Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Use of a series of aerial photographs to estimate growth of trees and standards Wang, Yumin 1965

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1965_A6 W3.pdf [ 12.28MB ]
Metadata
JSON: 831-1.0104969.json
JSON-LD: 831-1.0104969-ld.json
RDF/XML (Pretty): 831-1.0104969-rdf.xml
RDF/JSON: 831-1.0104969-rdf.json
Turtle: 831-1.0104969-turtle.txt
N-Triples: 831-1.0104969-rdf-ntriples.txt
Original Record: 831-1.0104969-source.json
Full Text
831-1.0104969-fulltext.txt
Citation
831-1.0104969.ris

Full Text

USE OF A SERIES OF AERIAL PHOTOGRAPHS TO ESTIMATE GROWTH OF TREES AND STANDS  by YU-MIN WANG B.S.F. Taiwan Prov. Chung-Hsing University, China,  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF FORESTRY  i n the Faculty of FORESTRY  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1965  In the  requirements  British  mission  f o r an  Columbia, I  available  for extensive be  cation.of without  my  Department  this  and  by  the  studyr of  the  I  this  Head  permission,*  / - t f t f t r s T/g^r~ Columbia,  fulfilment  of  the U n i v e r s i t y of •  Library shall  make i t  f u r t h e r agree  that  freely per-  thesis for scholarly  o f my  I t i s understood  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a • Date  degree at  thesis for financial  written  of  thesis in partial  that  copying  granted  representatives,.  this  advanced  agree  for reference  p u r p o s e s may his  presenting  Department  that-copying  gain  shall  not  or or  be  by publi-  allowed  ABSTRACT Although the conventional methods o f predicting growth of trees and stands by the measurements o f variables on the ground y i e l d a considerable degree of accuracy, they take a long time and are expensive.  Therefore, prediction o f growth  of trees and stands by the use of a e r i a l photographs as developed herein may be preferable i n some s i t u a t i o n s . A survey was made o f ten series of a e r i a l photographs taken at various times during the year with the use of several kinds o f photography.  One series was omitted because of too  much exaggeration of r e l i e f .  Of the nine s e r i e s , three were  regarded as inadequate f o r growth studies due to poor photo. graphy. Repeated measurements were made f o r 135 sample trees on d i f f e r e n t series of photographs i n terms of t o t a l height and crown width.  The tree images were c l a s s i f i e d as good, medium  and poor according to the v i s i b i l i t y of both top and the base of tree, and the accuracy of height measurements was defined i n terms of standard error of the mean difference from photomeasurements and the ground data.  In addition to the conven-  t i o n a l method o f taking an average of four parallax readings or two i d e n t i c a l readings, the writer set up a checking method  ii by which a high degree o f accuracy was secured.  The standard  e r r o r o f the mean d i f f e r e n c e f o r 95 heights o f good image trees was  't- 6.£5 f e e t .  When the good image trees were c l a s s i f i e d as  c o n i f e r s o r hardwoods, the standard e r r o r s o f the mean d i f f e r ences were - 0.30 f e e t and - 0.41 feet r e s p e c t i v e l y .  Generally  the measurements o f height f o r c o n i f e r s appeared to be more accurate than those f o r hardwood.  There was no c o n s i s t e n t  r e s u l t i n d i c a t i n g which species gives b e t t e r measurements. For height growth e s t i m a t i o n , Height/Age curves were used as a supplement to ground data, and a method o f pooling e r r o r s was a p p l i e d .  The use o f t h i s method f o r determining the  accuracy o f growth p r e d i c t i o n was assumed to be a p p l i c a b l e , and height estimates based on d i r e c t measurements on d i f f e r e n t s e r i e s o f photographs y i e l d e d a considerable  degree o f accuracy,  i f good q u a l i t y photographs were a v a i l a b l e . The accuracy o f crown width measurements was f a i r l y high.  The smallest standard e r r o r o f the mean d i f f e r e n c e was  - 0.21 f e e t f o r 53 Douglas f i r and the l a r g e s t standard e r r o r o f the mean d i f f e r e n c e was ±0.58 f e e t f o r 12 a l d e r s .  For  growth estimates o f crown width, the i n d i r e c t approach o f using Crown width/dbh r a t i o s was used as a s u b s t i t u t e f o r ground control.  I t was concluded that the p r e d i c t i o n o f growth o f  crown width can be made from a s e r i e s o f a e r i a l photographs.  iii The application of t h e o r e t i c a l values as c r i t e r i a i n determining the a c c e p t a b i l i t y of growth estimates of crown width might be practicable because v a r i a t i o n w i l l be reduced by the j o i n t computation of two pairs of observations.  However,  when Crown width/dbh r a t i o s are used as c o n t r o l , there tends to be a great deal of error, p a r t l y because of the use of ratios. Accuracy of growth studies on three d i f f e r e n t groups of plots varies with the composition of stand.  The group of  young natural regeneration plots showed a r e l a t i v e l y high degree of accuracy.  I t was concluded that where the stand  i s comparatively open, growth estimates on the photographs would give a useful degree of accuracy.  iv  ACKNOWLEDGEMENTS The writer wishes to thank Dr. J . H. G. Smith, Professor, and Mr. D. D. Munro, Assistant Professor, o f the Faculty of Forestry f o r t h e i r suggestions,  supervision, supply of a e r i a l  photographs and ground data, and c r i t i c i s m s . The writer also wishes to thank Dr. B. G. G r i f f i t h of the Faculty of Forestry f o r loaning his data on plots and trees, Mr.  J . Walters, Research forester o f the U.B.C. Haney Research  Forest f o r providing the s i t e index map, and Mr. A. Jakoy, graduate student of the Faculty of Forestry for h i s assistance i n c o l l e c t i o n of ground data. Special thanks are given to Mr. J . Hejjas, graduate student of the Faculty o f Forestry f o r h i s help i n programming, and s t a f f members of the electronic computing center a t the University o f B r i t i s h Columbia f o r t h e i r guidance and correction. The accomplishment of this thesis should be p a r t i a l l y attributed to my wife, Regina, her parents Dr. and Mrs. C.K. Yeh as well as a l l my s i s t e r s for their ceaseless encouragement through correspondence during the past two years.  V EXPERIENCE AND VISUAL ACUITY OF THE WRITER AS AN INTERPRETER A e r i a l photogrammetry i n f o r e s t r y was introduced i n Taiwan (Formosa) i n 1952 by f i v e s p e c i a l i s t s from the Forest S e r v i c e o f the U.S.  Department of A g r i c u l t u r e .  Having received h i s B.S.F. degree from Taiwan P r o v i n c i a l Chung-Hsing U n i v e r s i t y (College of A g r i c u l t u r e ) Department of F o r e s t r y , the w r i t e r spent one year i n the Reserve O f f i c e r ' s T r a i n i n g Corps and there he received a s h o r t period o f t r a i n i n g i n using a e r i a l photographs f o r m i l i t a r y reconnaissance.  In  1956, he was o f f e r e d a p o s i t i o n i n Taiwan P r o v i n c i a l A g r i c u l t u r a l and F o r e s t r y A e r i a l Survey Team.  U n t i l 1962, he p a r t i -  c i p a t e d i n a e r i a l mapping, data processing and f i e l d work concerned with f o r e s t management planning, and surveys o f f l o o d damage, marginal land u t i l i z a t i o n , sea-coast c o n t r o l and windbreaks . I n the f a l l of 1962, he s t a r t e d h i s post graduate work a t U.B.C. under the i n s t r u c t i o n of Dr. J.H.G. Smith and D.D.  Munro,  a c u i t y was  Mr.  As a p h o t o - i n t e r p r e t e r , h i s stereoscopic v i s u a l 100 percent by Moessner's t e s t and was regarded as  eminently s a t i s f a c t o r y f o r undertaking p h o t o - i n t e r p r e t a t i v e studies.  vi TABLE OF CONTENTS -•  PAGE  Abstract . . . . . . Acknowledgements . .  i . . . . . . . . . . .  iv  Experience and V i s u a l A c u i t y o f the W r i t e r as an I n t e r p r e t e r . . . . . . . . . . . . . . . . . . . .  v  Table o f Contents L i s t o f Tables . . . . . . . . . . . . . .  vi • . ix  INTRODUCTION  1  SURVEY OF LITERATURE  3  OBJECTIVES  5  HISTORICAL BACKGROUND OF AREA STUDIED. . . . . . . . . .  6  DESCRIPTION OF FIELD DATA. . . . . . . . . . . . . . . .  8  Observations f o r i n d i v i d u a l trees  8  Observations f o r i n d i v i d u a l p l o t s  10  L o c a t i o n o f trees and p l o t s .  . 13  time and date o f data c o l l e c t i o n  . 14.  SPECIFICATIONS OF AERIAL PHOTOGRAPHS  16  MEASUREMENTS OF PHOTO VARIABLES. . . . . . . . . . . . .  19  Accuracy o f measurements  ....  19  1.  Tree height  19  2.  Determination o f photo h e i g h t .  28  3.  Crown width.  32  4.  Determination o f photo crown width . . . . . . .  40  5.  Crown c l o s u r e . . . . . . . . . . .  6.  Determination o f photo crown c l o s u r e  . • 41 45  Factors which i n f l u e n c e accuracy o f measurements o f trees and stands  46  1.  Scale.  46  2.  P o s i t i o n o f o b j e c t s on the photos. . . . . . . .  47  vii PAGE 3.  Technique o f photo i n t e r p r e t e r  . . 47  4.  Shape.  49  5.  Tone  50  6.  Texture. . . . . . . . . . .  7.  Shadow . . . . . . . . . . . . .  8.  Equipment f o r p h o t o - i n t e r p r e t a t i o n . • . . • . 5 1  o . . . . . . . . 51 51  PROCEDURES IN PREDICTION OF GROWTH . . . . . . . . . . . . . 52 I n d i v i d u a l Trees . . . . . . . . . . . . . . . . .  . 52  1.  Definition of s i t e quality  53  2.  Y i e l d tables as c r i t e r i a o f growth estimates . 54  3.  Height/Age curves (H/A curves)  4.  Determination o f age  5.  P r e d i c t i o n o f t h e o r e t i c a l height growth. . . . 5 6  6.  R e l a t i o n s h i p s among CW, dbh and h e i g h t . . .... 57  7.  Photo values and curved values . . . . . . . . 59  . 54  Stands  55  59  1.  Compilation height . . . . . . . . . . . . . . . 60  2.  Crown width. . . . . . . . . . . . .  63  3.  Crown c l o s u r e . . . . . . . . . . . . . . . . .  64  4.  Number o f t r e e s . . . . . . . . . . . . . . . .  64  ANALYSES OF DATA  .67  I n d i v i d u a l trees  67  D e f i n i t i o n s o f symbols  .70  Accuracy o f height measurements on the photos. . . . 71 Comparisons o f photo-freights and curved h e i g h t s . . , 77 Region o f acceptance  . . . . . .  83  viii PAGE Accuracy o f growth estimates on height . . . . . . .  88  Accuracy o f crown width measurements on the photos • 95 Accuracy o f growth estimates on crown width. . . . . Stands  98 103  Accuracy o f measurements o f stand v a r i a b l e s . . . . . 104 1.  Compilation height . . . . . . . . . . . . . .  104  2.  Average crown width. . . . . . . . .  107  3.  Crown c l o s u r e . . . . . . . . . . . . . . . . .  109  Accuracy o f growth estimates f o r stands. . . . . . . 110 1.  Compilation height growth. . . . . . . . . . .  110  2.  Average crown width growth • • • • • • • • • •  111  3.  Crown c l o s u r e growth . . . . . . . . . . . . .  112  SUMMARY OF RESULTS CONCLUSION  . . . . . . . . . . . . . . . . . . . . . . . . .  113 .116  BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . .  120  APPENDICES . . . . . . . . . . . . . . . . . . . . . .  131  I. II. III.  L o c a t i o n o f Trees and P l o t s . . . . . . . . . . .  131  Basic ground Data f o r Trees and P l o t s . . . . . . 134 Procedures i n P r e d i c t i o n o f T h e o r e t i c a l Crown Width Growth (Example o f P.S.P.'s) . . . . . . 142  IV.  Average Height, CW, and CC f o r P l o t s Measured on the Photos. . . . . . . . . . . . . . . . .  143  ix LIST OF TABLES TABLE  PAGE  1.  P h y s i c a l c h a r a c t e r i s t i c s and stand data f o r f i v e G r i f f i t h study p l o t s , from G r i f f i t h (1960) Tables 11, 12 and 17 . . . . . . . . . . . . . . 11  2.  Summary o f 1958 ground data f o r f i v e 0.2-acre p l o t s a f t e r t h i n n i n g , from Lee (1959). . . . . .  12  3.  Composition o f f i v e n a t u r a l regeneration p l o t s i n May 1964  13  4.  S p e c i f i c a t i o n s o f a e r i a l photographs used f o r growth studies . . . . . . . . . . . . . . . . . .  17  5.  Number o f trees measured on the ground by species and year ..... 68  6.  Number o f trees measured and image q u a l i t y by species and year o f photographs (Height o n l y ) . . 69  7.  Image q u a l i t y expressed i n percentage f o r trees measured by species and year (Height o n l y ) . . .  69  8.  Accuracy o f height measurements f o r a l l species by q u a l i t y o f images . . . . . . . .  72  9.  Accuracy conifers Accuracy conifers  10*  o f heightmmeasurements f o r good image and hardwoods . . . . . . . . . . . . . o f height measurements f o r medium image and hardwoods . . . . . . . .  73 74  11.  Accuracy o f height measurements f o r good to medium image c o n i f e r s and hardwoods. . . . . . .  75  12.  Accuracy o f height measurements f o r good to medium trees by species.  76  13.  Comparison o f heights f o r good to medium image f i r s . . . . . . . . . . . . . . . . . . .  78  14.  Comparison o f heights f o r good to medium image red cedars . . . . . . . . . . . . . . . . . . .  79  15.  Comparison o f height measurements f o r good to medium image hemlocks.  79  16.  Comparison o f heights f o r good to medium image alders  80  17.  Comparison o f heights f o r good to medium image cottonwoods. • • . . . . • • . . . . . . . • • . 81  X  TABLE  PAGE  18.  Comparison o f height measurements f o r a l l tree species by year (good image) . . . . . . . . .  82  19.  Comparison o f height measurements f o r a l l tree species by year (medium image) . . . . . . . .  82  20.  Pooled standard e r r o r o f the mean d i f f e r e n c e i n f e e t f o r c o n i f e r s , hardwoods and a l l species by q u a l i t y o f images 84  21.  Pooled standard e r r o r o f the mean d i f f e r e n c e i n f e e t f o r good to medium image trees by species 85  22.  P e r i o d i c height growth f o r a l l species by i n t e r v a l o f year  89  23.  Accuracy o f height measurement f o r good to medium image trees by species (1949) . . . . .  91  24.  Accuracy o f height measurements f o r good to medium image trees by species (1955) . . . . . .  91  25.  Accuracy o f height growth estimates f o r good to medium image trees by species (1949-1955) . 92  26.  Accuracy o f height measurements f o r good to medium image trees by species (1955)  92  27.  Accuracy o f height measurements f o r good to medium image trees by species (1963) . . . . .  93  28.  Accuracy o f height growth estimates f o r good to medium image trees by species (1955-1963) . 93  29.  Doubled pooled standard e r r o r o f the mean d i f f e r e n c e i n f e e t f o r good to medium image trees by species . . . . . . . . . . . . . . .  94  30.  Number o f tree crowns measured on photos by species and year o f photography. . . . . . . .  96  31.  Comparisons o f accuracy o f crown width measurements f o r P—G and C—G by s p e c i e s . . . 96  32.  Pooled standard e r r o r o f the d i f f e r e n c e i n f e e t f o r crown width measurements by s p e c i e s . . . . 98  33.  Accuracy o f crown width measurements f o r trees by species (1963). . . . . . . . . . . . . . .  99  34.  Accuracy o f crown width measurements f o r trees by species (1955)  99  xi TABLE  PAGE  35.  Accuracy o f crown width measurements f o r trees by species  36.  P e r i o d i c crown width growth f o r trees by species. . . . . . 101  37.  P e r i o d i c crown width growth f o r trees by species (1949-63).  102  38.  P e r i o d i c crown width growth f o r trees by species (1955-63). . . . . . . .  102  39.  Comparison o f accuracy o f crown width growth by species  102  40.  Comparison o f measurements o f c o m p i l a t i o n height f o r group o f p l o t s .  105  41.  Comparison o f accuracy o f c o m p i l a t i o n height measurements by stand and year o f photography. . 106  42.  Accuracy o f average crown width measurements f o r , group o f plots. 107  43.  Comparison o f accuracy o f average crown width measurements by stand and year o f photography. , 108  44.  Comparison o f average crown c l o s u r e f o r stand by year o f photography . . . . . . . . . . . . . 109  45.  Comparison o f accuracy o f c o m p i l a t i o n height growth by stand and year o f photography. . . . . 110  46.  Comparison o f accuracy o f average crown width growth by stand and year o f photography. . . . .  47.  Comparison o f p e r i o d i c average crown c l o s u r e growth by stand and year o f photography. . . . . 142  100  Ill  USE OF A SERIES OF AERIAL PHOTOGRAPHS TO ESTIMATE GROWTH OF TREES AND  STANDS  INTRODUCTION The p r i n c i p a l purpose of a management program i s to meet the objectives of the forest owners.  A e r i a l photography  today i s being applied to an increasing v a r i e t y of f i e l d s . The use of a e r i a l photography i n f o r e s t inventory i s presently recognized  as an important a i d .  However, i t i s  important that the techniques of i n t e r p r e t a t i o n be improved. Photo-mensuration combined with s t a t i s t i c a l analysis i n resource inventory, when compared with ground methods, has proved i t s value i n saving a considerable amount of time and expense without lessening accuracy.  The value of a e r i a l  photography i s demonstrated e s p e c i a l l y i n r e l a t i v e l y large areas such as tree farm licenses, sustained y i e l d units or inaccessible areas where c o l l e c t i o n of ground data i s often d i f f i c u l t because of lack of funds and rugged topography. order to reduce the d i f f i c u l t y of surveying  In  large areas, good  photo-mensurational techniques should be developed. Such problems have stimulated several foresters to construct photo-volume tables by c o r r e l a t i n g photo variables  2.  such as stand height, crown closure, and crown width with ground data.  Despite the fact that these men  contributed much information to the new  confirmed  and  approach i n interpre-  t a t i v e methods, e f f o r t s made to predict the growth of trees and stands d i r e c t l y from the a e r i a l photographs are rare. Smith (1957c) i l l u s t r a t e d growth estimation by analysing the forest h i s t o r y of the U.B.C. Research Forest, Haney,  B.C.,  from three major series of a e r i a l photographs taken i n 1940,  and 1955.  1930,  He gathered information on growth and mor-  t a l i t y of trees and stands and further suggested that growth estimation based on a e r i a l photographs might be possible to a c e r t a i n extent. I t i s true that i n this dynamic age, theory can not go alone, and often the p r a c t i c a l approach i s f a r more important. Every time-consuming method which can be replaced by advanced and economical techniques must be encouraged.  Since forestry  tends to be increasingly more technological, and since the p o s s i b i l i t i e s of growth estimation and prediction from a series of a e r i a l photographs have proven e f f e c t i v e , more advanced research therefore should be done to develop a method of growth estimation which could be applied to a wide v a r i e t y of l o c a l i t y and species to help i n improving less economical method.  the conventional,  3  SURVEY OF LITERATURE The p o s s i b i l i t y o f d i r e c t estimates o f trees and stands by means o f a e r i a l photographs was mentioned by Smith (1957c). An i n d i r e c t method was c a r r i e d out by Willingham (1957a), who s t a t e d that r a d i a l growth, age and merchantable cubic volume are s i g n i f i c a n t l y r e l a t e d to height and crown c l o s u r e .  Also  dbh and volume are s i g n i f i c a n t l y r e l a t e d to the number of trees a t one per cent l e v e l .  No growth s t u d i e s were attempted  on the photographs u n t i l Rogers (1961) who i n surveying the Caspian f o r e s t o f I r a n , found that the photo measured v a r i a b l e "crown c l o s u r e " gave the best estimates of annual growth-perhectare.  His formula was:  G Where ~  t  = .8151(  .8997 + .331 X2")  i s annual growth-per-hectare (cubic meter) based on t  measurements o f annual r i n g s , and cent.  i s crown closure i n per  However, t h i s method was simply conventional r e g r e s s i o n  a n a l y s i s using ground data and measurements from only one s e t of a e r i a l photographs. A very s m a l l , y e t r e l a t i v e l y advanced p r o j e c t , was c a r r i e d out by the Survey D i v i s i o n of the Japanese Forestry Technique A s s o c i a t i o n i n 1961.  They s e l e c t e d 17 sample trees  knd one bamboo. new  Growth estimates were made i n terms of both  and o l d sets of photographs.  They concluded that height  growth of trees could be predicted by using a e r i a l photos taken at a five-year i n t e r v a l .  However, this report included neither  ground data nor s t a t i s t i c a l analysis and could only be thought of as a guide to further studies.  5.  OBJECTIVES The main purpose o f this study i s an attempt to e s t a b l i s h a method of growth prediction from a series o f a e r i a l photographs.  I f this investigation were to be proven  r e l i a b l e , forest mensuration might step into a new phase. The writer therefore intends to enquire into the following items: 1.  What would be the optimum i n t e r v a l of time f o r growth estimates on the photographs?  2.  What species gives the best r e s u l t s and to what extent of accuracy?  3.  How accurate w i l l height growth estimates be?  4.  How accurate w i l l the growth estimates of crown width be?  5.  Do growth estimates d i f f e r s i g n i f i c a n t l y among species?  6.  How does quality of photographs influence growth estimations?  7.  Can the growth of stands be predicted from a series of photographs? What sort o f stand gives better estimates - young growth o r o l d growth?  6. HISTORICAL BACKGROUND OF AREA STUDIED The U.B.C. Research Forest comprises various objects that w i l l serve to best advantage the needs of research.  The  h i s t o r i c a l changes i n forest conditions are remarkably well shown up on the d i f f e r e n t series of photographs. the  Effects of  f i r e which burned f o r 100 days i n the summer of 1931 on the  East side of the f o r e s t , as s p e c i f i e d i n the section e n t i t l e d " S p e c i f i c a t i o n of A e r i a l Photographs", can be seen on the f o r e s t today i n terms of poor stocking of conifers, galmonberry, s a l a l , huckleberry, and vine maple now gro.wirg on lands that should be supporting valuable conifers. became established a f t e r the f i r e .  Very few Douglas f i r  Some of these grew to a  height of 90 feet and a stump diameter of 18 inches i n only 25 years. Elevations within the forest range from sea l e v e l to 2,600 feet, but the area sampled ranges from 100 feet to 1,400 feet.  The entire forest region consists of overmature  old-growth, second growth, alder, reproduction and noncommercial cover.  Among the overmature and second growth types,  three major species occur:  western red cedar (Thuja p l i c a t a  Donn.). western hemlock (Tsuga heterophylla Sarg.). and Douglas F i r (Pseudotsuga menziesii Mirb.).  Yellow cedar  (Chamaecyparis nootkatensis Lamb.) i s growing at the higher  7. elevations on the poorer s i t e s and often i s of low-quality with considerable sweep and rapid taper.  Most of the white  pine (Pinus monticola Dougl.) has died i n recent years.  A  small volume of s i l v e r f i r (Abies smabilis (Dougl.) Forb.) grows i n a few patches mixed with hemlock.  S i t k a spruce  (Picea sitchenais (Bong.) Garr.) occurs occasionally. Alder (Alnus rubra Bong.) occurs on the gentler slopes of Compartment 2A, with a small patch on the northeast shore of Loon Lake. Most of the alder i s growing on a r e l a t i v e l y good s i t e capable of producing greater growth i f converted to c o n i f e r s .  Black  cottonwoods (Populus trichocarpa Torr. and Gray) are scattered at r e l a t i v e l y low elevations.  8.  DESCRIPTION OF FIELD DATA D e f i n i t i o n of the accuracy of measurements i s of paramount importance i n d i r e c t estimation of growth of trees and stands from a series of a e r i a l photographs. limited ground data are required.  Therefore,  Usually, before proceeding  to measurements of photo-variables, an o v e r a l l reconnaissance of the related areas increases the accuracy of interpretation. For this purpose, the writer spent three days i n October,  1963  i n the Haney Research Forest to measure i n d i v i d u a l trees and become f a m i l i a r with the l o c a l conditions p r i o r to commencement of this research.  Consequently, f o r studies of growth pre-  d i c t i o n , ground data were divided into two major categories: i n d i v i d u a l trees and i n d i v i d u a l plots. Observations f o r i n d i v i d u a l trees Since the U.B.C. Research Forest contains mostly western red cedar, western hemlock and Douglas F i r , and since f o r many decades, these trees have been highly valuable forest crops i n the P a c i f i c Northwest forests, a study was concentrated on these species. Growth of 23 young Douglas f i r was c l o s e l y observed. P a r t i c u l a r interest was paid to two hardwoods - red alder and black cottonwood.  The former has been regarded as the  most important hardwood i n Oregon and Washington while the latter"* i s one of the largest of the American poplars and i s the largest  9. broadleafed  tree i n the P a c i f i c Northwest (Harlow and  Harrar,  1950). Pearson (1962) stated that black cottonwool' i s one of the f a s t e s t growing hardwoods i n the P a c i f i c Northwest, gene r a l l y attaining a height o f 80 to 125 feet and a diameter of 3 to 4 feet.  Worthington et a l . (1962) indicated that indus-  t r i a l demand f o r red alder has been accelerating. of growth studies with these f i v e species was  The  choice  based on t h e i r  importance as well as a v a i l a b i l i t y of a e r i a l photographs taken at i n t e r v a l s of several years. The i n d i v i d u a l trees studied include: (1) 23 young Douglas f i r (the G r i f f i t h trees) around the junction of Spur 17 and Road S.  Their heights range from 34 to 68 feet and dbh's  range from 8.2 (P.S.T.'s), 53.0  to 19.9  inches; (2) 38 permanent sample trees  ranging from 71 to 160 feet i n height and 19.3  inches i n dbh.  