"Forestry, Faculty of"@en . "DSpace"@en . "UBCV"@en . "Ronay, Alexander"@en . "2012-01-10T23:10:59Z"@en . "1961"@en . "Master of Forestry - MF"@en . "University of British Columbia"@en . "The photo-interpreter has a difficult task when he is asked to identify the images of tree species recorded on aerial photographs. When a tree is examined on an aerial photo for such a purpose, the difficulty becomes more and more evident as it is realized that the different species can not always he identified by eyesight, even on large-scale photographs, but must be viewed stereoscopically, and the variations in appearance within the same species, even growing under the same conditions, are very great.\r\nIn comparison with identification on the ground, the interpreter must take an entirely new approach in the determination of various species from aerial photographs. This approach involves training the eyes to recognize plants appearing with various hues and grey tones on black and white photographs, at much smaller scale than usual in ground studies, in most cases from above or half-oblique view of the tree, which is strange to the inexperienced interpreter. Most of the trees appear on aerial photographs in vertical or oblique views, when the branching habit and the crown shape of a tree are easily visible. For this purpose it is desirable to know the characteristic branching habit and typical crown shapes of trees in order to use these factors in species identification.\r\nThis leads up to the problem that will be presented in this thesis. Factors which influence the ground characteristics of three major tree species in British Columbia are examined and analyzed. Various crown forms, with which Douglas fir, western hemlock and western red cedar occur in the vicinity of Haney and Vancouver, are described. The basic pictorial elements, with which these species appear and enable us to recognize them on aerial photographs, are analyzed. Influence of different films and filters on the appearance of species on air photos are also discussed. The thesis presents an analysis of identifications of species made by several interpreters. Requirements for photo-interpretation are also discussed. Finally, a dichotomous key is presented, which is constructed for Douglas fir, western hemlock and western red cedar, taking into account their appearance at various ages and locations."@en . "https://circle.library.ubc.ca/rest/handle/2429/39988?expand=metadata"@en . "i STUDY OF CROWN SHAPES OF DOUGLAS FIR, WESTERN HEMLOCK, AND WESTERN RED CEDAR AS AN AID IN THE IDENTIFICATION OF THESE SPECIES ON AERIAL PHOTOGRAPHS. \"by ALEXANDER RONAY B.S.F., Sopron D i v i s i o n , University of British. Columbia 1959 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF FORESTRY i n the Department of FORESTRY We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 196l I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f 3 r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s m a y b e g r a n t e d b y t h e H e a d o f my D e p a r t m e n t o r b y h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t b e a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r 8 , C a n a d a . i i ABSTRACT The photo-interpreter has a d i f f i c u l t task when he i s asked to i d e n t i f y the images of tree species recorded on a e r i a l photographs. When a tree i s examined on an a e r i a l photo f o r such a purpose, the d i f f i c u l t y becomes more and more evident as i t i s realized that the di f f e r e n t species can not always he i d e n t i f i e d by eyesight, even on large-scale photographs, but must be viewed stereoscopically, and the variations i n appearance within the same species, even growing under the same conditions, are very great. In comparison with i d e n t i f i c a t i o n on the ground, the interpreter must take an e n t i r e l y new approach i n the determination of various species from a e r i a l photographs. This approach involves t r a i n i n g the eyes to recognize plants appearing with various hues and grey tones on black and white photographs, at much smaller scale than usual i n ground studies, i n most cases from above or half-oblique view of the tree, which i s strange to the inexperienced interpreter. Most of the trees appear on a e r i a l photographs i n v e r t i c a l or oblique views, when the branching habit and the crown shape of a tree are e a s i l y v i s i b l e . For th i s purpose i t i s desirable to know the characteristic branching habit and t y p i c a l crown shapes'of trees i n order to use these factors i n species iden-t i f i c a t i o n . This leads up to the problem that w i l l be presented i n th i s thesis. Factors which influence the ground characteristics of three major tree species i n B r i t i s h Columbia are examined and analyzed. Various crown forms, with which Douglas f i r , western, hemlock and western red cedar occur i n the v i c i n i t y of Haney and Vancouver are described. The basic p i c t o r i a l elements^with which these species appear and enable us to recognize them on a e r i a l photographs, are analyzed. Influence of di f f e r e n t films and f i l t e r s on the appearance of species on a i r photos are also discussed. The thesis presents an analysis of i d e n t i f i c a t i o n s of species made by several interpreters. Requirements for photo-interpretation are also discussed. F i n a l l y , a dichotomous key i s presented, which i s constructed for Douglas f i r , western hemlock and western red cedar, taking into account t h e i r appearance at various ages and locations. i v CONTENTS Page TITLE PAGE i ABSTRACT i i CONTENTS i v TABLES v i ILLUSTRATIONS ACKNOWLEDGEMENTS INTRODUCTION 1 APPROACHES TO IDENTIFICATION OF SPECIES ON AERIAL PHOTOGRAPHS . . . 5 COLLECTION OF FIELD DATA 12 FIELD CHARACTERISTICS OF A TREE SPECIES THAT FACILITATE ITS IDENTIFICATION l 8 Size 18 Shape 22 The crown shape of Douglas f i r 25 The crown shape of western hemlock 26 The crown shape of western red cedar 27 FACTORS INFLUENCING CHARACTERISTICS OF DOUGLAS FIR, WESTERN HEMLOCK AND WESTERN RED CEDAR 29 INFLUENCE OF STOCKING 35 INFLUENCE OF AGE 39 Changes i n upper portion of the crown 39 Changes i n the lower portion of the crown k2 INFLUENCE OF ELEVATION k-2 PHOTO FACTORS WHICH FACILITATE SPECIES IDENTIFICATION kk VALUE OF TONE kk The importance of tone to the forest i n t e r p r e t e r kk Factors c o n t r o l l i n g the tone of an object 5^ V \u00E2\u0080\u00A2 CONTENTS (cont'd.) Page Measurement of tone 52 Changes in tone caused by scale of photos 53 VALUE OF TEXTURE 58 The importance of texture to forest interpreter 58 Factors influencing the texture of an object 59 Texture of individual trees 60 Texture of stands of trees 6k Measurement of texture 66 VALUE OF FILM AND FILTER 72 FILMS 72 Orthochromatic films 73 Panchromatic films 73 Infra-red films 75 Colour films 79 FILTERS 82 VALUE OF SEASON TO PHOTOGRAPHY 84 Spring and f a l l photography 8h Summer photography 85 Winter photography 86 EVALUATION OF DIFFERENT PHOTO SCALES IN INTERPRETATION OF TREE SPECIES 87 THE VALUE OF HUMAN FACTORS IN PHOTO-INTERPRETATION 93 Visual accuity 93 Mental accuity 95 KEY TO AERIAL IDENTIFICATION OF DOUGLAS FIR 97 CONCLUSION 101 REFERENCES CONSULTED 103 APPENDIX 107 v i TABLES Number Page 1 Averaged data f o r Douglas f i r , western hemlock, and western red cedar trees, with t h e i r standard deviations... 15 2 Variations i n some characteristics of Douglas f i r , western hemlock, and western red cedar i n U.B.C. Research Forest at Haney and i n U.B.C. Campus Forest 16 3 Averaged diameter f o r lowest dead branches 19 k Average height to the lowest dead and l i v e branches of Douglas f i r , western hemlock, and western red cedar with t h e i r standard deviations 20 5 Average l i v e branch length (FT.) of Douglas f i r , western hemlock, and western red cedar 21 6 Averaged crown width measurements (Ft.) i n Douglas f i r , western hemlock and western red cedar 21 7 Linear multiple-regression equations for dead branch diameter on d.b.h., age, s i t e , index and basal area 29 8 Linear multiple-regression equations for height to dead branches 30 9 Natural pruning of 52 mature Douglas f i r , 58 mature western hemlock and h'J mature western red cedar trees 31 10 Linear multiple-regression equations for height to l i v e branches 32 11 Regression equations for l i v e crown length on d.b.h., Total height and CW/D 32 12 Regression equations f o r percentage of l i v e crown on basal area per acre and H/CW 33 13 Relationships between Crown Width and d.b.h. of f u l l y open-grown Douglas f i r and western hemlock trees 3^ 14 Ratios of Crown Width/d.b.h. by species and stocking 36 15 Comparison of correlations between Crown Width/d.b.h. and height/Crown Width r a t i o s with eleven variables for Douglas f i r , western hemlock and western red cedar 37 16 Relationships among Crown Width, d.b.h., age, t o t a l height, s i t e index and basal area 38 vii TABLES (cont'd) Number Page 17 Regression equations for estimate of Crown Width/d.b.h. from height/CW., or height/CW from C\u00C2\u00A5/d.b.h., by species.. 38 18 Average top-angle values with their standard deviations for Douglas fir, western hemlock and western red cedar.... hO 19 Quotient of average top-angle and average crown height for Douglas fir, western hemlock and western red cedar.... hi 20 Distribution of crown shapes of Douglas fir (F), western hemlock (H), and western red cedar (C) hi 21 Changes in reflected light caused by angle of viewing h6 22 Human ability in separation of different tones 51 23 Reflected light densities from leaves of some Coniferous and Deciduous species 51 2h Changes in tone of Douglas fir on different scales of photos 56 25 Changes in tone of western hemlock on different scales of photos 56 26 Changes in tone of western red cedar on different scales of photos 57 27 Changes in texture of Douglas fir on different scales of photographs 70 28 Changes in texture of western hemlock on different scales of photographs 71 29 Changes in texture of western red cedar on different scales of photographs 71 30 Errors committed in recognition of species by different interpreters on various scales of photos 91 31 Percentage correctness of photo-interpretation figure for species 92 32 Percentage correctness of photo-interpretation figure for species in different age classes 92 viii ILLUSTRATIONS To follow Figure Pages Nos. On Page No. 1 Shape scale 2k 2 Variations in crown shapes of Douglas Fir 25 3 Variations in crown shapes of western hemlock 26 k Variations in crown shapes of western red cedar 28 Graph 1 Average top-angles over age for Douglas fir 39 2 Average top-angles over age for western hemlock 39 3 Average top-angles over age for western red cedar 39 Figure 5 Tone scale 52 6 Texture scale 68 7 Sensitivity curve of various types of f i l m 73 APPENDIX I. Photographs showing variations in crown shapes of Douglas fir 109 APPENDIX II. Photographs showing variations in crown shapes of western hemlock ... 113 APPENDIX III Photographs showing variations in crown shapes of western red cedar 115 ix ACKNOWLEDGEMENT The writer of t h i s t h e s i s wishes to express h i s sincere thanks to Dr. J . H. G. Smith, Associate Professor of Faculty of Forestry at the Un i v e r s i t y of B r i t i s h Columbia, for h i s useful suggestion, guidance, and encouragement. F i n a n c i a l assistance received from the Faculty of Forestry and from the Un i v e r s i t y of B r i t i s h Columbia Research Forest Committee i s g r a t e f u l l y acknowledged by the wr i t e r . Acknowledgement i s also due to the s t a f f members of the Un i v e r s i t y Research Forest f o r t h e i r assistance i n c o l l e c t i o n of f i e l d data, and the Un i v e r s i t y of B r i t i s h Columbia Faculty of Forestry f o r using t h e i r photographs and equipment. - 1 -STUDY OF CROWN SHAPES OF DOUGLAS FIR, WESTERN HEMLOCK, WESTERN RED CEDAR AS AN AID IN THE IDENTIFICATION OF THESE SPECIES ON AERIAL PHOTOGRAPHS. Introduction Aerial photographs have played an important role in developing Forestry since its first application in 1920 and particularly 19^+0-^5 in the United States and Canada. It is highly valued by Foresters, because it serves as an excellent record of contemporary forest conditions. In fact, aerial photographs are one of the best obtainable forest records, since they can be consulted and supplemented at any time. Foresters have made use of aerial photography in four major fields: a. mapping, b. mensuration, c. reconnaissance and management planning, d. interpretation of forest condition, and vegetation. Forest mapping is concerned with preparing planimetric base maps and detailed topographic maps of a forest property. Map preparation is greatly facilitated by the use of aerial photographs, which leads to greater efficiency and economy of manpower, field surveying time, and cartographic operations. - 2 -In forest mensuration, a e r i a l surveying methods have proved to be less expensive and often more accurate than ground cruising. Stand volume and conditions can be determined d i r e c t l y or i n d i r e c t l y from a e r i a l photographs. At the present, inventories are most widely accepted. In the s t r a t i f i e d and random sampling techniques, plot locations are f i r s t established on contact p r i n t s , and then located i n the f i e l d and cruised by conventional methods. The volume of the entire forest t r a c t i s then calculated by expanding the data from these sample pl o t s . Areas occupied by the various forest cover types are determined d i r e c t l y from a e r i a l photographs by simple methods (by dot-grid, or line-transect methods, etc.). Reconnaissance and forest-management planning also benefit from the \"bird's-eye view\" of an entire forest property provided from a e r i a l photography. Photographs help the forester to i d e n t i f y the pattern of l o c a l physiography, to separate forest cover types and stand conditions, and to reveal a progress of logging and management operations. The timber cruiser can u t i l i z e a e r i a l photos as one of the most e f f i c i e n t and economical means of locating valuable timber species and stands. In non-developed and inaccessible forest t r a c t s , i t i s often the only p r a c t i c a l means. The logging engineer can use the same photography i n planning logging settings and the roads needed for timber extraction. The forest manager and administrator can further u t i l i z e t h i s photography to divide the forest property into compartments consistent with the desired i n t e n s i t y of management. The f i e l d of interpretation of forest conditions i s concerned with i d e n t i f i c a t i o n and s p a t i a l d i s t r i b u t i o n of vegetative types plant species. - 3 -Forest-cover types are delineated on the basis of differences i n species composition of the dominant tree layer, stand height, density, and s i t e . With adequate f i e l d experience, i t i s possible to interpret and delineate cover types even from small scale a e r i a l photos. Much useful information can be obtained from a e r i a l photographs to be applied for forestry purposes, with s u f f i c i e n t degree of accuracy. Species i d e n t i f i c a t i o n , however, remains as one component, which i s excep-t i o n a l l y d i f f i c u l t to obtain r e l i a b l y i n this way. This i s due p a r t l y to the conditions under which the pictures were made, l i m i t a t i o n s of photographic equipment and materials, and the small scale of photographs. Species i d e n t i f i c a t i o n i s uncertain on small-scale photographs, but to take large-scale photographs always involves the question of available money. Large-scale photographs, covering smaller area than the small-scale photos, are expensive and i n certain cases not economical. Tree species are i d e n t i f i e d on a e r i a l photograpias