by plants of potassium,, rubidium,. cesium and calcium, strontium, barium from s o i l s . Soil S c i . 77(6): 419-425. Mes, M. G. 1954. Excretion (recretion) of phosphorus and other mineral elements by leaves under the influence of rain. S^. A f r i . J. S c i . 50: 167-172. Middleton, L. J . 1958. Absorption and translocation of strontium and cesium by plants from f o l i a r sprays. Nature 181:1300-1303. . 1959. Radioactive strontium and caesium in the edible parts of crop plants a f t e r f o l i a r contamination. Intern. «J_. Radi at. B i o l . 1:387-402.  84 Miettinen, J . K. 1967. Enrichment of r a d i o a c t i v i t y by A r c t i c ecosystems in Finnish Lapland. Inj D. J . Nelson and F. C. Evans (eds.), Symp. on Radioecology. Proc. 2nd National Symp., Ann Arbor, Michigan. USAEC (1969). Mina, V. N. 1965. Leaching of certain substances by p r e c i p i t a t i o n from woody plants and i t s importance i n the b i o l o g i c a l cycle. Soviet Soil S c i . 6:609-617. Moon, D. E. and J . P. Kimmins. Cs and Rb tracers f o r potassium (using 42K) i n nutrient cycling studies. Unpublished manuscript submitted to Ecology, April 25, 1972. Nishita, H., A. J . Steen and K. H. Larson. 1958. Release of strontium90 and cesium-137 from vina loam upon prolonged cropping. Soil S c i . 86:195-201. Nye, P. H. 1961. Organic matter and nutrient cycles under moist tropical forest. Plant Soil 13:333-346. Odum, H. T. 1970. Rain forest structure and mineral-cycling homeostasis. In: H. T. Odum (ed.), A Tropical Rain Forest: a study o f i r r a " diation and ecology at El Verde, Puerto Rico. U.S. Atomic Energy Commission, pp. H-3-H-52. Olson, J . S. 1965. Equations for cesium transfer i n Liriodendron forest. Health Phys. 11_: 1385-1394. . 1968. Use of tracer techniques f o r the study of biogeochemical cycles. Jj^ F. E. Eckardt (ed.), Functioning of t e r r e s t r i a l ecosysterns at the primary production l e v e l . Proc. o f Copenhagen Symp. UNESCO. and D. A. Crossley. 1963. Tracer studies of the breakdown o f forest l i t t e r . J_n: V. Schultz and A. W. Klement (eds.), Radioecology. Reinhold Publ. Corp. Osburn, W. S., J r . 1967. Accountability of nuclear f a l l o u t deposited in a Colorado High Mountain bog. lrv. D. J . Nelson and F. C. Evans (eds), Symp. on Radioecology.( Proc. 2nd National Symp., Ann Arbor, Michigan. USAEC.  F969T^  Ovington, J . D. 1962. Qualitative ecology and the woodland ecosystem concept. Adv. Ecol. Res. T_: 103-192'. . 1968. Some factors a f f e c t i n g nutrient d i s t r i b u t i o n within ecosystems. In.: F. E. Eckard (ed.), Functioning of t e r r e s t r i a l ecosystems at the primary production l e v e l . Proceedings of the Copenhagen Symposium - Unesco Natural Resources Research \/:95-105.  85 Pavlotskaya, F. I., E. B. Tyuryukariova and V. I. Baranov. 1966. On mobility of strontium and some other components of global f a l l o u t in s o i l s and t h e i r accumulation i n plants. J_n: B. Aberg and F. P. Hungate (eds.), Radioecological concentration processes. Proc. of Inter. Symp. Stockholm. Pergamon Press, London (1967). P e l l e t i e r , C. A., G. H. Whipple and H. L. Wedlick. 1965. Use of surfacea i r concentration and r a i n f a l l measurements to predict deposition of f a l l o u t radionuclides. J_n: A. W. Klement, J r . (ed.), Radioactive Fallout from Nuclear Weapons Tests, Germantown, Md. AEC Symposium Series, No. 5, C0NF-765. Petty, R. 0. and E. 0. Williams, J r . 1965. Rates and pattern of radioisotopes release from fresh tree l i t t e r of three levels of mesic forest development. Wabash C o l l . B i o l . Dep.:. Final Summ. Rep. C001006-4. Wabash, Ind. 97 pp. Polyakov, Yu. A., L. N. Kalishina and L. F. Nazarova. 