This group includes 14 Douglas f i r ,  to 11  cedar, 9 hemlock and 4 spruce randomly d i s t r i b u t e d around the areas close to the road; (3) 21 trees measured on the edges of 5 G r i f f i t h plots ( G r i f f i t h , 1960)  from 54 feet i n height  on  the SI 85 plot to 180 feet on the SI 180 p l o t , including 13 f i r , 5 hemlock and 3 cedar; (4) 20 trees well selected from 5 randomly located plots each with 4 sample trees ranging from 86 to 160 feet i n height and consisting of 10 hemlock, 6 cedar and 4 f i r ; (5) an a d d i t i o n a l group of very young trees of 8  10. cedar and 1 hemlock ranging from 22 to 60 feet i n height and 4.8 to 14.0 inches i n dbh.  These were randomly selected but  e a s i l y i d e n t i f i e d on the photographs.  They are scattered by  the road around the junction of Spur 17 and Road S. (6) 12 red alder randomly taken along the road i n the forest area ranging from 39 to 85 feet i n height; (7) A f i n a l group included 16 cottonwood of which two trees were discarded because of d i f f i c u l t y i n i d e n t i f y i n g them on the photographs.  These cottonwoods  also were chosen randomly along the logging road i n the forest areas. sea  The elevation ranges from 100 feet to 1,200 feet above  l e v e l and the tree height from 64 to 108 feet.  A l l of  these ground data are shown i n Tables 1 to 7 of Appendix I. Observations f o r i n d i v i d u a l plots Three groups of f i v e i n d i v i d u a l plots were used f o r growth estimation from the a e r i a l photographs.  These groups  include: (1) 5 G r i f f i t h plots established i n September 1951. The study area l i e s on either side of the main road to Loon Lake.  I t extended from immediately north of the northern boun-  dary of A. F. Marc's farm to Blariey Lake.  As reported by  G r i f f i t h (1960), the e n t i r e area was burned i n 1868 and subsequently i t reforested to Douglas f i r , western hemlock, and western red cedar.  The Douglas f i r trees were the f i r s t to  become established a f t e r the f i r e , the oldest ones being about 80 years of age i n 1952.  The western hemlock and western red  11. cedar trees are g e n e r a l l y younger than the f i r .  Each p l o t  w i t h the exception o f p l o t No. 8 i s 0.10 acres i n area and p l o t No. 8 i s 0.075 acres.  D i f f e r e n t s i t e i n d i c e s were  a s s o c i a t e d w i t h the f i v e p l o t s .  Table 1 contains the p h y s i c a l  c h a r a c t e r i s t i c s and stand data f o r the f i v e study p l o t s obtained i n May 1952. These p l o t s were c l e a r c u t i n 1956. Table 1: P h y s i c a l c h a r a c t e r i s t i c s and stand data f o r f i v e G r i f f i t h study p l o t s , from G r i f f i t h (1960) Tables 11, 12 and 17. Characteristics  1  4  Plot  Number 5 7  8  S i t e Index ( f t . )  180  85  160  150  140  Elevation ( f t . )  690 1370  1000  1080  1100  12  10  8  Slope (%)  13  12  Stand Data Ave. Age - D. F i r  71.6 59.4 74.9  77.4  76.5  5.1  4.4.  4.6  21.6  9.0 20.0  18.4  18.7  19.8  7.2 18.8  17.3  17.0  Ave. height growth o f Dom. and Codom. D. F i r (1952^1956) ( f t . )  6.5  2.7  Ave. Diameter o f Dom. and Codom. o f D. F i r (1952) (inches) Ave. Diameter o f Dom. and Codom. o f D. F i r (1956) (inches)  12. (2) The second group i s f i v e permanent sample p l o t s (P.S.P.'s) selected from a group o f 15 P.S.P.'s near the south-east corner o f Loon Lake and North o f Blaney Lake.  The e l e v a t i o n  ranges from 1,140 to 1,320 f e e t above sea l e v e l .  The stands  studied range i n age from 55 to 85 years and average 70 years. The average s i t e index i s assumed to be 140. Douglas f i r , western hemlock, western r e d cedar and s i l v e r f i r are the major species.  The s e l e c t i o n o f these f i v e p l o t s was made on the  most recent s e t o f photographs so as to avoid use o f p l o t s that had been c u t .  P l o t s were established i n 1954 and a c t u a l t h i n -  ning was done i n 1956. The s i z e o f p l o t i s one by two chains w i t h the long side o f the p l o t running north and south.  Table  2 shows ground data f o r f i v e o f these p l o t s a f t e r t h i n n i n g . Table 2:  Summary o f 1958 ground data f o r f i v e 0.2-acre p l o t s a f t e r t h i n n i n g , from Lee (1959).  Characteristics S i t e Index ( f t . a t age 100) Ave. dbh (In.) Ave. height o f Dom. and Codom. (ft.) Ave. CW o f Dom. and Codom. ( f t . ) CC (%) Number o f trees per acre  7  8  P l o t Number 9 10  11  140 12.1  146 13.9  146 13.7  148 14.8  117  134  126  120  93  21 81  27 88  32 81  29 81  20 88  155  205  135  165  320  145 10.7  13. (3) Five s t r i p p l o t s , each 1/5-acre i n s i z e and taken from the n a t u r a l l y regenerated stand south o f Marion Lake and northeast of Road S were e s t a b l i s h e d i n May 1964 by the w r i t e r .  The  e l e v a t i o n ranges from 1,200 to 1,400 feet above sea l e v e l . The stand i s very open w i t h some small Douglas f i r trees planted beside hemlock and cedar. i n Table 3.  Composition o f these p l o t s i s shown  The f i e l d data are attached i n Appendix I I , Table  8. Table 3:  Composition o f f i v e n a t u r a l regeneration p l o t s i n May 1964.  Characteristics S i t e Index ( F t . ) Ave. dbh (In.) Ave. height o f Dom. and Codom.(ft.) Ave. CW o f Com. and Codom.(ft.) Number o f trees per acre.2 Note 1: 2:  1  2  P l o t Number 3 4  140 140 140 120 4.45 5.98 5.75 4.69 34.8 33.3 45.3 41.7 (35.3r(47.3) (43.7) (36.8) 14.8 23.0 17.0 9.3 (15.8) (24.0) (18.0) (10.3) 125  80  75  210  5 120 3.85 13.0 (15.0) 5.6 ( 6.6) 10  Figures i n brackets are 1964 data. Number o f trees excluding seedlings.  Location o f trees and p l o t s A b l u e p r i n t o f the Research Forest p r i n t e d from the 1964 mosaic constructed by the f o u r t h year f o r e s t r y students i s included as Appendix I . to i l l u s t r a t e the d i s t r i b u t i o n o f trees and p l o t s sampled.  14. Time and date o f data c o l l e c t i o n Most o f the data p e r t a i n i n g to t h i s study were e i t h e r obtained from the e x i s t i n g records o r measured by the w r i t e r . The G r i f f i t h trees were measured i n 1957, 1961 and 1963 w i t h respect to four v a r i a b l e s - dbh, t o t a l h e i g h t , crown width and gge.v These data have come from Dr. G r i f f i t h . ground data were provided by Dr. Smith. h e i g h t , dbh, and crown width.  For the P.S.T.'s  Measurements included  Species and e l e v a t i o n s o f the  i n d i v i d u a l trees also were noted.  These data were c o l l e c t e d  i n June, 1954 f o r the purpose o f making comparisons of a e r i a l photos taken a t v a r i o u s s c a l e s w i t h s e v e r a l types of cameras f o r ground checking of measurements made on these photos and to e s t a b l i s h a b a s i s f o r e s t i m a t i o n o f growth.  The t h i r d group o f  21 trees along the edges of the G r i f f i t h p l o t s was measured by the w r i t e r and another graduate student i n May 1964.  Data on  the f o u r t h group o f 20 trees were c o l l e c t e d by the w r i t e r i n October, 1963.  The main purpose was to extend the range i n  height and diameter.  A d d i t i o n a l very s m a l l trees were measured  by the w r i t e r i n May 1964 when he spent one month on the Haney Research Forest.  These were s e l e c t e d i n order to o b t a i n  enough s m a l l trees f o r o b s e r v a t i o n o f age and s i z e r e l a t i o n ships.  For both a l d e r and cottonwood, ground data were c o l l e c t e d  by the w r i t e r and one graduate student i n May, 1964.  15. A l l the i n d i v i d u a l trees measured by the w r i t e r were chosen with concern f o r t h e i r r e l a t i v e p o s i t i o n s on the photos to make sure they could be e a s i l y i d e n t i f i e d and measured without i n t r o d u c i n g e r r o r s i n t o computation.  The samples were  chosen along o r near the road where tree p o s i t i o n could be pointed o u t on the photographs without any d i f f i c u l t y .  Shape  of tree was also an important f a c t o r because abnormal shape of trunk and crown would reduce accuracy.  Leaning trees o r  those with portions o f crown overlaping were excluded. a l l y speaking, these trees a r e growing i n the open.  Gener-  Ease and  accuracy i n measurements were the e s s e n t i a l c h a r a c t e r i s t i c s i n the s e l e c t i o n o f sample t r e e s . The date o f data c o l l e c t i o n f o r the p l o t s has been stated previously.  Subsequent measurements were made f o r the f i v e  G r i f f i t h p l o t s i n 1956.  The p e r i o d i c height growth and the  average diameters o f dominant and codominant Douglas f i r are shown i n Table 1. Ground data f o r f i v e P.S.P.'s were c o l l e c t e d by Lee (1959) during the summer o f 1958*  The f i v e n a t u r a l r e -  generation p l o t s e s t a b l i s h e d i n May 1964 were used both f o r growth and age studies on the photographs.  P l o t s were chosen  to represent l e s s than 50 per cent crown c l o s u r e .  16. SPECIFICATIONS OF AERIAL PHOTOGRAPHS A survey o f a v a i l a b l e a e r i a l photographs showed that the e a r l i e s t photographs o f the U.B.C. Research Forest were taken i n 1930.  They are t i l t e d and have poorly resolved images.  Ten years l a t e r , the same area was photographed, but the q u a l i t y o f the p r i n t s a l s o was poor.  S e v e r a l f l i g h t s were made  s i n c e 1949, but a t an i r r e g u l a r i n t e r v a l o f years.  The p i c -  t o r i a l elements d i f f e r s i g n i f i c a n t l y i n q u a l i t y from s e t to s e t . The a v a i l a b l e sets are the photos o f 1930, .1940, 1949, 1954, 1955, 1958, 1961, 1962, 1963 and 1964.  Specifications  f o r various s e r i e s o f photographs were examined f o r a c l u e to growth s t u d i e s .  These are shown i n Table 4.  The cooperation o f Hunting Survey Corporation i n prov i d i n g a e r i a l photography i s very much appreciated.  The 1964  s e t was adequate f o r d e s c r i p t i v e purposes but reduced g r e a t l y i n value f o r photo-mensuration by the haze that p r e v a i l e d during the period o f photography.  17, Table 4:  Year  1930  S p e c i f i c a t i o n s o f A e r i a l Photographs used f o r Growth Studies  Photo No. A2234: 43-46  Time/Date o f Name o f Photography .Camera May  Fairchild  A2235: 16-17  1940  1949  Focal Flying Length Height ( i n . ) (ft.ASL) 3.28  15,000  3.28  15,000  BC192: •41-83 •  June  Not A v a i l a b l e 12  BC203: 41-43 79-80  November  Not Available  May  Not A v a i l a b l e 12 12  15,500 15,500  107: 27-32 41-43  S112: 1-8 1954 18-19 34-38 55-59  5 5  B.C.Gov'  15,200 15,200  B.C.Gov'  212140 212140 212140 212140  12 12 12 12  15,600 12,700 9,850 9,850  July  Ross  12  15,900  328411958 32855  May  Ross  12  15,600  3283332836  May  Wild RC8  6  8,400  June  RC8  12  15,900  October  RC8  6  7,500  1961  32793295  5695556968  694801962 69483 6949769500  R.C.A.F.  15,500  April April April April  1955  Source  7,500  Photo Survey Corp. Aero Surveys Ltd.  Hunting Surveys Co. Hunting Surveys Co. Hunting Surveys Co.  18.  Year  Photo No.  Time/Date o f Photography  Name o f Camera  Focal F l y i n g Source Length Height ( i n . ) (ft.ASL)  1963  7255172567  May  RC8  12  15,900  1964  8176881774  June  RC8  12  17,200  Hunting Surveys Co. Hunting Surveys Co.  19. MEASUREMENTS OF PHOTO VARIABLES Accuracy of measurements 1.  Tree height. The determination of the t o t a l height of a  tree, or of the mean height of a stand of trees, i s one of the most important operations i n the measurement and appraisal of uncut timber.  The cubic wood content of the tree bole i s a  function of i t s height.  The dimensions products which may  cut from the stem of a tree depend upon i t s height.  be  Rate of  growth on various s i t e s i s expressed as rate of height growth-, and provides a basis f o r comparing the productivity of various sites.  Retarded height growth and the attainment of a low  maximum height, at maturity, are the main c h a r a c t e r i s t i c s of sub-marginal  stands incapable of producing merchantable timber.  Thus tree-height i s a most u s e f u l index, not only i n estimating the content of i n d i v i d u a l blocks of timber, but also i n c l a s s i f y i n g more extensive forest tracts f o r the  .purpose of  economic regulation and management. Measurement of the height of standing trees on a e r i a l photographs was developed by Seely (1935).  Andrews(1936)  reported a simple method based upon micrometer measurements of parallax difference readings from v e r t i c a l a e r i a l photographs.  20. For 56 trees o f average height 88 f e e t , the e r r o r was s i x feet when measured on 1:9,000 photos. Rogers (1946) gave some h e l p f u l h i n t s i n the use o f a p a r a l l a x wedge instrument.  He suggested three methods o f con-  v e r t i n g the p a r a l l a x wedge readings to t r e e heights i n feet w i t h an estimate o f the p o s s i b l e errors involved i n each case. Extensive c o n t r o l l e d t e s t data were not y e t a v a i l a b l e to demonstrate p r e c i s e l y the range i n accuracy o f t h i s instrument under a wide v a r i e t y o f conditions a t that time.  He suggested,  however, that h i s experience i n d i c a t e d the a p p l i c a t i o n o f the instrument i n northeastern f o r e s t s would meet acceptable standards. Spurr (1945) stated that i n t e s t s a t the Harvard  Forest,  an observer could measure tree h e i g h t w i t h the p a r a l l a x wedge on 1:12,000 photographs with an average e r r o r o f l e s s than three feet.  Many o f the e a r l i e r t e s t s were made using height measure-  ments o f i n d i v i d u a l trees under conditions by photo i n t e r p r e t e r s i n f o r e s t  r a r e l y experienced  inventory.  Spurr (1948) also stated that e r r o r s i n measurements o f i n d i v i d u a l tree heights by p a r a l l a x wedge ranged from 3 to 20 f e e t on 1:15,840 photographs o f the Harvard Forest. c a l systematic e r r o r ranged from 5 to 10 f e e t .  He  The t y p i therefore  concluded that the average i n t e r p r e t e r should be able to  21. c l a s s i f y trees i n t o f i v e - f o o t height c l a s s e s when using 1:12,000 photographs. A s k i l l e d p h o t o - i n t e r p r e t e r , i n two cases out of measuring tree heights with the U.S.  three,  Forest Service p a r a l l a x  wedge, can measure tree heights w i t h an e r r o r of l e s s than - 10 f e e t i f 1:12,000 s c a l e a e r i a l photographs are used (Garver and Moessner, 1949). Nash (1949) tested 1:7,200 photography i n measuring tree heights by the shadow method and found an average e r r o r of estimate of -2.2  feet.  Moessner (1950) again confirmed that  i t i s p o s s i b l e , on recent 1:20,000 photos of good q u a l i t y , to measure tree heights by an inexpensive  p a r a l l a x wedge with  an  average e r r o r of l e s s than 6 f e e t i n comparison with Abney l e v e l readings taken i n the f i e l d . G e t c h e l l and Young (1953) found that the greatest s i n g l e e r r o r i n the measurement of tree height was 1:15,840 photographs.  11 f e e t when using  They also suggested that a period of  to 18 hours would be necessary f o r experienced  12  photo-interpreters  to become p r o f i c i e n t i n the use of wedge-type p a r a l l a x ladders and f l o a t i n g - d o t attachments to lens stereoscopes f o r measuring tree heights on a e r i a l photographs. Losee (1953) examined both small and large s c a l e photographs of eastern Canadian f o r e s t s i n a comparison of  the  22. accuracy o f measurements on photos taken a t s e v e r a l d i f f e r e n t scales.  The average e r r o r o f height measurement using a  p a r a l l a x bar was 0.6- 2.1 f e e t on the 1:7,200 photographs a t p r o b a b i l i t y o f 95 per cent and 2.1- 0.5 f e e t on 1:1,200 photographs.  However, systematic e r r o r s o f minus 10 to plus  16 f e e t i n height measurement were obtained f o r c o n i f e r s on 1:7,200 s c a l e  photographs.  Ker (1953) agreed t h a t , although an appreciable e r r o r appeared to e x i s t , a reasonable degree o f consistency was a t t a i n e d i n the measurement o f t r e e heights from photographs w i t h a s c a l e o f approximately  1:15,840.  Worley and Landis (1954) using repeated measurements on i n d i v i d u a l trees made by parallax-wedge and p a r a l l a x - b a r , found no s i g n i f i c a n t d i f f e r e n c e i n the 8 to 10 f e e t standard e r r o r s o f estimate obtained by using these two instruments. They s t a t e d , however, that i n t e r p r e t e r s using the p a r a l l a x - b a r seemed to underestimate heights o f l a r g e r trees to a greater extent than those who used the parallax-wedge.  A l l i s o n (1956)  concluded that w i t h increase i n f l y i n g height o r s h o r t e r f o c a l length as w e l l as greater degree o f enlargement, height measurements and p r e c i s i o n was l e s s , but no s i g n i f i c a n t d i f ference was found between various q u a l i t i e s o f a e r i a l photographs.  Pope (1957), discovered that accuracy o f t r e e height  23. measurement v a r i e d considerably  among i n t e r p r e t e r s .  However,  no s i g n i f i c a n t d i f f e r e n c e e x i s t e d among photo scales o r f i l m type. Smith (1957) i l l u s t r a t e d that with 15 trees averaging 123 f e e t and ranging from 93 to 206 feet i n height, one operator secured an average estimate w i t h i n 4.7  f e e t of the mean a f t e r  15 hours of p r a c t i c e w i t h the height f i n d e r . he was w i t h i n 0.9 trees.  A f t e r 25 hours,  f e e t of the true mean h e i g h t of the same  Another operator improved h i s measurements from an  average e r r o r of -22.2  f e e t i n the f i r s t run to -6.5  the second s e r i e s of the same t r e e s .  feet i n  C o l l i n s (1957) found  that the standard e r r o r of i n d i v i d u a l h e i g h t estimates f o r 40 + + trees was -6.1 f e e t f o r dominant and codominant trees and -5.1 f e e t f o r dominant o n l y .  He f u r t h e r suggested that estimates  o f height f o r s i t e c l a s s i f i c a t i o n can be made with e x c e l l e n t r e l i a b i l i t y from a e r i a l photographs. Avery (1958), applying h e l i c o p t e r stereo-photography of f o r e s t p l o t s , found that h i g h l y s i g n i f i c a n t d i f f e r e n c e s e x i s t e d between height measurement on 1:20,000 photographs and a l l h e l i c o p t e r stereographs.  Tree heights were more accurately  determined on the h e l i c o p t e r photographs.  I n other words, each  i n t e r p r e t e r c o n s i s t e n t l y underestimated tree heights on 1:20,000 photos and c o n s i s t a n t l y overestimated them on h e l i c o p t e r  24. stereograms; e.g. on 1:20,000 photos, mean d i f f e r e n c e and  the  standard e r r o r of d i f f e r e n c e f o r i n t e r p r e t e r A are -6.8 f e e t + + and -6.3 f e e t , w h i l e f o r B they are -5.5 f e e t and -3.2 f e e t , respectively. 1.3 and -0.7  But on 300-foot photography both values are feet.  Johnson (1958) computed from the published data of G e t c h e l l and Young (1953), the mean e r r o r f o r the p a r a l l a x bar instrument as -0.8 was  -0.7  feet.  p a r a l l a x bar was was  3.78  f e e t , and that f o r the p a r a l l a x wedge  The standard d e v i a t i o n of the e r r o r s with 2.72  the  f e e t and that with the p a r a l l a x wedge  feet.  Johnson (1958) again described  the e f f e c t of photographic  s c a l e on the p r e c i s i o n o f tree-height measurement.  He suggested  that e r r o r i n tree height measurement on a e r i a l photographs i s not associated with photographic s c a l e a t l e a s t i n the range from 1:5,000 to 1:20,000.  The main e r r o r probably i s asso-  c i a t e d with tree c h a r a c t e r i s t i c s such as crown shape and size.  tree  Another cause o f e r r o r i s the v a r i a t i o n i n a b i l i t y of  d i f f e r e n t operators.  The systematic  e r r o r s and standard d e v i -  ations obtained  by operators I and I I were 0.6  + -7.72  feet, respectively.  + and -7.47  and 3.9  f e e t and  Rogers (1958) reported that the average height f o r dominant trees i n stands of hardwoods can be measured w i t h i n  25. 10 per cent two times out o f three.  The standard e r r o r of  estimate f o r i n d i v i d u a l tree heights was 9 f e e t on 1:12,000 photographs.  Bernstein (1958) concluded  that d e f i n i t e d i f -  ferences e x i s t e d among photo i n t e r p r e t e r s , but m a g n i f i c a t i o n d i d not seem to be an e f f e c t i v e means of improving tree height measurements. Three scales of a e r i a l photography were tested by Rogers et ajl. (1959) i n an attempt to determine the best s c a l e , to use i n f o r e s t surveying.  Results of analyses of variance  showed a s i g n i f i c a n t d i f f e r e n c e among s c a l e s and among i n t e r preters f o r photo estimates of average t o t a l h e i g h t , but the i n t e r a c t i o n o f scales and i n t e r p r e t e r s was not s i g n i f i c a n t . The a n a l y s i s a l s o revealed a s i g n i f i c a n t d i f f e r e n c e between mean photo heights and corresponding  f i e l d heights.  This d i f -  ference was negative f o r a l l s c a l e s and i n t e r p r e t e r s , i . e . , a l l photo heights were lower than the f i e l d average of 53 f e e t . A l s o , the " t " t e s t i n d i c a t e d that there was no s t a t i s t i c a l choice of photo scales f o r measuring t r e e h e i g h t s . The mean estimate of 48 f e e t on 1:5,000 photos was c l o s e s t to the true f i e l d v a l u e , but i t i s d o u b t f u l that the s l i g h t g a i n i n accuracy over 1:15,840 photos would j u s t i f y the increased cost of using the l a r g e r s c a l e . Lyons (1961) studied two-camera low-elevation stereophotography from h e l i c o p t e r s .  Several trees ranging from 50 to  26. 70 f e e t t a l l were measured on the ground and three o f these were measured on 9" by 9" enlargements and on contact p r i n t s u s i n g an Abrams height f i n d e r .  On the enlargements,  errors i n  tree height ranged from 1.2 f e e t to 2.1 f e e t and on the cont a c t s from 2.8 f e e t to 3.9 f e e t . Lyons (1964), again developed an advanced method o f 70mm stereophotography  from h e l i c o p t e r s to measure 682 trees ranging  i n height from 45 f e e t to 125 f e e t .  The standard e r r o r o f the  d i f f e r e n c e he obtained was -4.5 f e e t . Moessner (1961) compared three p a r a l l a x measuring i n struments i n the measurement and i n t e r p r e t a t i o n o f f o r e s t stands.  Better r e s u l t s were obtained f o r both p a r a l l a x wedge  and h e i g h t f i n d e r i n terms o f mean elapsed time.  Mean aggregate  d i f f e r e n c e s and standard e r r o r o f estimates expressed i n 0.001 i n c h u n i t s o f p a r a l l a x f o r p a r a l l a x wedge and height f i n d e r are 1.54 and 1.53 and 4.61 and 4.73 on 1:20,000 photos.  On 1:12,000  photos they were 2.41 and 2.21 and 8.62 and 8.21 r e s p e c t i v e l y . Smith, Lee and Dobie (1960) a f t e r dealing w i t h an i n tensive assessment o f f a c t o r s i n f l u e n c i n g photo-cruising  carried  out on the U.B.C. campus as w e l l as on Haney Research Forest concluded that the photo i n t e r p r e t e r himself i s the most important source o f v a r i a t i o n .  ,  27. A l l i s o n and Breadon (1960) conducted t e s t s to determine how many measurements of p a r a l l a x d i f f e r e n c e on the same tree were necessary to give a r e l i a b l e mean. were s e l e c t e d .  Twenty-five trees  A f i x e d number o f s i x t e e n p a r a l l a x measurements  was compared w i t h p a r a l l a x measurements made on a given tree u n t i l two i d e n t i c a l values o f p a r a l l a x d i f f e r e n c e were obtained. The standard e r r o r s f o r both 16 readings and 2 readings were + + -15.5 feet and -16.2 f e e t r e s p e c t i v e l y . M i t c h e l l (1961) used a s t a t i s t i c a l a n a l y s i s to t e s t the r e s u l t s o f the study conducted by A l l i s o n and Breadon (1960). He found that the standard e r r o r o f estimate was lower f o r 10 average readings than 6 readings.  His data suggested that tree  heights should be c a l c u l a t e d from an average o f 6 p a r a l l a x d i f f e r e n c e measurements i f minimum cost and maximum accuracy are to be obtained.  He f u r t h e r confirmed that the S E i s E  s l i g h t l y lower when heights are based on the mean p a r a l l a x d i f f e r e n c e as compared w i t h 2 i d e n t i c a l readings. I n summary, accuracy o f tree height measurements v a r i e s considerably  from i n t e r p r e t e r to i n t e r p r e t e r .  The importance  o f the i n t e r p r e t e r i s not r e a l l y s u r p r i s i n g ; however, i n t e r a c t i o n between method and i n t e r p r e t e r i s l i k e l y to be r e a l as i t i s very p o s s i b l e that each i n t e r p r e t e r obtains b e t t e r r e s u l t s when using a p a r t i c u l a r method.  The i n t e r a c t i o n between i n -  28. t e r p r e t e r and tree number i n d i c a t e s that each i n t e r p r e t e r secures more accurate heights when measuring c e r t a i n t r e e s . The importance o f method can not be overemphasized, ( M i t c h e l l 1961).  The accuracy o f the p a r a l l a x method v a r i e s d i r e c t l y  w i t h the d i f f e r e n t i a l p a r a l l a x between the top and bottom o f the t r e e , t h e r e f o r e , any f a c t o r which tends to increase d i f f e r e n c e w i l l add to the p r e c i s i o n o f the method.  this  I t follows  that other f a c t o r s being equal, the most accurate p a r a l l a x d i f f e r e n c e s w i l l be measured on photographs taken w i t h a maximum separation by a wide-angle lens a t a low e l e v a t i o n (Spurr, 1960).  I t should be p o s s i b l e f o r average  photo-interpreters  to o b t a i n tree height with a standard e r r o r o f -10 f e e t i f proper photographs are a v a i l a b l e .  Spurr (1960) reported  that  the height o f most trees reasonably adjacent to open ground can be determined on h i g h - q u a l i t y a e r i a l photographs o f average s c a l e (as 1:15,840) w i t h a standard e r r o r o f approximately 5 f e e t .  When the height o f a number o f trees are  averaged, measurements made on the a e r i a l photographs frequently d i f f e r by l e s s than 1 foot from mean height measurements made on the ground. 