through a process of elimination. The f i r s t step i s to eliminate those species whose appearance on an area i s impossible or highly improbable, because of location, physiography or climate. The second step i s through a knowledge of the common association and of t h e i r ecological and s i t e requirements, to establish which group of species occur or may occur i n the area examined. The i d e n t i f i c a t i o n of in d i v i d u a l tree species i n the group, using crown cha r a c t e r i s t i c s , usually i s the f i n a l stage of t h i s process. F i e l d experience and other studies of the forest concerned are es s e n t i a l , but intensive l o c a l knowledge i s also desirable. A e r i a l photographs are becoming more and more important i n - h -Forestry, especially here i n B r i t i s h Columbia. As the e x i s t i n g forests are depleted around sawmills, the interest turns to more distant v i r g i n forest. Examination of such areas by conventional ground-surveying techniques i s very expensive. Taking good forest inventory i n B r i t i s h Columbia i s very d i f f i c u l t due to i t s rough t e r r a i n , poor a c c e s s i b i l i t y , and weather conditions. Reliable information about the area examined can be secured cheaply and e f f i c i e n t l y from a e r i a l photographs. I f we can improve the techniques of species i d e n t i f i c a t i o n from photos, a e r i a l photographs i n the hands of a forest manager w i l l become v i r t u a l l y indispensable. - 5 -APPROACHES TO IDENTIFICATION OF SPECIES ON AERIAL PHOTOS ( REVIEW OF LITERATURE ) In. North America the f i r s t known application of a e r i a l photo-grammetry was by the Union Army i n May, 1862 when captive balloons were used i n photographing the t e r r a i n near Richmond, U.S.A. (Landen, 1952). Several authors have reported that at the turn of the Century several U. S. Forest Service o f f i c i a l s were cognizant of inherent p o s s i b i l i t i e s of a e r i a l photos, but not u n t i l 1919 clid Ralph Thelen put his thoughts on paper about usefulness of a e r i a l photos i n forestry. He outlined the experience of the U. S. A i r Force during World War I , and described a general approach f o r application of a e r i a l photos f o r mapping and resource study. His a r t i c l e brought no immediate results so f a r as p r a c t i c a l application by the U. S. Forest Service was concerned. The problem of interpretation of vegetation was apparent from the beginning of World War I , when photos were used f o r m i l i t a r y purposes. Knowledge of interpretation at that time involved only the separation of wi l d and cultivated vegetation, grassland from bushy land, shrubs from timber, coniferous forest from deciduous forests and the separation of dense and t h i n stands. Species recognition, however, was i n i t s very f i r s t stage. Recognition keys were not yet described, and therefore the application of species i d e n t i f i c a t i o n was very l i m i t e d . In the late 1920's, when oblique and v e r t i c a l photos were applied f o r forestry purposes for the f i r s t time, the problem of species recognition came up increasingly. In the early 1930's, when forest inventories were started i n Alaska, i n the - 6 -Rocky Mountain Region, and i n C a l i f o r n i a \"by the U. S. Forest Service, not only improved mapping procedures and equipment were developed, but also detailed keys and other interpretation aids were constructed and worked out, based upon the r e l a t i v e size and appearance of vegetation. In 1933 Harrison Ryker published his remarkable a r t i c l e about problems of species determination. In t h i s study he cal l e d attention f o r the f i r s t time to the determination of Northwest tree species from a e r i a l photos by use of t h e i r characteristic crown forms. The use of a e r i a l photos, by t h i s time, spread rapidly i n forest inventories, p a r t i c u l a r l y when the U. S. Department of Agriculture began i t s program of photography at an RF of 1 : 20,000. A r t i c l e s written during the early 1930's, however, discussed mainly the importance of tree-height measurements by parallax, hence the problem of species recognition f e l l into the background. Most of the studies were directed on German and other European achievements and the accuracy of photo versus f i e l d measurements. For about a decade a great number of papers were issued i n North America about the research of Huger-shoff, describing tests i n which forest stands were measured photogrametrically, and how these measurements are related to actual volume and other charac-t e r i s t i c s . Results of these studies established the e f f i c i e n c y of parallax measurements of tree height, direct photographic measurement of crown diameter, and the p o s s i b i l i t y of preparing volume tables based on these parameters. Although the problem of obtaining r e l i a b l e quantitative measure-ments was thrust into prominence, the question of recognition of various species has always been of interest, although progress was l i m i t e d u n t i l World War I I . The fact that the vegetation i s a r e l a t i v e l y r e l i a b l e indicator of ground conditions has been applied often for m i l i t a r y operations, and during the early 19^ 0's a great emphasis was placed by armed forces on photo interpretation. Many foresters, both i n the U. S. and Canada, were f i r s t introduced to the recognition of various tree and other vegetation species from a e r i a l photos. During World War I I most of the key characteristics were described, not only for recognition of in d i v i d u a l species, but also f o r associations. After the war the foresters employed by armed forces, such as H. A. Jensen, R. N. Colwell, and K. E. Moessner, to mention a few, already s k i l l e d i n interpretation of the vegetation and other t e r r a i n conditions, found i n forest inventories an opportunity to c a p i t a l i z e on both t h e i r c i v i l and m i l i t a r y experience. And so from 19^6 on, the l i t e r a t u r e i s f i l l e d with discussion of the technique of forest c l a s s i f i c a t i o n , the problem of i d e n t i f i c a t i o n of tree species, the use of both panchromatic and infrared photos i n forest interpretation with various scales, and the many problems of obtaining both quali t a t i v e and quantitative measurements. In 19^-6, Colwell published an a r t i c l e about the i d e n t i f i c a t i o n of various plant species, and provided a key as an a i d f o r such purposes. Soon i t was followed by Moessner's study (19^ 8), which also dealt with a e r i a l photographic interpretation of vegetation f o r forest inventories. Following these, numerous other a r t i c l e s were published about the problem of species recognition (Stoeckeler 19^ 9; 1952; Stone 19^ 8; Wieslander and Wilson 1953) and various recognition keys were constructed. Both des-criptive and dichotomous keys were developed f o r study of infrared and panchromatic fi l m s (Schulte 1951; O'Neill 1953). - 8 -Foresters s k i l l e d i n c l a s s i f y i n g forest types and i n species i d e n t i f i c a t i o n by means of key species i n ground inventories, naturally t r i e d to recognize the same species on a e r i a l photos. They t r i e d to r e l y on the tone of the photo and were confused when differences c l e a r l y v i s i b l e on ground, such as between dark conifers and much l i g h t e r hardwood fo l i a g e , were not always distinguishable on a e r i a l photos. I t was soon found that uniform timber stands register with many different tones and that the direc t i o n of l i g h t , the size and density of the f o l i a g e , and the res u l t i n g shadows have f a r more effect than the mere differences i n colour of the species, which appear on the ground. The l i m i t a t i o n s and uses of t h i s effect were achieved by application of different f i l m and f i l t e r s i n combination. A special kind of colour f i l m , c a l l e d camouflage detection f i l m , was developed during World War I I for detecting fresh l y cut trees or bushes used as camouflaging material. The foliage of cut trees appeared on t h i s kind of f i l m with a hue e n t i r e l y different from that of t h e i r surroundings, since they were r e f l e c t i n g wave-lengths different from l i v i n g f o l i a g e . Camouflage-detection f i l m i s a colour f i l m , i n which three emulsions, coated on a single f i l m base, are sensitive to v i s i b l e green, v i s i b l e red and infrared l i g h t s . The s e n s i t i v i t y of the f i l m i s such that high i n f r a r e d - r e f l e c t i v e objects, such as healthy green vegetation, r e g i s t e r as v i s i b l e red. Green objects which are not highly infrared-r e f l e c t i v e register as blue, and red objects which are not highly infrared-r e f l e c t i v e , register as green. Since the f i l m i s used i n conjunction with a Wratten 15 f i l t e r , which absorbs the v i s i b l e blue l i g h t , the blue objects register as black. Accordingly, red objects which are not highly infrared-- 9 -r e f l e c t i v e , such as rusted leaves, record as yellow or brown (Colwell 1956). Immediately after World War I I , many foresters thought that the problem of species i d e n t i f i c a t i o n could be solved by the use of camouflage-detection f i l m . Research after World War I I indicated that the application of such f i l m was useful only f o r studying certain kinds of insect damage. (Manual of Photographic Interpretation, i960.) The infrared, and modified infrared films which were developed..later, proved to be much more e f f i c i e n t i n species i d e n t i f i c a t i o n . Modified infrared f i l m s have been used with various f i l t e r s i n the Northeastern States f o r inventory and i n the Harvard Forest f o r research purposes with photos of RF 1 : 20,000 and 1 : 15,8^0. The p r i n c i p a l contributors on t h i s subject i n recent years have been Jensen and Colwell (19^9), Spurr (1959), Losee (1951), and Schulte (1951). In Canada, several foresters cooperated on studies and did some basic work on how f i l m s , f i l t e r s , scales, and other factors affect photo-graphy and the forestry values of fi n i s h e d p r i n t s , through a Subcommittee on Forest Surveys of the Canadian Society of Forest Engineers (Spurr 19^ -9) \u00E2\u0080\u00A2 At present, many forest interpreters are enthusiastic about the use of colour f i l m , seeing i n colour transparencies a means of recognizing species, provided the f i l m can be reduced i n cost and p r a c t i c a l means can be devised f o r using the transparencies outside the laboratory. However, the same variations i n tone due to the dir e c t i o n of the sun and shadows are present just as much i n colour p r i n t s , as i n panchromatic or infrared f i l m s , and may be equal as a source of misinterpretation (Waldo 1950)- The determination of species by t h e i r differences i n r e f l e c t i v i t y does not - 10 -necessarily involve the use of colour f i l m because i t can be made just as we l l on much cheaper black and white photographs. Based on Becking's (1959) experience, there seems to be l i t t l e advantage f o r colour f i l m i n summer photography for i d e n t i f i c a t i o n of species and forest types. However, r e l a t i v e l y l i t t l e research has been carried out in t h i s d i r e c t i o n to date. Spectral analysis has been used to f i n d the right f i l m - f i l t e r combinations which would register objects i n a desired tone. Hindley and Smith (1957) undertook a survey f o r t h i s purpose. Reflectance measurements were made from leaves of nine of B r i t i s h Columbia's major coniferous species. The measurements showed that the spectral analysis of tree foliage would not be p a r t i c u l a r l y h e l p f u l i n choosing the best f i l m - a n d - f i l t e r combinations for species i d e n t i f i c a t i o n , because the differences i n reflectance between two species were often smaller than the differences between two plants of the same species. If timber inventories are based on forest stand maps compiled from a e r i a l photographs, i t becomes necessary to check and v e r i f y the i d e n t i f i c a t i o n of forest types on the photographs before the type or stand maps are constructed. Failure to make such checks may lead to serious errors i n the determination of stand components i n the area summary, and subsequently i n the volume and growth estimates. The procedure of such checking i s called c l a s s i f y i n g or coding. This may be accomplished from either the ground or the a i r . From 1951, when i t was i n i t i a t e d , u n t i l 1953, B. C. Forest Service coding was confined to ground examination only. Since 1954 the B. C. Forest Service has done a great deal of a e r i a l coding. In 19^ 9, Chapman ( l ) published his remarkable a r t i c l e about the - 11 -use of helicopters f o r forest reconnaissance and mapping. He outlined the advantages over ground surveys of sketch mapping of forests from such machines and concluded with some comments on f l y i n g i n helicopters. Chapman's paper was followed by Johnson's (1952) a r t i c l e i n which was emphasized the necessity of checking forest photo-interpretation. Johnson also suggested that such checking can be done quickly and e f f i c i e n t l y from low-flying aeroplanes or helicopters, p a r t i c u l a r l y over large or inaccessible areas. To obtain good results a new method of interpretation had to be developed, which retained some techniques of photo-interpretation, but dif f e r e d largely from i t . In 1953, coding from the a i r commenced on an experimental basis and has consistently proved to be suitable f o r both reconnaissance and inventory standards of mapping. In 195^ and 1955 i t was used extensively i n the United States and Canada f o r inventory work, a period during which techniques were modified and improved. In 1956 intensive or \"special\" coding was commenced i n many parts of North America. In B r i t i s h Columbia ground coding remained as the p r i n c i p a l method of stand c l a s s i f i c a t i o n throughout 195^- and 1955, but by 1956 i t was replaced by a i r coding to a large extent. I t i s expected that i n the future a i r coding w i l l replace ground coding e n t i r e l y i n inventory work, except for surveys which require very intensive c l a s s i f i c a t i o n and for the coding- of small areas. - 12 -COLLECTION OF FIELD DATA V e r t i c a l a e r i a l photographs are of incalculable value to the forest manager as a source of information about the area examined. They are used i n almost every phase of forestry work. The single forestry a c t i v i t y i n which a e r i a l photographs are used most i s i n inventory. The problem of i d e n t i f y i n g i n d i v i d u a l tree species on a e r i a l photographs, -however, greatly hinders the wider application of photos i n forest inventory. Since most trees can be seen on a e r i a l photographs i n v e r t i c a l or oblique views, i t has been found advantageous to learn the characteristic branching habit and t y p i c a l crown form of tree species and to use mainly these factors i n t h e i r i d e n t i f i c a t i o n . This study w i l l deal, therefore, primarily with branching nabit and variations i n the crown form of three important B r i t i s h Columbia conifers; Douglas f i r , western hemlock, and western red cedar. The data f o r t h i s study were collected i n the U.B.C. Campus Forest and i n the University Research Forest at Haney, during the summer months of i960. Before discussion of the data, the Research Forest w i l l be described b r i e f l y . Location -- The University Research Forest i s located north of Haney, B.C. I t