1966. Distribution of 9^Sr in the s o i l p r o f i l e in the moderately northern latitudes of the U.S.S.R. ITK B. Aberg and F. P. Hungate (eds.), Radioecological Concentration Processes. Proc. Intern. Symp. Stockholm. Pergamon Press, London (1967). Richards, P. W. London.  1952.  The Tropical Rain Forest.  Cambridge Univ. Press,  137 Rickard, W. 1966. Accumulation of Cs i n l i t t e r and understory plants of forest stands from various climatic zones of Washington. In: B. Aberg and F. P. Hungate (eds.), Radioecological Concentration Processes. Proc. of an Intern. Symp. Stockholm. Pergamon Press,  London (1967"T  . 1967. Cesium-137 in Cascade Mountain vegetation - 1966. I_n: D. J . Nelson and F. C. Evans (eds.), Symp. on Radioecology. Proc. 2nd National Symp., Ann. Arbor, Michigan. USAEC (1969). . 1971. 158-1960.  Radiocesium f a l l o u t in the forest f l o o r .  Jour. For. 69:  Riekerk, H. 1967. The movement of phosphorus, potassium, and calcium in a Douglas-fir ecosystem. Ph.D. thesis, Univ. Washington, Seattle. 142 pp. . 1971. The mobility of phosphorus, potassium, and calcium in a forest s o i l . Soil S c i . Soc. Amer. Proc. 35:350-356. and S. P. Gessel. 1965. Mineral cycling in a Douglas-fir forest stand. Health Physics 11:1363-1369.  86 Ritchie, J . C , E.E.C. Clebsch and W. K. Rudolph. 1970. Distribution of f a l l o u t and natural gamma radionuclides i n l i t t e r , humus and surface mineral s o i l layers under natural vegetation i n the Great Smoky Mountains, North Carolina, Tennessee. Health Phys. 18:479-489. Rodin, L. E. and N. I. B a z i l e v i c h . 1967. Production and Mineral Cycling in T e r r e s t r i a l Vegetation. Oliver and Boyd, London, v + 288 pp. Romney, E. M., G. V. Alexander, W. A. Rhoads, K. H. Larson. 1959. Influence of calcium on plant uptake of strontium 90 and stable strontium. S o i l S c i . 87:160-165. , J . W. Neel, H. N i s h i t a , J . H. Olafson and K. H. Larson. 1957. Plant uptake of Sr 90, Y91, Rul06, Gs-137, and Cel44 from s o i l s . S o i l S c i . 83:369-376. Roser, F. X. and T. L. Cullen. 1965. Some aspects of f a l l o u t i n B r a z i l . In: A. W. Klement, J r . (ed.), Radioactive Fallout from Nuclear Weapons Tests. Germantown, Md. AEC Symp. Series, No. 5. C0NF-765. Ruhling, A. and G. Tyler. 1968. An ecological approach to the lead problem. Bot. Notiser 121:321-342. and . h i s t o r i c a l study.  1969. Ecology of heavy metals - a regional and Bot. Notiser 122:248-259.  and _ . 1970. Sorption and retention of heavy metals in the woodland moss Hylocomium splendens (Hedw.) Br. et Sch. Oikos 21:92-97. ;  Russel, R. S. 1966a. In;R. S. Russel: Oxford.  Direct contamination of plants with strontium-90. Radioactivity and Human Diet. Pergamon Press,  . 1966b. Uptake and accumulation of radioactive substances in t e r r e s t r i a l plants - the radiobiological aspect. In_: B. Aberg and F. P. Hungate (eds.), Radioecological Concentration Processes. Proc. of Inter. Symp. Stockholm. Pergamon Press, London (1967). and G. M. Milbourn. 1957. Rate of entry o f radioactive into plants from s o i l . Nature 180:322-324.  strontium  Salo, A. and J . K. Miettinen. 1964. Strontium-90 and cesium-137 i n A r c t i c vegetation during 1961. Nature 201:1177-1179. Sanford, W. W. 1969. The d i s t r i b u t i o n of epiphytic orchids i n Nigeria in r e l a t i o n to each other and to geographic location and climate, type of vegetation and tree species. B i o l . J_. Linn. Soc., j_:247285. Schofield, W. B.  1972.  Personal  communication.  87 Shacklett, H. T. 1965. Element content of Bryophytes. B u l l . 1198-D. U. S. Dept. of Int. 21 pp.  Geo!.  Survey  Shanks, R. E. and H. R. DeSelm. 