2.  Determination o f photo height. Comparisons o f advantages and disadvantages i n  using three p a r a l l a x measuring instruments were made by Moessner (1961).  Standard e r r o r o f estimates obtained  by using  29. the p a r a l l a x bar were s l i g h t l y lower than by u s i n g the p a r a l l a x wedge.  Lee (1959) i n h i s t h e s i s concluded that the Abrams  H e i g h t - f i n d e r was an e x c e l l e n t instrument f o r measuring heights.  tree  R e f e r r i n g to the past works and personal experience,  the w r i t e r decided to use an Abrams H e i g h t - f i n d e r f o r t h i s study.  L a t e l y , Avery (1964) suggested that although the par-  a l l a x bar i s more expensive than the p a r a l l a x wedge and y i e l d s r e s u l t s o f the same order of accuracy, many photo i n t e r p r e t e r s p r e f e r i t because the f l o a t i n g dot i s moveable f o r e a s i e r placement on the ground and a t crown l e v e l . I n order to avoid memory b i a s , f o r each group of i n d i v i d u a l t r e e s , measurements were made i n order o f numbering. However, i n s t e a d of taking four p a r a l l a x readings f o r each tree a t one time, only one reading was taken from f i r s t numbered sample tree throughout the l a s t numbered tree i n t h i s group. Repeated p a r a l l a x measurements were made on a given tree i n the same order u n t i l two i d e n t i c a l values of p a r a l l a x d i f f e r e n c e were obtained o r of four readings, was taken.  I t has been  confirmed by A l l i s o n and Breadon (I960) and M i t c h e l l (1961) that time i s saved by u s i n g t h i s method.  I t should be noted  that a f t e r each recurrence, photographs were s l i g h t l y moved i n order to avoid memory b i a s and meanwhile to e l i m i n a t e v a r i a t i o n due to i n c o r r e c t separation of photos.  30. The same methods of height measurement were followed for the r e s t of i n d i v i d u a l tree groups.  A p a r t i c u l a r check  method was applied by the writer i n this study, i . e . , f o r each sample tree, an additional measurement was made a t the very beginning of the day before proceeding to make other measurements.  In other words, f o r a group o f i n d i v i d u a l trees,  approximately one hour a day was spent i n the early morning i n checking the results obtained f o r each sample tree on the assumption  that the observer w i l l then have least fatigue.  Checking was not done when the w r i t e r did not have c l e a r eye vision.  This checking, j u s t as an ordinary checking job i n  any experiment, has proved i t s importance operation.  during the period of  I f parallax reading was not f a i r l y consistent with  the " i d e n t i c a l reading" or "four parallax readings", measurements were repeated f o r this p a r t i c u l a r tree and the checking was done f o r this tree together with the next group of i n d i v i d u a l trees.  Thus each sample tree has either " i d e n t i c a l "  or "four" parallax readings i n addition to f i n a l checking.  The  " i d e n t i c a l " reading was accepted as the mean parallax difference and an average of "four" readings was obtained i n order to convert i t into photo heights by the parallax formula: H dP  h  =  p + dP  31. Where  h  i s the tree height i n f e e t ;  H  the f l y i n g height  of a i r c r a f t above datum (base o f tree) i n f e e t ;  P the  absolute p a r a l l a x o f the base o f tree i n mm. and dP p a r a l l a x d i f f e r e n c e i n mm.  i s the  The conversion o f p a r a l l a x  readings i n t o photo heights was done a f t e r a l l the measurements were completed.  Thus each i n d i v i d u a l tree has e i t h e r  an " i d e n t i c a l " height o r an average o f "four" photo heights as w e l l as "checking" photo-height, i . e . , two kinds o f photo height. Measurements were s t a r t e d from the s e r i e s o f photos i n the year that f i e l d data were obtained.  Then succeeding  measurements were made by working from the most recent s e r i e s of photographs back to the e a r l i e s t s e r i e s o f the photographs. S p e c i a l a t t e n t i o n was paid to the r e l a t i v e p o s i t i o n s , tone, shapes o f crowns o r , o c c a s i o n a l l y , shadows, i n order to locate the a c t u a l trees which were measured on the ground. c a t i o n o f tree species described  Identifi-  by Munro i n photogrammetry  l e c t u r e s and SaynfWittgenstein (1960, 1961)  helped r e c o g n i t i o n  o f the c o r r e c t trees from s e r i e s to s e r i e s o f photographs. Some trees which were measured on the recent s e r i e s o f photographs could not be located on the e a r l i e r s e r i e s o f photographs because e a r l i e r , they were growing amid densely stocked stands, and there was considerable the c o r r e c t t r e e s .  risk i n locating  The same d i f f i c u l t y was found i n the case  32. o f t r e e s , measured on the e a r l i e r s e r i e s o f photographs, which could not be found on the recent s e r i e s o f photographs because of change i n f o r e s t composition such as t h i n n i n g o r c u t t i n g o r because o f the poor q u a l i t y o f photographs.  These u n c e r t a i n  trees were omitted from measurements i n order to avoid i n t r o ducing e r r o r i n t o f i n a l computation.  A l l the measurements  were taken under a combination o f d i r e c t and i n d i r e c t l i g h t i n g on a l i g h t t a b l e because Smith (1957b) revealed the r e l a t i v e e f f i c i e n c y o f using t h i s method. 3.  Grown width. For many y e a r s , crown width has been recognized  as an important f a c t o r that tends to a f f e c t the morphology and p r o d u c t i v i t y o f t r e e s .  I t can be studied from the f o r e s t  genetic point o f view as a guide to the degree o f t h i n n i n g r e q u i r e d to maintain maximum r a t e s o f growth f o r open grown trees.  Smith (1958) suggested that the assumption that slow  growth i s n e c e s s a r i l y i n d i c a t i v e o f wood o f h i g h q u a l i t y be reconsidered from the economic point o f view.  He concluded  that we must grow large trees o f h i g h q u a l i t y as economically as p o s s i b l e .  Therefore, he advocated an a l t e r n a t i v e way to  achieve qtaitek growth by using r e l a t i v e l y few trees per acre a t wide spacing. Minor (I960) concluded, f o l l o w i n g an i n v e s t i g a t i o n o f stem-crown diameter r e l a t i o n s i n 127 sawtimber-sized ponderosa pine, that the a b i l i t y to determine dbh o f trees  33. from measurements on a e r i a l photographs has s e v e r a l a p p l i c a tions and advantages.  Among these are b e t t e r stand maps,  more e f f i c i e n t road l o c a t i o n and logging plans, approximate volume determinations,  and development o f volume tables based  d i r e c t l y on crown diameter and t o t a l h e i g h t , f o r use a e r i a l photographs.  with  Dilworth (1959) a p p l i e d v i s i b l e crown  width i n c o n s t r u c t i n g photo volume tables f o r second-growth D o u g l a s - f i r and mature ponderosa pine stands i n Oregon. Apsey (1961) studied the growth and y i e l d of red a l d e r by the r e l a t i o n s h i p of crown width-diameter.  Pearson (1962)  made the same a n a l y s i s of crown width of open grown and f o r e s t grown black cottonwood as an a i d i n the p r e d i c t i o n o f y i e l d and growth. who  Another study was c a r r i e d out by Dobie (1963),  confirmed that crown width i s an i n d i c a t o r of tree s i z e  and the best measure o f a c t u a l lumber recovery values per tree ranging from $0.57 to $1.08  per cubic f o o t .  An i n v e s t i g a t i o n  conducted by Kozak et aj.. (1963) has shown that v a r i a t i o n s i n number o f cones produced were s i g n i f i c a n t l y c o r r e l a t e d with t r e e dbh ( r 0.05), t r e e height ( r 0.47)  and crown width  ( r 0.34). A number o f methods o f measurement have been a p p l i e d to crown width and various instruments were designed f o r such measurement ( B u e l l , 1936; Holdsworth, C u r t i s and McCleary, Nash, 1948;  Turnock and Ives, 1957;  Brewer, 1959).  Some  1936;  34. advantages o f using these devices were pointed out by Walters and Soos (1962), who  developed a gimbal-sight  for measuring  crown radius. Many t e s t s , however, indicated that crown width can be measured on a e r i a l photographs much more accurately than they can be measured r a p i d l y on the ground i f a portion of the crown i s not greatly overlapped by the adjoining trees.  The  extent of accuracy to which crown width can be measured varies with species, tonal contrast of p r i n t , l o c a t i o n , and above a l l , the scale.  Generally, i t can be assumed that the larger the  scale of photograph, the smaller the error of measurement w i l l be.  Spurr (1960) stated that tests have shown the minimum  s i z e of objects that can o r d i n a r i l y be seen on a e r i a l photographs to be 1 foot at 1:6,000; 2 feet at 1:12,000; 2% feet at 1:16,000 and 3 feet at 1:20,000.  I t can also be said that  measurement of crown width on the photographs for open grown trees or dominant trees i n the stands would give a more s a t i s factory degree of accuracy than those f o r trees i n densely stocked stands because i t i s easier to detect the actual shape of crown from above. Ronay (1961) studied crown c h a r a c t e r i s t i c s of Douglas f i r , heM^fck and cedar.  He found that (1) the crown shape of  Douglas f i r i s influenced by elevation; (2) among the many  35. factors influencing the texture of a tree image on a e r i a l photographs, the age and the scale are most important.  The  best photo scale f o r the recognition of these three species was found to be about RF 1:8,700. Avery (1964) stated that tree crowns are r a r e l y c i r c u l a r , but  because i n d i v i d u a l limbs are often i n v i s i b l e on a e r i a l  photographs, they usually appear roughly c i r c u l a r or e l l i p t i c a l . As only the portions of the crown v i s i b l e from above can be evaluated, photo measures of crown diameter are often lower than ground checks of the same trees.  Nevertheless, most i n -  terpreters can determine average crown diameter with reasonable p r e c i s i o n i f several readings are taken and there i s no constant bias i n measurement. Most commonly, crown width measurement i s made by the micrometer wedge, or shadow wedge, which i s also used i n measuring the length of tree shadows and other short distances on a e r i a l photographs (Spurr, 1960).  The most widely used  instruments are the crown wedge incorporated into the parallax wedge introduced by Wilson (1948), and the dot wedge constructed by Jensen (1958). Wilson (1946) i n his a e r i a l photo techniques b i b l i o graphy stated that on 1:20,000 photographs, crown widths could not  + be measured closer than -5 feet.  He also concluded that  36. crown width should not be c l a s s i f i e d i n l e s s than 10 f e e t groups when u s i n g t h i s s c a l e of photograph.  Spurr (1948)  found that experienced i n t e r p r e t e r s could c o n s i s t e n t l y measure crown widths w i t h an e r r o r of l e s s than 3 f e e t on 1:12,000 photographs. of  Nash (1949) obtained a standard e r r o r of estimate  -2.2 f e e t by studying image measurement o f crown widths on  o b l i q u e photos. Garver and Moessner (1949) reported that crown diameters are  u s u a l l y measured on the dominant trees of the sample p l o t .  I n t e r p r e t e r s can be expected to c l a s s i f y crown diameters cons i s t e n t l y by 5-foot c l a s s e s on 1:20,000 photographs when using a dot type wedge.  Minor (1951), studying  r e l a t i o n s h i p s i n southern pine, mentioned  stem-crown-diameter that crown width can  be c l a s s i f i e d i n t o 3-or 5-foot c l a s s e s . Losee (1953) stated that the r e l a t i o n s h i p between the measurement on 1:1,200 photographs and the f i e l d measurement was not s t r a i g h t as expected, but c u r v i l i n e a r , and that c o r r e l a t i o n was very h i g h , however, a very weak c o r r e l a t i o n was obtained between the measurements on the 1:7,200 photographs and the f i e l d measurements.  An average e r r o r of -0.09  -0.33  f e e t a t 0.95 p r o b a b i l i t y was obtained on 1:1,200 photographs. Worley and Meyer (1955) found that when u s i n g a shadow wedge, no s i g n i f i c a n t d i f f e r e n c e s e x i s t e d i n the accuracy of crown  37.  measurements f o r d i f f e r e n t s i z e .  I t was found that the stan-  dard error of measurement of the i n d i v i d u a l observers amounted to 4.2 feet f o r open grown trees and 3.0 feet f o r forest grown trees.  The average standard error was equal to 3.7 feet.  When using the dot transparency, differences between observers as large as f i v e feet were obtained from open grown trees while the maximum difference of forest grown trees was 2.4 feet.  Dilworth (1956) using multiple regression analysis for  v i s i b l e crown diameter/dbh r e l a t i o n s h i p found that when v i s i b l e crown diameters were used to estimate dbh, the standard error of estimate of dbh ranged from 1.17 to 2.53 inches.  The  simple c o r r e l a t i o n c o e f f i c i e n t s varied from 0.900 to 0.966. F i n a l l y , he interpreted that this relationship was influenced more o r less by tree species, geographical location, stand density, tree height, and s i t e quality. Rogers (1958) reported that crown widths were estimated consistently with a standard error o f 3.5 to 4.0 feet on 1:10,000 and 1:15,000 photographs. photographs, 1.9 feet.  On 1:5,000 and 1:7,000  standard errors of estimate ranged from 1.8 to  On a larger scale, 1:1,200, the standard error of  estimate was only 0.54 feet.  Rogers, Avery and Chapman (1959a)  compared three scales of a e r i a l photography f o r making stand measurements.  They suggested that there was a s i g n i f i c a n t  difference between scales f o r photo estimates of average crown  38. diameter, but the s i g n i f i c a n t i n t e r a c t i o n o f scales and i n t e r p r e t e r s i n d i c a t e d that no s i n g l e s c a l e was c o n s i s t e n t l y best f o r a l l i n t e r p r e t e r s . They concluded that average crown diameters can be determined as a c c u r a t e l y on 1:15,840 photos as on l a r g e r p r i n t s c a l e s . Moessner (1962), when c o n s t r u c t i n g p r e l i m i n a r y a e r i a l volume tables f o r $inyon-juniper  stands found that the mean  aggregate e r r o r , standard e r r o r of estimate, and c o e f f i c i e n t o f c o r r e l a t i o n f o r average crown diameter o f dominant stand were -.1 f o o t , -3.2 f e e t and .632 r e s p e c t i v e l y .  Spurr (1960)  i n d i c a t e d that i n t e s t s a t the Harvard F o r e s t , accurate r e s u l t s were obtained from p h o t o - i n t e r p r e t a t i o n i n most i n stances.  Although i r r e g u l a r and m u l t i p l e crowns were found  d i f f i c u l t to measure, the o v e r a l l accuracy of the crowndiameter measurements seemed to be good.  He f u r t h e r stated  that i n the 12-acre stand i n which a l l trees were s t u d i e d , the average v i s i b l e crown diameter measured on the  photographs  was 15.8 f e e t , compared with the average of 16.1 f e e t from the ground c r u i s e . Spurr (1960) concluded that crown diameters can be cons i s t e n t l y c l a s s i f i e d i n t o 2-foot classes a t a s c a l e of 1:12,000 3-foot c l a s s e s a t 1:15,840, and 5-foot c l a s s e s at 1:20,000.  40. I n general, as long as the s c a l e o f photographs i s not too s m a l l , crown widths could be measured w i t h a c o n s i derable degree o f accuracy i n comparison with ground methods. Accuracy would be increased with increase i n photo s c a l e i f the q u a l i t y o f photographs remains the same.  Since the photo-  graphs used i n t h i s study were a t the average s c a l e o f approxi mately 1:12,000, an average e r r o r o f 2 f e e t to 3 f e e t might be  expected. 4.  Determination o f photo crown width. Improved techniques o f measuring crown width  have been described by Jensen (1948) and Lee (1959).  Although  the dot s c a l e o f the Michigan p h o t o - i n t e r p r e t e r ' s a i d was regarded as the best f o r measuring crown widths i n s p i t e o f inaccurate d r a f t i n g o f the dot s e r i e s , f o r the smaller crowns these dots are l i k e l y to give inaccurate r e s u l t s .  The w r i t e r  has t r i e d to construct a crown wedge w i t h which minimum crown width o f 6 f e e t could be measured without any d i f f i c u l t y . This was done simply by u s i n g a very sharp needle (#9) to s c r i b e the wedge and graduations o f the U.B.C. photo-interpret e r ' s a i d on a transparent o v e r l a y .  A very f i n e narrow sharp  wedge was thus constructed and the china marking p e n c i l was used to r e s o l v e the s c r i b e d l i n e s f o r fteasy handling when placed on the photographs.  41. A l l crown measurements were made with t h i s s c r i b e d wedge.  Since measurement o f crown width i s not as d i f f i c u l t  as that o f tree height, the number o f measurements was r e duced to two per t r e e .  An average o f two measurements was  obtained which was m u l t i p l i e d by the average s c a l e o f that s p e c i f i c area to get crown width i n f e e t .  Measurements o f  crown widths were made i n the same sequence as i n determining photo heights f o r each i n d i v i d u a l t r e e . crown width i n f e e t was obtained  Only one value o f  f o r each t r e e instead o f two  values f o r height. No measurements were made w i t h trees poorly resolved on the p r i n t s .  For i n s t a n c e , very l i g h t crowns o f cottonwood  were not included. 5.  Crown c l o s u r e . A crown c l o s u r e measure i s intended  to help  determine the r e l a t i o n o f the average t r e e i n the stand to the maximum growing space i t could u t i l i z e and to the minimum growing space i t needs to l i v e .  The r e l a t i v e merits o f crown  c l o s u r e measurements d i r e c t l y on the a e r i a l photographs have been r e f e r r e d to by many f o r e s t e r s during the past decade. The s i g n i f i c a n c e o f using crown c l o s u r e as an important independent v a r i a b l e i n c o n s t r u c t i n g a e r i a l volume tables was demonstrated by Moessner, Brunson and Jensen (1951), Ferree (1953), G i n g r i c h (1955), Moessner (1957), A l l i s o n and Breadon  42. (1959), Rogers, Avery and Chapman (1959), Anonymous (1959a, 1959b), A l l i s o n and Breadon (1960), Smith, Lee and Dobie (1961), Moessner (1962), and Moessner (1963). U s u a l l y , crown c l o s u r e i s defined as the p r o p o r t i o n of the area o f stand o r other homogeneous u n i t covered by crowns of t r e e s .  On the ground, a s p h e r i c a l dehsiometer has been  found by Lemmon (1956) to be a s u i t a b l e instrument f o r permanent p l o t estimates of r e l a t i v e canopy c l o s u r e of d e n s i t y i n f o r e s t and range e c o l o g i c a l s t u d i e s .  Brown (1962) set up  a canopy camera that takes wide-angle, overhead photographs of v e g e t a t i o n canopies.  Photographs of t h i s type provide a  means of studying the r e l a t i o n s h i p s between canopy coverage and t r e e growth. Estimates of crown c l o s u r e on a e r i a l photographs r e q u i r e only a l i t t l e practice.  Since the i n t e r p r e t e r can see the  e n t i r e stand from above, crown canopy should be  determined  under a stereoscope more e a s i l y than i t could be estimated from the ground.  A crown-density s c a l e designed by Moessner (1947,  1948) has been accepted f o r assessing crown c l o s u r e d i r e c t l y on a e r i a l  photographs.  The e a r l i e s t method described by Andrews (1934) was to planimeter the crown openings d i r e c t l y on a e r i a l photographs f o r e s t i m a t i n g crown c l o s u r e . This was too tedious f o r general application.  Spurr and Brown (1946) i n d i c a t e d that crown  43. closures can be estimated to the nearest 10 per cent on photos of 1:10,000 to 1:18,000.  Moessner (1947) reported that by  using the density s c a l e , crown c l o s u r e can be estimated cons i s t e n t l y w i t h i n ten per cent. repeated  Garver and Moessner (1949)  that although care must be taken to compare o n l y tree  crowns and not shadows, w i t h t h i s s c a l e , the v a r i a t i o n of t h i s reading among i n t e r p r e t e r s seldom exceeds 10 per cent. I n analysing the c o r r e l a t i o n between the photographically determined d e n s i t y on the 1:7,200 photos and f i e l d measurements f o r spruce stands, Losee (1953) found that i t was necessary to introduce the f a c t o r of distance from the p r i n c i p a l p o i n t . This was because the strong displacement of the 6-inch lens used f o r t h i s photography reduced the apparent s i z e of crown openings toward the edges of the photographs. e r r o r on 1:7,200 photographs was -0.3% -5.5%, ( a t 0.95  P.).  -1.3% -9.9%  The average (at 0.95  P.)  and  The d i f f e r e n c e between the average  e r r o r at the two scales was not s i g n i f i c a n t . G i n g r i c h (1955) conducted an i n v e s t i g a t i o n of r e l a t i v e accuracy of dot g r i d s and crown d e n s i t y s c a l e s .  He i n d i c a t e d  that the dot g r i d method i s somewhat s u p e r i o r to the a p p l i c a t i o n of a crown d e n s i t y s c a l e .  The a c c i d e n t a l e r r o r of  i n d i v i d u a l measurements i s about 10 per cent f o r both methods, but the i n d i v i d u a l systematic e r r o r , which may  amount to as  much as 5 to 10 per cent, i s s l i g h t l y smaller f o r the dot g r i d  44. method.  Worley and Meyer (1956) found that i n d i v i d u a l ob-  servers have a tendency to e i t h e r over-estimate o r underestimate the r e l a t i v e crown cover o f a stand using e i t h e r dot counts o r g r i d comparisons.  Rogers (1958) obtained standard  e r r o r o f estimate o f 8.7 per cent i n c o n s t r u c t i n g stand volumes of hardwood f o r e s t s .  He a l s o s t a t e d t h a t on 1:12,000 and  1:20,000 photographs, stand volumes of hardwood f o r e s t can be estimated w i t h i n 10 per cent.  Avery and Myhre (1959) main-  tained 10 per cent i n t e r v a l s f o r crown c l o s u r e i n c o n s t r u c t i n g composite a e r i a l volume tables f o r southern Arkansas.  They  found that inexperienced persons tend to overestimate crown c l o s u r e , o f t e n f a i l i n g to make proper allowance f o r s m a l l stand openings, crown shadows, o r trees which were too s m a l l to cont a i n merchantable volume. Rogers, Avery and Chapman (1959) t e s t e d the.usefulness of.stand v a r i a b l e s f o r making volume estimates from a e r i a l photographs.  They secured the highest s i n g l e c o r r e l a t i o n w i t h  gross volume ( r 0.6827) f o r crown c l o s u r e , and concluded t h a t 10 per cent c l a s s e s represented the most r e f i n e d estimates of crown c l o s u r e that could be made c o n s i s t e n t l y w i t h a e r i a l photographs.  In the same year, Rogers, Avery and Chapman (1959)  compared three s c a l e s of a e r i a l photography f o r making stand measurements.  The crown c l o s u r e estimates on 1:1,000 photos  were about 4 per cent lower than the f i e l d average o f 55 per  45. cent.  On 1:5,000 photos, estimates averaged about 4 per cent  higher than the f i e l d value.  But n e i t h e r o f the two d i f f e r e d  s i g n i f i c a n t l y from the f i e l d value.  On 1:15,840 photos, the  average crown c l o s u r e estimate was 65 per cent.  This f i g u r e  was s i g n i f i c a n t l y d i f f e r e n t from the 55 per cent f i e l d average, but was s t i l l w i t h i n g e n e r a l l y acceptable  limits.  Moessner  (1962) computed c o r r e l a t i o n s and tested the three v a r i a b l e s f o r t h e i r usefulness i n c o n s t r u c t i n g p r e l i m i n a r y a e r i a l volume t a b l e s f o r panyon-guniper stands.  He obtained  the lowest cor-  r e l a t i o n between crown c l o s u r e and cubic volume but the highest c o r r e l a t i o n between crown c l o s u r e and number o f fence posts when using 10 per cent c l a s s e s .  However, both were s i g n i f i -  cantly correlated. 6.  Determination o f photo crown c l o s u r e . R e l a t i v e crown closure was determined separately  f o r each p l o t and not f o r the stand as a whole.  Since i t was  confirmed by Moessner (1947, 1948) that the crown d e n s i t y s c a l e s are more e a s i l y a p p l i e d and are, i n general, used by f o r e s t e r s , the w r i t e r has chosen the U.B.C. Photo-interpreter•s A i d f o r growth s t u d i e s .  Percentage crown closure was recorded  f o r each p l o t on three d i f f e r e n t s e r i e s o f photographs. w i l l be discussed  later.  These  46. Factors which i n f l u e n c e accuracy o f measurements o f trees and  stands 1.  Scale. A e r i a l photo-mensurational  techniques, being  a p p l i c a b l e to tree o r stand height e s t i m a t i o n , may be c a r r i e d out on photographs having optimum s c a l e o f approximately 1:12,000.  Since s c a l e i s a f a c t o r that tends to i n f l u e n c e  r e s o l u t i o n o f d e t a i l to a s u b s t a n t i a l degree, the smaller the s c a l e , the l e s s d e t a i l w i l l be resolved on the photographs. This i s e s p e c i a l l y true f o r those trees having l e s s than 3 f e e t i n crown diameter.  The chance o f underestimating height  o f c o n i f e r s therefore could be considered g r e a t e r than t h a t o f underestimating hardwood h e i g h t s .  The accuracy o f height  measurements on the photographs can be assumed to be d i r e c t l y p r o p o r t i o n a l to the s c a l e o f photography, provided the f o c a l length o f the camera, amount o f o v e r l a p , and other v a r i a b l e s are h e l d constant.  Various e f f e c t s o f s c a l e on height measure-  ments have been discussed by Andrews (1936), Bateman (1952), Lossee (1953), A l l i s o n (1956), Smith (1957), Pope (1957), and Johnson (1958).  Among them, no s i g n i f i c a n t d i f f e r e n c e was  found i n height measurements on photographic s c a l e s ranging from 1:7,000 to 1:20,000.  From the economical p o i n t o f view,  1:12,000 photos are considered to be an optimum.  