covers about 10,000 acres, situated within the Coastal Mountains of southern B r i t i s h Columbia. The Forest i s bounded by Garibaldi Park, P i t t Lake, and the a g r i c u l t u r a l lands of P i t t Meadows. Topography -- The elevation range of the Forest i s from sea l e v e l to - 13 -2,600 feet above sea l e v e l . The area contains three p a r a l l e l valleys each with a more or less southerly aspect. In the most easterly v a l l e y l i e s Marion Lake and the west fork of the Worth Alouette River. The most westerly v a l l e y contains Loon Lake, which i s about one mile long and 120 acres i n area. The ridges of t h i s v a l l e y contain numerous rock outcrops and variable slopes. The t h i r d v a l l e y slopes to the northeast u n t i l i t reaches 2,600 feet i n elevation. Then f i n a l l y the southern portion of the Forest has an e n t i r e l y southern exposure with low elevation. Slopes of this portion of the area have numerous rock outcrops and b l u f f s and vary greatly i n steepness (U.B.C. Forest Committee, 1959)-S o i l -- The s o i l of the Research Forest i s mainly of g l a c i a l - t i l l o r i g i n . I t i s exceedingly rocky and of a sandy-loam texture, varying i n depth from a few incnes to three or more feet ( G r i f f i t h , i 9 6 0 ) . Forest Types -- There are four main forest types i n the Research Forest: ( l ) Old growth, (2) Scattered old growth, (3) Second growth, and (k) Reproduction. (1) Old growth -- About 80$> of the east slope of north central ridge i s covered by t h i s type of stand. The stands consist of over-mature cedar-hemlock-fir, with scattered white pine and balsam. (2) Scattered old growth -- This type i s found predominantly i n the western portion of the Forest. Douglas f i r i s the major species i n these scattered stands and occurs i n groups or as single trees. (3) Second growth -- About 20$ of the entire Forest i s covered with second-growth stands, which are about eighty years old. The major species i n the second-growth are hemlock and cedar. A few s i l v e r f i r s can be found i n small patches within these stands. - 14 -(4) Reproduction -- Reproduction occupies about 45$ of the productive area of the Forest. The logged areas i n the di f f e r e n t parts of the Forest have various stages of reproduction. Douglas f i r i s uniformly but sparsely distributed through the area, together with many hemlock and cedar trees. Scattered white pines and small patches of alder occur i n the Forest. Most of the measured trees were chosen from the second growth of the Forest, situated i n the western v a l l e y at elevations from 700 to 1,200 feet, with ages of 70 to bO years. Older Douglas f i r trees, with ages of about 130 to 150 years, were also measured there. Old western hemlock and western red cedar trees were measured i n the northern part of the area at Gwendoline Lake, at approximately 1,900 to 2,200 feet elevation. Procedure -- During the survey, 57 young and 52 old Douglas f i r , 58 young and 58 old western hemlock, and 55 young and 47 old western red cedar trees were measured. Each tree was randomly chosen on the ground from the group of trees e a s i l y v i s i b l e on each of the photos to be studied. Each tree was marked on each photograph. Measurements were taken of the d.b.h., t o t a l height, and crown width of each tree. Every chosen tree's crown shape was drawn i n p r o f i l e and cross-section views, and l a t e r was compared with i t s appearance on each kind of photograph. The averages of the collected data are presented i n Table 1. In addition to these trees, 184 Douglas f i r , l66 western hemlock and 77 western red cedar trees were studied. These represented various environmental conditions and covered a wide range of age classes, i n order to obtain more knowledge about the natural pruning a b i l i t y and thereby more about - 15 -Table 1. Averaged data for Douglas f i r , western hemlock, and western red \u00E2\u0080\u00A2 cedar trees, with t h e i r standard deviations Douglas f i r Western hemlock Western red cedar Average S.D. Average S.D. Average S.D. D.b.h. (in.) Height ( f t . ) Crown width ( f t . ) h2.b ik.Q 162.7 37.3 27.1 28.5 28.7 8.7 126.8 19.7 22.8 15.1 37.7 14.9 131.8 23-6 2k.6 lk.8 the size of the crown components and shapes of these species. The collected and evaluated data on these trees are presented i n Table 2. The author assisted i n the c o l l e c t i o n and i n some of the analysis of these data which have been used by Smith, Ker and Csizmazia (1961). Crown class i n Table 2 means that tree crowns were classed as 10 f o r dominant, 20 for codominant and 30 f o r intermediate. Distance to competitors represents the average values for nearest competing trees i n each of W, S, E, and W quadrants, i n r e l a t i o n to the tree being studied. Dead and l i v e branch length and diameters represent d.o.b. and total-length estimates, averaged from values for each of W, S, E, and W quadrants. Total heights were measured with a Haga height-finder. Total ages were based upon borings at breast height with corrections f o r years to reach breast height. Site index was determined f o r each tree using tables f o r s i t e index constructed by Meyer and Bruce (19^ 9) for Douglas f i r and hemlock tables by Barnes for both western hemlock and western red cedar (Forestry Handbook for B r i t i s h Columbia, pp. 369-371)- Average crown width was determined by the v e r t i c a l projection of the crown measured i n two opposite directions. The height of average maximum crown width was recorded. Basal area per acre Table 2. Variations in some characteristics of Douglas f i r , western hemlock and western red cedar in U.B.C. Research Forest at Haney and in U.B.C. Campus Forest s p E C I E S Items Douglas f i r Western hemlock Western red cedar Avg. SD. Min Max. Avg. SD. Min . Max. Avg. SD. Min. Max. Crown class 11.7 4.1 10.0 30.0 12.9 4.6 10.0 20.0 16.1 5.2 10.0 30.0 D.b.h. (In.) 19.0 9.6 6.0 50.0 16.4 6.6 5.0 35-0 15.7 7-2 2.6 36.0 Dist. to comp. (Ft.) 15.6 9.9 0 38.0 15.5 6.4 4.0 43.0 15.3 7-2 5-0 34.0 Dead br. length (Ft.) 1.8 1.4 0.5 a.8 1.8 1.3 0.5 8.0 2.3 1-7 0.5 8.5 Dead br. diam. (in.) 0.58 0.35 0.1 2.3 0.62 \u00E2\u0080\u00A237 0.2 1-9 \u00E2\u0080\u00A255 0,62 0.1 1-3 Live br. length (Ft.) 9-4 3-7 1.5 22.0 8.7 3.4 3.5 18. 5 6-5 2.9 1.3 14.3 Live br. diam. (In.) 1.3 0.6 0.3 3-3 1.1 .55 0.4 2.5 \u00E2\u0080\u00A2 \u00C2\u00AB3 0.34 0.3 1.8 Total height (Ft.) 110.0 44.0 29.0 236.0 98.0 35.0 35.0 162.0 82.0 32.0 25.0 128.0 Total age (Yrs.) 59-7 28.5 20.0 151.0 65.O 28.0 23.0 125.0 57.8 29.8 22.0 188.0 Site index (@ 100) 152.0 37-0 60.0 260.0 130.0 25.0 00.0 180.0 116.0 20.0 80.0 165.0 Avg. crown width (Ft.) 21.5 7-3 8.0 4o.o 18.9 6.7 7.0 42.0 17.9 0.5 10.0 38.0 Avg. crown height (Ft.) 71.5 38.7 6.0 190.0 59-0 29.4 3.0 108.0 46.4 27.4 4.0 95-0 Basal area (Sq.Ft./ac.) 157.0 63.0 20.0 20.0 370.0 164.0 59.0 80.0 290.0 164.0 55.0 30.0 Avg. Height to dead br. (Ft.) 14.8 17.3 1.0 84.0 17.9 19.6 1.0 93-0 9-1 8.1 1.0 30.0 Avg. Height to live br. (Ft.) 54.5 30.5 2.0 145.0 44.8 25.0 2.0 88.0 29.7 19.6 2.0 75-0 - IT -was determined from a prism count of tre e s surrounding and i n c l u d i n g the studie d t r e e . Average neight of dead branches represents averaged height measurements to the lowest dead branch i n each of N, S, E, and W quadrants. Average height to l i v e branches was determined s i m i l a r l y . Every chosen tre e has been marked w i t h a p i n p o i n t on each photograph. There were f i v e d i f f e r e n t kinds of photos a v a i l a b l e : (a) Photographs made i n A p r i l 195^ w i t h a 20-inch f o c a l - l e n g t h camera on panchromatic f i l m and p r i n t e d with, a sca l e o f 330 f e e t / i n c h or about RF 1 : 4,000. (Jo) Photographs made i n A p r i l 1954, w i t h a 20-inch f o c a l - l e n g t h camera w i t h the same f i l m and f i n i s h i n g as i n (a) above, w i t h a sca l e of 720 f e e t / i n c h or about RF 1 : 8,700. (c) Photographs made i n May 1958, w i t h a 6-inch f o c a l - l e n g t h camera on panchromatic f i l m and p r i n t e d on Gevaert paper w i t h g l o s s y f i n i s h , w i t h a sca l e of 1,200 f e e t / i n c h , or about RF 1 : 14,400. (d) Photographs made i n June 1959, w i t h a b-inch f o c a l - l e n g t h camera on the same f i l m and paper as i n (c) above, w i t h a s c a l e of 1,500 f e e t / i n c h or about RF 1 : 16,000. (e) And f i n a l l y , photos made i n May 1958, w i t h a 6-inch f o c a l - l e n g t h camera, on the same f i l m and f i n i s h as i n (c) above and w i t h a scale of 2,400 f e e t / i n c h or abour RF 1 : 28,000. The c o l l e c t e d data were evaluated w i t h the Alwac I I I . E. computer at the U n i v e r s i t y o f B r i t i s h Columbia. - 18 -FIELD CHARACTERISTICS OF A TREE SPECIES THAT FACILITATE ITS IDENTIFICATION (1) Size Size is a relative impression which relates the surface or volume dimension of an object to the surface or volume dimensions of another known object. It is therefore called Relative Size. If the size of a tree is associated with its shape, it may be a very valuable factor in forest photo-interpretation, because it not only helps us to identify the object, but also it can tell something more about it. In our case, with the help of size and shape we can separate not only merchantable timber from immature stands, but we may also determine some of the tree species in the examined stand. It has been observed for a long time that the size of Douglas fir trees, in most cases, is greater than than of western hemlock or western red cedar, provided that all the three species are of the same age. In Table 2 it can be seen that the averaged diameter at breast height for Douglas fir has been found to be 19-0 inches with a standard deviation of 9-6 inches; for western hemlock, 1.6.k inches with standard deviation of 6.6 inches; whereas for western red cedar, average d.b.h. is 15-7 inches with standard deviation of \"J.2 inches. The differences in size may be pointed out also in the diameter and length of branches for these three tree species. On 36 Douglas fir, grown at average spacing in the University Research Forest at Haney, the diameter of - 19 -b r a n c h e s i n t h e f i r s t w h o r l a b o v e b r e a s t h e i g h t a v e r a g e d 0.62 i n c h e s ; O.58 i n c h e s a v e r a g e b r a n c h d i a m e t e r was f o u n d f o r 33 h e m l o c k t r e e s , a n d 0.57 i n c h e s f o r 15 w e s t e r n r e d c e d a r t r e e s . D i f f e r e n c e s s h o w e d u p i n d i a m e t e r o f t h e l o w e s t l i v e a n d d e a d b r a n c h e s o f t h e s e s p e c i e s . A v e r a g e d i a m e t e r s f o r l i v e b r a n c h e s h a v e b e e n f o u n d t o b e 1.31 i n c h e s f o r D o u g l a s f i r , 1.12 f o r h e m l o c k , a n d O.83 f o r r e d c e d a r . T h e a v e r a g e d i a m e t e r f o r d e a d b r a n c h e s i s p r e s e n t e d i n T a b l e 3 b e l o w . T a b l e 3- A v e r a g e d d i a m e t e r f o r l o w e s t d e a d b r a n c h e s S p e c i e s A v . D i a m . SD D o u g l a s f i r W. h e m l o c k W. r e d c e d a r O.58 i n . 0.62 \" 0.55 \" 0.53 i n . 0.37 \" 0.62 \" S i g n i f i c a n t d i f f e r e n c e s a r e p o i n t e d o u t a l s o i n n a t u r a l p r u n i n g o f t h e s e t h r e e t r e e s p e c i e s . T h e m e a s u r e o f p r u n i n g h a s b e e n e s t a b l i s h e d a s h e i g h t t o t h e l o w e s t d e a d a n d l i v e b r a n c h e s m e a s u r e d i n f o u r q u a d r a n t s f o r e a c h t r e e . The a v e r a g e d a t a o b t a i n e d a r e p r e s e n t e d i n T a b l e k. F o r t h e s a k e o f s p e c i e s r e c o g n i t i o n t h e d i f f e r e n c e s j u s t d i s c u s s e d h a v e l i t t l e v a l u e b e c a u s e t h e y c a n n o t b e m e a s u r e d o r d i s c e r n e d o n a e r i a l p h o t o s . T h e f o l l o w i n g i t e m s may s u p p l y much m o r e i n f o r m a t i o n a b o u t t h e s p e c i e s w h i c h c a n b e u s e d i n d i r e c t l y i n s e p a r a t i o n o f s p e c i e s . D i f f e r e n c e s i n s i z e may b e d i f f e r e n c e s i n h e i g h t , c r o w n w i d t h , l e n g t h o f c r o w n a n d p e r c e n t a g e o f l i v e c r o w n o n a t r e e . A v e r a g e h e i g h t f o u n d f o r D o u g l a s f i r was 110 f e e t w i t h SD o f kk - 20 -Table 4. Average height to the lowest dead and live branches of Douglas f i r , western hemlock, and western red cedar, with their standard deviations Dead branches Live branches Avg. Ht. SD. Avg. Ht. SD. Ft. Ft. D. f i r 14.8 17.3 5^-5 30.5 w. hemlock 17-9 19.6 44.8 25.0 \u00C2\u00A5. r. cedar 9-1 8.1 29.7 19.6 feet. Minimum height among 184 Douglas f i r trees was found to be 29 and maximum 236 feet whereas, for 167 western hemlock trees, the average height was 98 feet with SD 35 feet. Minimum and maximum measurements in height were 23 and 125 feet. Average height for western red cedar was found to be 82 feet, with SD 32 feet and minimum and maximum measurements of 25 and 128 feet. Crown width may play a great role in separation of tree species. Since the crown width is determined by the length of live branches in two opposite directions, i t is worthwhile to examine the length of live branches in order to obtain more knowledge about crown width. In Table 5 the average live branch lengths are given for 184 Douglas f i r , 167 western hemlock and 77 western red cedar. Averaged crown width measurements for Douglas f i r , western hemlock and western red cedar are given in Table 6. According to these figures the widest crown width measurement has been found for Douglas f i r , which may be explained by the genetic and ecological nature of this species. - 21 -Table 5- Average l i v e branch length (Ft.) of Douglas f i r , western hemlock, and western red cedar. Species Ave. length. Stand Dev. Minimum Maximum measurement s Douglas f i r 9 ^ 3 7 1-5 22.0 W. hemlock 8.7 3 h 3-5 18.5 \u00C2\u00A5. r. cedar 6.5 2 9 1-3 14.3 Table 6. Averaged crown width measurements (Ft.) i n Douglas f i r , western hemlock, and western red cedar. Species Ave. width Stand, dev. Minimum Maximum measurements Douglas f i r 21.5 7-3 8.0 4-0.0 W. hemlock 18.9 6.7 7-0 42.0 W. r. cedar 17.9 6.5 10.0 38.0 On the trees studied for natural pruning the average length of crown for Douglas f i r has been found to be 55 feet with SD 23 feet, and feet for western hemlock with SD 20 feet, and f i n a l l y 52 feet for western red cedar with SD 25 feet. Percentage tree crown on the same trees also has been averaged. They were found to be 53$ with SD l 8 $ i n Douglas f i r , 58$ with SD 19$ i n western hemlock, and 65$ with SD 20$ i n western red cedar. The application of the size of trees i n determination of t h e i r species i s a very weak clue. It can give us just a guess about the species to be i d e n t i f i e d . I t does not have any importance alone, but using i t i n combination with other recognition factors i t may become very useful. - 2 2 -When a p p l y i n g s i z e i n i n t e r p r e t a t i o n , knowledge of the scal e of the photographs i s e s s e n t i a l , because the scal e i n d i c a t e s the r e a l s i z e of an o b j e c t . There are some s p e c i a l cases when approximate s i z e s can be obtained without s c a l e , i f objects w i t h a known dimension are recognized on photographs. F a m i l i a r o b j e c t s can help us t o set the scal e of a p i c t u r e by comparison. Where opp o r t u n i t y of comparison and scale are m i s s i n g , s i z e l o s e s much of i t s importance. ( 2 ) Shape Shape i s the general form and o u t l i n e or c o n f i g u r a t i o n of an ob j e c t , which i s seen In two dimensions on s i n g l e photographs. I n p a i r e d photographs i t appears i n three dimensions when viewed s t e r e o s c o p i c a l l y , g r e a t l y f a c i l i t a t i n g the i d