1963. Factors related to concentration of radiocesium in plants growing on a radioactive waste disposal area. J_n: V. Schultz and A. W. Klement, J r . (eds.), Radi oecol ogy. Reinhold Publ. Corp., N. Y. Schulz, R. K. 1965. 1317-1324.  Soil chemistry of radionuclides.  ,.;R. Overstreet and I. Barshad. 1960. cesium 137. Soil Science 89:16-27. Silverberg, R. N. V.  1967.  Health Phys. 11:  On the s o i l chemistry of  The World of the Rain Forest.  Meredith  Press,  Spikes, J. D. 1963. Radiation effects and peaceful uses of atomic energy in the plant and s o i l sciences. In_: V. Schultz and A. W. Klement (eds.), Radioecology. Reinhold Publ. Corp., N. Y. 137 Squire, H. M. and L. J. Middleton. 1966. Behaviour of Cs in s o i l s and pastures: a long term experiment. Radi at. Bot. 6^:413-423. S t e n l i d , G. 1958. S a l t losses and r e d i s t r i b u t i o n of s a l t s in higher plants. Encycl. Plant Physiol. 4:616-637. Sudia, T. W. and A. J. Linck. 1963. Methods for introducing radionuclides into plants. J_n: V. Schultz and A. W. Klement (eds.), Radi oecol ogy. Reinhold Publ. Corp., N.Y. 137 Svensson, G. K. 1966. The increasing Cs level i n f o r e s t moss in r e l a t i o n to the total 1 C s f a l l o u t from 1961 through 1965. J_n: B. Aberg and F. P. Hungate (eds.), Radioecological concentration processes. Proceedings of an Intern. Symp. Stockholm. Pergamon Press, London (1967). 95 and K. Li den. 1965a. The quantitative accumulation of Zr anr>95|\|b and 140Ba + l L a in carpets of forest moss. A f i e l d study. Health Phys. 11_:1033. 137 and . 1965b. The transport of Cs from lichen to animal and man. Health Phys. 11:1393. 37  4 0  Sviridova, I. K. 1960. Results of a study of the washing p f nitrogen and ash elements from crowns of trees. Dokl. Akad. NaU:k. SSSR 133: 706-708. Tamm, C. 0. 1951. Removal of plant nutrients from tree crowns by rain. Physiol. Plant. 4:184-188.  88 Tamm, C. 0. 1953. Growth, y i e l d and n u t r i t i o n i n carpets of a forest moss (Hylocomium splendens). Medd. Stat. Skogsforskn. 43:1-140. . 1964. Growth of Hylocomium splendens in r e l a t i o n to tree canopy. Bryologist 67:423-426. Thomas, W. A. 1967a. Dye and calcium ascent in dogwood trees. Physiol. 42:1800-1802.  Plant  45 1967b. Cycling of Ca by dogwood trees. J J K D. J. Nelson and F. C. Evans (eds.), Symposium on Radioecology. Proc. 2nd Nat. Symp., Arm Arbor, Michigan. USAEC~Tl969)~! .  Yukey, H. B. and J . V. Morgan. 1962. The occurrence of leaching from above-ground plant parts and the nature of the material leached. In: Proc. 16th. Intern. H o r t i c u l . Congr. Brussels, Belgiurn 4: 146-153. , H. B. Tukey, J r . and S. H. Witter. 1958. Loss of nutrients by f o l i a r leaching as determined by radioisotopes. Proc. Amer. Soc. Hort S c i . 71:496-506. Tukey, H. B., J r . 1966. Leaching of metabolites from above-ground plant parts and i t s implications. Bui 1. Torrey Bot. Club 93:385-401. . 1970a. Leaching of metabolites from foliage and i t s implication in the tropical rain f o r e s t . In_: H. T. Odum (ed.), A Tropical Rain Forest. USAEC. . 1970b. The leaching of substances from plants. Plant Physiol. 21_:305-321.  Annual  Rev.  , R. A. Mecklenburg and J . V. Morgan. 1965. A mechanism for the Teaching of metabolites from f o l i a g e . In_:- Isotopes and radi-ation in s o i l - p i a n t n u t r i t i o n studies. IAEA, Vienna, pp. 371-385. and J . V. Morgan. 1963. Injury to foliage and i t s e f f e c t upon the leaching of nutrients from above ground plant parts. Physiol. Plant., 16.:557-564. and H. B. Tukey. 1959. Nutrient loss from above-ground parts by leaching. Atompraxis 5:213-218. and . 1962. The loss or organic and inorganic materials by leaching from leaves and other above-ground plant parts. In: Radioisotopes in s o i l - p l a n t n u t r i t i o n studies. Intern. Atomic Energy Agency. Vienna. Tyuryukanova, E. B., F. I. Pavlotskaya and V. I. Baranov. 