47. Since the greater the s c a l e , the more the d e t a i l s w i l l be resolved on the photographs, accuracy of crown width measurements w i l l be increased w i t h increase i n s c a l e , provided the q u a l i t y o f the photographs remains the same.  This f a c t has  been proven by d i f f e r e n t i n t e r p r e t e r s w i t h various s c a l e s . The e r r o r s obtained were ranging from 0.54 photos to 4 f e e t on 1:15,000 photos.  f e e t on 1:1,200  In general, f o r s p e c i a l  purposes of crown c h a r a c t e r i s t i c s t u d i e s , i f the cost i s not the main f a c t o r , l a r g e r s c a l e photography i s recommended. However, f o r the combined purposes, i t would be preferable to use a s c a l e o f 1:12,000 f o r measurement o f crown width. E s t i m a t i o n of crown c l o s u r e from a e r i a l photographs i s i n v e r s e l y p r o p o r t i o n a l to photographic s c a l e s .  Since  smaller  s c a l e photographs tend to obscure minor openings, there i s a tendency to overestimate  crown c l o s u r e .  Under-estimate o f  crown closure by the s k i l l f u l i n t e r p r e t e r i s r a r e , whereas underestimate on the ground i s frequent.  On the whole, accep-  t a b l e scales f o r estimating crown c l o s u r e range from 1:7,000 to 1:20,000.  Systematic e r r o r s o f 5 to 10 per cent are regarded  as "not uncommon". 2.  P o s i t i o n of objects. P o s i t i o n o f o b j e c t s on the photographs as w e l l  as on the ground i s one of the f a c t o r s t h a t a f f e c t accuracy of  48.  photo-interpretation. the  The c l o s e r the image o f the object to  center of the photographs, the greater the accuracy of  measurement would be expected.  On the contrary, the data  recorded around the margin of the photographs are subject to maximum errors from aberrational defects, d i s t o r t i o n , underexposure, and t i l t .  Further, i n the case of tree images,  near the edge of the photograph, the bases of the trees are more obscured by the increasedc.dlsplacement of neighboring tree-tops.  I f the photograph i s t i l t e d , the scale on the  nadiAside of the photo i s greater, and error i n crown width measurement w i l l be introduced.  Since the image of the object  i s r a d i a l l y displaced outwardly from the p r i n c i p a l point, crown width should be measured perpendicular to the r a d i a l l i n e from the  p r i n c i p a l point through the tree image.  For p r a c t i c a l  purposes, s p e c i f i c a t i o n s o f photos should be stated.  Photos  with t i l t that exceed three degrees should be rejected f o r photo measurements.  The same e f f e c t would apply to crown  closure measurement around the edges of the photograph because i t would r e s u l t i n an underestimate of percentage crown cover due to excessive displacement of images that obscure portions of  crown canopy. Position of objects on the ground also influences ac-  curacy o f measurement.  Therefore interpreters should consider  49. whether the trees are open grown o r f o r e s t grown.  Accuracy  i n measurements o f height of open grown trees would be  greater  than that o f f o r e s t grown t r e e s , because the observers can e a s i l y detect the base o f t r e e .  A l s o , a smaller e r r o r w i l l  be obtained f o r independent trees because no c l o a k i n g o f branches occurs.  In a dense f o r e s t , t r e e height estimates  o n l y be approximate.  can  Spurr (1960) s t a t e d that trees growing  i n s m a l l v a l l e y s , r a v i n e s , and other depressions are frequently underestimated, while trees growing on k n o l l s and ridges are u s u a l l y overestimated,  owing to the i n a b i l i t y o f the observer  to see the ground a t the base o f the t r e e and h i s tendency to r e f e r h i s measurements to nearby openings a t d i f f e r e n t e l e v a t i o n s . 3.  Technique o f photo i n t e r p r e t e r s . I t has been repeatedly emphasized by d i f f e r e n t  photo-mensurationists  that the p h o t o - i n t e r p r e t e r i s the main  source o f e r r o r i n measurement o f t r e e height (Pope, Smith, 1957b; Johnson, 1958; Rogers, 1958; Oobie, I960).  1957;  and Smith, Lee  and  The d i f f e r e n c e s among i n t e r p r e t e r s have been  summarized by Colwe11 e t a l . (1954) as those o f v i s u a l a c u i t y and mental a c u i t y . 4.  Shape. Shape o f crown v a r i e s from species to species,  age to age and l o c a t i o n to l o c a t i o n .  The a b i l i t y o f the  50, observer to detect the a c t u a l top o f the crown requires knowledge o f morphology and l o c a l c o n d i t i o n s .  Hind l e y and Smith  (1957) suggested that improved s p e c i e s - i d e n t i f i c a t i o n w i l l come from b e t t e r knowledge o f t r e e shape and h a b i t a t .  Esti-  mates o f tree heights f o r hardwoods could be much more accurate than f o r c o n i f e r s , because the former possess r e l a t i v e l y f l a t crowns.  The e f f e c t o f a v e r y t h i n crown has been discussed  previously.  Influence o f i r r e g u l a r crowns on crown width  measurements might be greater than those o f c o n i c a l , pyramidal and dome shaped crowns.  Measurements o f crown widths f o r  hardwoods probably have g r e a t e r e r r o r s because o f i r r e g u l a r branches which can not r e g i s t e r on the p r i n t . 5.  Tone. E f f e c t o f t o n a l v a r i a t i o n o f photographic images  on p h o t o - i n t e r p r e t a t i o n depends mostly upon p o s i t i o n o f the sun w i t h respect to the camera and the topography.  The excessive  l i g h t e r o r darker t o n a l c o n t r a s t i s s u b j e c t to e r r o r i n photointerpretation.  Another source o f the tone o f an o b j e c t as  shown on an a e r i a l photograph i s d i r e c t l y a f f e c t e d by the amount and wavelength o f the l i g h t r e f l e c t e d from i t . (Hindley and Smith, 1957).  They concluded that emphasis should not be  placed too much upon t o n a l d i f f e r e n c e s through v a r y i n g f i l m f i l t e r combinations i n species i d e n t i f i c a t i o n .  51. 6.  Texture. The minuteness o f texture i s a key to recog-  n i t i o n of actual tree p o s i t i o n o r plot l o c a t i o n with respect to adjoining trees.  Texture also i s affected by the r e l a t i v e  p o s i t i o n o f the sun and the camera.  The e f f f e c t o f texture on  photo-interpretation would be the same as that o f tone. 7.  Shadow. The major e f f e c t on measurements of photo  variables i s shadow, because i t tends to obscure d e t a i l from being seen by the observer. a l l d e t a i l w i l l be Lost. measure photo-variables  On the shaded sides of mountains,  However, shadow can be used to such as tree height and crown width.  In this study, shadows of several trees were a great help where crowns were not well resolved on the photographs. 8.Equipment f o r photo-interpretation. The most important factor i n the process of photo measurements i s the i n t e n s i t y of l i g h t .  Underestimates  occur when measurements are made i n a r e l a t i v e dark room.  Using  a l i g h t table to have the combination of d i r e c t and i n d i r e c t l i g h t i n g i s regarded as the best procedure. scope i s commonly recognized of  photo-variables.  The pocket stereo-  as the best t o o l i n measurements  PROCEDURES IN PREDICTION OF GROWTH I n d i v i d u a l trees Growth, i n terms o f f o r e s t mensuration i s the amount o f increment over a given period o f time.  When i t a p p l i e s to  i n d i v i d u a l t r e e s , growth can be considered f o r s e v e r a l items such as t r e e h e i g h t , crown width, crown length, bark thickness and volume.  Growth information f o r t r e e h e i g h t , dbh, crown  width and crown length can be obtained by measuring the same sample trees a t c e r t a i n i n t e r v a l s .  These methods are u s u a l l y  c a l c u l a t e d as c u r r e n t annual increment o r mean annual increment. Determination o f volume growth f o r i n d i v i d u a l trees g e n e r a l l y takes the form of increment borings covering the l a s t ten years, o r of stem a n a l y s i s .  Various methods o f growth e s t i -  mation have been presented by many f o r e s t e r s .  Among them,  growth p r e d i c t i o n s as presented by Chapman and Meyer (1949) are most commonly used today.  Recently, Smith (1962) developed  a convenient way to summarize the r e s u l t s o f stem a n a l y s i s by c a l c u l a t i n g the r a t i o s of h e i g h t s and dbh a t d e s i r e d ages to those expected a t the reference age.  Following t h i s , Newnham  (1964) worked out a mathematical model by I.B.M. 7090 e l e c t r o n i c computer which describes the growth o f Douglas f i r stands on an i n d i v i d u a l tree, b a s i s , over a wide range o f s i t e c o n d i t i o n s , stand d e n s i t i e s , amounts and d i s t r i b u t i o n s of m o r t a l i t y , and t h i n n i n g regimes.  53. For the past decades, s t u d i e s i n regard to i n d i v i d u a l tree growth were concentrated on dbh r a t h e r than t r e e height o r crown width.  This i s mainly due to the f a c t that measure-  ments o f t r e e height and crown width used to take longer time and o f t e n d i f f i c u l t to o b t a i n accurate data.  However, s t u d i e s  made by d i f f e r e n t i n t e r p r e t e r s have convinced some f o r e s t e r s that growth estimates based on good q u a l i t y photographs can be made by s k i l l f u l p h o t o - i n t e r p r e t e r s w i t h o n l y l i m i t e d e r r o r s . 1.  Definition of site quality. S i t e i s the key f a c t o r i n determining what the  f o r e s t growth w i l l be. S i t e index i s Gommonly used as the height reached by f o r e s t stand a t a given stage i n i t s development.  Spurr (1952) s t a t e d that age and height make up s i t e  index, which i s an accepted measure o f s i t e q u a l i t y .  McArdle  et a l . (1949) defined s i t e index as the average t o t a l height o f dominant and codominant trees reached a t a given age-100 years f o r Douglas f i r i n the P a c i f i c Northwest.  Smith (1957a)  i n d i c a t e d that height and age are much more r e l i a b l e i n d i c a t o r s o f s i t e than a r e dbh and age, s i n c e growth i n height i s i n fluenced l e s s than dbh by competition.  I n the same r e p o r t , he  used l e s s e r v e g e t a t i o n as a basis i n c l a s s i f y i n g s i t e c l a s s e s f o r black cottonwood.  Worthington e t a l . (1960) a p p l i e d  height a t age 50 f o r determining s i t e index o f red a l d e r .  54. Smith (1962) has given f a c t o r s f o r converting height a t age between 10 and 100 years to h e i g h t a t age 50 years as s i t e index f o r Douglas f i r .  An i n d i r e c t assessment o f s i t e q u a l i t y  by using a e r i a l photos was c a r r i e d out by Smith and Bajzak (1961).  They found that s i t e q u a l i t y was s i g n i f i c a n t l y cor-  r e l a t e d w i t h moisture regime. 2.  Y i e l d tables as c r i t e r i a o f growth estimates. I n order to s e t up a c r i t e r i o n f o r growth  estimates on the photographs, d i f f e r e n t height/age curves were a p p l i e d to f i v e species.  The assumption was t h a t height  growth p r e d i c t e d from the photographs would be equal to a c t u a l growth o f the same tree on the ground.  Because i t was im-  p r a c t i c a l to o b t a i n past growth data f o r these sample t r e e s , o n l y i n d i r e c t data were considered.  Despite the f a c t that  when applying these y i e l d tables f o r growth e s t i m a t i o n , they themselves are subject to e r r o r , there was no s u b s t i t u t e to be chosen.  Smith and Ker (1956) concluded that even the best  o f s i t e measures were r e l a t i v e l y poor estimaters o f present o r past y i e l d , y e t they could f i n d no good s u b s t i t u t e f o r s i t e and age i n p r e d i c t i n g f u t u r e growth. 3.  Height/Age curves (H/A c u r v e s ). Sources o f the H/A curves used are as f o l l o w s :  Douglas f i r  - McArdle, Meyer and Bruce (1949)  Western hemlock- Barnes (1962)  55. Western red cedar - Smith, Walters, and Ker (1961) Red a l d e r  - Bishop and Johnson (1958)  Black cottonwood  - Smith (1957a).  This t a b l e was  from  Hesmer (1951) but was confirmed  by  extensive sampling i n the Lower Fraser R i v e r V a l l e y o f B r i t i s h Columbia. 4.  Determination o f  age.  Methods of determining age o f trees have been described by s e v e r a l f o r e s t e r s . Belyea (1946) suggested four ways of determining age o f t r e e s .  Bruce and Schumacher (1950)  combined the t h i r d method (increment boring) and the f o u r t h method ( r i n g count) to present three methods of age ation.  determin-  A l l o f these methods can be a p p l i e d to d i f f e r e n t s i z e s  o f trees f o r v a r i o u s purposes.  For example, the whorl count  method can o n l y apply to younger c o n i f e r s w h i l e increment boring can not be used to determine the true age o f trees w i t h radius greater than the length o f increment borer. E s t i m a t i o n of age o f trees from the photographs was considered to be impossible by Spurr (I960).  Studies o f stand  age e s t i m a t i o n i n even-age Douglas f i r was c a r r i e d out by B e r n s t e i n (1964).  He found that the standard d e v i a t i o n of the  d i f f e r e n c e between f i e l d and photo ages was  -17 years.  There-  56. f o r e , he concluded that u s i n g a e r i a l photographs to determine a usable stand age was i m p r a c t i c a l *  A new concept o f age  e s t i m a t i o n from the a e r i a l photographs has been developed by Wang (1965) through the use o f a s e r i e s o f photographs.  This  method i n v o l v e s the d e t e c t i o n o f the approximate year o f establishment o f trees and stands.  R e s u l t s o f t h i s study are  summarized i n h i s F o r e s t r y 564 r e p o r t . 5.  P r e d i c t i o n o f t h e o r e t i c a l h e i g h t growth. I n applying H/A curves, s i t e index f o r each  i n d i v i d u a l tree was f i r s t determined.  According to previous  surveys, s i t e i n d i c e s f o r Douglas f i r , western hemlock, and western r e d cedar were r e a d i l y obtained from the U n i v e r s i t y Research Forest S i t e Index Map (Smith and Bajzak, 1961). S l i g h t adjustment was made f o r trees on the boundaries o f d i f f e r e n t types. S i t e i n d i c e s f o r r e d a l d e r s were determined w i t h r e f erence to the g e n e r a l appearance, ecology and s i t e requirements (Worthington e t a l . , 1962) as well as r e l a t i v e r e l a t i o n s h i p s o f dbh to height (B.C. Forest Service Y i e l d Table f o r Red Alder). Assessment o f s i t e i n d i c e s f o r b l a c k cottonwoods were made by means o f the s i t e c l a s s i f i c a t i o n described by Smith (1957a).  Approximate r a t i o o f dbh and h e i g h t were checked from  Hesmer's yield table (1951).  57. Once s i t e i n d i c e s f o r a l l the i n d i v i d u a l trees were determined, a c t u a l t r e e heights were p l o t t e d on the corrected H/A  curves to f i n d corresponding ages.  For example, f o r a  Douglas f i r , assume i t s s i t e index was found to be 120, and a c t u a l ground height measured i n 1954 was 110 f e e t .  By l o c a t i n g  t h i s point on the SI 120 curve, then p r o j e c t i n g down to the a b s c i s s a , reference age f o r t h i s tree would be  determined.  For example, the years elapsed during the time o f photography 1954 - to next period o f photography, say 1963, then p r o j e c t the new age up to f i n d the i n t e r s e c t i o n o f t h i s l i n e and the SI 120 curve; t h i s i s supposed to be the height i n 1963.  The  d i f f e r e n c e between the two i s the t h e o r e t i c a l height growth. S i m i l a r l y , by counting back to the time o f previous photography, another t h e o r e t i c a l height ^during the e a r l i e r stage can be found. 6.  R e l a t i o n s h i p s among crown width, dbh and height. Determination of t h e o r e t i c a l crown width growth  i s r e l a t i v e l y more complicated than that of height growth.  For  determining t h e o r e t i c a l crown width growth, r a t i o s o f crown width to dbh (CW/D) (Smith e t a l . 1961b) were a p p l i e d .  Pro-  cedures i n p r e d i c t i n g t h e o r e t i c a l crown width growth are i l l u s t r a t e d i n Appendix I I I . Since a v a i l a b l e r a t i o s o f CW/D  were l i m i t e d to o n l y  Douglas f i r , hemlock, and red cedar, a l t e r n a t i v e methods were  58. adopted f o r red a l d e r and black cottonwood.  For red a l d e r ,  three "best f i t " equations were worked o u t f o r trees growing at d i f f e r e n t s i t e s .  They a r e :  1.  D = 0.2415 + 0.4605A  SI 80 and under,  N=38,  r=0.74  2.  D =2.9408 + 0.3829A  SI 90-100,  N=16,  r=0.8699  3.  D = 7.9303 + 0.2771A  SI 110+,  N=7,  r=0.6671  D  =  dbh i n inches;  N = number o f t r e e s ;  A  =  age i n years;  r = simple c o r r e l a t i o n c o e f f i c i e n t .  where:  The basic data were s e l e c t e d from Apsey's t h e s i s (1961). Equat i o n s were worked out by the w r i t e r .  A f t e r dbh's were c a l c u -  l a t e d , they were s u b s t i t u t e d i n t o the CW equation to o b t a i n CW.  The equation worked out by Apsey (1961) was: CW  where CW  =  8.032 + 1.530D  = crown width i n f e e t ,  D  =  dbh i n inches.  The same approach was a p p l i e d to cottonwood.  Basic data f o r 43  open grown cottonwood were s e l e c t e d from Pearson's t h e s i s (1962). The equation f o r c a l c u l a t i n g dbh i s : D = 3.4933 + 0.4405A  SI 0 - 79 a t 25 years. r=0.6535  and the basic CW equation worked out by Pearson was: CW  =  0.543 + 1.616D  59.  The expected crown width growth f o r both alder and cottonwood was the difference of two t h e o r e t i c a l widths at d i f f e r e n t periods. 7.  Photo values and curved values. After a l l the calculations were completed,  photo measurements and curved values were tabulated f o r height and crown width i n d i v i d u a l l y f o r comparisons of growth e s t i mates on the photos with t h e o r e t i c a l growth.  As has been  mentioned, t h e o r e t i c a l values are a r e s u l t of mathematical execution combined with s t a t i s t i c a l theory.  To a t t a i n i d e n t i -  c a l results i n successive samples, of course, i s r a r e l y expected except by chance.  Therefore t h e o r e t i c a l values are by no  means the best measure with which to determine accuracy o f photo growth estimates, but they can be used as c r i t e r i a .  Stands Among various methods, prediction o f growth f o r stands usually takes the form of estimating volume growth i n terms of making comparisons between growth of diameter classes.  This  i s on the basis that the response of the trees i n a forest to t h e i r environment i n terms of growth i s considered to be a recurring series of phenomena, which i s repeated by each s i z e class i n i t s normal progression from dimension to dimension.  60.  Some foresters use graphic projection of the past growth of diameter classes as a basis f o r predicting volume growth of stands, and other prefer to predict growth based on growth variables such as age, s i t e classes, density of stands  and  merchantability, etc. Recent developments i n the use of a e r i a l photographs to estimate timber volume f o r various species at d i f f e r e n t l o c a l i t i e s have acquired public support and p r a c t i c a l a p p l i cation.  Photo variables such as average stand height, average  crown width, and crown closure could also be used as growth variables on the ground, provided s u i t a b l e a e r i a l photographs taken at succeeding periods of the year were a v a i l a b l e . Growth estimates based on the photo-mensurational  method might  greatly reduce the cost i f compared with ground methods.  For  this purpose, studies were concentrated on three items: compil a t i o n height (H), crown closure (CC) and crown width  (CW),  whereas the fourth v a r i a b l e , number of trees (or tree count) was neglected because i t has been frequently rejected as a l e a s t s i g n i f i c a n t v a r i a b l e i n f i t t i n g the equation of stand volume.  Tree count w i l l be discussed at the end of t h i s section. 1.  Compilation height. Stand height i n terms of compilation height  o f t e n i s defined as the average height of dominant and codominant  61. trees i n the stand.  Meyer (1940) described a mathematical  expression o f height growth by using the average height o f 40 trees per acre i n the dominant and codominant c l a s s e s .  Smith  e t a l . (1960) a p p l i e d average height and standard d e v i a t i o n o f the 10 t a l l e s t trees on each o f 0.1 acre p l o t s i n d i s c u s s i n g the r e l a t i v e merits o f n a t u r a l and conventional height/age curves f o r Douglas f i r .  Spurr (1963) has t e n t a t i v e l y  suggested  that the mean height o f 40 l a r g e s t diameter stems per acre would be the best measure o f stand h e i g h t .  Newnham (1964)  advocated p r e d i c t i o n o f mean height growth f o r the 100 l a r g e s t diameter trees per acre r a t h e r than f o r the average h e i g h t . I f the rough r u l e o f thumb a p p l i e s , f o r f o r e s t grown P a c i f i c Coast s p e c i e s , the dbh i n inches i s equal to the crown diameter i n f e e t .  However, f o r stands where trees a r e densely  stocked, there always e x i s t s a tendency o f greater c l o a k i n g o f tree crowns.  This may lead to i n c o r r e c t s e l e c t i o n o f the  l a r g e s t t r e e s , although t h i s chance o f making a wrong d e c i s i o n i s not great. Conventionally, volume estimates based on a e r i a l photographs measure average height o f dominant and codominant trees i n a plot.  Avery and Myhre (1959) used the average t o t a l  height o f three t a l l e s t trees on one acre c i r c u l a r p l o t f o r c o n s t r u c t i n g a composite a e r i a l volume t a b l e f o r southern  62. Arkansas.  I n the same year Avery and Meyer (1959) measured  the four t a l l e s t trees on each one-acre p l o t i n c o n s t r u c t i n g a e r i a l volume tables f o r Northern Minnesota.  Moessner (1962)  used f i v e o f the t a l l e s t trees to make f i v e measurements on one-acre p l o t s .  However, r e l a t i v e l y i n t e n s i v e measurements  were made by Rogers £t §±. (1959) and Pope (1962).  They  s e l e c t e d three t a l l e s t trees on o n e - f i f t h - a c r e p l o t as a basis f o r determining stand h e i g h t , and Smith e t al.(1960) made four height measurements f o r 0.2-acre p l o t s i n checking the e f f e c t of s c a l e to photo-measurements.  Rogers (1961) applied the  three t a l l e s t trees as a basis i n surveying Caspian f o r e s t s of I r a n . The d e c i s i o n as to how many trees are necessary can be c a l c u l a t e d s t a t i s t i c a l l y i n terms o f standard d e v i a t i o n and allowable e r r o r .  I n p r a c t i c e , the conventional  has been w e l l accepted.  approach  Therefore, f o r the f i f t e e n p l o t s so  f a r s t u d i e d , the w r i t e r has chosen the four t a l l e s t trees as a c h a r a c t e r i s t i c o f each p l o t .  The t o t a l height and crown  width f o r each o f the four trees were measured.  Repeated  measurements were made f o r both permanent sample p l o t s (P.S.P.'s) and the n a t u r a l regeneration s e r i e s o f photographs taken i n 1963,  p l o t s on the three  1955 and 1949.  I n order  to get a s u i t a b l e number o f years f o r growth comparisons o f the G r i f f i t h p l o t s , the 1930 s e r i e s was used i n s t e a d o f 1963  63.  because h i s p l o t s were c l e a r - c u t i n 1958. For  each p l o t , the average o f four heights was taken.  A l s o t h e o r e t i c a l c o m p i l a t i o n heights were prepared and theore t i c a l height growths were compared w i t h the height growths obtained from the photographs.  The d i f f e r e n c e between the  two sets o f photographs was the growth o f p l o t o r p l o t s . 2.  Crown width. The method o f measurement o f crown widths f o r  the p l o t s was the same as that f o r i n d i v i d u a l t r e e s .  To reduce  e r r o r s due to i n c o r r e c t l o c a t i o n , crown widths were measured immediately a f t e r p a r a l l a x readings o f the four trees i n a p l o t were taken.  Two wedge readings were recorded f o r each  tree to o b t a i n an average.  Photo-crown widths were c a l c u l a t e d  by m u l t i p l y i n g corresponding s c a l e to average wedge readings. T h e o r e t i c a l crown widths were c a l c u l a t e d w i t h the same methods a p p l i e d to i n d i v i d u a l t r e e s , but average o f "open" and "dense" CW/D r a t i o s were used i n s t e a d o f using a s i n g l e r a t i o , CW/D (open) + CW/D (dense) i . e . , CW = 2 (dbh) where CW = t h e o r e t i c a l crown w i t h i n f e e t and dbh = diameter from D/Age curves, i n inches.  Thus average crown width f o r  each p l o t was obtained as a basis f o r growth estimates between two d i f f e r e n t periods. f e r e n t stands.  Comparisons were made f o r three d i f -  64. 3.  Crown c l o s u r e . The t h i r d v a r i a b l e f o r growth s t u d i e s i s  crown c l o s u r e . out  Measurements o f crown c l o s u r e were c a r r i e d  w i t h the a i d o f U.B.C. crown d e n s i t y s c a l e s .  A double  s c a l e w i t h a s l i p o f white paper attached to the lower surface of each s c a l e was a p p l i e d because Lee (1959) acquired s a t i s f a c t o r y r e s u l t s by using t h i s method.  The importance o f  crown c l o s u r e as a unique v a r i a b l e i n e s t i m a t i n g annual growth was found by Rogers (1961).  Crown c l o s u r e i n t h i s study was  recorded i n terms o f 10-per cent c l a s s e s f o r each p l o t throughout a l l s e r i e s o f photographs.  A l l t e s t s f o r crown  c l o s u r e growth were analyzed on a r e l a t i v e basis s i n c e no standards f o r comparison were a v a i l a b l e . 4.  