e n t i f i c a t i o n of the d e s i r e d o b j e c t , by f a c t o r s such as height, topography, l e s s e r v e g e t a t i o n , f o r e s t stands, roads, l a k e s , r i v e r s , and c u l t u r a l f e a t u r e s . On v e r t i c a l a i r photographs, t r e e s are seen i n an unusual p e r s p e c t i v e , so th a t many key c h a r a c t e r i s t i c s , by which t r e e s o r d i n a r i l y are i d e n t i f i e d , are no longer v i s i b l e , and s e v e r a l new ones appear. For inst a n c e , the trunk of a t r e e may be hidden by the crown, but the branching h a b i t i n the upper part o f the crown may show i t s e l f d i s t i n c t l y . In general i t i s e a s i e r t o i d e n t i f y t r e e s i n side view, since more p a r t s of the crown of the examined t r e e can be seen. For t h i s reason, t r e e species can be b e t t e r recognized on ob l i q u e s , than on v e r t i c a l photographs. This f a c t , however, does not exclude the use of v e r t i c a l a e r i a l photographs i n the i n t e r p r e t a t i o n of t r e e species by t h e i r crown shapes, because t r e e s near the edges on v e r t i c a l photos are u s u a l l y s u f f i c i e n t l y - 23 -displaced to be seen from the side. The best advantage of v e r t i c a l a e r i a l photographs i s that trees can be viewed stereoscopically, whereas i n oblique photographs t h i s i s more d i f f -i c u l t . Without a stereoscopic view i t often i s d i f f i c u l t to recognize even the most general shape of an object. The growth-form of trees, which i s characterized by t a l l , woody, erect stems, may be separated i n several classes that are useful for recog-n i t i o n of tree species. Several such s c i e n t i f i c shape-classification terms have been developed, but these terminologies did not spread widely i n p r a c t i c a l application. They are either d i f f i c u l t to s p e l l , pronounce and understand, when compared with corresponding terms, or are rarely applicable i n the f i e l d of forest interpretation (e.g. hippo-crateriform, meaning \"horse-shoe shaped\"; fundibuliform, meaning \"funnel-shaped\"; pandurate, meaning \"fiddle-shaped\"; etc., just to mention a few). A shape scale for forest photo-interpretation should f u l f i l the following requirements: a. I t should be ea s i l y spelled, pronounced, understood and therefore useful i n many technical keys as well as i n non-technical ones, b. I t should be precise i n i t s meaning and mathematically defined, c. The terms should be applicable to a great many objects which the forest photo-interpreter wishes to describe. The only suggestion f u l f i l l i n g these requirements that has come to the writer's attention i s that of Colwell (1952). Colwell suggested use of the shape scale already defined i n dendrology for describing the shapes of leaves. To apply t h i s suggestion the terms were taken from Harlow and Harrar ( l 9^l) . Ten such terms were used as shape scales i n examination of crown - 2k -shapes of Douglas f i r , western hemlock and western red cedar. They are represented i n Figure 1 and defined as follows. 1. Linear - more than four times as long as wide, with nearly p a r a l l e l sides, 2. Oblong - about three times as long as wide, with nearly p a r a l l e l sides, 3- Lanceolate - about four times as long as wide, and broadest below or about the middle; lance-shaped, k. Oblanceolate - inversely lanceolate, i . e . about four times as long as wide, and broadest near the apex, 5. Ovate - having an outline l i k e the longitudinal section of a hen's egg, and broadest near the base, 6. Obovate - inversely ovate, i . e . having an outline l i k e the longitudinal section of a hen's egg, and broadest near the apex,* 7. E l l i p t i c a l - about two times as long as wide, and having an outline l i k e an e l l i p s e , 8. Deltoid - wide at the base, pointed at the top. Shaped l i k e the Greek l e t t e r delta; triangular, 9. Rhomboid - similar to rhombus, with equal sides but unequal angles. In other words, i t can be ca l l e d diamond-shaped, 10. Irregular - no corresponding shape. These above-defined shapes were found to be quite representative of various crown shapes of different tree species which occur either i n the open or i n dense stands. * \"Ob\" i s a L a t i n p r e f i x s i g n i f y i n g inversion. ** Added to Harlow and Harrar's l i s t ; \"lobed\" might be better. To follow page 2k F i g - I S h a p e s c a l e To follow page 25 - 25 -In many cases there are several t y p i c a l crown shapes for each species even at the same age and growing under the same conditions. There w i l l be many deviations from t y p i c a l crown forms, because shape of the crown varies greatly due to the influence of environment. Some species are less variable than others, but i n no case can rules regarding crown shapes be set up, from which exceptions do not e x i s t . Some species, at a certain age, have t y p i c a l crowns, which can be e a s i l y described by d e f i n i t e terms, such as conical, oblong and d e l t o i d . Often, when trees approach t h e i r maturity, description of shapes i s more d i f f -i c u l t . Because of many i r r e g u l a r i t i e s i n mature crowns, they usually can be described simply as irregular i n shape. The Crown Shape of Douglas F i r The most conspicuous characteristic of mature Douglas f i r trees i s t h e i r gigantic s i z e . Douglas f i r i s usually the t a l l e s t i n d i v i d u a l i n a mixed stand and the one with the broadest crown. Douglas f i r crowns are usually t h i c k , thicker than those of western hemlock, and have an erected p e n c i l - l i k e top. The lower branches are straight, but the middle and the upper ones tend upward, making the margin of the crown serrulate. Most of the branches have numerous long-hanging side branchlets. In younger ages, i f the Douglas f i r grows within open stands, the whole trunk i s covered with branches, appearing with broadly pyramidal or d e l t o i d form (Fig. 2a Appendix I.a). By the time the surrounding trees form a dense stand, the trunk becomes f a i r l y clear, with a t y p i c a l ovate crown shape (Fig. 2d Appendix I.c). Young trees growing i n f a i r l y dense stands usually have narrower crowns with much longer t i p s , than those growing i n more open stands. As the tree reaches the age of 60 to 70 years, the variations i n crown shape are the F i g 2 V a r i a t i o n s in C r o w n S h a p e s o f D o u g l a s f i r F i g - 2 c o n t ' d V a r i a t i o n s in C r o w n S h a p e s o f D o u g l a s f i r F i g - 2 c o n t ' d V a r i a t i o n s in C r o w n S h a p e s o f D o u g l a s f i r - 26 -greatest. The crown form of Douglas f i r varies i n t h i s age from a narrowly pointed t i p to a very th i c k top, due to i t s p a r t i c u l a r inherent, environment, or l o c a l i t y factors (Fig.2.f.h. Appendix I . f . j . h . ) . As the Douglas f i r trees approach maturity, the i r r e g u l a r form of the crown becomes more and more evident. The i r r e g u l a r i t y of the crown appears i n enlargement of the branches and the distances between surviving whorls. With diminishing of the v i t a l processes i n the tree, some crown components become needless. Some of the branches and whorls accomplishing t h e i r functions i n the l i f e of the tree die, making by t h i s process large gaps between the rem-aining l i v i n g branches and whorls ( F i g . 2 . i . j . ) . The top of such immature Douglas f i r s may appear either flattened, or with dead tops, forming a \"broom-l i k e \" t i p (Fig.2.k.l. Appendix I.o.p.). The Crown Shape of Western Hemlock Western hemlocks are t a l l trees, with crown length approximately one-third of t o t a l tree height. The shape of immature western hemlock trees i s t y p i c a l l y conical with a narrow top. I t i s always narrower than that of Douglas f i r or western red cedar trees i n the same age group. The top twig droops gracefully, which i s the most important distinguishing mark for separ-ation of hemlock trees from other major species. The branches are long, slender, and i r r e g u l a r l y spaced on the trunk. In most of the cases the end of the branches i s pointing downward, i n contrast to Douglas f i r , with ends of i t s branches usually tending upward (Appendix I I . a . & I I . d . ) . With increase of age, the long, narrow crown top becomes shorter, thereby the crown shape changes to a t y p i c a l pyramidal form, from conical (Fig.3-b.d.). As the tree reaches i t s mature age the top becomes more shortened and the upper portion of the crown w i l l turn To follow page 26 F i g - 3 V a r i a t i o n s in C r o w n S h a p e s o f W e s t e r n h e m l o c k c d F i g - 3 c o n t ' d V a r i a t i o n s in C r o w n S h a p e s o f W e s t e r n h e m l o c k - 27 -into a de f i n i t e dome-shaped form (Fig. 3-e.f \u00E2\u0080\u00A2 ) , i n which l i v e whorls are located with large gaps and spaces between branches (Fig. 3\u00C2\u00ABg.h.). In most cases, the crown shapes of immature hemlock trees growing within dense stands cannot be attributed to a t y p i c a l and d e f i n i t e form as eas i l y as those of Douglas f i r , or western red cedar. Generally the dark-green foliage of hemlock trees i s thick, but the crown i s thinner i n appearance than that of Douglas f i r , despite the fact that the l a t t e r requires more l i g h t than the former. The Crown Shape of Western Red Cedar The most prominent characteristic of western red cedar trees i s t h e i r conical crown form. I t can be seen most d i s t i n c t l y , p a r t i c u l a r l y i n young trees, which are straight, appearing with t y p i c a l conical crowns reach-ing almost to the ground i f growing i n the open, and tapering to a sharp top (Fig. k.a. Appendix I l l . b . ) . The slender leader may often nod i n a graceful curve. In open growth, cedar trees r e t a i n a l l t h e i r branches u n t i l they reach 25 - 30 years, and may become much older without losing t h e i r lowest branches (Appendix I I . c ) . On young trees the slender limbs a l l curve upward, but later 1 they become very long. With increase of age the end of branches d e f i n i t e l y point downward. As the tree approaches i t s maturity the crown shape may remain s t i l l pointed, but i t often changes to a round-shaped form (Fig. k.d.e.). I t can be described as a short, blunt, or round-topped conical head. I t has been observed i n the Research Forest at Haney that round-shaped mature cedar trees occurred more often i n denser than i n open stands (Fig. k.f.). However, over-mature cedar trees often tend to develop a long, narrow top and may have a dead or spike top, by which they can be distinguished even at a long distance - 28 -from other species (Fig. k.h. Appendix I l l . f . ) . Long, irregular branches of over-mature trees, p a r t i c u l a r l y at the lower portion of the crown, downward, and others, i n the upper portion of the crown, may tend s l i g h t l y upward. Branches of over-mature cedar trees droop much more than that of Douglas f i r , or western hemlock. A notable feature of old red cedar trees i s the frequent occurrence of two or more top leaders, which cause a dense crown, or may form an irregular crown shape outline. In the Research Forest at Haney, most of the mature cedar trees that appeared with rounded shape had more than one top leader. Crown density of cedar trees i s about the same as that of hemlock, although there may occur wide variations i n crown densities, even within trees of the same age. This may be explained by differences i n stocking, site index, and environment, as w e l l as inherent conditions. To follow page 28 Fig- 4 Variations in Crown Shapes of Western red cedar Fig- 4 cont'd Variations in Crown Shapes of Western red cedar - 29 -FACTORS INFLUENCING CHARACTERISTICS OF DOUGLAS FIR WESTERN HEMLOCK AND WESTERN RED CEDAR TREES The components of a tree crown change with tree age. Changes appear mainly i n enlarging of sizes and i n reconstruction of the crown shapes of the tree. There are many factors which influence the changes i n crown components of a tree, such as age, s i t e index, basal area, stocking, etc. Linear multiple-regression equations were used i n examination of effects of these factors. The f i r s t step involved the examination of dead-branch diameter .in regression with d.b.h., s i t e index, and basal area. Dead-branch diameters i n Douglas f i r and western hemlock were strongly associated with d.b.h. and age of the tree. In the case of western red cedar i t was almost impossible to correlate the diameter of dead branches with any variable. The li n e a r multiple-regression equations are presented i n Table 7 below. Table 7\u00C2\u00AB Linear multiple-regression equations f o r dead-branch diameter on d.b.h., age, si t e index and basal area Species Intercept Regression coefficients for dead-branch diameter on: SE E R2 d.b.h. Age SI Basal area In. Douglas f i r 0.35 0.0156 .00439 -.00099 .00113 \u00E2\u0080\u00A2 27 39-7 W. hemlock -0.15 0.0150 .OO765 .00005 .00011 .23 62.4 W.r. cedar 0.20 0.0129 .00074 -.00109 .00140 .60 6.0 The amount of pruning, however, i . e . the height to the dead branches i s influenced by more factors. In Douglas f i r , western hemlock - 30 -and western red cedar the height of the dead branches increased with the height, age, s i t e index, crown width and height to l i v e branches. The height to the dead branches of hemlock and cedar species decreased with d.b.h. and basal area, whereas i n Douglas f i r i t decreased with d.b.h., but increased with basal area, i n contrast to that of hemlock and cedar. In each of these three species, however, age was the most important single factor c o n t r o l l i n g t h e i r natural pruning. The multiple-regression equations of height to dead branches on d.b.h., age, and t o t a l height were s t a t i s t i c a l l y s i g n i f i c a n t . These equations are presented i n Table 8. Table 8. Linear multiple-regression equations for height to dead branches Species Intercept Regression coefficients for height to the dead branches (Y) on: SE E R 2 d.b.h. Age Total Ht. Douglas f i r -15.7 -0.215 0.036 0.515 9.6 85.I W. hemlock -15-3 -1.372 0.287 0.423 13.3 53-7 W.r. cedar -4.8 -0.642 0.179 O.163 4.9 63.3 Examination of the data summarized i n Table 9 shows that old-growth Douglas f i r s are much better pruned than western hemlock or western red cedar at Haney. Differences i n natural pruning of old-growth Douglas f i r , unlike hemlock and cedar, were mainly associated with d.b.h. and height. The v a r i a t i o n i n heights to the lowest l i v e branches of young trees (Table 2) depends on the differences i n d.b.h., t o t a l height of a tree, age and basal area per acre. The l i n e a r multiple-regression equations for height to l i v e branches (presented i n Table 10), show that i n a l l three species the d.b.h. was the most important factor which influenced the height to the - 31 -Table 9. Natural pruning of 52 mature Douglas f i r , 58 mature western hemlock and 47 mature western red cedar trees S t a t i s t i c s Species V a r i a b 1 e s D.b.h. (In.) T.Ht. (Ft.) Avg.Ht. of lowest l i v e branches (Ft.) Crown Width (Ft.) Ht. to Avg.Crown width (Ft.) Avg.Ht. of lowest l i v e branches (Ft.) F 42.6 162.7 84.2 27.1 l 4 o . 7 71.4 Means H 28.7 126.8 55.8 22.8 109.2 42.5 C 37-^ 131.9 45.0 24.6 111.4 28.7 F 14.8 37-3 27.4 7.8 32.4 28.6 Standard Deviation is H 8.7 19.8 14.9 4.6 19.1 15-1 C 15.0 23.7 19.9 6.7 24.5 14.8 Correlation coef- F 0.52 0.77 0.89 0.33 0.79 1.00 f i c i e n t s with Av. H 0.29 o.4o 0.65 0.15 0.43 1.00 Ht. of lowest live i C 0.28 0.33 0.74 0.23 0.37 1.00 branches $ of variance i n F 1.4 31.1 67.0 -1.6 -16.5 81.3 Av.Ht. of lowest H 7.1 -15.1 44.7 0.9 11.3 48.9 dead branches ex- C -3-2 -10.5 63.3 5-7 7.0 59.