1966. Pecul i a r i t i e s of radiostrontium d i s t r i b u t i o n in some landscapes of the southern taiga. In_: B. Aberg and F. P. Hungate (eds.), Radioecological concentration processes. Proc. Intern. Symp. Stockholm. Pergamon Press, London (1967).  89 van der Westhuizen, M. 1969. Radioactive nuclear bomb f a l l o u t - A r e l a t i o n ship between deposition, a i r concentration and r a i n f a l l . A tin. Environ. 3:241-248. Voigt, G. K. 1960a. Alteration of the composition of rainwater by trees. Amer. Midland Natur. 63_:321-326. . 1960b. S c i . 6:2-10.  Distribution of r a i n f a l l  under forest stands.  Forest  Walker, R. B., E. E. Held, and S. P. Gessel. 1961. Radiocesium in plants grown in Rongelap A t o l l s o i l s . In: Recent Advances in Botany. Univ. of Toronto Press, Toronto, Ont. Waller, H. D. and J. S. Olson. 1964. Prompt transfer of cesium-137 to the forest f l o o r and s o i l of a tagged t u l i p poplar forest. Health Phys. 10:620-621. and _. 1967. Prompt transfers of cesium-137 to the s o i l s of a tagged Liriodendron forest. Ecology 48:15-25. Walton, A. 1963. The d i s t r i b u t i o n in s o i l s of r a d i o a c t i v i t y from weapon tests. J_. Geophys. Res. 60:1485. Watson, D. G., W. C. Hanson and J . J . Davis. and animals of A r c t i c Alaska. 1959-61.  1964. Strontium-90 i n plants Science 144:1005-1009.  Weetman, G. F. 1967. Nitrogen d e f i c i e n t black spruce on raw humus s o i l s in Northern Quebec - response to thinning and area treatment. 14th. IUFRO Congr., Munich. and V. Timmer. 1967. Feather moss growth and nutrient content under upland black spruce. Pulp and Paper Res. Inst, of Can. Tech. Report 503. W i l l , G. M. 1955. Removal of mineral nutrients from tree crowns by rain. Nature (London) 176:1180. . 1957. Variations in the mineral content of radiata pine needles with age and position in tree crown. New Zealand J. S c i . Techno!. 38 (Sec. B):699-706. . 1959. Nutrient return in l i t t e r and r a i n f a l l under some exotic conifer stands in New Zealand. New Zealand J. Agr. Res. 2_:719-734. Witherspoon, J . P. J r . , 1963. Cycling of cesium-134 in white oak trees on s i t e s of contrasting s o i l type and moisture. I. 1960 growing season. In: V. Schultz and A. W. Klement (eds.), Radioecology. Reinhold Publ. Corp., N. Y.  '  90  Witherspoon, J . P., J r . 1964. Cycling of cesium-134 i n white oak trees. Ecol. Monogr. 34(4):403-420. Witkamp, M. and M. L. Frank. 1964. F i r s t year movement, d i s t r i b u t i o n and a v a i l a b i l i t y of Csl37 i the forest f l o o r under tagged t u l i p poplars. Radiat. Bot. 4:485-495. n  Wojcik, Z. 1970. Primary production of the herb layer and plant f a l l in a dry pine f o r e s t (Cladonio-Pinetum Kobendza 1930) i n the Kampinos National Park. EkologTTToTsTa Vol. XVIII, No. 18. Woods, F. W. 1970. I n t e r s p e c i f i c transfer of inorganic materials by root systems of woody plants. J_. Appl. Ecol. 7_: 481-486. and K. Brock. 1964. I n t e r s p e c i f i c transfer of Ca-45 and P-32 by root systems. Ecology 45:886-889. Zimmermann, M. H.  11:167-90.  1960. Transport  i n phloem.  Ann. Rev. Plant. Physiol.  Zinke, P. J . 1962. The pattern of influence of individual forest trees on s o i l properties. Ecology 43:130-133.  APPENDIX  Figure 17.  Changes i n the a c t i v i t i e s of Sr and Cs i n twigs and needles of individual inoculated hemlock trees on Plots 1,2, and 3. Legend:  Needles  •  Twi gs  B  Tree on Plot #1 = A Tree on Plot #2: " Tree on Plot #3=  c  Tree on Plot #3= °  1600  85Sr  800.  1971  Ai^|7  1972  Jon  28  Sampling  Mar  date  13  Apr  18  

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