Number o f Trees. Counts o f number o f stems i n terms o f v i s i b l e  crowns on a e r i a l photographs can be made w i t h a c e r t a i n amount of accuracy o n l y under conditions where medium o r large s c a l e photographs are a v a i l a b l e and i n d i v i d u a l crowns are separate and d i s t i n c t l y seen under the stereoscope. Requirements f o r photographs are ftheisameeastifor crown width measurements. I t can be assumed that the l a r g e r the photographic s c a l e , the higher c o r r e l a t i o n with a c t u a l ground counts w i l l be obtained. Overestimates o f crown counts are r a r e but underestimates are  65. common, because trees w i t h very small crowns are o f t e n d i f f i c u l t to detect on the photographs.  On small s c a l e photographs  underestimates o f 50 per cent are q u i t e common where homogeneous densely stocked stands are present.  Spurr (I960) i n d i c a t e d  that i n e a r l y German t e s t s w i t h photographs o f from 1:4,000 to 1:7,500, underestimates o f dominant crown counts i n managed c o n i f e r stands d i d not exceed 5 per cent o f the number o f v i s i b l e crowns, but on smaller s c a l e photographs, crown counts cannot o r d i n a r i l y be made w i t h such accuracy.  G i n g r i c h and  Meyer (1955) obtained very poor c o r r e l a t i o n between the tree counts on the photographs and the a c t u a l t r e e number f o r mixed hardwood stands.  Lee (1959) found h i g h l y s i g n i f i c a n t c o r r e -  l a t i o n between tree counts and a c t u a l number o f trees on the plot.  However, i n m u l t i p l e r e g r e s s i o n estimates o f stand  volume, tree count d i d not Increase the m u l t i p l e c o r r e l a t i o n c o e f f i c i e n t (R). Conventionally, i n c o n s t r u c t i n g stand volume t a b l e s , crown count has seldom been accepted as an important v a r i a b l e . Since Smith and Ker (1957b) stated that number o f trees i s one o f the most commonly studied f o r e s t v a r i a b l e s , i f l a r g e s c a l e photographs are a v a i l a b l e , " v i s i b l e crown counts" can be used f o r large area reproduction surveys as studied by Smith and Ker (1958).  S e l e c t i o n o f the best a v a i l a b l e papers  66.  i s an important f a c t o r governing q u a l i t y o f photo image d e t a i l because a t e s t made by Meyer and TrantGRS (1957) showed that the i n t r o d u c t i o n o f a brown tone i n t o the photo i n t e r p r e t a t i o n process had harmful e f f e c t s upon the success o f the crown counts.  They found a h i g h l y s i g n i f i c a n t d i f f e r e n c e  between the mean counts produced by the two types o f photo processing. I n t h i s study, however, no a t t e n t i o n was paid to v i s i b l e crown counts due to i t s l i m i t e d importance i n photomensuration.  67 ANALYSIS OF DATA Individual trees The effects of various factors which influence the accuracy o f photo-measurements have been mentioned. However, i n order to carry out a r e l a t i v e l y detailed analysis, photographic images were c l o s e l y examined f o r each tree on various series of photographs. Three grades o f image quality were set up by the writer:  "good", "medium" and "poor".  Defini-  tions f o r these three levels are: Good  - both the base and the top of the tree can be seen very c l e a r l y .  Medium  - either the base or the top o f the tree can not be seen c l e a r l y due to shadow, l i g h t r e f l e c t i o n or narrow crown, e t c .  Poor  - both the base and the top of the tree can not be seen c l e a r l y and only give a vague image.  The results o f photo-measurements and curved values f o r both tree heights and crown widths were tabulated f o r each group of i n d i v i d u a l trees by image q u a l i t y , s i t e q u a l i t y and years. As can be seen from Table 5, the number of trees measured on the ground were summarized by species and year of measurement.  The t o t a l number of sample trees which can be  used as control f o r defining the accuracy of measurements  68. i s 135, o f which 95 are "good", 34 are "medium" and 6 are "poor".  However, i t was impossible that a l l o f the 135 trees  could be measured on each s e t o f photographs because o f changes i n f o r e s t c o n d i t i o n o r imperfect photographic coverage o f the f o r e s t area. Table 5:  Number o f trees measured on the ground by species and year.  Year  F  C  1964  13  11  1963  27  1954  H  AL  CW  51  6  12  16  58  6  10  0  0  43  14  11  9  0  0  34  54  28  25  12  16  135  Table 6 shows the number o f trees measured and image q u a l i t y by species and year o f photography.  The t o t a l number o f trees  measured on the photographs i s 634, but the number o f trees d i f f e r s from year to year o f photography w i t h species and a l l species.  Table 7 was produced by converting the number o f  ' trees shown i n Table 6 i n t o percentage i n terms o f t o t a l number o f trees measured i n the year f o r f i v e d i f f e r e n t species and a l l species. Obviously from Tables 6 and 7, two s e r i e s o f photographs - 1930, 1940 - should be r e j e c t e d f o r growth s t u d i e s because the number o r percentage o f poor image trees i s f a r  Table 6. Year  Number o f trees measured and image q u a l i t y by species and year of photography (height o n l y ) .  1964  G 4  F M 7  P 2  1963  37  7  4 48  1961  20  16  3  1958  17  11  1955  21  1954  r  13  S p e c i e s C x G M P 8 13 1 22  G 4  H  M 9  P 0  X 13  G 5  AL M 7  69.  -A l l Spp  CW P 0  I 12  G  M  P  -  -  .-  x  G 21  M 36  P 3  X 60  21  4  G  25  13  5  0  18  11  1  0  12  11  5  0  16  93  22  4  119  39  2  6  0  8  4  4  0  8  11  0  1  12  11  0  1  12  47  28  4  15  43  0  6  2  8  0  6  1  7  8  5  1 14  25  28  19  79 72  16  3  40  10  13  2  25  6  11  0  17  6  3  1  10  3  9  2 14  46  52  8  106  16  15  5  36  5  6  0  11  2  4  3  9  3  5  1  9  3  4  7  14  29  34  16  79  1949  21  6  0  27  7  7  1  15  1  13  1  15  3  5  1  9  1  14  38  38  4  80  0  3  5  8  0  0  4  4  0  0  2  2 -  0  0  12  12  3  23  26  0  1  4  5  0  1  4  5  0  1  2  3 -  -  -  0  1930  -  7  1940  -  6  --  0  3  10  13  136  82  42 259  53  56  14 123  30  53  9  39  21  64  41  32  23  96 299  244  91  634  x  92  Table 7:  Image q u a l i t y expressed i n percentage f o r trees measured by species and year (height o n l y ) .  Year  F (%•) G  M  S p e c C (7,) P  G  M  i e s  G  4  -  CW  A l ( %>  H (%)  P  -  -  M  P  G  M  A l l Spp (%)  (%) G  M  P  P  G  M  P  _  -  -  35.0  60.0  5.0  1964  30.8  53.8  15.4  36.4  59.1  4.5  30.8  69.2  0  41.7  58.3  0  1963  77.0  14.6  8.4  84.0  16.0  0  72.2  27.8  0  91.7  8.3  0  68.8  31.2  0  78.2  18.5  3.3  1961  51.3  41.0  7.7  25.0  75.0  0  50.0  50.0  0  91.7  0  83.3  16.7  0  59 .4  35.5  5.1  1958  39.5  25.6  34.9  0  75.0  25.0 0  85.7 14.3  -  8.3  -  -  57.1  35.7  7. 2  34.7  38.9  26.4  1955  52.5  40.0  7.5  40.0  52.0  8.0  35.3  64.7  60.0  30.0  10.0  21.4  64.3  14.3  43.4  49.1  7.5  1954  44.4  41.6  14.0  45.5  54.5  0  22.2  44.4 33.4  33.3  55.6  11.1  21.4  28.6  50.0  36.7  43.0  20.3  1949  75.0  21.4  3.6  46.7  46.7  6.6  86.6  33.3  55.6  11.1  42.9  47.5  47.5  5.0  1940  0  37.5  62.5  0  0  100.0  0  7. 1 5Q.0 Q 100.0  0  11.5  88.5  1930 X  0  20.0  80.0  0  20.0  80.0  0  0  23.1  76.9  52.5  31.7  15.8  43.1  45.5  11.4  32.6  38.5  14.3  6.7  0  0 7.7 100.0  33.3 66.7 57.7  9.7  -  -  60.9  32.8  -  6.3  0  -  -  -  38.7  39.6  21.7  40.2  70. greater than those o f medium image t r e e s .  No good image tree  was found on these two s e t s o f photographs.  The w r i t e r ,  t h e r e f o r e , decided not to consider e i t h e r the 1930 o r the 1940 s e r i e s f o r the f u r t h e r s t u d i e s o f i n d i v i d u a l t r e e e s t i mates o f growth. D e f i n i t i o n s o f symbols The f o l l o w i n g d e f i n i t i o n s o f the symbols w i l l apply throughout t h i s t h e s i s h e r e a f t e r , they a r e : N  =  number o f observations ( t r e e s ) ,  X  = mean v a l u e s , i n f e e t ,  SEg =  standard e r r o r o f the mean d i f f e r e n c e , i n f e e t ,  P  =  an< average o f f o u r photo-heights, i n f e e t ,  Ck  =  checking-photo-height, i n f e e t ,  G  =  ground data, i n f e e t ,  C  =  curved v a l u e , i n f e e t (except s p e c i f i e d by Spp),  Spp = s p e c i e s , P--G=  an average o f f o u r heights and ground data  Codes f o r species (Spp): F  =fir,  C  =  western red cedar,  H  =  western hemlock,  Al  =  red alder,  Cot =  black cottonwood.  71. Accuracy of height measurement on the photos In order to define the accuracy o f growth estimation on the photographs, the accuracy of height measurements was determined f i r s t .  Calculations f o r both mean heights and  standard errors of the mean difference were executed by I.B.M. 7040 f o r photo measurements and ground data.  Statistically,  either mean value o r standard error of the difference can be independently applied f o r making comparisons between photo measurements and ground data.  Standard error o f the mean  difference was used to set up a l i m i t f o r further comparisons between photo measurements and curved values.  The formula  applied to c a l c u l a t i o n o f standard error o f the mean difference is:  / D? - ( D SE=  =  / — ^  J  ) /N 2  J  N( N - l )  . . . .from Steel and Torrie (1960)  where: SEg  =  standard error o f the mean difference,  =  sum of differences squared,  N  =  number of observations,  N-l  =  degree of freedom.  2 D  Table 8 shows the results o f computation f o r 135 trees measured on the ground and on the photographs. significantly  The mean error increased  with l e v e l o f image quality f o r Ck--G, but a  72. Table 8: Accuracy o f h e i g h t measurements f o r a l l species by q u a l i t y o f images. Quality of Image  •*  X  N  P  Good  95  88.7  Medium  34  95.1  6  102.9  G-M  129  91.4  G-P  135  91.5  Poor  (ft.)  Mean E r r o r ( f t . )  SE£ ( f t . )  G  P--G  Ck—G  P—G  Ck—G  88.5  89.0  -0.3  -0.5  0.29  0.25  93.6  94.7  +0.4  -1.1  0.93  0.89  103.7 109.9  -7.0  -6.2  4.43  5.23  90.8  91.6  -0.3  -0.9  0.33  0.30  91.0  92.2  -0.7  -1.2  0.40  0.39  Ck  r e l a t i v e l y smaller e r r o r appeared i n the case o f medium image trees f o r P—G.  The SE5 increases remarkably from good image  trees to poor image trees f o r both P—G and Ck—G.  The  greatest e r r o r s were found i n the case o f poor image t r e e s , a f a c t which corresponds to the assumption that the poor q u a l i t y of tree images a f f e c t s the accuracy o f growth estimates, and consequently, photo-series which have a greater number o f poor image trees should be r e j e c t e d f o r growth s t u d i e s .  The increase  i n S E D from good through poor may p a r t l y be accounted f o r by the corresponding decrease i n number o f trees measured. Since  G  can be used as c o n t r o l , comparison off: the  accuracy o f h e i g h t measurements o f P made from the mean e r r o r o f P—G o f P—G show that  and Ck—G. P  and Ck  and C k — G  can r e a d i l y be o r , from SE5  From Table 8, the r e s u l t s o f mean e r r o r  i s s u p e r i o r to Ck. However, the SE^ shows a  tendency o f Ck  to be s u p e r i o r to P.  Therefore, i t seems  73. to be impossible to apply both mean e r r o r and SEg i n d e f i n i n g the accuracy o f  P  and  Ck.  I f o n l y the SE5 i s a p p l i e d , a  r e l a t i v e l y c o n s i s t e n t conclusion might be obtained, i . e . , the accuracy o f height measurements i s p r o p o r t i o n a l to l e v e l o f image q u a l i t y , and though  Ck  i s s l i g h t l y superior to  (except poor), the d i f f e r e n c e between  P  and  P  Ck, does not  seem to be s i g n i f i c a n t . A - f u r t h e r a n a l y s i s was made f o r both c o n i f e r s and hardwoods.  Table 9 shows the r e s u l t s f o r good image c o n i f e r s and  hardwoods. Table 9:  I t can be seen that f o r c o n i f e r s , mean e r r o r f o r Accuracy o f height measurements f o r good image c o n i f e r s and hardwoods. N  Spp  X  P  Ck  ( f t . ) Mean e r r o r ( f t . ) SEp ( f t . ) G P—G Ck—G P--G Ck—G  Conifers  74  94.8  94.7  95.4 -0.6  -0.7  0.35  0.30  Hardwoods  21  74.3  73.6  73.9 +0.4  -0.3  0.48  0.41  P--G i s s m a l l e r than that f o r C k — G .  However, the d i f f e r e n c e  i s o n l y -0.1, and the d i f f e r e n c e between P—G SE5  i s 0.05, but Ck i s s u p e r i o r to  SEQ e x i s t s .  P  and C k — G under  because a smaller  I n f a c t , these s m a l l d i f f e r e n c e s can be regarded  as not s i g n i f i c a n t .  For hardwoods, both mean e r r o r and SEg  give c o n s i s t e n t r e s u l t s ; the values obtained from Ck' s seem to give much more accurate r e s u l t s than those from P's.  In  74. the same t a b l e , determination o f the accuracy o f height measurements f o r c o n i f e r s and hardwoods i s a l s o d i f f i c u l t due to d i f f e r e n t r e s u l t s obtained from mean e r r o r and SE£. Assuming that o n l y SEg i s a p p l i e d , measurements o f c o n i f e r s appeared to be much more accurate than those o f hardwoods. In order to d e f i n e the accuracy o f height measurements, a single s t a t i s t i c  (SEp) can account f o r d i f f e r e n c e between  two groups o f data. Table 10 shows the r e s u l t s obtained f o r medium image c o n i f e r s and hardwoods.  The SEjj's showed a c o n s i s t e n t agreement  Table 10: Accuracy o f h e i g h t measurements f o r medium image c o n i f e r s and hardwoods. SPP  N  P  x(ft.) C G  Mean e r r o r ( f t . ) SE5 ( f t . ) P--G Ck—G P—G Ck—G  Conifers 27 100.9 99.9 100.9 +0.  -1.0  1.11  1.11  Hardwoods 7  -0.7  1.52  0.92  72.7 69.3  71.0 +1.7  w i t h the r e s u l t s o f hardwoods shown i n Table 9. to be s u p e r i o r to P.  The Ck appears  For the c o n i f e r s , the SEj^s remain the  same f o r both P and Ck.  The c o n i f e r s showed b e t t e r r e s u l t s  than the hardwoods f o r P--G, but showed r e s u l t s i n f e r i o r to the hardwoods f o r C k — G , although the d i f f e r e n c e was not great. A summary o f both good and medium image trees f o r the c o n i f e r s and hardwoods i s shown i n Table 11.  75. Table 11: Accuracy o f height measurements f o r good to medium image c o n i f e r s and hardwoods. x (ft.)  Spp  Mean e r r o r ( f t . ) SE" •( f t . )  P  C  G  P--G  Ck—G  P--G Ck—G  Conifers 101  96.3  95.9  96.8  -0.5  -0.9  0,39 0.37  Hardwoods 28  73.7  72.4  72.8  +0.9  -0.4  0.51 0.35  N  I t can be concluded from Tables 9 to 11 that the accuracy o f height measurements f o r the c o n i f e r s i s greater than that f o r the hardwoods, and that Ck method i s s l i g h t l y b e t t e r than the P method.  The allowable standard e r r o r o f the mean d i f f e r e n c e  f o r the small number o f 27 c o n i f e r s i s +1.11 f e e t and f o r 7 hardwoods i s +1.52 f e e t when the q u a l i t y o f image i s medium. For the good image t r e e s , standard e r r o r o f the mean d i f f e r e n c e decreased to +0.35 f e e t f o r the c o n i f e r s and +0.48 f e e t f o r the hardwoods.  This r e s u l t i s contrary to the assumption that  measurements o f height f o r the hardwoods would be g i v i n g b e t t e r r e s u l t s than that f o r the c o n i f e r s .  I t can not be concluded  from these three tables that the accuracy o f height measurements f o r the hardwoods i s l e s s than that o f the c o n i f e r s because, as the number o f observations woods, the e r r o r might be smaller. same number o f observations  i s increased f o r hard-  I t i s p o s s i b l e that i f the  was taken f o r both c o n i f e r s and  hardwoods, the hardwoods would give greater accuracy than the conifers.  The checking method though appeared to be b e t t e r  76. than the c o n v e n t i o n a l method o f u s i n g an average o f f o u r measurements, y e t the d i f f e r e n c e does not seem to be ficantly Table 12:  Spp  N  signi-  great. Accuracy o f h e i g h t measurements f o r good to medium t r e e s by s p e c i e s . P  x(ft.) Ck G  mean e r r o r ( f t . ) SE5 ( f t . ) P—G Ck—G P—G Ck—G  F  51  95.1  95.3  96.4  -1.3  -1.1  0.48  0.48  C  28  88.8  88.2  88.1  +0.7  +0.1  0.84  0.49  H  22  108.6  107.2 108.5  +0.1  -1.3  0.83  0.81  Al  12  66.2  66.2  66.2  +0.  +0.  0.81  0.47  Cot  16  79.3  77.1  77.7  +1.6  -0.6  0.63  0.51  An attempt was made, i n a n a l y s i n g the data o b t a i n e d ,  to  f i n d the accuracy o f h e i g h t measurements f o r f i v e s p e c i e s . None o f the SEg's shown i n Table 12 exceeds +1.0  feet.  It is  i m p o s s i b l e to determine which s p e c i e s g i v e s b e t t e r r e s u l t s u n l e s s the same number o f o b s e r v a t i o n s were o b t a i n e d f o r each s p e c i e s , o r c o n s i d e r a t i o n i s g i v e n to the number o f samples involved. A c o n s i s t e n t r e s u l t was  obtained  f o r each s p e c i e s  (except Douglas f i r ) t h a t Ck i s b e t t e r than P.  I t would be  p r e f e r r a b l e to have a s u f f i c i e n t and an e q u a l number o f  obser-  v a t i o n s randomly o r s y s t e m a t i c a l l y chosen f o r each s p e c i e s i n o r d e r to proceed w i t h a n a l y s i s o f v a r i a n c e and determine the levels of significance.  S i m i l a r i l y , i f a s u f f i c i e n t and  an  e q u a l number o f o b s e r v a t i o n s c o u l d be o b t a i n e d f o r each s p e c i e s  77. on d i f f e r e n t s e r i e s o f photographs,  there would be no d i f f i -  c u l t y i n determining the accuracy o f growth estimates from the photographs,  and the v a r i e d l e v e l s of accuracy of measure-  ments f o r d i f f e r e n t species would be defined. Comparisons o f photo-heights and curved heights A f t e r the accuracy of height measurements on the photographs was determined by comparing the photo-heights w i t h ground h e i g h t s , a l l the photo-measurements, excepting the poor image t r e e s , were computed together w i t h curved v a l u e s . S t a t i s t i c s w i t h respect to f i v e species were obtained and summarized i n Tables 13 to 17, according to the year of photography.  The purpose o f a n a l y s i s of the i n d i v i d u a l species was  to detect whether c o n s i s t e n t r e s u l t s could be obtained i n the s e l e c t i o n o f proper photo-series, and a t the same time, to d i f f e r e n t i a t e the accuracy o f height measurements between P and Ck.  Another o b j e c t i v e was to f i n d whether great d e v i a t i o n s  e x i s t e d between the photo-heights and the heights obtained from the H/A  curves. According to Table 13, two s e r i e s o f photographs -  1940 and 1964 - have o b v i o u s l y shown greater e r r o r s than the remaining s e r i e s o f photos.  The s m a l l number o f observations  might be the main source o f d e v i a t i o n , but a survey on the photographs showed poor photography w i t h these two s e r i e s o f  N  photos.  ^  78.  The SE^'s f o r 1958 s e r i e s were next h i g h e r to 1940  and 1964 s e r i e s , w h i l e none o f the  SE5's obtained  from 1963,  1961, 1955, 1954 and 1949 s e r i e s exceeded +1.0 f o o t f o r both P—C and Ck--C. Table 13:  Comparison of heights f o r good to medium image f i r s . x(ft.) C Ck  Year  N  1964  11  133.3  1963  44  91.5  91.5  1961  36  75.0  1958  28  1955  P  mean e r r o r ( f t . ) P — C Ck—C  132.8 126.4 +6.9  SEg ( f t . ) Ck—C P—C  +6.4  3.14  2.58  91.8 -0.3  -0.3  0.85  0.77  75.0  76.0 -1.0  -1.0  0.60  0.64  71.9  71.0  72.9 -1.0  -1.9  1.06  1.11  37  70.0  69.8  70.8 -0.8  -1.0  0.94  0.96  1954  31  71.7  71.8  71.0 +0.7  +1.8  0.84  0.90  1949  27  52.8  53.1  56.7 -3.9  -3.6  0.77  0.98  1940  3  110.3  110.0 121.3 -11.0 -11.3  7.51  9.02  In Table 14, both 1930 and 1940 s e r i e s were excluded from computation because o f the poor photography.  The SEg's  obtained were g e n e r a l l y h i g h e r f o r hemlocks than those f o r f i r s . This could be accounted f o r by the f a c t that there were o n l y a s m a l l number o f o b s e r v a t i o n s . However, the source o f e r r o r might be the g r e a t e r d i f f e r e n c e s between a c t u a l heights and curved v a l u e s .  The determination o f r e l a t i v e e f f i c i e n c y be-  tween P and Ck f o r the cedars i s a l s o a problem because the SEQ'S  for  P—C  and C k — C d i f f e r from s e r i e s to s e r i e s . (This  would be examined by AMoUA to t e s t i n t e r a c t i o n of year and methods)  79.  Table 1 4 : Year  Comparison of heights f o r good to medium image red cedars. mean e r r o r ( f t . ) SE5 ( f t . ) x(ft.) P-„C Ck—C P—C Ck—C P Ck C  N  1964  21  88.5  88.5  86.2  +2.3  +2.3  1.30  1.31  1963  25  93.2  92.8  90.5  +2.7  +2.3  1.20  1.21  1961  8  106.6  104.6  106.0  +0.6  -1.4  1.82  1.69  1958  6  91.2  90.0  91.8  -0.6  -1.8  2.82  2.32  1955  23  84.5  84.6  83.3  +1.2  +1.3  0.54  0.95  1954  11  90.5  89.7  89.2  +1.3  +0.5  1.72  1.02  1949  14  89.8  90.1  98.9  -9.1  -8.8  1.73  1.81  The greatest S E Q i s found i n 1 9 5 8 series of Table 1 5 . Table 1 5 : Year  Comparison of height measurements f o r good to medium image hemlocks P  N  x(ft.) Ck C  mean e r r o r ( f t . ) SE5(ft.) P—C Ck—G P--C Ck—C  1964  13  121.8  121.2  118.4  +3.4  +2.8  1.85  1.74  1963  18  114.6  114.2  115.0  -0.4  -0.8  1.08  1.16  1961  8  103.0  102.7  105.6  -2.6  -2.9  1.36  1.49  1958  6  97.7  97.3  108.5  -10.8  -11.2  2.69  3.98  1955  17  101.2  100.4  104.6  -3.4  -4.2  2.03  1.85  1954  6  91.0  88.3  90.2  +0.8  -1.9  2.06  1.62  1949  14  98.6  99.6  107.6  -9.0  -8.0  1.62  1.49  The SEg's of hemlocks are generally higher than those of f i r s and cedars.  There i s no consistency i n results which might  indicate the r e l a t i v e e f f i c i e n c y of method P or Ck. The greater SEfj's might be attributed to the presence of a small number of observations.  80. I n Tables 14 and 15 the same number o f observations i s shown i n the 1949 s e r i e s *  The SEjjj's show that the measure-  ment o f heights f o r hemlocks are b e t t e r than those o f r e d cedars.  No c o n s i s t e n t r e s u l t can be used to determine whether  P o r Ck i s b e t t e r . Both Tables 16 and 17 show s m a l l e r SEg's f o r the alders and the cottonwoods than those o f f i r , hemlock and cedar. I t can be seen t h a t , d e s p i t e the f a c t that the number o f observ a t i o n s f o r hardwoods are s m a l l e r than those o f c o n i f e r s , measurements o f heights f o r hardwoods a r e much more accurate than those o f c o n i f e r s .  The assumption that height measure-  ments f o r hardwoods would be much more accurate than those o f c o n i f e r s , can be supported by the concurrence o f evidence shown i n the Tables 16 and 17.  This s i t u a t i o n may also be explained  that deciduous trees have shorter average h e i g h t . Table 16: Comparison of heights f o r good to medium image a l d e r s . Year 1964 1963 1961 1955 1954 1949  N  P  12 12 11 9 8 8  69.5 66.2 66.7 49.3 49.7 41.9  x ( f t . )i C Ck 71.1 66.2 66.6 48.6 52.1 41.9  68.2 66.2 66.2 50.0 52.9 43.0  mean e r r o r ( f t . ) SEp ( f t . ) P—C C k — G P--C C k — C +1.3 ±0. +0.5 -0.7 -3.2 -1.1  +2.9 +0. +0.4 -1.4 -0.8 -1.1  0.55 0.81 0.73 1.04 1.37 1.54  0.99 0.47 0.64 1.18 1.57 1.60  81. Table 17: Comparison o f heights f o r good to medium image co ttonwoods. Year  x(ft.) Ck C  P  N  mean e r r o r ( f t . ) SE5 ( f t . ) P—C C k — C P—C C k — C  1963  16  79.3  77.1  77.7  +1.6  -0.6  0.63  0.51  1961  12  72.2  71.7  71.7  +0.5  +0.  0.56  0.52  1958  13  69.6  70.8  68.8  +0.8  +2.0  0.85  1.24  1955  12  63.7  64.7  63.2  HKJ.5  +1.5  1.16  1.46  1954  7  56.3  55.4  54.6  +1.7  +0.8  1.06  0.67  1949  13  46.8  47.2  *44.9  +1.9  +2.3  1.54  1.54  mm  The reason why the measurement o f heights f o r hardwoods r e s u l t e d i n g r e a t e r accuracy might a l s o be i n t e r p r e t e d to mean that the use o f H/A curves f o r these two species i s t h e o r e t i c a l l y sound. F i n a l l y , a n a l y s i s was made f o r a l l species i n terms o f image q u a l i t y by year.  R e s u l t s shown i n Tables 18 and 19 cor-  respond to those shown i n Tables 8, 9 and 10. The f a c t that the accuracy o f h e i g h t measurements f o r good image trees i s g r e a t e r than that f o r medium image t r e e s , can be confirmed by these f i v e t a b l e s . I n Tables 18 and 19, comparatively h i g h SE'j's are found i n the 1949 s e r i e s .  This might be accounted f o r by a v a r i a t i o n  i n c l i m a t e that a f f e c t e d the growth o f t r e e s .  The H/A curve  a p p l i e d to the same tree would have to be r e p l a c e d by another curve i n the year 1949.  An exception was found i n the case o f  s e v e r a l G r i f f i t h trees i n the 1949 s e r i e s where trees w i t h  bigger crowns were shorter than those trees w i t h narrower crowns although they appeared to be t a l l e r than the l a t t e r i n a l a t e r s e r i e s o f photos. studies.  This/phenomenon requires f u r t h e r  However, the w r i t e r d i d not attempt to i n c l u d e i t i n  t h i s study. Table 18: Comparison o f h e i g h t measurements f o r a l l tree species by year (good image). Year  N  P  1964 1963 1961 1958 1955 1954 1949 1940  21 93 47 25 46 29 38 0  92.0 89.1 68.6 58.2 70.5 77.0 53.2  x <ft.) C Ck  mean e r r o r ( f t . ) SE5 i( f t . ) P--C C k — C P--C C k — G  91.7 88.9 68.4 58.0 70.6 77.1 53.8  +3.9 +0.5 +0.2 +1.2 -0.7 -0.4 -3.6  88.1 88.6 68.2 57.0 71.2 77.4 56.8  +3.6 +0.3 9-042 +1.0 -0.6 -0.3 -3.0  1.26 0.43 0.39 0.62 0.49 0.42 0.86  1.42 0.41 0.41 0.60 0.47 0.45 0.92  Table 19: Comparison o f h e i g h t measurements f o r a l l tree species by year (medium image). Year  N  1964 1963 1961 1958 1955 1954 1949 1940  36 22 28 28 52 34 28 3  P  x(ft.) C Ck  105.9 106.2 100.1 98.2 98.2 97.9 92.7 92.2 81.1 80.7 67.7 68.0 68.8 68.7 110.3 110.0  103.0 98.5 100.4 96.8 81.7 67.1 72.7 121.3  mean e r r o r ( f t . ) SEg ( f t . ) P—C Ck—C P--C C k — C +2.9 +3.2 +1.6 -0.3 -2.2 -2.5 -4.6 -4.1 -0.6 -1.0 +0.6 +0.9 -3.9 -4.0 -11.3 -11.0  1.23 1.71 0.81 1.37 0.96 1.05 1.34 7.51  1.02 1.62 0.78 1.58 1.05 0.93 1.45 9.02  83. Region o f acceptance In order to determine to what extent the r e s u l t s o f measurements should be r e j e c t e d , the w r i t e r has t r i e d to apply a method o f pooling e r r o r s .  Since the H/A curve i t s e l f has an  experimental e r r o r , an allowance should be made f o r the e r r o r obtained between photo-measurements and ground c o n t r o l .  From  Table 9, the SEj«s are 0.35 and 0.30 f o r the c o n i f e r s and, 0.48 and 0.41 f o r the hardwoods.  