^ plained by regress >ion l i v e branches i n Douglas f i r and western hemlock, although i t did not play such an important role i n the case of western red cedar. Length of l i v e crown was also studied. The most important variables were d.b.h., t o t a l height, and crown width/crown diameter. Linear - 32 -Table 10. Linear multiple regression equations f o r height to l i v e branches Species Intercept Regression coefficients for height to l i v e branches (Y) R 2 D.b.h. T.Ht. Age BA/acre (Ft.) (*) Douglas f i r -7.32 0.343 0.288 0.413 - 15.5 74.2 Douglas f i r -12.kk ' 0.606 0.230 0.296 0.084 15.0 75-6 W. hemlock -13.42 -0.637 0.622 0.118 - 13.6 73-5 W. hemlock -20.76 -0.274 O.518 0.055 O.095 12.9 70.4 W.r. cedar 0.81 -1.943 0.549 0.251 - 14.2 47.9 W.r. cedar -8.80 -I.367 0.353 0.191 0.123 13-3 53-9 multiple-regression equations are given for t h i s relationship i n Table 11. Table 11. Regression equations for l i v e crown length on D.b.h., Total height and CW/D Species Intercept Regression coef f i c i e n t s f o r l i v e crown l i v e crown length on: R 2 D.b.h. Tot.Ht. CW/D (Ft.) W Douglas f i r -11.9 0.755 0.332 13.1 14 63.3 15-2 0.997 0.193 - 14 60.6 13.1 1.938 - 4.3 15 58.9 W. hemlock -14.1 O.69I 0.389 14.6 13 58.3 13-5 0.546 0.316 - 14 52.7 10.0 2.090 - 7-4 15 43.5 W.r. cedar -7.0 1.175 0.428 4.5 15 65.7 1.6 1.050 0.417 - 15 65.2 6.7 2.699 - 2.5 16 57.8 - 33 -The percentage of l i v e crown was also analysed, with several variables. These were d.b.h., t o t a l height, age, s i t e index and basal area per acre, crown width/diameter (C W / D ) , height/crown width (Ht / C W ) , and length of l i v e branches. The most s i g n i f i c a n t factors influencing percentage of l i v e crown were basal area and height/crown width. As the basal area per acre and the r a t i o of tree height to crown width increased, the percentage of l i v e crown decreased. Linear multiple-regression equations are given i n Table 12 below. Table 12. Regression equations f o r percentage of l i v e crown on basal area per acre and H/CW Species Intercept Regression coefficients f o r percentage of l i v e crown on: basal area per acre and H/CW SE E R 2 Basal area H/CW (Ft.) (*) Douglas f i r 83 -0.11 -2.3 15 32.3 W. hemlock 98 -0.14 -3.0 15 44.7 W.r. cedar 105 -0.14 -3.6 16 36.8 Relationships among crown width/d.b.h. r a t i o s and d.b.h., age, t o t a l height, s i t e index and crown width were studied by Smith and Ker ( i960), and multiple regression analysis of the data was used on 96 open-growth Douglas f i r and 84 western hemlock open-growth at Haney. The analysis showed that the most important variable was d.b.h. f o r estimation of crown width. D.b.h. accounted f o r so much v a r i a t i o n i n both crown width and crown width/ d.b.h. that there was l i t t l e merit to use of other variables i n addition to d.b.h. Relationships between d.b.h. and crown width of f u l l y open Douglas f i r and western hemlock trees are given i n Table 13\u00E2\u0080\u00A2 - 3^ -Table 13. Relationships between Crown Width and D.b.h. of F u l l y Open-grown Douglas f i r and Western Hemlock Trees Species Equations SE E No. of trees Douglas f i r CW = 5.88 + 1.496 D.b.h. 2.33 96 W. hemlock CW = 4.23 + 1.423 D.b.h. 2.56 84 Douglas f i r CW r 2.73 - 0.054 D.b.h. D.b.h. 0.24 96 W. hemlock CW a 3.19 - 0.110 D.b.h. D.b.h. 0.55 84 - 35 -(1) INFLUENCE OF STOCKING Well-stocked stands of Douglas f i r and western hemlock at Haney were studied by Smith and Ker (i960), to determine relationships between crown width and other variables. Pope (19^9) and Dilworth (1957) have also determined relationships between v i s i b l e crown width and d.b.h. on a number of Douglas f i r growing i n Washington and Oregon. Their data showed that i n well-stocked stands the r a t i o of crown width to d.b.h. i s around one for Douglas f i r and western hemlock trees larger than eight inches i n d.b.h. For f u l l y open grown Douglas f i r and western hemlock trees larger than eight inches i n d.b.h. the r a t i o of crown width to d.b.h. i s about two. Douglas f i r , western hemlock and western red cedar trees were studied in r e l a t i o n to stocking at Haney. Ratios of crown width/d.b.h. by species and stocking, for open and densely grown trees are given i n Table lk. According to these data the next conclusion can be drawn. The r a t i o of crown width/d.b.h. was greatest f o r open grown Douglas f i r and smallest f o r densely grown western hemlock. As d.b.h. increased the r a t i o of CW/d.b.h. decreased f o r a l l three species independently of density of stocking conditions. The r a t i o was greater for a l l three species growing i n open conditions, than i n dense stocking con-ditions . During the study i t was also found that the r a t i o of tree height/ crown width was closely related to the r a t i o of tree height and to average spacing distance. Simple correlation coefficients are given i n Table 15 for height/crown width and crown width/d.b.h. - 36 -Table lk. Ratios of Crown Width/d.b.h. by species and stocking. Aveg.D.b.h. i n . Open grown Densely grown. F H c F H 2 3.4 2.8 3-0 1.7 -k 2.9 2.3 2-3 1.4 1.1 6 2.4 2.0 1.9 1-3 1.0 8 2.2 1.9 1.8 l . l 1.0 10 2.1 1.9 1-7 1.1 0.9 12 2.0 1.8 1-7 1.0 0.9 lk 1-9 1.7 1.6 1.0 0.9 16 1.8 1-7 1.6 1.0 0.9 18 1.8 1.6 1-5 0.9 0.9 20 1.8 1.6 1-5 0.9 0.8 22 1.7 1.6 1-5 0.9 0.8 2k 1.7 1-5 1.4 0.9 0.8 26 1.7 1.5 1.4 0.9 0.8 Height/crown width values are required to be, f o r significance at p .05 percent confidence l e v e l , 0 . l 4 f o r Douglas f i r , 0.15 f o r western hemlock and 0.23 f o r western red cedar. Basal area has also been studied i n connection with crown width/d.b.h. together with other variables such as d.b.h., t o t a l height, age, site index and crown width. Percentages of v a r i a t i o n i n crown width/d.b.h. and single correction coefficients are given i n Table 16, f o r Douglas f i r , western hemlock and western red cedar. Regression equations f o r estimate of crown width/d.b.h. from height/crown width, or height/crown width form crown width/d.b.h. for each of these species are given i n Table 17. Table 15. Comparison of c o r r e l a t i o n s between crown width/d.b.h. and height/crown width, r a t i o s w i t h eleven v a r i a b l e s f o r Douglas f i r , western hemlock and western red cedar. Species V a r i a b l e s D Ht. A. SI. cw. B.A. CW/D CC Ht/CW io I.e. L.1.c. Douglas F i r CW/d.b.h. 0.60 0.73 0.64 0.35 0.03 0.48 1.00 0.02 0.76 0.49 o.4i Ht/CW 0.24 0.51 0.49 0.23 0.35 0.48 0.76 0.39 1.00 0.44 0.21 W.hemlock CW/d.b.h. 0.53 O.58 0.58 0.10 0.16 O.50 1.00 0.09 0.76 0.54 0.24 Ht/CW 0.l4 0.48 0.45 0.13 0.45 O.54 O.76 0.25 1.00 0.55 0.12 W.r.cedar CW/d.b.h. O.58 0.54 0.31 0.44 o.o4 0.28 1.00 o.i4 0.71 0.12 o.4i Ht./CW 0.28 0.53 0.28 0.35 0.27 0.51 0.71 0.06 1.00 0.50 0.22 Where the abbr e v i a t i o n s are as f o l l o w s : D-D.b.h. CW/D. Ht - Height CC. A - Age Ht/CW SI - S i t e index $ I.e. CW - crown width L.1.c. B.A.-basal area r a t i o of crown width to D.b.h. crown c l a s s r a t i o of height to crown width percent of l i v e crown l e n g t h of l i v e crown. - 38 -Table l 6 . Relationships among crown width d.b.h., age, t o t a l height, s i t e index, crown width and basal area. Species Percentage of v a r i a t i o n i n crown width/d.b.h. explained i n multiple regression by: D.b.h. Ht. Age SI. CW. BA. A l l Douglas f i r ( 0 ) 192.7 -21.5 14.8 0.7 -97.4 89.3 0.11 Douglas f i r 58.5 52.3 -25.6 -^\u00E2\u0080\u00A25 - 3-0 2.8 80.5 0.19 W. hemlock 53-3 15.7 - 6.6 -0.8 14.9 6-5 83.3 0.16 W.r. cedar 58.6 14.3 - 3-7 2.8 3-2 1.0 76.2 0.23 Simple correlation c o e f f i c i e n t s f o r d.b.h. on: crown width/ Douglas f i r ( O ) -.714 -.673 -.684 -.088 -.489 - - -Douglas f i r -.603 -.719 -.636 -.313 -.033 -.479 - -W. hemlock -.530 -.580 -.581 -.182 \u00E2\u0080\u00A2 159 -.498 - -W.r. cedar -.582 -.544 -.313 -.435 -.638 -.277 - -Symbol i n Table 16 \" 0 \" , means \"open\" Table 17\u00E2\u0080\u00A2 Regression equations f o r estimate of crown width/ d.b.h. from height/crowm width, or height/crown width from crown width/d.b.h., by species. Species Intercept Regression coef f i c i e n t s f o r CW/d.b.h. on height/CW S E E f t . R 2 1o Douglas f i r 2.134 -0.164 O.278 57-^ W. hemlock 2.03 -0.144 0.245 57-^ W.r. cedar 2.22 -0.206 0.321 50.4 Regression coef f i c i e n t s f o r height/CW on Cw/d.b.h. Douglas f i r 9.83 -3.572 1.30 57-^ W. hemlock i o . 4 i -3.976 1.34 57-4 W.r. cedar 7.72 -2.416 1.10 50.4 - 39 -(2) INFLUENCE OF AGE The age of an i n d i v i d u a l tree influences i t s crown form. Very young trees have not developed t h e i r more or l e s s c h a r a c t e r i s t i c crown form. Young Douglas f i r , western hemlock and western red cedar take on t y p i c a l crown shape about 30-35 years, i f growing within dense stands. For each species can be found c h a r a c t e r i s t i c crown forms which are t y p i c a l f o r the various age period of a tree examined. I t has been observed at Haney, that the upper portion of a crown changes quite d i f f e r e n t l y from i t s lower portion, and independently of the stocking within which the examined tree was grown. This f a c t suggested d i s -cussion of the changes i n crown caused by age, separately f o r upper and lower portions. a. Changes i n upper portion of the crown. Every tree studied was drawn i n d i v i d u a l l y i n p r o f i l e and cross section views. A f t e r the sketches had been arranged by the age groups of trees (21 - kO, kl - 60, e t c . . . . ) , i t was evident that the top angle of crown shapes was increased by age of trees. By measuring angles from the sketches i t was found that the changes i n angle were l i n e a r f o r Douglas f i r and western hemlock from 30 to 130 years and f o r western red cedar from 30 to 100 years of age (Graphs 1,2,3). Increase i n top-angle over 130 i n Douglas f i r , western hemlock and over 100 years of age i n the western red cedar i s not as rapid as i n youth. The curve also shows that as the tree approaches i t s maturity the top becomes almost f l a t t e n e d . Average top-angle values with t h e i r standard deviations are presented i n Table 18, f o r Douglas f i r , western hemlock and western red cedar trees by d i f f e r e n t age groups. The average top-angle values To follow page 39 80 Age in Years G r a p h I A v e r a g e t o p a n g l e s o v e r a g e f o r D o u g l a s f i r 80 L_< I I I I I L_ < 30 50 70 90 110 130 Age in Years Graph I Average top angles over age for Douglas fir Age in Years Graph 2 Average top angles over age for Western hemlock - ko -i n some cases have been found s u f f i c i e n t l y t y p i c a l to d i s t i n g u i s h i n d i v i d u a l species i n c e r t a i n age groups. U n f o r t u n a t e l y , i n the m a j o r i t y of the cases there was such a great overlap i n these values t h a t i t was h a r d l y p o s s i b l e to use the technique i n se p a r a t i o n of species. The overlap of values was found to be the l a r g e s t i n western hemlock and western red cedar. Table 18. Average top-angle values w i t h t h e i r standard d e v i a t i o n s f o r Douglas f i r , western hemlock and western red cedar. Age c l a s s (Yrs.) 21-40 41-60 61-80 81-100 101-120 121-Douglas f i r No.of tr e e s 48 12 59 10 11 44 Avg.top-angle \u00C2\u00B0 4 9 53 57 63 65 73 Stand. Dev. \u00C2\u00B0 12.7 9-2 7-7 9-7 4.1 3-8 Range o 25-60 40-65 45-67 50-70 55-75 70-89 W. hemlock No. of tre e s 38 6 7^ 27 10 36 Avg. top-angle \u00C2\u00B0 27 35 43 49 5^ 57 Stand. Dev. \u00C2\u00B0 9-1 11.2 11.5 11.6 3-6 3-9 Range \u00C2\u00B0 15-28 25-37 33-45 43-56 50-67 61-80 W. r . cedar No. of tre e s 18 5 21 7 - 37 Avg.top-angle \u00C2\u00B0 27 35 48 55 - lh Stand. Dev. \u00C2\u00B0 8 . 4 l 9.8 10.5 ' 13-9 - 5-2 Range \u00C2\u00B0 15-35 29-4o 36-51 57-75 - 67-83 - i n -Another characteristic figure was found for each species, the quo-ti e n t of average top-angle and average crown height. Figures are presented i n Table 19. Table 19. Quotient of average top-angle and average crown height for Douglas f i r , western hemlock, and western red cedar. Species Age classes (Yrs.) 21-40 41--6o 61-80 81--120 101-120 121-Douglas f i r 1.20 0 96 0.60 0 50 0.45 0.45 W. hemlock 1.50 0 TO 0.54 0 52 0.47 0.42 W.r. cedar 1.45 0 92 0.71 0 68 - 0.49 As has been previously mentioned, each recorded crown shape was compared with a shape-scale. The effect of age can be pointed out very d i s t -i n c t l y i n t h i s way, since the top of crowns of each species become wider with age. The data of t h i s survey are presented i n Table 20. The frequency of appearance of species i n respective crown shape-scale and age class i s expressed i n percentages. Table 20. D i s t r i b u t i o n of crown shapes of Douglas f i r (F), western hemlock (H ) , and western red cedar (C) Shape Age Classes (Yrs. ) 20^40 4o-6o 61-80 81-100 F H C F H C F H C F H C Percentage of t o t a l number of trees i n each species and age class Linear - 6 12 - - - 8 4 - - 8 -Oblong 12 6 12 20 8 24 5 6 25 - - -Lanceolate 34 6 35 26 20 9 14 4 10 - - 14 Oblanceolate 12 - 18 7 - 17 - - 15 -Ovate 9 27 - 4o 34 38 19 18 25 - 8 14 Obovate - - - 7 - - 23 - - -E l l i p t i c a l - - - - - 12 - 10 - - - 14 Deltoid 28 4 l 17 - 38 - 18 19 10 - 19 43 Rhomboid 5 - - - - - 8 - 10 - - 15 Irregular - 14 6 - - - 5 39 5 - 65 -100 /olOOfo LOO/o 100#100#100# lOOfolOO/olOO/o \" . - lOO/olOOfo - k2 -b. Changes i n lower p o r t i o n of the crown. The- e f f e c t of age on the lower p o r t i o n of the crown i s not conspic-uous u n t i l n a t u r a l pruning s t a r t s . The beginning of the n a t u r a l pruning may be seen i n death of the lowest branches at about 25 years i n Douglas f i r , 30 years i n western hemlock, and 35 years i n western red cedar, growing i n normal c o n d i t i o n s at Haney. The e f f e c t of age, however, on the lower p o r t i o n i n con t r a s t w i t h the.upper p o r t i o n of the crown w i l l show up d i s t i n c l y only at 6l-80 years of age, when branch s i z e s and the dis t a n c e s between them are q u i t e l a r g e . The ends of lower branches of mature Douglas f i r w i l l p o i n t down, i n contrast w i t h young Douglas f i r t r e e s , where the lower branches w i l l p o i n t upward. The lower branches of hemlock and cedar t r e e s w i l l l e a n extremely downward. These f a c t o r s can be seen most prominently when the t r e e s of these species reach t h e i r mature age (Appendix I a.p.; I l l a. & f . ) . (3) INFLUENCE OF ELEVATION Influ e n c e s of e l e v a t i o n on crown shape of t r e e s has been observed by s e v e r a l authors already. Rohmeder and Schonbach (1959) have d i f f e r e n t i a t e d three v a r i a t i o n s i n crown of Norway spruce, ( P i c e a e x c e l s a ) , i n the German A l p s . An e f f e c t of e l e v a t i o n has been observed a l s o i n C o a s t a l Douglas f i r , found i n the v i c i n i t y of Haney and Vancouver. I f a Douglas f i r i s growing over 2,000-2,500 f e e t e l e v a t i o n i t s crown w i l l appear much narrower than t h a t of a s i m i l a r t r e e growing near sea l e v e l . The d i f f e r e n c e s i n the two crown types w i l l appear most d i s t i n c t l y i n the upper p o r t i o n of the crown. D o u g l a s - f i r t r e e s growing at higher e l e v a t i o n s w i l l have a narrower, and more po i n t e d tops than those growing i n lower lands, which w i l l have a shorter t i p w i t h a f l a t t e r top-angle (Appendix I h . i . j . k . l . ) . These d i f f e r e n c e s are most evident i n D o u g l a s - f i r t r e e s at ages of about kO t o 100 years, and are not so n o t i c e a b l e i n mature t r e e s . - k-3 -The d i f f e r e n c e s i n crown shapes may be ex p l a i n e d mainly by d i f f e r -ences i n weather and p r e c i p i t a t i o n between low and high e l e v a t i o n s . P o s s i b l y the more severe w i n t e r and -the greater amount of