To o b t a i n a pooled SE£J, the  f o l l o w i n g formula was a p p l i e d : SE^  Where:  =  A / (SE5 L )  2  +  (SEgp  2  S E § = pooled standard e r r o r o f the mean d i f f e r e n c e = standard e r r o r o f the mean d i f f e r e n c e f o r  SEjj|  population 1. SE52  standard e r r o r o f the mean d i f f e r e n c e f o r  =  population 2. The pooled S E Q f o r the c o n i f e r s alone t h e r e f o r e , i s : SE£  C  =  A /  o.35 + 0.30 2  =A/0~L225 + 0.0900  2  0.2125  = +0.46  The pooled SEg f o r the hardwoods alone i s : SE5  h  =  A/0.48  2  + 0.41  2  = 0.60 (approx.)  The pooled SE^ f o r good image trees i s : the weighted o f pooled  SEQ»S  f o r the c o n i f e r s and hardwoods.  S E 5 ( a l l Spp) -  N1(SE5 ) + N2(SEj ) C  N l + N2  h  Thus:  average  84. Where:  SEg  ( a l l Spp) = the pooled SEg f o r good image t r e e s .  Nl  =  number o f observations (sample s i z e ) f o r the conifers.  N2  =  number o f observations (sample s i z e ) f o r the hardwoods.  SE5 = C  S E  Dh  =  pooled SEp f o r the c o n i f e r s . pooled SEg f o r the hardwoods.  The pooled SE" f o r good image trees t h e r e f o r e , i s : S E  -  74(0.46) + 21(0.60) , 74 + 21  =  \ ( a ln l spp) t  From the above example, the pooled SE~'s than the o r i g i n a l SE^'s. SEQ'S  =  +  0 # 4 7  are o b v i o u s l y greater  Table 20 shows a summary o f the pooled  to be used to i n d i c a t e the r e g i o n o f acceptance.  Table 20:  Pooled standard e r r o r o f the mean d i f f e r e n c e i n f e e t f o r c o n i f e r s , hardwoods and a l l species by q u a l i t y of images.  o Good  p p  ,  Q u a l i t y of Image Medium ?  Good-Mediutri  Conifers  0.46  1.60  0.53  Hardwoods  0.60  1.78  0.62  0.47  1.64  0.55  Conifers and Hardwoods Source:  1. From Table 9; 2. from Table 10; 3. from Table 11.  S i m i l a r l y , Table 21 was constructed f o r f i v e species. Since the w r i t e r ' s hypothesis p r i o r to t h i s study was that as long as the e r r o r measurements do not exceed the  85  Table 2 1 : Pooled standards e r r o r o f the mean d i f f e r e n c e i n f e e t f o r good to medium image trees by species. Species F S E  0.75  D  Source:  C  H  Al  Cot  0.97  1.16  0.94  0.81  1 . From Table 1 2 .  experimenter's e r r o r , photo-measurements a r e regarded as acceptable.  Therefore, once the pooled standard e r r o r s o f the  mean d i f f e r e n c e between the ground c o n t r o l s and the photomeasurements have been determined, these errors can be used as c r i t e r i a to determine the r e g i o n o f acceptance. From Table 2 0 , the S E Q f o r a l l species o f good image trees i s 0 . 4 7 .  I f t h i s f i g u r e i s used to determine the r e g i o n  of acceptance f o r a l l the good image trees i n Table 1 8 , three s e r i e s - 1 9 6 4 , 1 9 5 8 and 1 9 4 9 - w i l l be r e j e c t e d .  However,  even these three s e r i e s seem to be acceptable because the mean e r r o r s f o r them do not seem to be very h i g h .  The g r e a t e s t S E Q  obtained f o r 1 9 6 4 s e r i e s i n Table 1 8 w i l l correspond to the f a c t s shown i n Table 1 3 . The 1 9 5 8 s e r i e s which shows a r e l a t i v e l y lower S E Q than 1 9 6 4 and 1 9 4 9 i s showing a higher S E Q i n Tables 1 4 and 1 5 , and the t h i r d h i g h e s t i n Table 1 3 . I f the SEp o f the medium image c o n i f e r s and hardwoods  86.  i n Table 2 0 i s used to determine the region of acceptance f o r a l l the medium image trees i n Table 1 9 , only the 1 9 4 0 series w i l l be rejected.  This condition might be v a l i d because even  the best series - 1 9 6 3 - which has demonstrated i t s accuracy throughout the tables, shows a greatest SEjj i n Table  19.  To determine the accuracy o f measurements f o r f i v e species by the use of H/A curves, Table 2 1 i s used.  The SE^'s  of f i r shown i n Table 1 3 are s l i g h t l y higher than those shown i n Table 2 1 .  Only the 1 9 6 1 series shows a smaller S E Q than  the allowable pooled error  (0.75)  shown i n Table  21.  Three  s e r i e s : 1 9 6 4 , 1 9 5 8 , and 1 9 4 0 are to be rejected i f this pooled error i s used as a c r i t e r i o n .  The smaller SE^'s obtained f o r  1 9 6 3 , 1 9 5 5 , 1 9 5 4 and 1 9 4 9 series can be assumed to be not s i g n i f i c a n t l y d i f f e r e n t from the experimenter's error because the mean errors are generally small. In the case o f cedar (Table 1 4 ) , only the 1 9 5 5 series w i l l be acceptable.  The f i r s t series to be rejected i s 1 9 5 8 ,  and 1 9 4 9 i s the second.  The same s i t u a t i o n appears i n Table  1 5 ; and the 1 9 5 8 series i s f a r beyond the range o f pooled error. The 1 9 6 3 series i s within the acceptable region while the 1 9 6 1 series shows a closer value to 1 . 1 6 shown i n Table 2 1 . In applying the pooled S E g 1 6 , three s e r i e s :  (0.94)  to the alders i n Table  1 9 6 4 , 1 9 6 3 and 1 9 6 1 are acceptable.  The  1 9 5 5 series i s much closer to the allowable error while 1 9 4 9  87. s e r i e s gives the greatest SE5.  The same c o n d i t i o n occurs to  the cottonwoods i n Table 17. On the whole, the use o f H/A curves as c r i t e r i a f o r growth studies seems to be p r a c t i c a b l e .  Although o c c a s i o n a l l y  i n c o n s i s t e n t r e s u l t s were found, the main source o f e r r o r i n measurements may have been the i n s u f f i c i e n t number o f observ a t i o n s , the poor v i s i b i l i t y o f some t r e e images and poor photography. The pooled SEjj's a p p l i e d to determine the a c c e p t a b i l i t y o f photo-series obtained  are g e n e r a l l y low i f compared to the e r r o r s  from past studies o f ±6.3 f e e t SEg ( i n t e r p r e t e r A)  and ±3.2 f e e t SE5 ( i n t e r p r e t e r B) reported by Avery (1958), of +5.1 and f6.1 f e e t S E obtained D  by C o l l i n s (1957), and o f  2.72 f e e t obtained by Johnson (1958).  None o f the pooled  SEp's a p p l i e d to t h i s growth study i s greater than the smallest standard e r r o r c a l c u l a t e d by C o l l i n s (1957) from G e t c h e l l and 1  Young (1953). I f the smallest SE£ (+2.7 f e e t ) o f C o l l i n s (1957) i s a p p l i e d to the tables made f o r comparisons o f height measurements i n terms o f image q u a l i t y , tree s p e c i e s , and the year o f photography, two s e r i e s o f photographs: 1940 and 1958 w i l l be rejected.  The 1964 s e r i e s o f Douglas f i r (Table 13) i s also  not acceptable.  By r e f e r r i n g to these f a c t s , the w r i t e r decided  88. to use three s e r i e s o f photographs: 1963, 1955, and 1949 f o r r e l a t i v e l y intensive studies. Accuracy o f growth estimates on height The w r i t e r ' s i n t e n t i o n , i n p a r t , was to f i n d the optimum i n t e r v a l o f years f o r growth estimates on the photographs.  Of  the ten s e r i e s o f photos which were a v a i l a b l e , the 1962 s e r i e s was omitted because o f the great exaggeration o f tree images. The nine s e r i e s used f o r growth s t u d i e s were compiled i n various combinations o f p e r i o d i c growth as shown i n Table 22. According to formula: C  n(n-1)(n-2)(n-3)....-(n-r+1)  n  •i  r Where  i s the number o f combinations;  number o f p h o t o - s e r i e s ; and i n a combination.  r  n  i s the t o t a l  i s the number o f photo-series  Therefore, the t o t a l number o f combinations  is: G  CT 2  =  9*8)  = 36  2  Table 22 shows o n l y 34 combinations because no data were a v a i l a b l e f o r p e r i o d i c growth between 1940 and 1958, and 1930 and 1958.  From t h i s t a b l e , the g r e a t e s t SE^'s are found i n  the p e r i o d i c growth between 1930 and 1964 w i t h the SE-'s o f + 9.44 f e e t and + 9.20 f e e t , and the s m a l l e s t SEg's are found  89. Table 22: P e r i o d i c height growth f o r a l l species by i n t e r v a l o f year.  1963-64 1961-64 1958-64 1955-64 1954-64 1949-64 1940-64 1930-64 1961-63 1958-63 1955-63 1954-63 1949-63 1940-63 1930-63 1958-61 1955-61 1954-61 1949-61 1940-61 1930-61 1955-58 1954-58 1949-58 1954-55 1949-55 1940-55 1930-55 1949-54 1940-54 1930-54 1940-49 1930-49 1930-40  N  P  47 9 17 47 17 33 12 5 53 46 69 38 55 13 9 46 33 32 32 10 8 23 22 22 51 62 16 12 42 16 14 16 12 11  2.2 12.1 22.9 12.4 15.3 24.3 34.5 55.0 4.2 12.0 13.8 16.5 27.5 32.9 56.7 7.6 13.6 12.9 27.2 24.9 49.7 8.7 8.7 22.7 0.5 13.6 18.9 42.4 13.8 19.8 42.3 5.9 31.5 24.4  x(ft.) Ck C 2.3 10.9 23.6 12.3 16.5 23.5 36.7 56.0 4.9 13.5 13.7 17.2 26.8 34.0 58.8 8.4 14.2 14.3 26.7 27.8 50.1 7.7 8.7 21.5 0.9 12.8 20.7 43.2 13.2 20.9 42.4 9.3 33.7 24.7  1.0 2.3 5.1 9.0 9.0 13.2 21.6 25.6 3.0 7.7 11.9 16.6 20.2 27.2 37.7 5.3 11.8 13.5 21.7 21.9 33.7 6.9 9.2 19.0 1.6 8.1 16.2 29.3 7.8 14.7 27.6 10.2 22.1 12.6  Mean e r r o r ( f t . ) P—C Ck—C + 1,.2 + 9 ,4 +17,,8 + 3,.4 + 6,,3 +11.,1 +12,,9 +29,A + 1,,2 + 4,,3 + 1.,9 -0.1 + 7,,5 + 5,,7 +19,,0 + 2,,3 + 1,,8 a 0,,6 + 5. 5 + 3,0 +16. 0 + 1,8 - 0,.5 + 3,,7 - 1..1 + 5.5 + 2.,7 +13. 1 + 6.0 + 5. 1 +14, 7 - 4.,1 + 9,4 +11. 8  + 1,.3 + 8,.6 +18,.5 + 3,.3 + 7,,5 +10.,3 +15,,1 +30.,4 + 1,,9 + 5,,8 + 1,.8 + 0,,6 + 6,,6 + 6,,8 +21, 1 + 3,.1 + 2,,4 + 0,,8 + 5,.0 + 5,9 +16,,4 + 0,8 - 0,5 + 3,.5 - 0,,7 + 4,,7 + 4..5 +13,.9 + 5,4 + 6,2 +14, 8 - 0.9 +11, 6 +12, 1  SE5(ft.) P—C C k — C 1.09 2.45 3.00 1.27 2.28 1.72 3.66 9.44 1.03 1.45 0.84 1.37 1.28 4.15 6.77 1.37 1.02 1.04 1.21 3.41 5.79 0.91 1.02 1.03 0.81 1.06 2.50 4.66 1.13 2.90 4.34 2.99 3.91 3.72  1.20 2.35 3.53 1.21 1.79 1.42 4.37 9.20 1.05 1.48 0.89 1.21 1.22 4.63 8.14 1.21 1.00 0.99 1.05 3.55 5.46 0.74 0.68 1.01 0.78 1.00 3.26 5.92 1.05 3.26 5.06 2.89 4.75 3.90  90. i n the p e r i o d i c growth o f 1955 to 1963 - + 0.84 f e e t and ±0.89 feet.  The p e r i o d i c growth group Ixueombination w i t h the 1930  s e r i e s shows greatest SE5's among 34 combinations o f p e r i o d i c growth estimates.  A l l the combinations where 1940 s e r i e s i s  present give second higher SEg's.  The combinations with 1964  s e r i e s had the t h i r d highest  and those with the 1958  series, fourth.  SEQ'S  A l l these f a c t s w i l l confirm the studies made  f o r height-measurements. I n general, the determination o f the optimum i n t e r v a l o f years f o r growth estimates on the photographs i s d i f f i c u l t unless the same q u a l i t y o f photographs a r e obtained.  The f l i g h t  l i n e s f o r d i f f e r e n t s e r i e s o f photos should p r e f e r a b l y be the same so that the p o s i t i o n s o f trees on the photographs w i l l not d i f f e r g r e a t l y and a f f e c t the accuracy o f measurements. The mean e r r o r s shown i n Table 22 are mostly p o s i t i v e .  There  i s a tendency o f overestimates o f height growth when H/A curves are used as c r i t e r i a .  The greatest mean e r r o r i s +30.4 f e e t  between 1930 and 1964,  and the smallest mean e r r o r i s -0.1  f e e t between 1954 and 1963.  I f the three s e r i e s - 1930, 1940  and 1964 - were omitted, the mean e r r o r would range from -0.1 f e e t to +6.0 f e e t . For f u r t h e r i n t e n s i v e s t u d i e s , three s e r i e s , 1963, 1955, and 1949 were used.  A n a l y s i s was made w i t h f i v e species.  The  91. r e s u l t s o f the accuracy o f height measurements are summarized i n Tables 23, 24, 26 and 27 and, the accuracy o f height growth estimates i s shown i n Tables 25 and 28. Table 23: Accuracy o f height measurement f o r good to medium image trees by species (1949). Spp  N  P  x(ft.) Ck C  mean e r r o r ( f t . ) SEg ( f t . ) P--C C k — G P—C Ck—C  F  30  49.2  49.5  53.9  -4.7  -4.7  0.87  1.00  C  15  88.0  87.9  96.5  -8.5  -8.6  1.70  1.69  H  14  98.6  99.6 107.6  -9.0  -8.0  1.62  1.50  Al  7  40.3  40.1  42.1  -1.8  -2.0  1.57  1.54  12  46.0  46.5  43.7  +2.3  +2.8  1.62  1.58  Cot  Table 24: Spp  N  Accuracy o f height measurements f o r good to medium image trees by species (1955). P  x(ft.) Ck C 62.2  mean e r r o r ( f t.) SES ( f t . ) P--C C k — C P--C Ck—G 4-2.8  1.04  1.05  +0.7  +0.6  0.68  1.41  -4.2  -5.3  2.41  2.12  54.1  +0.0  -1.2  1.05  1.39  63.2  +0.5  +1.5  1.16  1.46  F  30  62.7  C  15  103.7  103.7 103.1  H  14  109.4  108.3 113.6  Al  7  54.1  52.9  Cot  12  63.7  64.7  64.Q  From Tables 23 and 24, i t can be seen that w i t h the same number o f the same t r e e s , there i s a c o n s i s t e n t r e s u l t i n the case o f each s p e c i e s .  The SEg's shown i n Table 24 as  smaller than i n Table 23 again confirmed the f a c t that the 1955 s e r i e s i s very good.  However, there i s no means o f determining  92. that e i t h e r the 1955 o r the 1963 s e r i e s i s b e t t e r (from Tables 26 and 27), except by using a r i t h m e t i c sum o f  I f this  SEQ'S.  i s reasonable, the 1963 s e r i e s i s the best (see Tables 26 and 27). The determination o f s i g n i f i c a n c e can be made by a n a l y s i s o f variance w i t h unequal s i z e o f observations. Table 25: Accuracy o f height growth estimates f o r good to medium image trees by species (1949-1955). Spp  P  N  x (ft.) Ck C  mean e r r o i• ( f t . ) S E D ( f t . ) P--C C k — C P--G C k — C  F  30  13.5  12.8  10.1 +3.4  +2.7  1.33  1.04  C  15  15.7  15.9  6.6 +9.1  +9.3  1.63  1.95  H  14  10.8  8.7  6.0 +4.8  +2.7  3.09  2.46  Al  7  13.9  12.7  12.0 +1.9  +0.7  2.37  2.32  Cot  12  17.7  18.2  19.4 +1.4  +1.2  1.82  1.85  Table 26: Spp  Accuracy o f height measurements f o r good to medium image trees by species (1955). P  N  x (ft.) Ck C  mean e r r o r ( f t . ) SETJ ( f t . ) P—C C k — G P--C C k — C  F  29  57.7  57.8  58.3 -0.6  -0.5  1.02  0.98  C  20  83.2  82.7  81.8 +1.4  +0.9  0.60  1.04  H  13  107.3  106.5 111.0 =2.7  -3.5  2.65  2.42'  Al  9  49.3  48.6  50.0 -0.7  -1.4  1.04  1.18  Cot  12  63.7  64.7  63.2 +0.5  +0.5  1.16  1.46  93. Table 27: Accuracy o f height measurements f o r good to medium image trees by species (1963). Spp N  mean e r r o r ( f t . ) S E J J ( f t . ) P — C Ck—C P--C C k — C  x (ft.) Ck C  P  F  29  74.6  74.7  73.7  +0.9  +1.0  1.10  0.94  C  20  94.7  94.2  91.2  +3.5  +3.0  1.43  1.48  H  13  118.4  118.1  117.6  +0.8  +0.5  1.36  1.41  9  62.3  62.6  62.1  +0.2  +0.5  1.02  0.50  12  81.9  80.2  80.5  +1.4 -0.3  0.82  0.58  Al Cot  Table 28:  Spp  N  Accuracy o f height growth estimates f o r good to medium image trees by species (1955-1963). P  x (ft.) Ck C  F  29  16.9  16.8  C  20  11.5  11.5  H  13  11.1  11.5  Al  9  13.0  14.0  Cot  12  18.2  15.6  mean e r r o r ( f t . ) SEp ( f t . ) P — C Ck—C P — C -Ck—C  15.4 +1.5  +1.4  1.18  1.01  9.4  +2.1  +2.1  1.43  1.94  6.6  +4.5  +4.1  2.31  2.20  12.1  +0.9  +1.9  1.78  1.57  17.3  +0.9  -1.7  1.22  1.44  The SEg's obtained f o r p e r i o d i c growth estimates o f t r e e heights from 1949 and 1955 s e r i e s (Table 25) are g e n e r a l l y higher than those obtained from 1955 and 1963 s e r i e s (Table 28).  I n order to determine  from the photographs,  the accuracy o f growth estimates  the l i m i t s should be defined.  As the  SEg o f growth estimates i s a combined e f f e c t o f variances from two d i f f e r e n t s e r i e s o f photos, i . e . , f o r population 1 (e.g. 1949 s e r i e s ) , there i s an independent v a r i a n c e (S.) between  94. the mean d i f f e r e n c e o f photo-measurements and a c t u a l h e i g h t s , f o r population 2 (e.g., 1955 s e r i e s ) , there i s another inde2 pendent variance  (S^) between the mean d i f f e r e n c e o f photo-  measurements and a c t u a l h e i g h t s . The maximum variance f o r growth estimates between the two s e r i e s o f photos can be 2 2 assumed as the a r i t h m e t i c sum o f and S^. Since the pooled 2 standard e r r o r s obtained  i n Table 21 were supposed to be S^  f o r s p e c i e s , i f these values were doubled, they could be thought o f as the maximum acceptable regions f o r f i v e d i f f e r e n t species.  Thus the c r i t e r i a f o r growth estimates i n terms o f  doubled standard e r r o r o f the mean d i f f e r e n c e are tabulated i n Table 29. Table 29: Doubled pooled standard e r r o r o f the mean d i f f e r e n c e i n f e e t f o r good to medium image trees by species. e  F SE  1.50  5  Source:  C  -  Specxes  1.94  H 2.32  1  Al 1.88  Cot 1.62  1. From Table 21. I f the SEg's i n Table 29 are a p p l i e d , no species i n  Table 28 w i l l be r e j e c t e d while o n l y the f i r i s acceptable i n Table 25. The main source o f greater d i f f e r e n c e s i n Table 25 than i n Table 28 i s associated with the greater obtained  from the 1949 s e r i e s .  differences  P r e d i c t i o n o f growth f o r hemlock  95. i n t h i s study revealed the l e a s t accuracy while the f i r appeared to be the best.  This f a c t could be because a group  o f G r i f f i t h trees with t h e i r ages known were computed together w i t h the mature f i r whose ages were determined i n d i r e c t l y . Therefore, as the H/A curves are a p p l i e d , are c l o s e r to the curved values.  photo-measurements  I t i s p o s s i b l e to d i f f e r e n t i a t e  from Table 25 and Table 28, the d i f f e r e n c e s o f the accuracy o f growth estimates among s p e c i e s .  However, a f u r t h e r a n a l y s i s  o f Variance w i t h unequal sample s i z e would be p r e f e r a b l e i n order to d e f i n e the s i g n i f i c a n c e o f d i f f e r e n c e s among species. The e s s e n t i a l f a c t o r s i n the p r e d i c t i o n o f the growth o f trees from the photographs are that the i n t e r p r e t e r must be w e l l t r a i n e d and the same q u a l i t y o f good photographs must be prepared.  The use o f a s e r i e s o f photographs to estimate the  growth o f tree height can t e n t a t i v e l y be assumed to be p r a c t i c a b l e . Accuracy o f crown width measurements on the photos Of the 557 tree crowns measured on the photographs, 135 were measured on the ground.  Table 30 shows the number o f tree  crowns measured on the photos by species and the year o f photography. The decrease i n the number o f observations i n comparison w i t h the 633 measurements o f h e i g h t , has come from the w r i t e r ' s p o i n t of view that no measurements were to be made when the  96. Table 30: Number o f t r e e crowns measured on photos by species and year o f photography. Species  Year  F  C  H  Al  1964  49  21  15  12  14  111  1963  49  23  17  12  14  115  1961  14  3  4  1958  35  3  2  1955  37  23  17  1954  44  10  9  1949  38  16  19  1930  4  1  1  270  100  84  Z  Cot  -  -  12  14  -  -  12  13  -  -  48  55  trees were poorly resolved on the p r i n t s .  21 17 103 63 98 6 557  A l l the crowns  measured were assumed to be good, but no grades were s e t up. Comparisons o f the accuracy o f crown width measurements w i t h f i v e species were made i n terms o f d i f f e r e n c e s between photo measurements and ground v a l u e s , and between curved values and ground values.  The r e s u l t s o f a n a l y s i s w i t h P, C, and G are  shown i n Table 31. Table 31: Spp F C H Al Cot  N 53 28 25 12 14  Comparisons o f Accuracy o f crown width measurements f o r P--G and C—G by species. x (ft.) mean e r r o r ) f t . ) SE5 ( f t . ) P C G P--G C--G P--G C--G 27.3 21.7 20.6 33.5 24.3  26.2 21.5 21.3 30.7 24.4  27.3 21.7 20.6 30.0 25.6  +0. -1.1 +0. -0.2 +0. +0.7 +0.5 +0.7 -1.3 -1.2  0.21 0.29 0.21 0.58 0.41  0.94 1.48 1.19 1.03 1.61  9  7  «  The SEg's of P—G f o r f i v e species are much smaller than those obtained f o r C—G.  I t means that photo measurements are  much closer to the actual values than the results obtained from the t h e o r e t i c a l approach.  The errors i n the case of f i r ,  cedar, and hemlock are approximately f i v e times greater f o r C — G than f o r P—G, four times i n the case of cottonwood where only twice as much i s found f o r the alder.  The measure-  ments of crown width f o r both alder and cottonwood on the photographs i s less accurate than that f o r f i r , cedar, and hemlock.  This i s true because the crown shapes o f the alder  and cottonwood  tend to be i r r e g u l a r and the tone i s often  l i g h t e r than that o f conifers.  Measurement with the minor  branches can be e a s i l y neglected, and greater error i s thereby introduced.  The smallest difference between P—G and C—G i s  found f o r alder showing that the use of t h e o r e t i c a l approach i n predicting growth of crowns of alder tends to be acceptable. On the whole, the prediction of the growth of tree crown from the photographs would give a considerable degree of accuracy.  The use of t h e o r e t i c a l methods tends to be less  accurate and takes a longer time i n c a l c u l a t i o n than d i r e c t measurements on the photographs.  Where photographs are not  a v a i l a b l e , the i n d i r e c t approach of using CW/D r a t i o should take error measurement into consideration.  The mean errors  obtained f o r C—G (Table 31) are f a r greater than those of  98. Lossee (1953), Spurr (1960), and Moessner (1962); however, a c o n s i s t e n t zero value i s found f o r P—G  f o r f i r , cedar and  hemlock. Accuracy o f growth estimates on crown width Since no ground c o n t r o l s were o b t a i n a b l e as a basis of determining the accuracy of growth estimates of crown width, the t h e o r e t i c a l approach was a p p l i e d .  I t i s necessary that  l i m i t s should be defined before determining the accuracy of growth estimates on the photographs.  Since the e r r o r of  P--C  i n the case of crown width i s the combined e f f e c t of P—G  and  C—G,  i t would be p r e f e r a b l e to use pooled SEp's of P—G  C—G.  and  For example, the pooled SEg of f i r from Table 31 i s : 0.21 • 0.94  =  1.15.  Table 32 shows pooled SEp's i n terms o f s p e c i e s , as c r i t e r i a to d e f i n e the accuracy o f growth estimates of crown widths. Table 32: Pooled standard e r r o r of the d i f f e r e n c e i n f e e t f o r crown width measurements by s p e c i e s .  Source:  F  C  Species* H  Al  Cot  1.15  1.77  1.40  1.61  2.02  From Table 31.  99. Three s e r i e s o f photographs, 1963, 1955, and 1949, were used f o r t e s t i n g the accuracy o f growth e s t i m a t i o n f o r crown widths.  I n order to detect the d i f f e r e n c e s o f accuracy among  three s e r i e s o f photographs, data f o r the maximum number o f i d e n t i c a l trees were c o l l e c t e d from the photo-measurements. The number o f trees was the same f o r each i n d i v i d u a l species on three s e r i e s o f photos.  The r e s u l t s o f a n a l y s i s i n terms o f  f i v e species are summarized f o r three s e r i e s i n Tables 33, 34 and 35. Table 33: Accuracy o f crown width measurements f o r trees by species (1963). ~T F C H Al Cot  x (ft.) C  N  P  33 12 12 12 13  26.6 25.9 20.7 30.5 24.2  24.3 27.3 24.3 30.7 24.5  Mean e r r o r ( f t . ) SEg ( f t . ) P--C P--C +2.3 -1.4 -3.6 -0.2 -0.3  1.07 2.98 1.73 0.77 1.65  Table 34: Accuracy o f crown width measurements f o r trees by species (1955). ~7 p p  F C H Al Cot  N 33 12 12 12 13  P 19.9 24.5 18.8 24.2 16.7  x (ft.) C 19.0 26.3 22.9 25.8 18.9  Mean e r r o r ( F t . ) SEg ( f t . ) P—C P—C +0.9 -1.2 -4.1 -1.6 -2.2  1.31 2.98 1.87 0.66 1.75  I t can be seen from Tables 33, 34 and 35 t h a t , i f the SEg's i n Table 32 are a p p l i e d , o n l y the a l d e r s and the c o t t o n  100. woods w i l l be accepted.  This c o n d i t i o n w i l l c o n t r a d i c t the  statement made p r e v i o u s l y that measurement of crown widths f o r alders and cottonwoods i s l e s s accurate than that f o r f i r s , cedar, and hemlock. due to the use of f i r , etc.  However, i t can be explained that e r r o r C  f o r the a l d e r i s smaller than those o f  The c r i t i c a l e r r o r f o r the cottonwoods may  be too  great. Table 35:  Spp F C H Al Cot  Accuracy of crown width measurements f o r trees by species. X  N  P  33 12 12 12 13  15.5 22.0 16.4 18.6 12.6  (ft.) G  Mean e r r o r ( f t . ) SE]j ( f t . ) P—C P--C  15.8 24.7 21.8 22.0 14.5  -0.3 -2.7 -5.4 -3.4 -1.9  1.18 3.07 1.73 0.72 1.90  I t would be i n t e r e s t i n g to know that when any two s e r i e s o f the three s e l e c t e d s e r i e s were used to p r e d i c t the growth of crown width, the e r r o r s of three p e r i o d i c crown width growth are summarized i n Tables 36, 37, and  38.  I t was assumed a t the beginning o f t h i s study that the g r e a t e s t e r r o r , which can be a p p l i e d as a b a s i s to set a r e g i o n of acceptance, would be twice the numerical quantity o f pooled standard e r r o r of the mean d i f f e r e n c e shown i n Table 32. However, the f a c t i s that the SE^'s  f o r growth estimates  are  even smaller than those obtained f o r a s i n g l e s e r i e s of photo-  101. graphs.  The r e d u c t i o n i n SE^'s f o r growth estimates can be  accounted f o r by the f a c t that the r e s u l t s of e r r o r measurements obtained f o r one s e r i e s of photos are a s s o c i a t e d w i t h those f o r the o t h e r .  In other words, s i z e of SEg 's i s r e -  duced because photo values and t h e o r e t i c a l values of two i n d i v i d u a l s e r i e s tend to be l a r g e o r s m a l l together ( o r positively correlated).  The source of extraneous v a r i a n c e of  the d i f f e r e n c e s i s , t h e r e f o r e , e l i m i n a t e d . Tables 36, 37 and 38 show a summary of s t a t i s t i c s computed i n terms of species f o r three d i f f e r e n t periods o f growth p r e d i c t i o n . Table 36: Spp F C H Al Cot  P e r i o d i c crown width growth f o r trees by s p e c i e s . X  N  P  33 12 12 12 13  4.4 2.5 2.4 5.7 4.1  (ft.) C 3.5 1.5 1.1 3.8 4.5  Mean e r r o r ( f t . ) P—C +0.9 +1.0 +1.3 +1.9 +0.4  SE5 (  P—C  0.33 0.63 0.38 0.24 0.77  The o r i g i n a l assumption of u s i n g double numerical q u a n t i t y o f pooled standard e r r o r of the mean d i f f e r e n c e seems to be unreasonable.  Therefore, the pooled SE~'s i n Table 32  are to be a p p l i e d as c r i t e r i a to growth estimates of crown widths. I f the f i g u r e s i n Table 32 are a p p l i e d , none of the growth estimates w i l l be r e j e c t e d (Tables 36, 37, and 38). The SEp's f o r the period 1949-1955 are the s m a l l e s t w h i l e those  102.  Table  37:  Periodic crown width growth f o r trees by species. X  bpp F C H Al Cot Table  P  N  38:  Mean error ( f t . ) P--C  SEJ5 ( f t . )  P--C  33  11.1  8.5  +2.6  0.60  12  3.9  3.4  +0.5  0.98  12  4.3  2.5  +1.8  0.42  12  11.9  8.7  +3.2  0.46  13  11.5  10.0  +1.5  0.94  Periodic crown width growth f o r trees by species X  J>PP  (ft.) C  (ft.) C  Mean e r r o r ( f t . ) P--C  (ft.) F--C  SEQ  N  P  F  33  6.7  5.3  +1.4  0.65  G  12  1.4  1.1  +0.3  1.33  H Al Cot  12  1.9  1.4  +0.5  0.56  12  6.2  4.8  +1.4  0.45  13  7.5  5.5  +2.0  0.46  f o r the period  1955-1963  are the largest.  When the number of  observations i s disregarded, the comparison o f differences i n terms o f species may e a s i l y be made by c a l c u l a t i n g the a r i t h metic sum o f SEg's f o r three periods.  Table 3 9 shows the  r e s u l t s of these. Table 3 9 : Comparison of Accuracy of crown width growth by species Spp F C H Al Cot  SED  N  1949-1955  (P—c)  1949-.1963  (ft.) 1955-1963  33  0.33  0.60  0.65  1.68  12  0.63  0.98  1.33  2.94  12  0.38  0.42  0.56  1.36  12  0.24  0.46  0.45  1.15  13  0.77  0.94  0.46  2.17  103. From Table 39, the sum o f SE^'s  f o r cedar i s the  greatest w h i l e t h a t of a l d e r i s the s m a l l e s t .  The accuracy of  growth estimates i s i n v e r s e l y associated w i t h the values o f SE5.  Therefore, growth estimates o f crown width o f hemlock  seems to be the best.  Since the number o f observations f o r  f i r i s greater than that f o r the r e s t of the s p e c i e s , an a n a l y s i s of variance w i t h unequal sample s i z e would t e l l whether s i g n i f i c a n t d i f f e r e n c e s e x i s t among species o r periods. I t may  be concluded that p r e d i c t i o n of growth o f crown  width can be made from a s e r i e s of a e r i a l photographs.  The  a p p l i c a t i o n of t h e o r e t i c a l values as a c r i t e r i a i n determining the a c c e p t a b i l i t y of growth estimates o f crown width i s pract i c a b l e because e r r o r w i l l be e l i m i n a t e d by the j o i n t of two p a i r s of observations.  computation  However, when the t h e o r e t i c a l  values are used as c r i t e r i a f o r s i n g l e crown width measurements, the e r r o r tends to be great.  The best method i s to have  ground c o n t r o l s to define the accuracy of measurements.  Stands The methods of measurements o f stand v a r i a b l e s have been stated previously i n this thesis.  The r e s u l t s of photo-  measurements i n terms of average h e i g h t , average crown width and crown c l o s u r e f o r each of the f i f t e e n p l o t s were summarized i n Tables 1, 2 and 3 o f Appendix IV.  104. Accuracy o f measurements o f stand v a r i a b l e s 1.  Compilation h e i g h t . Since ground data f o r G r i f f i t h p l o t s , per-  manent sample p l o t s and the n a t u r a l regeneration p l o t s were taken o n l y i n 1956, 1958 and 1964, there was d i f f i c u l t y i n o b t a i n i n g s u i t a b l e ground data c o n t r o l .  Therefore, these  ground data were converted i n t o the values o f corresponding year o f photography.  From Table 1, average height growth o f  dominant and codominant tree f o r each o f the G r i f f i t h p l o t s was d i v i d e d by 4 to o b t a i n the average annual h e i g h t growth f o r each p l o t .  The t h e o r e t i c a l c o m p i l a t i o n heights f o r each p l o t  corresponding to the years 1955, 1949 and 1930 were c a l c u l a t e d by s u b t r a c t i n g a l l the products o f annual h e i g h t growth and year.  For the group o f permanent p l o t s , i t was found from the  H/A curves t h a t annual height growth f o r trees a t the c o r r e s ponding age o f the stands s t u d i e d would be approximately 1.5 f e e t f o r a l l o f the f i v e p l o t s , because t h e i r s i t e i n d i c e s are about the same.  Therefore, 4.5 f e e t (1.5 f t . x 3) was sub-  t r a c t e d from the 1958 ground data o f each o f P.S.P.'s to get t h e o r e t i c a l c o m p i l a t i o n height o f 1955. The same adjustment was made f o r both 1963 and 1949 s e r i e s .  For the group o f f i v e  n a t u r a l regeneration p l o t s , an average o f 2 f e e t height growth per tree was assumed to apply a n n u a l l y , t h e r e f o r e 2 f e e t was  105. subtracted from the average height o f each plot measured i n 1964  to obtain compilation height of 1963. Similar adjustment  was made for both 1955 and 1949 s e r i e s . Consequently, these adjusted ground values were compared with photo values by c a l c u l a t i n g mean errors and SE^'s f o r defining the accuracy o f measurements of compilation height. Table 40 shows the results of computation. Table 40: Comparison of measurements of compilation height for group of plots Error ( f t . ) Aggregate Mean  Stand  N  G r i f f i t h plots P.S.P.»s Natural regen. plots  5 5  +19.3 -42.7  +3.9 -8.5  1.62 2.49  5  + 7.0  +1.4  0.23  SEJJ ( f t . )  I t can be seen from Table 40 that the measurements of compilation height for the group of natural regeneration plots gives the best r e s u l t while the group of P.S.P.'s shows the least accuracy.  This i s true because the dominant and co-  dominant trees measured on the natural regeneration plots are open grown and there was no d i f f i c u l t y to detect the base o f the tree.  On the contrary, i t was r e l a t i v e l y hard to fuse the  dot of the height finder exactly on or near the base o f the tree measured within stands.  The chance o f making error  measurements therefore, i s greater for the P.S.P.'s than f o r the natural regeneration p l o t s .  The group o f G r i f f i t h plots  106. showing medium accuracy i n Table 40 can be accounted f o r by the l e s s e r canopy on these p l o t s . Further comparison on mean errors and SE^'s i n terms o f stands and years was made.  The r e s u l t s o f computation are  summarized i n Table 41. Obviously from t h i s t a b l e , the SEp's f o r n a t u r a l regeneration p l o t s are the s m a l l e s t while f o r P.S.P.'s Table 41: Comparison o f accuracy o f c o m p i l a t i o n height measurements by stand and year o f photography. Year  S t a n d G r i f f i t h plots P. S. P.'s Nat.regen. p l o t s N Mean e r r o r S E Q N Mean e r r o r SE- N Mean E r r o r SEp (ft.) (ft.) (ft.). (ft?) (ft.) (f  1963  5  -19.7  3.59  5  +1.4  0.23  1955  5  +3.9  1.62  5  - 8.5  2.49  4  +1.6  1.17  1949  5  =1.7  2.84  5  -10.9  7.87  4  +2.0  1.41  1930  5  +12.8  2.51  the  SEQ'S  are the g r e a t e s t . I t can be concluded that the  measurement o f c o m p i l a t i o n height f o r young open stands i s much more accurate than that f o r the o l d e r , densely stocked stands. Also from t h i s t a b l e , the best s e r i e s o f photographs i s found to be 1963 because a s m a l l e s t SE5 o f +0.23 f e e t i s found f o r the n a t u r a l regeneration p l o t s .  A c o n s i s t e n t r e s u l t i s obtained  f o r 1955 s e r i e s which i s the second best.  Although SEp f o r  1930 s e r i e s i s smaller than that o f 1949, i t s mean e r r o r i s considerably higher than that o f 1949 s e r i e s .  A l l these f a c t s  are corresponding to the r e s u l t s obtained f o r the height measurements o f i n d i v i d u a l trees s t u d i e d .  107.  2.  Average crown width. In order to determine the accuracy of measure-  ments of average crown width f o r 3 groups of p l o t s , ground data i n Tables 2 and 3 were adjusted to the corresponding year of photography f o r P.S.P.'s and natural regeneration plots individually.  However, for the group of G r i f f i t h p l o t s ,  t h e o r e t i c a l crown widths f o r the trees on each p l o t were c a l culated to obtain an average crown width for the plot.  Methods  of adjustment for f i v e natural plots are shown i n Table 3 . For the f i v e P.S.P.'s, an average of 0 . 2 feet annual crown width growth was calculated from a group of forest grown trees studied previously.  The r e s u l t s of photo-measurements and  the adjusted ground values (or t h e o r e t i c a l values) were computed and summarized  i n Table 4 2 .  Table 4 2 : Accuracy of average crown width measurements for group of plots Stand  N  Error ( f t . ) Aggregate Mean  SEQ  (ft.)  G r i f f i t h plots  5  +9.7  +1.9  1.56  P.S.P.»s  5  -18.4  -3.7  1.35  Natural regen. plots  5  +2.6  +0.5  0.10  A very small S E Q i s found i n Table 4 2 f o r the natural regeneration p l o t s .  I t i s hard to t e l l whether the G r i f f i t h  plots o f the P.S.P.'s give results which are closer to the actual values, because although the SEg o f P.S.P.'s i s less  108. than that o f the G r i f f i t h p l o t s , the mean e r r o r o f P.S.P.'s i s more than that o f the G r i f f i t h p l o t s .  Both o f the o l d e r stands  give l e s s e r accuracy than the young stand because the e r r o r s are  introduced by the o v e r l a p p i n g o f branches.  The SEg of  f0.10 f e e t i s found to be l e s s than those o f i n d i v i d u a l Douglas f i r , cedar and hemlock i n Table 31. S i m i l a r to c o m p i l a t i o n h e i g h t , f u r t h e r a n a l y s i s was made i n terms o f stands and year o f photography.  Table 43  shows the r e s u l t s o f computation. Table 43: Comparison o f accuracy o f average crown width measurements by stand and year o f photography. s  t  a  n  d  G r i f f i t h plots P. S. P.'s Nat. regen. p l o t s Year N Mean E r r o r SED N Mean E r r o r SE"} N Mean E r r o r SEp (ft.) (ft.) (ft.) (ft.) (ft.) (ft.) 1963 1955 5 1949 5  +1.9 -0.1  1.56 1.31  5 5 5  -3.5 -3.7 -2.5  1.89 1.35 1.43  5 4 3  +0.5 +1.8 +2.8  0.10 0.80 0.47  From Table 43, the s m a l l e s t SEp's are found f o r the group o f n a t u r a l r e g e n e r a t i o n p l o t s .  The group o f G r i f f i t h  p l o t s appears to be the second and P.S.P.'s the t h i r d .  However,  no c o n s i s t e n t r e s u l t s can be used to determine which s e r i e s of photographs i s the best.  The l e a s t SE£ among the three  groups o f p l o t s i s +_0.10 f e e t while the g r e a t e s t i s +1.89 feet.  There was a tendency o f overestimates o f crown width  109. f o r the n a t u r a l regeneration p l o t s but a c o n s i s t e n t underestimate o f crown width e x i s t s i n P.S.P.'s.  I t should be  concluded that the accuracy o f average crown width measurements i s g r e a t l y a f f e c t e d by the stand c o n d i t i o n s . 3.  Crown c l o s u r e . Since no ground data on crown closure f o r the  e a r l y years were obtained, comparison can o n l y be made i n terms of mean values.  Table 44 shows the average crown c l o s u r e o f  three groups o f p l o t s i n terms o f year o f photography. Table 44: Comparison o f average crown c l o s u r e f o r stand by year o f photography. Year  G r i f f i t h plots N Ave. CCfi%)  1963  stand P.S.P.'s N Ave. CC(%)  N a t u r a l regen.plots N Ave. CC(%)  5  61  5  26  1955  5  77  5  75  5  19  1949  5  71  5  69  5  9  1930  30  67  From Table 44, i t can be seen that crown c l o s u r e f o r each group o f p l o t s increases w i t h the year o f photography. Only one exception i s found i n 1963 s e r i e s o f P.S.P.'s where the average crown c l o s u r e decreased.  This was explained by  t h i n n i n g o f a group o f P.S.P.'s between 1955 and 1963.  The  r e d u c t i o n i n average crown c l o s u r e f o r t h i s group o f p l o t s confirms the accuracy o f crown c l o s u r e measurements.  110. Accuracy o f growth estimates f o r stands 1.  Compilation H i i e h t ^ G y o w f l a y t , For determining the accuracy o f c o m p i l a t i o n  h e i g h t growth estimates, both photo values and the t h e o r e t i c a l values were used.  The accuracy o f height growth estimates i n  terms o f mean e r r o r and SEn between photo-measurements and t h e o r e t i c a l values were c a l c u l a t e d and summarized i n Table 45. Table 45: Comparison o f accuracy o f c o m p i l a t i o n height growth by stand and year o f photography. Year  S t a n d s G r i f f i t h plots P. S. P.'s _ Nat. regen. p l o t s N Mean e r r o r SEp N Mean e r r o r SEp N Mean e r r o r SEg  19301949 5  -15.5  7.86  19301955 5  - 8.6  2.93  19491955 5  + 5.9  4.09 5  +2.2  0.41  4  -0.1  0.91  19491963  5  -7.3  0.93  4  -0.5  1.46  19551963  5  -9.7  0.64  4  -0.1  0.96  From Table 45, i t can be seen that the greatest e r r o r e x i s t s i n the group o f G r i f f i t h p l o t s .  This s i t u a t i o n seems  to c o n t r a d i c t the r e s u l t s obtained f o r measurements o f compila t i o n height alone; however, the great variance has come from underestimates  f o r p l o t No. 5 on the 1949 s e r i e s and over-  111. estimates f o r p l o t No. 7 on the 1930 s e r i e s .  The l e a s t e r r o r  i s found w i t h i n the group o f P.S.P.'s p l o t s .  This f a c t again  c o n t r a d i c t s the c o n c l u s i o n made f o r the e s t i m a t i o n o f compil a t i o n height alone that P.S.P.'s give the l e a s t accuracy.  The  s i t u a t i o n can o n l y be accounted f o r by the j o i n t computation of photo heights and t h e o r e t i c a l heights which compensated i n d i v i d u a l e r r o r measurements, and thus reduced great e r r o r i n growth estimates.  I n f a c t , the group of n a t u r a l regeneration  p l o t s seems to give the best r e s u l t s because the mean e r r o r s are g e n e r a l l y very small i f compared w i t h the other two groups of plots. 2.  Average crown width growth. S i m i l a r l y , average crown width growth f o r the  stands i n terms o f mean e r r o r s and SEj-j between photo values and t h e o r e t i c a l values were computed. Table 46 exceeds +1.0 f e e t .  None o f the SEp's i n  The greatest e r r o r s are found i n  the group o f P.S.P.'s which would correspond to the f a c t s obtained f o r the average crown width measurements alone. Table 46:  Year  Comparison o f accuracy o f average crown width growth by stand,year o f photography.  s t a n d s G r i f f i t h plots P. S. P. 's Nat. regen. p l o t s N Mean e r r o r SEg N Mean e r r o r SEg N Mean e r r o r SEg (ft.) (ft.) (ft.) (ft.) (ft.) (ft.)  19491955 5 19491963 19551963  -2.0  0.46'S 5  -0.02  0.52  3  -1.8  0.37  5  -1.0  0.48  3  -1.8  0.10  5  -1.0  0.13  4  -1.3  0.67  112. No c o n s i s t e n t r e s u l t s can be used to determine which s e r i e s o f photo-combinations gives the highest degree o f accuracy i n Table 46.  The values o f e r r o r s f o r the growth  estimates o f average crown width depend on the combined e f f e c t o f j o i n t computation o f photo-measurements  and t h e o r e t i c a l  values• 3.  Crown c l o s u r e growth. The same approach o f comparison f o r crown c l o s u r e  growth w i t h crown c l o s u r e measurements alone was made i n terms o f p e r i o d i c mean growth.  The r e s u l t s shown i n Table 47 were  c a l c u l a t e d from Table 44. Table 47:  Year  Comparison o f p e r i o d i c average crown c l o s u r e growth by stand and year o f photography.  G r i f f i t h plots N Ave.CC Growth ;  S t a n d s P. S.. P. 's N Ave. CC Growth  m  Nat. regen.plots N Ave. CC Growth  (%)  (%)  19301949  5  4  5  10  5  6  19301955 19491955  5  4  5  10  1963  5  -8  5  17  19551963  5 - 1 2  5  7  1949-  113. SUMMARY OF RESULTS  Of 135 open grown trees measured on the ground, 95 trees showed good images on the photographs, 34 trees appeared medium, while 6 trees r e g i s t e r e d very poor images on the photographs.  The smallest standard e r r o r o f the mean d i f f e r e n c e  between photo-measurements and heights obtained on the ground was +0.25 f e e t f o r the good image trees and the greatest standard e r r o r o f the mean d i f f e r e n c e was +5.23 f e e t f o r the poor image t r e e s .  The errors obtained  f o r the checking method  were g e n e r a l l y lower than those f o r the conventional methods. However, they do not seem to be s i g n i f i c a n t l y d i f f e r e n t . Although there was a tendency that measurements o f heights f o r the c o n i f e r s were s l i g h t l y b e t t e r than those f o r the hardwoods, as the number o f observations  f o r hardwoods i s increased, they  might give b e t t e r r e s u l t s . When H/A curves were used as c r i t e r i a , the greatest standard e r r o r o f the mean d i f f e r e n c e f o r the p e r i o d i c growth o f 5 observations  was +9.44 f e e t and the smallest was +0.84  f e e t f o r 69 observations  between 1955 and 1963.  e r r o r ranged from -0.1 f e e t to +30.4 f e e t . 1930,  The mean  However, i f the  1940, and 1964 s e r i e s were excluded, the e r r o r ranged  from -0.1 f e e t to +6.0 f e e t .  114. There was no c o n s i s t e n t r e s u l t which would give a clue to determine which species gives the best height  estimates.  Measurements o f crown width were revealed to be f a i r l y accurate.  The minimum standard e r r o r o f the mean d i f f e r e n c e  was +0.21 f e e t f o r Douglas f i r when compared with the ground data, and the maximum e r r o r was +0.58 f e e t f o r a l d e r .  When  comparisons were made i n terms o f mean e r r o r s , cottonwood showed the l e a s t accuracy ( -1.3 f e e t ) while a c o n s i s t e n t mean e r r o r o f zero was obtained  f o r Douglas f i r , cedar and hemlock.  The use o f t h e o r e t i c a l values as c r i t e r i a f o r crown width measurements o n l y , tends to r e s u l t i n greater e r r o r f o r f i v e species than when ground c o n t r o l s were used.  The standard  e r r o r o f the mean d i f f e r e n c e ranges from &0.94 f e e t f o r f i r to +1.61  f e e t f o r cottonwood. I t was observed that when using the t h e o r e t i c a l approach  i n p r e d i c t i n g the growth o f crown width, a l d e r gave the smallest standard e r r o r o f the mean d i f f e r e n c e .  However, t h i s  f a c t i s assumed to be because the t h e o r e t i c a l values f o r a l d e r are c l o s e r to the a c t u a l values than those f o r the r e s t o f four species. For the growth estimates o f stand v a r i a b l e s , the smallest mean e r r o r ( -OJ-feet ) was found f o r the compilation  height  115. among the group o f n a t u r a l regeneration  plots.  The greatest  mean e r r o r ( -15.5 f e e t ) i s found i n the case o f G r i f f i t h p l o t , however, i t was detected  that the great e r r o r has come  from underestimates o f heights on one p l o t , Estimation o f average crown width growth was g e n e r a l l y good.  The smallest  SE5 was found to be +0.10 f e e t f o r the group o f n a t u r a l regeneration  p l o t s but the greatest SEp o f +0.67 f e e t was also  found f o r the same group o f p l o t s .  I t was concluded that the  values o f e r r o r s f o r the growth estimates o f average crown width depend p a r t l y by the combined e f f e c t o f j o i n t computation of photo-measurements and t h e o r e t i c a l values. On the whole, methods o f p r e d i c t i o n o f growth o f stands by the use o f a s e r i e s o f a e r i a l photographs should be u s e f u l unless the stand i s so densely stocked that i t would a f f e c t the measurements o f compilation  height.  116. CONCLUSION The p o t e n t i a l use o f a e r i a l photographs i n estimating the growth o f the trees and stands described has been demonstrated.  i n this thesis  I t i s hoped that t h i s method w i l l be  u s e f u l to o t h e r f o r e s t e r s o r f o r e s t managers.  P a r t i a l con-  c l u s i o n s are found a t the end o f each a n a l y s i s i n t h i s t h e s i s . However, the w r i t e r would l i k e to s t r e s s the f o l l o w i n g items: 1.  The method o f p r e d i c t i o n o f growth o f trees and stands from a s e r i e s o f photographs i s theoret i c a l l y sound.  2.  The degree of accuracy w i t h which the growth estimates can be achieved v a r i e s g r e a t l y with kinds of photography, q u a l i t y o f photographs, and above a l l , the v i s i b i l i t y o f tree images.  3.  The highest degree o f accuracy i s associated  with  good image trees r e g i s t e r e d on the good q u a l i t y photographs.  Poor photography i s subject to  great e r r o r . 4.  The best photos are those taken i n the year 1963, with 12-inch f o c a l length l e n s , a t an e l e v a t i o n o f 15,900 f e e t with an RC 8 camera.  117. 5.  H/A curves were s u i t a b l e c r i t e r i a o f growth f o r the f i v e species s t u d i e d .  6.  There was no c o n s i s t e n t r e s u l t as to what species gives the best growth estimates, but w i t h l i m i t e d p a i r s o f trees measured on the photographs, Douglas f i r has demonstrated the highest degree of accuracy, and hemlock, the l e a s t .  7.  When H/A curves were used, the s m a l l e s t standard e r r o r o f the mean d i f f e r e n c e was +3.09 f e e t f o r hemlock and the g r e a t e s t e r r o r was +11.01 f e e t for f i r .  8.  I t was found that the H/A curves when they are a p p l i e d to a l d e r and cottonwood y i e l d b e t t e r r e s u l t s than to Douglas f i r , cedar and hemlock.  9.  There was a tendency to o b t a i n p o s i t i v e mean errors when the H/A curves were used as c r i t e r i a f o r growth estimates.  10.  The measurements o f crown width f o r both alders and cottonwood on the photographs were l e s s accurate than those f o r f i r , cedar, and hemlock.  11.  The use o f t h e o r e t i c a l values as c r i t e r i a f o r measurements o f crown width tends to r e s u l t i n greater e r r o r than when the ground c o n t r o l s were compared.  118. 12.  The t h e o r e t i c a l approach i n p r e d i c t i n g the growth of crown width f o r a l d e r tends to be more acceptable than f o r the other four s p e c i e s .  13.  G e n e r a l l y , the growth o f crown width can be e s t i mated d i r e c t l y from a s e r i e s o f good q u a l i t y photographs taken a t an optimum s c a l e o f 1:12,000.  14.  I t was found that the checking method would y i e l d some improvement i n accuracy o f height measurement.  15.  No s u i t a b l e i n f o r m a t i o n was found to d e f i n e whether there e x i s t s i g n i f i c a n t d i f f e r e n c e s among s p e c i e s , q u a l i t y o f images, methods and year o f photography. Perhaps a n a l y s i s o f variances w i t h unequal sample s i z e should be c a r r i e d o u t .  16.  For the p r e d i c t i o n o f the growth o f stand, best r e s u l t s were obtained f o r r e l a t i v e l y open young stands a t an average crown c l o s u r e o f 25 per cent.  17.  I t was found that i n d e f i n i n g the accuracy o f growth estimates f o r stand v a r i a b l e s , the value o f e r r o r i s a combined e f f e c t o f variances o f photo-measurements and t h e o r e t i c a l v a l u e s .  119. Cost analysis on the growth estimation was made i n this study.  not  However, time required to  measure tree height and crown width have been approximated.  On the average, four minutes  needed to take parallax readings f o r one  was  tree,  and one minute f o r measuring crown width per tree. These measurements, i f made i n the f i e l d would have taken longer, and would also have required t r a v e l from tree to tree.  Therefore, i n some  cases some work and cost may  be saved i f growth  estimates are made on the photographs. In the previous studies, no information  was  obtained to determine the significances among species, q u a l i t y of image, methods and year of photography, also the interactions between species and quality of images, species and methods, etc. These problems could be studied by further analysis of these and other data.  I f further  studies are to be c a r r i e d out, measurement with equal and s u f f i c i e n t number of trees i s recommended.  120. REFERENCES A l l i s o n , G. W. 1955. An a p p l i c a t i o n of an a e r i a l photo volume t a b l e to f o r e s t inventory work i n B r i t i s h Columbia. For. Chron. 31:367-370. . 1956. The accuracy of tree height measurements on various q u a l i t i e s o f a e r i a l photographs. For. Chron. 32:444-450. A l l i s o n , G. W. and R. E. Breadon. 1958. P r o v i n c i a l a e r i a l photostand volume tables f o r I n t e r i o r B.C. For. Chron. 34(1):77-83. . 1960. Timber volume estimates from a e r i a l photographs. For. Survey Note. B.C. For. Ser. No. 5, 25 pp. Andrews, G. S. 1934. A i r survey and f o r e s t r y developments i n Germany. For. Chron. 10:91-107. • 1936. Tree heights from a e r i a l photographs by simple p a r a l l a x measurements. For. Chron. 12:152-197. American S o c i e t y o f Photogrammetry. 1960. Manual o f photographic i n t e r p r e t a t i o n . Benta Publ. Co. Menasha, Wis., 868 pp. Anonymous. 1959a. A e r i a l volume tables f o r spruce stands i n I n t e r i o r o f A l a s k a . U.S. For. Ser., For Surv. Alaska For. Res. S t a . F i l e Data. . 1959b. A e r i a l volume t a b l e . Modoc N a t i o n a l For. U.S. For. Ser. P a c i f i c Southwest Expt. S t a . F i l e Notes. Apsey, T. M. 1961. An e v a l u a t i o n o f crown widths of opengrown red a l d e r as an a i d to the p r e d i c t i o n of growth and y i e l d . U.B.C. Graduate's t h e s i s . 57 pp. Avery, G. 1957. Forester's guide to a e r i a l p h o t o - i n t e r p r e t a t i o n . U.S. For. Ser. Southern For. Expt. S t a . Occas. Pap. 156, 41 pp.  121. Avery, G. 1958a. H e l i c o p t e r stereo-photography of f o r e s t p l o t s . Photogram. Eng. 24:617-625. . 1958b. Composite a e r i a l volume tables f o r southern pine and hardwoods. J . For. 56(10):741-745. . 1962. Recent trends i n f o r e s t photogrammetry. J . For. 60(7):458-461. . 1964. Forester's guide to a e r i a l photo i n t e r p r e t a t i o n . Southern For. Expt. S t a . Occas. Pap. 156. U.S. Dept. o f Agr., 42 pp. Avery, G. and M. P. Meyer. 1959. Volume tables f o r a e r i a l timber e s t i m a t i n g i n northern Minnesota. S t a . Pap. Lake S t . For. Expt. S t a . No. 78 pp i i + 21. Avery, G. and D. Myhre. 1959. Composite a e r i a l volume tables f o r southern Arkansas. Occas. Pap. Southern For. Expt. S t a . No. 172 9 pp. Baker, F. S. 1953. 95-97.  Stand d e n s i t y and growth. J . For. 51(Z):  Barnes, G. H. 1962. Y i e l d o f even-aged stands o f western hemlock. Tech. B u l l . No. 1273. U.S. Dept. Agr. 52 pp. B. C. For. Ser. 1947. Y i e l d t a b l e s f o r B.C. Economics D i v i s i o n . V i c t . B.C. Mimeo. Belyea, H.C. 1946. Forest measurement. John Wiley & Sons Inc. London, Chapman 6c H a l l L t d . 319 pp. Bernsten, C. M. 1958. A look a t red a l d e r - p u r e , and i n mixture w i t h c o n i f e r s . Proceedings S o c i e t y o f American F o r e s t e r s . 157-158. . 1962. A 20-year growth r e c o r d f o r three stands o f red a l d e r (Alnus r u b r a ) . Res. Note PNW For. Range Expt. S t a . No. 219. 9 pp. B e r n s t e i n , D. A. 1958. Does m a g n i f i c a t i o n improve measurements o f stand heights on a e r i a l photographs? For. Chron. 