snow at higher e l e v a t i o n s f o r c e the t r e e s t o develop a narrow crown. Trees w i t h narrow crowns would not hol d up as much snow than those w i t h wider crowns and would s u f f e r l e s s breakage from excessive loads of snow. S t r i c t r u l e s i n t h i s matter cannot be set up, because i t o f t e n happens t h a t t r e e s w i t h two qu i t e d i f f e r e n t crown types w i l l be found side by side (Appendix I f . ) . The d i f f e r e n c e s i n frequency, however, of these two crown types of D o u g l a s - f i r t r e e s are evident. No d i f f e r e n c e s i n crown shapes of western hemlock and western red cedar t r e e s could be a t t r i b u t e d t o d i f f e r e n c e s i n e l e v a t i o n . - kk -PHOTO FACTORS WHICH FACILITATE SPECIES IDENTIFICATION VALUE OF TONE 1. The importance of tone to the forest interpreter. Tone i s a function of the b r i l l i a n c e of l i g h t reflected from the subject, which appears on black and white photographs as the range of gray from black through to the white. To i d e n t i f y an object the i n t e r -preter uses the p i c t o r i a l q u a l i t i e s i n i t s recognition. Among the p i c t o r i a l q u a l i t i e s there are only four forms of information available for the interpreter of a e r i a l photographs: shape (including s i z e ) , texture, shadow pattern, and tone. Among these c h a r a c t e r i s t i c s , i n most cases, the tone of an image i s used i n i t s recognition. An image has a shape, but the shape i s only shown by a tone at i t s edges that d i f f e r s from the tone of i t s background. I t has been proven that the o p t i c a l nerves of the human eyes respond only to changes i n illumination (Katz 1950). I t follows then that the boundaries of the images give the eye i t s most intense impression. The interpreter requires therefore a d i s t i n c t change i n the tone of the edges of images, to c a l l his attention to the. existence of those images. This i s the f i r s t step i n i d e n t i f i c a t i o n of images and t h i s i s the place i n which' resolution i s of the f i r s t importance. However, once the interpreter has recognized the existence of an image, i t i s e s s e n t i a l to take into consideration the tone of the whole image area and of the surroundings of the examined object, before the - 45 -image i t s e l f can be recognized. Through, t h i s preliminary examination, which i s not directed on the subject i t s e l f , but on i t s surroundings, involving the comparison of tone, size and texture differences and examination of environment, the interpreter can gain a large amount of information about the object i t s e l f which may be very valuable clues i n i t s recognition. P a r t i c u l a r l y important i n the f i e l d of forestry^,- i s the separation of timber stands from bogs and meadow by tonal differences of images. In c l a s s i f i c a t i o n of the stands, tone i s an indispensable character, and within the c l a s s i f i e d stand, or i n an open po s i t i o n , the tone may give the f i n a l separation of some in d i v i d u a l tree species, such as Douglas f i r from western red cedar, where the l a s t one appears always the l i g h t e r tone. 2. Factors co n t r o l l i n g the tone of an object. I t can be stated generally that the tone of an image on a photo depends on the amount and the quality of l i g h t reflected from the object to the l i g h t , sensitive material. According to t h i s , as more l i g h t i s r e f l e c t e d from an object, i t s image tone w i l l be l i g h t e r , and objects which absorb much l i g h t w i l l have a dark tone on a photograph. Then the tone of one image i s controlled mainly by the colour of the surface, the nature of surface of the objects and the amount of haze i n the a i r . In addition there are three more factors which largely control the tone of photographs. These are l o c a l topography, kind of camera, and position of the sun. a. Colour of surface. I t i s known generally that the l i g h t e r the colour of an object, - 46 -the more l i g h t i s refl e c t e d from i t s surface. But two s i m i l a r l y green objects, i n our case trees, may appear on photos with a different tone. With leaves hanging at various angles from the twigs, or i n the case of evergreens, standing out around the twig, and viewing i n d i v i d u a l trees from different angles on different parts of photos, there i s an appreciable v a r i a t i o n i n the colour of given species on one photo, even assuming that every tree of that species i s i n the same physiological state. The variations i n tone within photographs are due to the angle of view and amount of shadowed and s u n - l i t portions of the tree examined. There might be some s l i g h t differences i n physiological state, related to si t e conditions, or attack of insects and disease, but the detection of these differences would require more extensive examination of species on the whole area, which f a l l s beyond the scope of t h i s study. As was mentioned above, the tone varies with the amount of r e f l e c t i o n , but the r e f l e c t i o n may largely depend on the angle of viewing of the l i g h t . The res u l t s of such an experiment are shown i n Table 21 (Wallis 1943). Table 21. Changes i n refl e c t e d l i g h t caused by angle of viewing. Incidence Leaf viewed from Percent of refl e c t e d l i g h t from surface of a mulberry l e a f . Blue Green Red 0 45 incidence 0 45 incidence 0 150 0 50 23.1 25.O 14.0 39.3 35-8 35-7 Examination of the leaves of various species shows there i s p r a c t i c a l l y no v a r i a t i o n i n the way they r e f l e c t v i s i b l e red l i g h t . The situa t i o n regarding the refl e c t e d green l i g h t i s quite different as i t can - 47 -be c l e a r l y r e a l i z e d by examination of mixed stands. I t i s due to the va r i a t i o n of green colour a l l the way from yellow-green to dark blue-green. b. Nature of surface. Glossy surface. The percentage of incident l i g h t r e f l e c t e d to the camera depends largely upon the smoothness of the r e f l e c t i n g surface, and i n the case of very smooth surfaces, the angles of incidence and r e f l e c t i o n . Water on a calm day i s an i d e a l example of a smooth surface. If the angle of the sun and camera to the water surface i s such that the rays of the sun are not refl e c t e d d i r e c t l y to the camera, the water w i l l appear white. I t follows that the photographhic image of water i s either very l i g h t or very dark. This condition i s common also i n interpretation of forest type, p a r t i c u l a r l y when i t i s necessary to deal with deciduous forest type, or other species which have glossy leaves. Rough surfaces. Rough surfaces vary very l i t t l e i n t h e i r photographic tone with changes i n angles of incidence and r e f l e c t i o n . The tone of images of glossy surfaces i s influenced mainly by the base colour of the object. In general, however, they are intermediate i n tone, due to the dispersion of much of the l i g h t they receive. There are, however, some parts of the irregular surface which r e f l e c t l i g h t to the camera. In such cases when dispersion and r e f l e c t i o n of l i g h t are caused on the same surface, the effect of \"contained shadow\" w i l l appear (Wallis.-1943)\u00E2\u0080\u00A2 This i s the effect of innumerable small shadows of the protuberances and dents of the surface which are too small to register i n d i v i d u a l l y , because they exceed the l i m i t of resolution. The degree of darkening w i l l depend upon the density of such shadows and t h e i r shadowed area. - kd -Contained shadows are the c h i e f reason f o r the darker tone of softwoods compared t o hardwoods. Each i n d i v i d u a l needle i n the crown causes a t i n y shadow, because they are q u i t e separate and the cumulative e f f e c t i s t o darken the area occupied by the image of the crown. With hardwoods, the much l a r g e r leaves overlap w i t h few shadows and form a r e l a t i v e l y smooth surface which always appears l i g h t e r . Contained shadow i s very u s e f u l i n separation of undergrowth The t a l l e r and t h i c k e r the undergrowth, the darker w i l l be i t s tone on photographs. c. Haze. Haze c o n s i s t s c h i e f l y of dust, smoke and water p a r t i c l e s . I t conside r a b l y decreases the v i s i b i l i t y of an object on photos and reduces both the hue and b r i g h t n e s s , due t o the e f f e c t of q u a l i t a t i v e and q u a n t i t a t i v e changes i n the l i g h t r e c e i v e d by the camera. Q u a l i t a t i v e l y , haze s c a t t e r s the blue l i g h t , thus reducing the amount of blue l i g h t reaching the o b j e c t s photographed and reducing i t again when r e f l e c t e d from the object t o the camera. The r e s u l t of t h i s event i s t h a t g e n e r a l l y more blue l i g h t reaches the camera, which gives a b l u i s h cast i n c o l o r photographs, and reduces contrast i n b l a c k and white photos. With l i g h t haze, a y e l l o w f i l t e r w i l l permit photography and giv e s b e t t e r tone rendering, as f a r as s p e c t r a l e f f e c t s are considered. G e n e r a l l y , the choice of f i l t e r depends upon the amount of haze, the type of f i l m being used and the- d e s i r e d tone. The more blue l i g h t the f i l t e r cuts out, the b e t t e r w i l l be the haze p e n e t r a t i o n . The atmospheric haze a f f e c t s the r e f l e c t i o n of l i g h t q u a n t i t a t i v e l y - k^ -a l s o , which a c t s against rendering of good tone. The amount of l i g h t reach-i n g the object being photographed ( t h i s i s very much t r u e when the object photographed i s a f o r e s t stand), i s reduced so much that the contrast be-tween shadow and l i g h t e d p o r t i o n s of an object i s h i g h l y softened. I n extreme cases the shadow may disappear completely, and even the wide tone d i f f e r e n c e s between hardwoods and softwoods may be l o s t . d. T op ography. On h i l l y l a n d , the sun may r e f l e c t o f f only the t r e e s on the sunny side of the h i l l and the other side of the h i l l w i l l be shady. T h i s d i f f e r e n c e i n exposure w i l l , of course, cause some t o n a l d i f f e r e n c e s on the photo a l s o ; the stand on the sunny side of the h i l l w i l l appear l i g h t e r because f i l m i s a f f e c t e d by the g r e a t e r amount of l i g h t energy s h i n i n g on the t r e e crowns, than on the l e s s w e l l l i g h t e d side of the h i l l . e. Camera. This f a c t o r o r i g i n a t e s from the nature of lenses used i n the camera. Some lenses tend t o admit more l i g h t through t h e i r center p o r t i o n than through t h e i r p e r i p h e r a l p o r t i o n s . Therefore, the edges of photos w i l l be darker and t h e i r center p o r t i o n w i l l r e g i s t e r i n l i g h t e r tone. This v a r i a t i o n i n tone may be l i m i t e d by a t h i n blue cover around the p e r i p h e r a l p o r t i o n of the l e n s , or w i t h a m u l t i p l e lens system combined w i t h f l a t p l a t e s . f . P o s i t i o n of the sun. Taking photographs over a f l a t a rea, the t r e e s away from the sun w i l l r e g i s t e r i n l i g h t e r tones than those toward the sun. One of the reasons i s t h a t t r e e s away from the sun w i l l catch more s u n l i g h t and r e f l e c t i t t o the camera, than the others which are toward the sun. Another reason - 50 -i s t h a t the greater the distance the sun's rays t r a v e l through the atmos-phere, the greater w i l l be the haze e f f e c t . According t o t h i s , as the sun's e l e v a t i o n decreases, the e f f e c t of the haze i n c r e a s e s . A v a r i a t i o n i n the sun's e l e v a t i o n w i l l a l s o a f f e c t the amount of l i g h t r e f l e c t e d up from the ground. The c l o s e r the ground surface i s o t o forming a 90 angle t o the sun's r a y s , the smaller w i l l be the shadows of i r r e g u l a r i t i e s , and t h e r e f o r e the more l i g h t ground w i l l r e f l e c t t o a v e r t i c a l camera. 3. Measurement of tone. The measurement of tone can be done i n two ways: a. Recognition by unaided eye, and b. Measurement by comparison. a. Recognition by unaided eye. The only work d e a l i n g d i r e c t l y w i t h the question of the number of tones recognizable i n a e r i a l photographs without a i d s of any k i n d , t h a t has come t o the w r i t e r ' s a t t e n t i o n , i s t h a t of Leighton ( l 9 ^ l ) . In h i s s e r i e s of t e s t s he t r i e d t o separate images w i t h d i f f e r e n t r e f l e c t i o n d e n s i t y , i . e . , images appearing w i t h d i f f e r e n t tone, and p o i n t e d out t h a t there must be a great range i n r e f l e c t i o n d e n s i t i e s of images t o d i s c e r n them, and t o be able t o separate them. The r e s u l t s of h i s experiment are shown i n Table 22. There were two observers chosen. A, almost completely inexperienced i n i n t e r p r e t a t i o n , and B, an i n t e r p r e t e r w i t h s e v e r a l years of experience. Both had t o separate equal numbers of p l a t e s of d i f f e r e n t hues of tone, without any reference or comparison. - 51 -Table 22. Human a b i l i t y i n separation of d i f f e r e n t tones. Obser-ver T o t a l No. of Steps I d e n t i f i e d No. of E r r o r s i n v a r i o u s Density D i f f e r e n c e s Classes steps c o r r e c t l y .00 .05 - . 0 6 -.10 . 1 0 -\u00E2\u0080\u00A2 15 .16-.20 .21-\u00E2\u0080\u00A2 25 .26- .31 \u00E2\u0080\u00A230 .35 A kk 21 7 9 1 - 2 3 1 B kk 29 6 2 2 k 1 -T o t a l s 88 50 13 11 3 k 3 3 1 To ensure 95$ success i n i d e n t i f y i n g tone under such, given c o n d i t i o n s , the experienced i n t e r p r e t e r B would r e q u i r e a d e n s i t y d i f f e r e n c e i n tone of 0.21 or more, and the inexperienced 0.31 or more. These f i g u r e s become more v a l u a b l e when Table 23 i s examined. According t o t h i s t a b l e , the f i g u r e s show t h a t i n t e r p r e t e r A could separate a shadowed white pine from a shadowed white spruce only w i t h d i f f i c u l t y , because the d i f f e r e n c e be-tween these two species i n r e f l e c t i o n d e n s i t y i s only 0.10. I n Table 23, some values of r e f l e c t i o n d e n s i t i e s are given f o r s e v e r a l t r e e species obtained from sets of f a l l photos on panchromatic f i l m w i t h RF of 1 : 7>500 and g l o s s y f i n i s h (Losee 1951)\u00E2\u0080\u00A2 Table 23. R e f l e c t e d l i g h t d e n s i t i e s from leaves of some Coniferous and Deciduous species. S p e c i e s R e f l e c t e d d e n s i t i e s . White b i r c h and aspen ( s u n l i g h t side) o.ok White p i n e , red pine ( s u n l i g h t side) 0.54 White sp r u c e ( s u n l i g h t s ide) 0.84 Black spruce (shadowed and s u n l i g h t sides i n unresolved complex) 1.25 White pine (shadowed side) 1.35 - 52 -2. Measurement by comparison. I n d e a l i n g w i t h object i d e n t i f i c a t i o n of a e r i a l photographs, r e c o g n i t i o n keys are i n d i s p e n s a b l e . Such r e c o g n i t i o n keys are u s u a l l y made up of s e v e r a l fundamental f a c t o r s : tone, t e x t u r e , shape, shadow p a t t e r n , general appearance, and d i s t r i b u t i o n . A l l of these f a c t o r s , except tone and i n some cases t e x t u r e t o o , can be discussed w i t h concrete terminology. Tone r e f e r s t o the b r i l l i a n c e w i t h which l i g h t i s r e f l e c t e d by an o b j e c t . Objects w i t h d i f f e r e n t b r i l l i a n c e w i l l have d i f f e r e n t tone. On co n v e n t i o n a l b l a c k and white photos, the tone i s r e g i s t e r e d i n v a r y i n g shades of grey. I n many r e c o g n i t i o n keys, the tone i s c l a s s i f i e d by words such as dark, medium or l i g h t , e t c . I t i s obvious t h a t what might be medium tone t o one observer would not n e c e s s a r i l y be so considered by a second observer. I n d e s c r i b i n g the c h a r a c t e r i s t i c tone of c e r t a i n photo-graphic images i t i s u s e f u l t o make a reference t o a standard \"grey s c a l e \" , which i s shown i n F i g . 