34(4):435-437. B i c k f o r d , C. A. 1959. A t e s t o f continuous i n v e n t o r y f o r n a t i o n a l f o r e s t management based upon a i r photos, double sampling, and remeasured p l o t s . Proc. Soc. Amer. For. 143-148.  122. Bishop, D. M., Johnson, F. A. and G. R. S t a e b l e r . 1958. S i t e curves f o r red a l d e r . U.S. Dept. Agr. For. Ser. PNW For. & Range Expt. S t a . Res. Note No. 162. 7 pp. Brewer, L. C., Byrd, D. 0. and P. W. Rea e t a l . 1959. A device f o r measuring crown diameters of open grown t r e e s . J . For. 57(8):577. Brown, N. E. 1962. The canopy camera. S t a . Pap. Rocky Mt. For. Range Expt. S t a . No. 72. 22 pp. Bruce, D. and F. X. Schumacher. 1950. Forest mensuration. McGraw-Hill Book Co. Inc. 483 pp. Chapman, H. H. and W. H. Meyer. 1959. F o r e s t mensuration. McGraw-Hill Book Co. Inc. New York. 522 pp. C o l l i n s , J . R. 1957. A check on the accuracy of t r e e heights taken from a e r i a l photographs. For. Chron. 33:168-169. C o l w e l l , R. N., Bradshaw, K. E., Smith, H.T.U., Thoren, R. and C. A. J . Von Drabbe. 1952. Report of Commission VII (Photographic I n t e r p r e t a t i o n ) to the I n t e r n a t i o n a l S o c i e t y of Photogrammetry. Photgram. Eng. 18:375-451. D i l w o r t h , J . R. 1956. The use of a i r photos i n c r u i s i n g second-growth D o u g l a s - f i r stands. Unpublished t h e s i s f o r the degree of Doctor o f Philosophy. Univ. Wash. 153 pp. . 1959. A e r i a l photo-mensuration t a b l e s . Res. Note For. Res. Div. Ore. Agr. Expt. S t a . No. 46. 8 pp. Dobie, J . 1963. A m i l l i n g study of 150-year o l d D o u g l a s - f i r i n c o a s t a l B.C. Publ. Dep. For. Can. No. 1032, 18 pp. Duffy, P. J . B. and M. P. Meyer. 1962. A p r e l i m i n a r y study of a e r i a l photographs volume t a b l e c o n s t r u c t i o n f o r Lodge pole pine i n West C e n t r a l A l b e r t a . For. Chron. 38:212-219. Ferree, M. J . 1953. A method of e s t i m a t i n g timber volumes from a e r i a l photographs. State. Univ. of N.Y. College o f For. Tech. Pub. 75. 50 pp. Garver, R. D. and K. E. Moessner. 1949. Forest S e r v i c e use o f a e r i a l photographs. Photogram. Eng. 15:504-517.  123. G e t c h e l l , W. A. and H. E. Young. 1953. Length o f time necessary to a t t a i n p r o f i c i e n c y w i t h height f i n d e r s on a i r photos. For. Dept. Univ. o f Maine, Tech. Note No. 23. 2 pp. Gevorkantz, S. R. and W. A. Duerr. 1938. Growth p r e d i c t i o n s and s i t e determination i n uneven-aged timber stands. J . Agr. Res. 56:81-98. G i n g r i c h , S. F., and H.A. Meyer. 1955. C o n s t r u c t i o n o f a e r i a l stand volume t a b l e f o r upland oak. For. S c i . 1:140-147. G r i f f i t h , B. G. 1960. Growth o f D o u g l a s - f i r a t the U.B.C. Research Forest as r e l a t e d to c l i m a t e and s o i l . Fac. o f For. For. B u l l . No. 2. 58 pp. Haack, P. M. 1962. E v a l u a t i n g c o l o u r , i n f r a r e d , and panchromatic a e r i a l photos f o r the f o r e s t survey o f I n t e r i o r Alaska. Photogram. Eng. 28(4):592-598. . 1963. A e r i a l photo volume tables f o r I n t e r i o r Alaska tree species. U.S. For. Ser. Res. Note Northern For. Expt. S t a . No. NOR-3. 8 pp. Harlow, W. H. and E. S. Harrar. 1950. Textbook o f dendrology. McGraw-Hill Book Co. Inc. 542 pp. Hindley, E. 1959. C o r r e c t i o n f a c t o r s f o r heights o f immature trees measured on a e r i a l photographs. For. Chron. 35(4):327-328. Hindley, E. and J . H. G. Smith. 1957. Spectrophotometrie a n a l y s i s o f f o l i a g e o f some B.C. c o n i f e r s . Photogram. Eng. 23(5):894-895. Honer, T. G. and L. Sayn-Wittgenstein. 1963. Report o f the committee on f o r e s t mensuration. J . For. 61(9):663-667. Jensen, C.E. 1958. Dot-type s c a l e f o r measuring tree crown diameters on a e r i a l photographs. U.S. For. Ser. C e n t r a l States For. Expt. S t a . Note No. 48. 4 pp. Johnson, E. W. 1954. Shadow-height computations made e a s i e r . J . For. 52:438-442. . 1958a. E f f e c t o f photographic s c a l e on p r e c i s i o n o f i n d i v i d u a l tree height measurement. Photogram. Eng. 24(1):142-152.  124. Johnson, E. W. 1958b. A t r a i n i n g program f o r men measuring t r e e h e i g h t with p a r a l l a x instruments. Photogram. Eng. 24(1):50-55. John, H.H. and M. P. Meyer. 1961. Comparative f o r e s t a e r i a l photo i n t e r p r e t a t i o n r e s u l t s from v a r i a b l e contrast and s i n g l e - c o n t r a s t paper p r i n t s . Photogram. Eng. 27(5):698-704. K e n d a l l , R.H. and L. Sayn-Wittgenstein. 1961. A t e s t o f the e f f e c t i v e n e s s o f a i r photo s t r a t i f i c a t i o n . For. Chron. 37:350-355. Ker, J . W. 1953. The e s t i m a t i o n o f t r e e heights from a i r photographs. An unpublished r e p o r t submitted to Yale School o f Forestry as a requirement f o r the degree o f Doctor o f Forestry. 62 pp. Ker, J . W. and J . H. G. Smith. 1957. How much and how f a s t f o r e s t measurement today. Fac. For. U.B.C. Reprinted from Feb. and Mar. Issues o f B.C. Lumberman. 6 pp. Kozak, A., S z i k l a i , 0., G r i f f i t h , B.G., and J.H.G. Smith. 1963. V a r i a t i o n i n cone and seed from young open-grown D o u g l a s - f i r s on the U.B.C. Research Forest. U.B.C. Res. Pap. No. 57. 8 pp. Lee, Y. 1959. A comparison o f some 12-inch and 6-inch f o c a l length photographs f o r photo mensuration and f o r e s t typing. U.B.C. M.F. Thesis. 123 pp. Lemmon, P. E. 1956. A s p h e r i c a l densiometer f o r estimating f o r e s t o v e r s t o r y d e n s i t y . For. S c i . 2:314-320. Losee, S.T.B. 1953. Timber estimates from l a r g e - s c a l e photographs. Photogram. Eng. 19:752-762. Lyons, E. H. 1961. P r e l i m i n a r y studies o f two camera, lowe l e v a t i o n stereo-photography from h e l i c o p t e r s . Photogram. Eng. 27(l):72-76. -  1964. Recent developments i n 70 mm. stereophotography from h e l i c o p t e r s . Photogram. Eng. 30(5): 750-756.  MacLean, C D . and R. P. Pope. 1961. Bias i n the estimation o f stand h e i g h t from a e r i a l photographs. For. Chron. 37(2):160-161.  125 McArdle, R. E., Meyer, W. H. and D. Bruce. 1949. The y i e l d table o f D o u g l a s - f i r i n the P a c i f i c Northwest. U.S.D.A. Tech. B u l l . No. 201. 74 pp. Meyer, H. A. 1940. A mathematical expression f o r height curves. J . For. 38:415-420. '  1942. Methods o f f o r e s t growth determination. Pan. State College Agr. Expt. S t a . B u l l . No. 435. 93 pp.  Meyer, M. P. 1957. A p r e l i m i n a r y study o f the i n f l u e n c e o f photo paper c h a r a c t e r i s t i c s upon stereo image percept i o n . Photogram. Eng. 23:149-155. . 1960. Transfer o f points from o l d to new a i r photos. Minn. For. Note No. 93. 2 pp. •  1961. A e r i a l volume tables f o r Northern Minnesota. Minn. For. Note No. 105, 106. 2 pp.  Meyer, M. P. and L. H. Trantow. 1957. Some observed e f f e c t s o f v a r i a t i o n s i n photo paper emulsion and tone upon stereo perception o f tree crown. Photogram. Eng. 23(5):896-900. Meyer, W. H. 1934. Growth i n s e l e c t i v e l y cut ponderosa pine f o r e s t s o f the P a c i f i c Northwest. U.S. Dept. Agr. Tech. B u l l . No. 407. 64 pp. Miner, C. 0. 1951. Stem-crown diameter r e l a t i o n i n southern pine. J . For. 49:490-493. . 1960. Estimating tree diameters o f A r i z o n a Ponderosa pine from a e r i a l photographs. Res. Note Rocky Mt. For. Range Expt. S t a . No. 46. 2 pp. M i t c h e l l , K. 1961. An e v a l u a t i o n o f two methods o f choosing a r e p r e s e n t a t i v e p a r a l l a x d i f f e r e n c e . U.B.C. Unpublished paper. Moessner, K. E. 1947. A crown d e n s i t y s c a l e f o r photo-interp r e t a t i o n s . J . For. 45:434-436. . 1948. A crown d e n s i t y s c a l e f o r photo-interp r e t a t i o n s . J . For. 47:569.  126. Moessner, K. E. 1950. P r i n c i p l e uses o f a i r photos by the Forest S e r v i c e . Photogram. Eng. 16:301-304. •  1955. The accuracy o f stand height measurements on a e r i a l photographs i n the Rocky Mountains. U.S. For. Ser. I n t e r . For. Range Expt. S t a . Res. Note No. 25. 5 pp. • 1957. P r e l i m i n a r y a e r i a l volume tables f o r c o n i f e r stands i n the Rocky mountains. U.S. For. Ser. I n t e r . Mt. For. Range Expt. S t a . Res. Pap. No. 41. 17 pp. . 1960. Basic techniques i n f o r e s t photo i n t e r p r e t a t i o n . A t r a i n i n g book, U.S. For. Ser. I n t e r . Mt. For. Range Expt. S t a . Res. Pap. No. 41. 17 pp. . 1961. Comparative usefulness o f three p a r a l l a x measuring instruments i n the measurements and i n t e r p r e t a t i o n o f f o r e s t stands. Photogram. Eng. 27(5):705-709. . 1962. P r e l i m i n a r y a e r i a l volume tables f o r Pinyan-juniper stands. Res. Pap. I n t e r Mt. Range Expt. Sta. No. 69 12 pp.  •  1963a. Composite a e r i a l volume tables f o r c o n i f e r stands i n the mountain s t a t e s . U.S. For. S e r . Note I n t e r Mt. For. Range Expt. S t a . No. INT-6. 4 pp. • 1963b. Why not use b l u e p r i n t s ? U.S. Dept. Agr. I n t e r Mt. For. Range Expt. S t a . U.S. For. Ser. Res. Note INT-4. 2 pp.  Moessner, K. E., Brunson, D.F., and C. E. Jensen. 1951. A e r i a l volume tables f o r hard wood stand i n the C e n t r a l States. U.S. For. Ser. C e n t r a l States Expt. S t a . Tech. Pap. No. 122. 15 pp. Moessner, K. E. and E. J . Rogers. 1957. P a r a l l a x wedge procedures i n f o r e s t surveys. U.S. For. Ser. I n t e r Mt. For. Range Expt. S t a . Misc. Pub. No. 15. 22 pp. Myhre, D. W. and M.P. Meyer. 1961. V a r i a t i o n s i n a e r i a l photo image recovery r e s u l t i n g from d i f f e r e n c e s i n f i l m and p r i n t i n g technique. Photogram. Eng. 27:595-600. Nash, A.J. 1949. Some t e s t s o f the determination o f tree heights from a e r i a l photographs. For. Chron. 25(4): 243-249. Pearson, R. 1962. A n a l y s i s o f crown width o f open grown and f o r e s t grown black cottonwood as an a i d i n the p r e d i c t i o n of y i e l d and growth. B.S.F. t h e s i s . F a c u l t y o f F o r e s t r y , U.B.C.  127. Pope, R. B. 1957. The e f f e c t o f photo s c a l e on the accuracy of f o r e s t r y measurements. Photogram. Eng. 23(5):369-873. . 1960. Occular estimates o f crown d e n s i t y on a e r i a l photographs. For. Chron. 36(l):89-90. . 1962. Constructing aerial-photovolume t a b l e s . P.N.W. Pap. No. 49. 22 pp. Rogers, E. J . 1946. Use o f the p a r a l l a x wedge i n measuring tree height on v e r t i c a l a e r i a l photographs. Northeastern For. Expt. S t a . For. Survey Note No. 1. 17 pp. 1958. Report o f working group 4 ( f o r e s t e r s ) Commission V I I , I n t e r n a t i o n a l S o c i e t y o f Photogrammetry. Photogram. Eng. 24(4):603-616. . 1960. Forest survey design applying a e r i a l photographs and r e g r e s s i o n technique f o r the Caspian f o r e s t s of I r a n . Photogram. Eng. 26(3):441-444. . 1961. A p p l i c a t i o n s o f a e r i a l photographs and r e g r e s s i o n techniques f o r surveying Caspian f o r e s t s o f I r a n . Photogram. Eng. 27(5) :8U-817. Rogers, E. J . , Avery, G. and R. A. Chapman. 1959a. Three scales of a e r i a l photography compared f o r making stand measurements. For. Res. Note Northwest For. Expt. S t a . No. 88, 4 pp. Rogers, E. J . , Avery, G. and R. A. Chapman. 1959b. S e l e c t i o n o f stand v a r i a b l e s i n southern Maine f o r making volume estimates from a e r i a l photographs. For. Res. Note Northeast For. Expt. S t a . No. 89. 3 -pp. Ronay, A. 1961. Study o f crown shapes o f D o u g l a s - f i r , western hemlock, and western red cedar as an a i d i n the i d e n t i f i c a t i o n o f these species on a e r i a l photographs. B.S.F. t h e s i s . Faculty o f F o r e s t r y . U.B.C. 116 pp. Sayn-Wittgenstein, L. I960. Recognition o f tree species on a i r photos by crown c h a r a c t e r i s t i c s . Tech. Note. Dept. For. Can. No. 95, 56 pp. . 1961. Phenological aids to species i d e n t i f i c a t i o n on a i r - p h o t o s . Tech. Note. Dept. For. Can. No. 104. 26 pp. Seely, H. E. 1935. The use o f a i r photographs f o r f o r e s t r y purpose. For. Chron. 11:287-293. Smith, J . H. G. 1957a. Some f a c t o r s i n d i c a t i v e o f s i t e q u a l i t y f o r black cottonwood (Populus t r i c h o c a r p a Torr.& Gray). J . For. 55(8):578-580.  128 Smith, J . H. G. 1957b. Problems and p o t e n t i a l uses o f photomensurational techniques f o r e s t i m a t i o n o f volume o f some immature stands o f D o u g l a s - f i r and western hemlock. Reprint from Photogram. Eng. June:595-599. For.  . 1957c. Forest h i s t o r y from a e r i a l photographs. Chron. 33(4):390-392.  . 1958. B e t t e r y i e l d s through wider spacing. J . For. 56(7):492-497. . 1962. Preparation o f a method f o r p r e d i c t i n g stand development form stem a n a l y s i s . U.B.C. Unpublished paper. 12 pp. . 1963. A n a l y s i s o f crown development can estab l i s h b i o l o g i c a l and economic l i m i t s to growth o f trees and stands. Comm. W. For. Rev. 42(l):27-33. Smith, J . H. G. and J . W. Ker. 1956. Some problems and approaches i n c l a s s i f i c a t i o n o f s i t e i n j u v e n i l e stands o f Douglas f i r . For. Chron. 32(4):417-428. . 1957a. Timber volume depends on D2H. B.C. Lumbermen. 41(9):28-30. . 1957b. Some d i s t r i b u t i o n s encountered i n sampling f o r e s t stands. For. S c i . 3 ( 2 ) : 137-144. . 1958. Sequential sampling i n reproduction. J . For. 56(2):107-109. Smith, J . H. G., Ker, J . W. and L. Heger. 1960. N a t u r a l and conventional height-age curves f o r D o u g l a s - f i r and some l i m i t to t h e i r refinement. Proc. 5th. World For. Congr. S e a t t l e , 546-551. Smith, J.H.G., Lee, Y. and J . Dobie. 1960. Intensive assessment o f f a c t o r s i n f l u e n c i n g photo-cruising shows that l o c a l expressions o f photo volume are best. Photogram. Eng. June:463-469. Smith, J.H.G. and D. Bajak. 1961. Photo i n t e r p r e t a t i o n provides a good estimation o f s i t e index f o r f i r , hemlock and cedar. J . For. 59:261-263. Smith, J.H.G., Walters, J.W. and J.W. Ker. 1961a. P r e l i m i n a r y estimates o f growth and y i e l d o f western r e d cedars. Fac. For. U.B.C. Res. Pap. No. 42. 8 pp. Smith, J.H.G., Ker, J.W. and J . Csizmazia. 1961b. Economics o f r e f o r e s t a t i o n o f Douglas f i r , western hemlock and western red cedar i n the Vancouver Forest D i s t r i c t . Fac. For. U.B.C. For. B u l l . No. 3, 144 pp.  129. Spurr, S. H. 1945. P a r a l l a x wedge measuring devices. Photogram. Eng. 11:85-89. . 1948. A e r i a l photographic techniques i n f o r e s t r y . Photogram. Eng. 20:551-560. . 1952. Forest inventory. Ronald Press Co., N.Y. 476 pp. . 1960. Photogrammetry and photo i n t e r p r e t a t i o n . 2nd. ed. Ronald Press Co. N.Y. 472 pp. . 1963. Growth o f D o u g l a s - f i r i n New Zealand. Tech. Pap. N.Z. For. Res. I n s t . 43, 54 pp. S t e e l , R.G.D. and J . H. T o r r i e . 1960. P r i n c i p l e s and procedures of s t a s t i s t i c s . McGraw-Hill Book Co. N.Y. 488 pp. S t i c k l e r , G.S. 1959. Use of the densiometer to estimate d e n s i t y o f f o r e s t canopy on permanent sample p l o t s . Res. Note P a c i f i c N.W. For. Range Expt. S t a . No. 180, 5 pp. Survey d i v i s i o n Japanese F o r e s t r y Technical A s s o c i a t i o n . 1961. An attempt to estimate growth o f trees from o l d and new s e r i e s of a i r photos. For. A e r i a l Survey. 28:502-503. Turnock, W.J. and W.G.H. Ives. 1957. An instrument f o r measuring the r a d i i o f t r e e crowns. For. Chron. 33(4)355-357. Walters, J . and J . Soos. 1962. The gimbal s i g h t f o r the proj e c t i o n o f crown r a d i u s . U.B.C. Res. Pap. No. 39, 6 pp. Wang, Y.M. 1965. E s t i m a t i o n of age of immature trees and stands from a s e r i e s o f a e r i a l photographs. A report submitted i n p a r t i a l f u l f i l m e n t o f the requirements f o r For. 564 i n the F a c u l t y o f F o r e s t r y a a t U.B.C. 20 pp. Wellwood, R. W. and J . H. G. Smith. 1962. V a r i a t i o n i n some important q u a l i t i e s o f wood from young D o u g l a s - f i r and hemlock t r e e s . U.B.C. Res. Pap. No. 50. 15 pp. Willingham, J.W. 1957a. The i n d i r e c t determination o f f o r e s t stand v a r i a b l e s from v e r t i c a l a e r i a l photographs. Photogram. Eng. 23(5):892-893. .1957b. Estimation o f f o r e s t management inventory data from a e r i a l photographic measurements. For. S c i . 3(3)-.270-274. Wilson, R. 1946. A e r i a l photo techniques. U.S. For. Ser. Tech. Conf. Mimeo. 22 pp. . 1948. Photo i n t e r p r e t a t i o n aids f o r timber survey. J . For. 46:41-44.  130. Worley, D. P. and G. H. Landis. 1954. The accuracy of height measurements with parallax instruments on 1:12,000 photographs. Photogram. Eng. 20:823-829. Worley, D. P. and H. A. Meyer. 1955. Measurement of crown diameter and crown closure and their accuracy on 1:12,000 photographs. Photogram. Eng. 21:372-375. Worthington, N.P., Ruth, R. H. and E. E. Matson. 1962. Red alder i t s management and u t i l i z a t i o n . U.S. Dept. Agr. 6c For. Misc. Pub. No. 881. 44 pp. Worthington, N.P., Johnson, F.A., Staebler, G. R. and W. J . Lloyd. 1960. Normal y i e l d tables f o r red alder. P a c i f i c Northwest For. Range Expt. Sta. U.S. Dept. Agr. Res. Pap. No. 36. 29 pp.  APPENDIX I LOCATION OF TREES AND PLOTS  UNIVERSITY OF BRITISH COLUMBIA RESEARCH FOREST, HANEY, B- C-  A Approximate Scales l " = 2 0 0 0 '  II  Date of Photography-June 17,1964 Prepared by Fourth Year Photogrammetry Class, Faculty of Forestry, U- B- COctober, 1964  APPENDIX II GROUND DATA  134. Table 1.  Dbh, h e i g h t , crown width, and age o f G r i f f i t h ' s Douglas F i r trees i n 1963.  Tree No.  Species  1  D. F i r  Dbh (in.)  T o t a l Height (ft.)  Crown Width (ft.)  Age (Yrs.)  11.1  46  24  25  2  II  9.4  42  22  22  3  II  15.3  49  28  32  4  II  10.3  50  21  20  5  II  13.1  45  26  26  7  II  13.6  56  24  32  9  II  11.8  46  24  23  10  II  10.5  45  21  31  15.0  58  28  32  14  it  23  II  16.5  66  30  28  27  II  8.4  42  20  23  28  II  8.2  42  19  19  29  II  8.2  51  27  26  32  II  8.7  53  19  21  36  ii  8.5  42  20  22  37  ii  19.9  68  31  32  38  II  9.4  54  20  22  39  II  11.5  48  18  26  43  li  13.5  53  26  28  47  ii  9.1  46  21  21  48  II  15.1  56  22  28  49  II  11.0  51  24  24  8.7  47  16  27  53  it  Note: The f o l l o w i n g codes w i l l apply to Tables 1 through 5. D. F i r ( o r F) C H S  = = =  Douglas F i r Western red cedar Western hemlock Spruce  135. Table 2. Tree No. 1 2 3 4 5 8 9 10 11 12 14 15 16 18 19 20 21 22 23 24 25 26 27 28 29 31 32 33 34 35 36 37 38 39 40 41 42 43 Note:  Dbh, height and crown width o f permanent sample trees measured i n 1954.  Species F C F S F H H H F F S S F C H C F F S C C H C H F C C C C H H H C F F F F F  Dbh (in.) 23.7 24.5 39.4  -  26.5 29.7 25.4 30.8 38.2 15.5 51.2 53.0 26,2 40.3 30.9  -  18.8 44.5 23.5 25.0  -  26.9 25.1 19.5  -  31.5 26.9 30.5 21.3 19.3 24.5 34.5 34.5 25.0 31.6 29.6 32.6  T o t a l Height Crown Width (ft.) (ft.) 103 105 152 148 131 127 120 135 155 72 142 143 101 123 93 71 80 146 97 90 85 82 83 93 108 98 78 77 78 83 73 117 93 160 108 126 135 113  Remarks  23.5 24.5 31.5  -  24.5 25.5 29.0 27.5 30.0 18.0 44.0 46.0 35.0 29.0 27.0 27.0 27.5 34.0 18.0 25.0 27.0 20.0 23.0 19.0 22.0 25.5 mm  23.5 25.5 19.0 22.5 26.0 29.5 30.0 24.0 36.0  Leaning Twin trees Dying  Twin Four tops  Fork -  -  36.0  Three tops  The tree numbers are based on the o r i g i n a l numbers  136. Table 3.  Plot No.  Dbh, height and crown width of trees on s i t e 85 to s i t e 180 measured around the edge of G r i f f i t h plots.  Tree No.  #1  #4  #5  #7  #8  Note 1:  Species  Dbh (in.)  Total Height (ft.)  Crown Width Remarks (ft.)  1 2 3 4  F C C C  31.0 15.9 33.0 22.0  180 140 130 114  37 28 30 23  Measured  1 2 3 4  F H H F  8.2 10.1 12.1 22.5  54 83 87 58  14 12 16 31  Measured  1 2 3 4  F F F F  34.3 29.9 24.0 25.0  178 156 144 168  42 32 28 30  Measured  1 2 3 4  F F F F  30.8 31.0 22.4 26.2  173 149 142 143  40 27 25 29  Measured  1 2 3 4 5  F H H H F  31.0 18.6 13.0 21.0 18.5  144 121 116 120 134  30 22 16 26 20  Measured  in  1963  m 1964  in  1964  in  1964  in  1964  Dbh •s of trees on plots #4 to p l o t #8 were 1964 ground data  2:  Total height f o r each tree on plot #4 to plot #8 was obtained by subtracting one foot from the 1964 measurement.  3:  Crown widths were assumed to be the same f o r both 1963 and 1964 data.  4:  F = Douglas F i r ; C = Western red cedar; H = Western hemlock; S = Spruce  <  137.. Table 4. Plot No.  Dbh, height and crown width o f trees measured along Road F (1963).  Tree No>.  Species  Dbh (in.)  T o t a l Height (ft.)  Crown Width (ft.)  1 2 3 4  H H H H  28.7 24.5 19.1 24.2  118 114 114 99  17 24 12 14  1 2 3 4  C H H H  39.5 25.3 27.0 24.0  121 131 130 145  30 25 25 25  1 2 3 4  C H C H  79.3 32.0 54.0 28.0  143 156 170 139  21 74 22 26  #4  1 2 3 4  C C C H  51.3 16.0 37.0 16.0  160 86 141 127  20 12 20 19  #5  1 2 3 4  F F F F  50.0 42.6 29.7 33.7  139 120 125 160  56 39 23 26  #2  #3  138. Table 5.  Dbh, height and crown width o f trees randomly selected a t the j u n c t i o n o f Spur 17 and Road S (1964).  Tree No.  Species  Dbh (in.)  T o t a l Height (ft.)  Crown Width (ft.)  1  C  5.0  33  8  2  C  14.0  60  22  3  C  8.0  29  16  4  C  10.4  35  16.5  5  C  9.5  32  14.5  6  C  9.5  32  15.5  7  C  4.8  22  11.0  8  C  9.3  39  15.5  9  H  8.3  32  13.0  Note  1:  Dbh's are o r i g i n a l data.  2:  T o t a l height f o r each tree was obtained by s u b t r a c t i n g one f o o t from the 1964 measurement.  3:  Crown widths were assumed to be the same f o r both 1963 and 1964 dates.  139. Table 6.  Tree No.  Dbh, height and crown width o f red a l d e r measured on U.B.C. Haney Research Forest (1964) Dbh (in.)  T o t a l Height (ft.)  Crown Width (in.)  1  18.0  85  29  2  14.5  80  34  3  16.6  75  30  4  16.0  79  34  5  18.2  60  30  6  12.1  50  26  7  18.2  65  32  8  13.7  52  24  9  13.2  72  25  10  12.8  78  30  11  15.1  60  34  12  10.9  38  28  Note  1:  Dbh's are o r i g i n a l data.  2:  T o t a l height f o r each tree was obtained by s u b t r a c t i n g two f e e t from the o r i g i n a l measurement.  3:  Crown width f o r each tree was obtained by s u b t r a c t i n g one foot from the o r i g i n a l measurement.  140. Table 7.  Tree No.  Dbh, height and crown width o f black cottonwood measured on U.B.C. Haney Research Forest (1964)  Dbh (in.)  T o t a l Height (ft,)  Crown Width (in.)  1  14.2  78  23  2  17.0  87  30  3  10.8  68  26  6  10.0  72  16  7  10.0  64  18  8  12.4  70  24  9  12.0  73  23  10  14.2  90  28  11  16.5  75  32  12  15.6  80  23  13  12.8  80  28  14  15.2  75  26  15  26.4  108  48  16  15.0  100  28  Note  1:  Dbh's are o r i g i n a l data.  2:  T o t a l height f o r each tree was obtained by s u b t r a c t i n g two f e e t from the o r i g i n a l measurement.  3:  Crown width f o r each tree was obtained by s u b t r a c t i n g one foot from the o r i g i n a l measurement.  141. Table 8.  Plot No.  #1  #2  #3  #4  #5  Dom. and codom. of trees on f i v e n a t u r a l regenerated p l o t s i n 1964.  Tree No.  Species  Dbh (in.)  1 2 3 4  H H C C  5.4 5.4 10.7 6.4  39 37 33 32  10 15 14 24  1 2 3 4  F C H H  13.2 10.3 8.5 6.5  58 50 37 44  28 22 22 24  1 2 3 4  H C F H  10.0 8.5 8.9 8.3  50 43 43 39  26 17 16 13  1 2 3 4  F H C C  6.8 6.7 8.2 7.0  39 35 36 37  12 10 9 10  1 2 3  F F  4.5 3.2  18 12  8 5  T o t a l Height Crown Width (ft.) (ft.)  142 APPENDIX I I I Procedures i n p r e d i c t i o n o f t h e o r e t i c a l growth: Example o f P . S . T . ' s : Tree No.  Age  1 9 6 3 D CW/D CW  crown width  19 4 9 D CW/D  Age  CW  120  1  81  12.2  1.98  24  67  10.3  2.07  23  140  5  96  16.4  1.80  30  82  14.2  1.87  27  140  40  78  12.4  1.97  25  54  10.1  2.08  21  from the U . B . C . Research F o r e s t S i t e map (Smith and B a j a k , 1961).  Index  .  Tree N o . .  . . P . S . t r e e numbered i n .  1954.  corresponding ages o b t a i n e d by p l o t t i n g a c t u a l t r e e h e i g h t s on the c o r r e c t e d H/A c u r v e s .  D . . . . . . . dbh i n inches were found by p l o t t i n g Ages on the c o r r e c t e d D/A c u r v e s . CW/D.  .  .  . . crown width to dbh r a t i o s (1961b): T a b l e 26. .  from Smith e t  al.  t h e o r e t i c a l crown width i n f e e t was o b t a i n e d by m u l t i p l y i n g D to CW/D: e.g.  The t h e o r e t i c a l  ( 1 2 . 2 ) ( 1 . 9 8 ) = 24 ( a p p r o x . ) .  .  . .  1963  ( 1 0 . 3 ) ( 2 . 0 7 ) = 23 ( a p p r o x . ) .  .  .  1949  .  CW growth between 1949 and 1963 t h e r e f o r e .24 - 23 = 1  (ft.)  is:  143. APPENDIX IV Average h e i g h t , CW and CC f o r p l o t s measured on the photos. Table 1. Average h e i g h t , CW and CC f o r f i v e G r i f f i t h p l o t s measured on the photos. Plot No. 1 4 5 7 8  Ave. height o f Dom. and Codom. ( f t . ) 1955 1949 1930 161.0 72.0 145.3 142.0 134.8 655.1 131.0  150.3 62.3 124.0 135.0 118.5 590.1 118.0  140.0 57.3 121.8 123.5 108.0 550.6 110.1  Ave, CW o f Dom. and Codom(ft.) 1955 1949 28.0 13.0 29.3 20.2 28.3 118.8 23.8  23.5 10.5 25.5 18.5 24.3 102.3 20.5  Crown Closure (%) 1955 1949 1930 65 85 75 75 85 385 77  65 75 75 65 75 355 71  55 65 75 65 75 335 67  Table 2. Average h e i g h t , CW and CC f o r f i v e permanent sample p l o t s measured on the photos. Plot No. 7 8 9 10 11  Ave. height o f Dom. and Codom. ( f t . ) 1963 1955 1949 103.8 101.5 89.8 93.5 97.8 83.0 117.5 116.0 104.5 116.8 113.0 100.8 90.8 101.3 100.8 537.2 524.8 468.9 107.4 105.0 93.8  Ave. CW o f Dom. and Codom. ( f t . ) 1963 1955 1949 21.5 19.3 22.0 19.3 20.3 20.0 25.5 26.0 25.3 23.8 25.5 24.5 22.5 22.8 19.8 116.6 113.8 107.7 23.3 22.8 21.5  Crown Closure £%) 1963 1955 1949 75 60 75 55 70 60 75 60 70 75 55 60 75 80 80 305 375 345 75 61 69  Table 3. Average h e i g h t , CW and CC f o r f i v e n a t u r a l regenera t i o n p l o t s measured on the photos. Plot No. 1 2 3 4 5  Ave. height o f Dom. Ave. CW o f Dom. and Codom. ( f t . ) and Codom. ( f t . ) 1955 1949 1955 1949 1963 1963 4.5 34.5 10.8 15.9 20.0 8.0 11.3 47.5 15.8 33.3 20.0 23.0 12.5 17.0 10.0 5.3 43.3 25.0 5.5 10.3 7.8 35.8 19.3 _ 6.0 14.0 21.1 51.1 72.2 39.3 178.1 97.6 35.6 24.4 14.4 9.8 12.8 7.0  Crown Closure 1963 20 20 30 55 5 130 26  1955 1949 15 5 15 5 20 10 25 40 5 0 95 45 19 9  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0104969/manifest

Comment

Related Items