5 ( C o l w e l l 1952). F i g . 5. Tone s c a l e . Such a scale of tone was used i n d e s c r i p t i o n s of tone changes of Douglas f i r , western hemlock, and western cedar on d i f f e r e n t s c a l e s of photos. I t might be w e l l t o mention t h a t , i f the t e n degrees of tone q u a l i t y are cut apart and mounted on separate s t r i p s of l i g h t cardboard, comparison under the stereoscope would be f a c i l i t a t e d . Such a tone sc a l e - 5 3 -should become standard equipment f o r i n t e r p r e t e r s of a e r i a l photos. 3- Changes i n tone caused by scale of photos. A l o g i c a l approach t o the d i f f e r e n t i a t i o n of t r e e species on a e r i a l photos would be the determination of the d i f f e r e n t tones produced by the species t o be d i f f e r e n t i a t e d . I t i s l o g i c a l because the n a t u r a l appearance of mixed f o r e s t and a l s o d i f f e r e n t i n d i v i d u a l t r e e species does show up considerable v a r i a t i o n i n hue and b r i g h t n e s s . A l l the c o n i f e r s are darker than the deciduous t r e e s , and l i s t s of these and other intermediate species could be made ranging from the darkest t o l i g h t e s t . I f the tone would be s u f f i c i e n t l y constant f o r a given species, then the i n t e r p r e t e r s would have t o measure and compare only the tones assuming t h a t a l l the a v a i l a b l e photos are the same q u a l i t y . The f i r s t o b s t a c l e , however, comes from what has been i n d i c a t e d i n previous paragraphs, t h a t the b r i g h t n e s s , hue and haze are too v a r i a b l e t o set up such a scale of tones f o r d i f f e r e n t species t o be used as a r e l i a b l e standard key f o r species i d e n t i f i c a t i o n . J u s t t o mention a few such o b s t a c l e s , i t i s known th a t the tone of a given species v a r i e s w i t h the l o c a t i o n r e l a t i v e t o .the center of the photograph, being darker at the edges. V a r i a t i o n s i n tone a l s o can be caused p a r t i a l l y by p r i n t i n g . The tone v a l u e s , under such c o n d i t i o n s , w i l l always be r e l a t i v e v a l u e s . During the examination of changes i n tone of d i f f e r e n t species on d i f f e r e n t scale of photos, i t has been found t h a t the d i f f e r e n c e s i n tone were caused not only by the p r e v i o u s l y described reasons, but by the scale a l s o . There were f i v e d i f f e r e n t kinds of photos a v a i l a b l e (see page 17 ) . - 54 -The survey i n v o l v e d the examination of twenty i n d i v i d u a l t r e e s of the three major species of B.C.'s c o a s t a l f o r e s t s : Douglas f i r , western hemlock and western red cedar. Ten t r e e s were young growth and t e n were o l d growth. They were chosen randomly from a group of t r e e s e a s i l y v i s i b l e on a l l photos. Every t r e e was examined i n d i v i d u a l l y on each photo, and every r e c o g n i t i o n f a c t o r was s t u d i e d under the stereoscope. U n f o r t u n a t e l y the tone of each t r e e species could not be compared d i r e c t l y w i t h each other, because the s p e c i f i c a t i o n s of a v a i l a b l e photos were not i d e n t i c a l . Instead of a number on a tone s c a l e , words have been used f o r tone c l a s s i f i c a t i o n i n t h i s survey as, Medium ( M ) , Medium l i g h t (ML), Medium dark (MD), e t c . These l e t t e r s represent numbers on the tone scale as f o l l o w s : 1-2 Very l i g h t (VL) 3-4 L i g h t (L) 5 Medium l i g h t (ML) 6 Medium ( M ) 7-8 Medium dark (MD) 9 Dark ( D ) 10 Very dark (VD) The r e s u l t s of the survey are given i n Tables 24, 25 and 26. Examining the given t a b l e s , the f o l l o w i n g conclusions can be drawn: Changes i n tone of young Douglas f i r are caused by decrease of photo s c a l e . As the scale of photos i s decreased, the tone i s changed from Medium ( M) t o Medium l i g h t (ML). T h i s change i n tone was not the same f o r o l d growth Douglas f i r , where the changes i n tone were i n the opposite - 55 -d i r e c t i o n . As the photo scale was decreased, the tone changed from l i g h t e r t o darker, from Medium (M) t o Dark (D). Changes i n tone of young and o l d western hemlock are the same. As the photo scale decreases the tone changes from darker t o l i g h t e r , from Medium ( M ) t o Medium l i g h t (ML.) i n young growth, and from Medium dark (MD) t o Medium l i g h t (ML) i n o l d growth. Changes i n tone of young and o l d western red cedar a l s o have \"been found. As the photo scale was decreased the tone became l i g h t e r , i . e . from Medium l i g h t (ML) t o Very l i g h t (VL). The percentages given i n the t a b l e s mean the number of t r e e s corresponding t o the tone s c a l e . For example, kO^o i n Table 2k means tha t f o u r t r e e s out of t e n occurred w i t h Medium ( M) tone. A s i m i l a r procedure has been f o l l o w e d f o r a l l three species. Douglas f i r and western hemlock have intermediate tone on b l a c k and white photos; u n f o r t u n a t e l y the ranges of tones i n many cases overlap, although i n some cases they are t y p i c a l and the two species can be segregated by the tone alone. The wide range of overlap i n tone of these two species may be exp l a i n e d by s p e c t r a l a n a l y s i s of the f o l i a g e , according t o which the d i f f e r e n c e s i n r e f l e c t i o n between two species i s o f t e n smaller than the d i f f e r e n c e between two p l a n t s of the same species (Hindley and Smith 1957)- Many c h a r a c t e r i s t i c s of t r e e s , such as t h e i r age, y i g o r and genetic c o n s t i t u t i o n , c o n t r i b u t e t o d i f f e r e n c e s i n l i g h t r e f l e c t a n c e . - 56 -Table 24. Changes i n tone of Douglas f i r on d i f f e r e n t s c a l e s of photos. Photo sc a l e T o n e s c a l e VL L ML M MD D Y o u n g g r o w t h Percent of t r e e s i n tone c l a s s 330 f t . / i n . - 10 20 4o 30 _ 720 f t . / i n . \u00E2\u0080\u00A2 - 10 40 20 30 1,200 f t . / i n . - 30 40 30 - -1,500 f t . / i n . - 10 70 10 10 -2,4-00 f t . / i n . - 10 70 20 f_ 0 1 d g r o w t h 1,200 f t . / i n . _ _ 10 80 10 _ 1,500 f t . / i n . - - - 20 70 10 2,400 f t . / i n . - - 10 10 10 70 Table 25. Changes i n tone of western hemlock on d i f f e r e n t s c a l e of photos. Photo scale T o n e s c a l e VL L ML . M MD D Y o u n i I g r o w t h Percent of t r e e s i n tone c l a s s 330 f t . / i n . ., - 10 20 40 30 _ 720 f t . / i n . - 10 20 70 - -1,200 f t . / i n . - 10 50 20 20 1,500 f t . / i n . - 20 50 30 - -2,400 f t / i n . - - 6o 30 10 -0 1 d g r o w t h 1,200 f t . / i n . _ _ _ 80 20 1,500 f t . / i n . - - 70 30 - -2,400 f t . / i n . - - 80 20 - -- 57 -Table 26. Changes i n tone of western red cedar on d i f f e r e n t s c a l e of photos. Photo T o n e s c a 1 e scale VL L ML M MD D Y o u n g ; g r o w t h Percent of tr e e s i n tone c l a s s 330 f t / i n 20 50 30 720 f t / i n - 20 6o 20 - -1,200 f t / i n ho 6o - - - -1,500 f t / i n 70 30 - - - -2,400 f t / i n 80 20 - - - -0 1 d g r o w t h 330 f t / i n _ _ 80 20 - _ 720 f t / i n - 10 20 70 - -1,200 f t / i n 10 70 20 - - -1,500 f t / i n 70 30 - - - -2,400 f t / i n 80 20 - - - -Legend: VL - Very l i g h t L - L i g h t ML - Medium l i g h t M - Medium MD - Medium dark D - Dark. - 58 -Western red cedar always appears w i t h l i g h t e r tone than t h a t of Douglas f i r or western hemlock, due to i t s t h i n n e r crown and b i g g e r l e a v e s . This l i g h t e r tone i n most of the cases i s s u f f i c i e n t to separate i t from the two other species. C e r t a i n l y , i n species i d e n t i f i c a t i o n , tone plays an important r o l e . When due allowances are made, photographic tone i s a va l u a b l e and necessary i d e n t i f i c a t i o n f a c t o r , p a r t i c u l a r l y when i t i s used i n combination w i t h crown shape, t e x t u r e , shadow p a t t e r n , and a s s o c i a t i o n of the p a r t i c u l a r s p e c ies. This i s e s p e c i a l l y true when l a r g e homogeneous stands are represented on a p i c t u r e . On l a r g e s c a l e photos where the d e t a i l s are more obscured the tone becomes extremely important. Obviously, tone has a great value i n general p h o t o - i n t e r p r e t a t i o n and species i d e n t i f i c a t i o n , but i t i s s t r o n g l y emphasized t h a t i t should not form the sole b a s i s of our judgments. VALUE OF TEXTURE 1. The importance of texture to the f o r e s t i n t e r p r e t e r . The t e x t u r e i s the frequency of tone change w i t h i n the image. I t s components are s i z e , shape, tone and d i s t r i b u t i o n of u n i t f e a t u r e s across the image. I t i s described i n terms such as smoothness, f i n e n e s s or roughness. The r o l e played by texture i s very important I n f o r e s t type mapping. For example, water w i t h a f l a t surface on a calm day w i l l - 59 -appear w i t h a smooth t e x t u r e . * F u l l y stocked young stands, becuase of t h e i r s i m i l a r crown s i z e and small s i z e of image d e t a i l s , w i l l show as a f i n e l y t e xtured p o r t i o n of a photograph. Old growth, which has many l a r g e r d e t a i l s , w i l l appear coarse. 2. Factors i n f l u e n c i n g t e x t u r e . Components of te x t u r e vary w i d e l y i n s i z e . I f the components are r e l a t i v e l y s m a l l , texture w i l l appear f i n e . When fine n e s s i s reduced to the p o i n t where the d e t a i l s are so minute t h a t they are not d i s c e r n i b l e any more, the e f f e c t i s smooth t e x t u r e . With l a r g e r d e t a i l s , r e f l e c t i n g more l i g h t than s m a l l e r , the minute changes i n tone w i l l be more frequent and consequently the te x t u r e w i l l appear rough or coarse. The images of f o r e s t stands and other o b j e c t s can be used to i l l u s t r a t e the cl a s s e s of t e x t u r e . The image of a very young timber stand has a f i n e t e x t u r e . The component t r e e s of such a stand are so small t h a t l i g h t r e f l e c t e d by each tre e i s not v i s i b l e on photographs. A combination of many such small stand components l o c a t e d side by s i d e , produces a f i n e t e x t u r e . Mature timber stands, on the other hand, have l a r g e components, which i n c l u d e : t h i c k branches of the t r e e s , i r r e g u l a r crown shapes, and frequent openings i n crown canopy, a l l of which are l a r g e enough f o r p a r t s of the stand to be r e g i s t e r e d on f i l m as i n d i v i d u a l images, thereby causing coarse t e x t u r e . * I t might be w e l l to remember t h a t the word \" t e x t u r a \" o r i g i n a l l y comes from the L a t i n verb \"to weave\". - 6o -Every component of such a stand i s l a r g e enough to r e f l e c t enough l i g h t to the camera to be r e g i s t e r e d on l i g h t , s e n s i t i v e m a t e r i a l s o l e l y as an image of an o b j e c t . In subjects such as a lawn, a f i e l d or very young t r e e s , d e t a i l s of such objects are so small or \" f i n e \" on o r d i n a r y photographs t h a t the f i l m cannot reproduce any of the minute d e t a i l s . The t e xture of an image may be c o n t r o l l e d by the s i z e of grains i n the emulsion on l i g h t , s e n s i t i v e photographic m a t e r i a l . The smaller the grains i n emulsion are, the more s e n s i t i v e i s the f i l m , the more d e t a i l s of an image w i l l be r e g i s t e r e d , and the coarser the te x t u r e w i l l be. Ge n e r a l l y , where the a l t e r a t i o n of l i g h t and dark tones i s frequent, the texture on photographs r e g i s t e r s rough and coarse. 3. The texture of i n d i v i d u a l t r e e crowns. The texture p a t t e r n formed by i n d i v i d u a l t r e e crowns can be recognized. Texture of tree crowns on photographs can be described as the arrangement of the h i g h l i g h t s and shadows and the r e l a t i v e amounts of each. A f i f t y - f i f t y d i v i s i o n of b l a c k s and whites i n extremely small u n i t s produces a v e r y f i n e t e x t u r e . G e n e r a l l y the l a r g e r and more i r r e g u l a r the u n i t s of b l a c k and white are, the coarser i s the t e x t u r e . The texture o f a t r e e i s the sum t o t a l of a l l f a c t o r s t h a t cause t e x t u r e , such as c o l o u r , shape, age, spacing between the branches - 61 -and whorls, q u a l i t y of f o l i a g e and general d e n s i t y of the crown. Colour. The colour of a t r e e i s an i n d i r e c t f a c t o r of t r e e - t e x t u r e , because as such i t can be e i t h e r dark or l i g h t i n tone, due to the colour and nature of s u r f a c e , e t c . , of p l a n t s being photographed. Trees are u s u a l l y l i g h t e r i n colour i n the springtime. Shape. Shape i s an important f a c t o r i n texture o f i n d i v i d u a l t r e e crowns. On spiked and i r r e g u l a r crowns the l o c a t i o n of branches i s always v i s i b l e unless the s c a l e i s very s m a l l . The r e g i s t r a t i o n of i n d i v i d u a l branches on the f i l m makes the texture coarse. The s i t u a t i o n i s much d i f f e r e n t i n the case of tre e s w i t h a r e g u l a r , rounded shape. The branches on such tr e e s are l o c a t e d on the trunk i n a p a t t e r n to o b t a i n more s u n l i g h t , f o r which the rounded shape has proved to be the optimum form. Spaces between the secondary branches are occupied w i t h dense l e a f f o l i a g e . The te x t u r e of such tre e s w i l l always be f i n e , unless the leaves are bunchy, as i n oaks, which appear w i t h coarse t e x t u r e . S i z e . A group of l a r g e objects r e f l e c t s more l i g h t to the camera, causing more i r r e g u l a r b l a c k and white u n i t s , t h a n a group of small o b j e c t s . The te x t u r e of l a r g e tree-crown objects w i l l appear rougher than t h a t of s m a l l o b j e c t s . - 62 -Age. I t i s w e l l known i n forestry that the crown shape of a tree changes with age. Since the eff e c t of age involves the change of spacing between the branches and whorls themselves, these factors w i l l be discussed here. From the viewpoint of texture, the eff e c t of age i s most important when the tree approaches maturity, because t h i s i s the period when i t s crown becomes i r r e g u l a r . By slackening of the v i t a l processes of the tree, some of the whorls having accomplished t h e i r function become useless to the tree and die. I r r e g u l a r i t y i s e a s i l y v i s i b l e on mature western hemlock and even more def i n i t e on mature Douglas f i r , where branches may form patches on the trunk, with large gaps between them (Fig. 2 j and Appendix I n.o.). The texture of such trees w i l l appear extremely coarse on photos. In the case of mature western red cedar, where the whorls are not d i s t i n c t , the eff e c t of maturity shows up i n enlarging of distances between the branches and i n size of the branches with dead top, s t i c k i n g up l i k e a sharp s t i c k (Appendix I I I f ) . These natural factors cause i r r e g u l a r i t i e s i n crown and coarser texture on photographs, independently of the kind of f i l m , paper and f i n i s h i n g . I t i s worthwhile to mention also that the changes i n crown shape are di f f e r e n t i n various parts of the crown. The lowest portion of the crown usually changes i n a much di f f e r e n t way than the middle portion. The sharpest differences i n change are between the upper and lower portions of the crown. Because of these above-mentioned reasons, a thorough examination of changes i n shape cannot be li m i t e d just to - 63 -one p o r t i o n of the crown, but must be extended to the whole, i t i s p a r t i c u l a r l y important when the t r e e s are examined from d i f f e r e n t views. I f the t r e e i s examined from a v e r t i c a l view, the changes i n a l l three p o r t i o n s of the crown are e q u a l l y important i n c o n t r o l of t e x t u r e . Q u a l i t y of f o l i a g e and general d e n s i t y of the crown. I t can be s t a t e d g e n e r a l l y t h a t the denser the crown, the f i n e r i t s t e x t u r e w i l l appear on a photograph. The general d e n s i t y of the crown i s i n f l u e n c e d by the q u a l i t y of the f o l i a g e . At f i r s t i t would seem t h a t c o n i f e r s , having denser f o l i a g e and smaller leaves than deciduous t r e e s , would have f i n e r t e x t u r e on photos than deciduous t r e e s w i t h broad l e a v e s , which may r e f l e c t enough l i g h t to be r e g i s t e r e d i n d i v i d u a l l y . The t e x t u r e i n the case of c o n i f e r s w i l l be determined mainly by s i z e of the branches and j u s t s e c o n d a r i l y by the s i z e of the leaves and d e n s i t y of f o l i a g e , because the leaves are i n any case so s m a l l t h a t they cannot be r e s o l v e d a t a l l . Since the branches are r e l a t i v e l y l a r g e r o b j e c t s than the l e a v e s , the t e x t u r e of c o n i f e r s w i l l be coarser. In the case of deciduous s p e c i e s , on the other hand, desp i t e t h e i r b i g g e r l e a v e s , the t e x t u r e w i l l be f i n e r because the broad leaves of these species are h i d i n g the more or l e s s t h i c k branches of the t r e e , and the t e x t u r e i s determined by l e a v e s . The amount of l i g h t r e f l e c t e d to the camera-by broad leaves i s undoubtedly l a r g e r than t h a t by needle leaves of c o n i f e r s . However, these cannot be r e s o l v e d i n d i v i d -u a l l y , because most of the r e f l e c t e d l i g h t i s i n d i r e c t because of - 6h -the l a r g e v a r i e t i e s of angles w i t h which the leaves hang on the twi g s , and the s i z e of the leaves which are not l a r g e enough to be r e s o l v e d even on l a r g e s c a l e photos. h. Texture of stands of t r e e s . The d i f f e r e n c e i n te x t u r e o f a mixed stand i s very h e l p f u l i n r e c o g n i t i o n of the species forming the stand i t s e l f . S i n g l e t r e e s may have a p e c u l i a r crown t e x t u r e , but they are extremely d i f f i c u l t to recognize i n mixed stands, unless the scale i s l a r g e . The t e x t u r e of a stand i s i n f l u e n c e d by almost the same f a c t o r s as the te x t u r e of i n d i v i d u a l t r e e s : shape, age ( i n c l u d i n g s i z e of tre e s and spacing between tre e s w i t h i n the stand), and f o l i a g e . Shape. The shapes of crowns have a great i n f l u e n c e on the stand t e x t u r e . Since the a e r i a l p i c t u r e s are studi e d i n s t e r e o s c o p i c p a i r s the crown shape i s more or l e s s apparent. Most of the c o n i f e r s , e s p e c i a l l y the spruces and f i r s , have c o n i c a l crowns, which are u s u a l l y easy to recognize, as such. Trees w i t h crown shapes narrowing upward form a dense stand canopy i n lower p o r t i o n s of the crown, but between the upper p o r t i o n of t h e i r crowns, the space i s more extended. The tex t u r e of such stands may appear coarse. Deciduous t r e e s , on the other hand, u s u a l l y have rounded crown shapes. The space u t i l i z a t i o n of round objects i s always b e t t e r than t h a t of c o n i c a l , t h e r e f o r e there w i l l be l e s s space u t i l i z e d - 65 -(shadow spaces) hy a canopy of round t r e e s than by one of t r e e s having a c o n i c a l shape. Despite the f a c t t h a t the. c o n i f e r s form a denser stand than deciduous t r e e s , the t e x t u r e of the l a t t e r w i l l be f i n e r . G e n e r a l l y the more compact the crowns are the more even the te x t u r e w i l l be. Age. As has been mentioned b e f o r e , the e f f e c t of age as such i s the most important f a c t o r i n c o n t r o l l i n g t e x t u r e , not only of the i n d i v i d u a l t r e e s , but a l s o of the stand. Throughout the stand's l i f e , changes are produced i n the stand s t r u c t u r e i t s e l f . The e f f e c t shows up f i r s t of a l l i n e n l a r g i n g of the whole t r e e as the major component of the stand. Bulky i r r e g u l a r crowns w i t h large branches are the b a s i c f a c t o r s i n change of t e x t u r e . There i s , however, another f a c t o r which i s s t i l l more important than the s i z e of the t r e e s , from the viewpoint of the stand t e x t u r e - - t h e spacing between t r e e s themselves. The spacing of the i n d i v i d u a l p l a n t s i s the c h i e f f a c t o r t h a t produces t e x t u r e of a stand on a photograph. The competition among the t r e e s r e s u l t s i n overgrowth i n a f o r e s t stand. The fast e r - g r o w i n g t r e e s , over-growing the s m a l l e r , slower-growing ones, k i l l the weaker i n d i v i d u a l s , c r e a t i n g an increased growing space f o r each t r e e . The remaining t r e e s are i n some cases so wide l y s c a t t e r e d t h a t they appear on a e r i a l photographs as i n d i v i d u a l t r e e s . Only some s o - c a l l e d h e a v i l y timbered stands show up w i t h con-tinuous stand t e x t u r e . G e n e r a l l y , the more i n t o l e r a n t the t r e e s are, the more s c a t t e r e d and more upon the crowns, and the l a r g e r and more i r r e g u l a r - 66 -the shadow places a r e , the coarser the t e x t u r e of the stand w i l l be. F o l i a g e . Deciduous stands, having denser f o l i a g e covering the la r g e components of the t r e e s , w i l l appear on summer photos w i t h f i n e r t e x t u r e than t h a t of c o n i f e r s . Most of the stands of deciduous species i n t h e i r o l d age are never as i r r e g u l a r e i t h e r i n shape or i n spacing as the c o n i f e r s , which i s another c h i e f reason f o r t h e i r f i n e r stand t e x t u r e . The f i n e r t e x t u r e of these stands i s the second most important f a c t o r a f t e r tone i n d i f f e r e n t i a t i n g the two kinds of stands. 5. Measurement of t e x t u r e : Texture i s very commonly used as a d i s t i n g u i s h i n g c h a r a c t e r i s t i c i n r e c o g n i t i o n keys. When f i n e ' p a t t e r n s such as t e x t u r e s are being considered, i t i s w e l l t o remember t h a t t e x t i l e s might very w e l l be used when seeking t o define d i f f e r e n t types of t e x t u r e and t o place them on some k i n d of b a s i s where the meaning would be c l e a r t o everyone. The use of such a scale would be a great help i n hands of p h o t o - i n t e r p r e t e r s , because the t e x t u r e of sp e c i e s , j u s t l i k e the tone, i s named by words i n keys. I t o f t e n happens t h a t what i s a f i n e t e x t u r e t o one observer would not n e c e s s a r i l y be so recognized by a second observer. I n connection w i t h t h i s t h e r e f o r e , a set of t e x t i l e s d i s t r i b u t e d by the C o t t o n - T e x t i l e I n s t i t u t e has been used as a standard so t h a t when any t e x t u r e i s encountered, there i s a t e x t i l e which can be used t o match i t . When i t i s s a i d t h a t c e r t a i n vegetation'resembles \" c h e n i l l e \" * (or any other * \" C h e n i l l e \" i s a t u f t e d cord f o r embroidery. - 67 -f a b r i c ) , the t e x t u r e on the photograph i s being r e f e r r e d t o a standard term set up by t h i s I n s t i t u t e ( O ' N e i l , 1953)-Sandpaper as another instance w i l l give a s o r t of t e x t u r e appearance on a photograph. Cottage cheese and many other t h i n g s are suggested by d i f f e r e n t authors as the standards of t e x t u r e s , but they are not w e l l standardized. They have not been used as a i d s i n photo-i n t e r p r e t a t i o n , w i t h the exception of sandpaper and the t e x t i l e . There are many d i f f e r e n t sandpapers w i t h d i f f e r e n t grades of sands and i t i s p o s s i b l e t o f i n d among them t e x t u r e s c l o s e l y resembling v e g e t a t i o n or c u l t i v a t e d f i e l d s as shown on a e r i a l photographs. The use of t e x t i l e s and sandpaper f o r the stand t e x t u r e measurements, however, has many weaknesses. T e x t i l e s are made of e n t i r e l y d i f f e r e n t m a t e r i a l s than photos, and sandpaper appears com-p l e t e l y d i f f e r e n t than the stands on photographs. Both f a c t o r s may e a s i l y be a source of m i s i n t e r p r e t a t i o n . They are a l s o inconvenient t o use, thus n e i t h e r of these standards i s used i n a e r i a l photo i n t e r p r e t a t i o n . C o l w e l l (1952) suggested c u t t i n g out a p a r t from a photo appearing w i t h d i f f e r e n t t e x t u r e d f o r e s t stands and us i n g t h i s as a standardized scale f o r measurement of stand t e x t u r e ( F i g . 6 ) . The scal e s of t e x t u r e would not be named by words, but numbered, and t h i s number would represent the t e x t u r e of the stand. - 68 -Figure 6. Texture Scale. In addition to Colwell's suggestion the present writer would advise that i t may be useful also to work out a similar type of texture scale for each scale of photos that are most widely used i n the f i e l d of forestry, because i t may happen that the stand which i s represented by texture scale No. 10 would have a f i n e r texture on a smaller scale photograph, and could match with the number of another f i n e r scale. I t i s obvious that stands represented on texture scale No. are not i n the same condition as stands represented by No. 10. The use of such a texture scale would give us the same scale of texture f o r a very young and very old stand on two different scales of photos. Such a change would make the texture scale available f o r wider application such as for measuring textures of indi v i d u a l tree crowns, etc., and certainly would give the true representation of the stand. k. Changes i n texture of Douglas f i r , western hemlock and western red cedar caused by d i f f e r e n t scale of photos. During the examination of changes i n texture of different species on various scale of photos, i t has been found that differences i n texture were caused not only by the previously described reasons, but by the scale also, which was found to be one of the most important - 69 -factors i n con t r o l l i n g of texture. The changes i n texture were studied on the same f i v e kinds of photos, discussed on page 15. During the survey, 20 Douglas f i r , 20 western hemlock and 20 western red cedar trees were examined. Ten of each of these species were young growth and ten, old growth. Instead of numbers on a texture scale, words have been used f o r the texture c l a s s i f i c a t i o n s such as Rough, Coarse, Fine, etc., which represent numbers on the texture scale, as follows: 1-2 Fine (F) 3-k Medium fine (MF) 5-6 Medium (M) 7-8 Coarse (C) \u00E2\u0080\u00A2 9-10 Rough (R) The re s u l t s of the survey are given i n Tables 27, 28 and 29-Examining Table 27 i t can be realized that changes i n texture of young Douglas f i r trees are caused mainly by decrease of photo scale. As the scale of photos i s decreased, the texture i s changed from Rough (R) to Fine ( F ) , and respectively f o r old growth. The change i n texture of young western hemlock i s almost i d e n t i c a l to young Douglas f i r . A s l i g h t change may be observed from the figures. Douglas f i r trees appear with f i n e r texture than that of western hemlock trees. Unfortunately, the ranges i n texture i n many cases overlap, just as t h e i r tone ranges overlap. However, overlapping - TO -occurs less often i n texture than i n tone i n these two species. Changes i n texture of young and old western red cedar trees show up most d i s t i n c t l y . These may be explained by different foliage and different changes i n shape and crown structure of cedar i n comparison with Douglas f i r and hemlock than that of the two previous species. Generally, as the photographic scale progressively diminishas, texture of a given object becomes progressively f i n e r and eventually disappears. Table ZJ. Changes i n texture of Douglas f i r on different scales of photographs. Photo ' T e x t u r e s c a 1 e scale R C M MF F Percent of trees i n texture class Y 0 .u ;n g g r 0 w t h 330 f t / i n . TO 10 20 _ -729 40 30 30 - -1,200 40 30 20 - 10 1,500 - 40 30 20 10 2,400 \" - 10 20 60 10 0 1 d g r o w t h 1,200 f t / i n . 20 80 _ 1,500 - - - 20 80 2,400 \" - - - - 100 - 71 -Table 28. Changes i n t e x t u r e of western hemlock on d i f f e r e n t s c a l e s of photographs. Photo T e X t u r e s c a 1 e S CQ-ls R C M M F F Percent of t r e e s i n tex t u r e c l a s s Y o u n g g r o w t h 330 f t / i n . 6o 20 20 - -720 i i 50 30 20 - -1,200 1! - 20 50 30 -1,500 It - 30 20 50 -2,400 1! - - 20 30 50 0 I d g r o w t h 330 f t / i n . 6o 30 10 _ _ 720 n 50 30 20 - -1,200 i t - 70 20 10 -1,500 - 10 80 10 -2,400 M - - - 10 90 Table 29. Changes i n t e x t u r e of western red cedar on d i f f e r e n t s c a l e s of photographs. Photo T e x t u r e s c a 1 e scale R C M M F F \u00E2\u0080\u00A2 Percent of t r e e s i n te x t u r e c l a s s Y o u n g g r 0 w t h 330 f t / i n . - 60 - 30 10 720 11 - 20 80 - -1,200 t i - - 20 70 ' 10 1,500 11 - - 20 30 50 2,400 11 - - - 10 90 0 1 a g r 0 w t h 330 f t / i n . 4o 30 30 _ _ 720 n 30 50 30 4o -1,200 11 - - 60 20 20 1,500 11 - - - 70 30 2,400 11 - - - 10 90 - 72 -VALUE OF FILM AND FILTERS Films F i l m consists of two parts; the f i l m base or support, and a l i g h t , sensitive layer, c a l l e d the emulsion. The emulsion consists of two parts: the l i g h t , sensitive s i l v e r compound ca l l e d grains, and a gelatin base. The smaller the grains, the greater the s e n s i t i v i t y of the f i l m . The greater i n t e n s i t y of exposure by l i g h t reaching the c r y s t a l s , the darker w i l l be the portion of the f i l m . S i l v e r crystals which are not struck by l i g h t remain undevelopable and w i l l be transparent after processing. The degree of darkening i s dependent upon the density of l i g h t . The higher the density, the darker the f i l m . There are two types of film s used i n forest photogrammetry, black and white and colour f i l m . Because of t h e i r expense and weak s e n s i t i v i t y , colour f i l m s are not used intensively, although species i d e n t i f i c a t i o n might be made with a higher degree of accuracy than on black and white f i l m s . The s e n s i t i v i t y of black and white fi l m s i s different f o r different colour parts of the v i s i b l e spectrum. The v i s i b l e colour spectrum consists of the following colours: V i o l e t kOO - kh6 millimicron Blue kk6 - 500 \" Green 500 - 578 \" Yellow 578 - 592 Orange 592 - 620 \" Red 620 - 700 - 73 -The forest plants r e f l e c t the green colour (500-578 millimicron) and those colours which are over the v i s i b l e spectrum. According to t h e i r s e n s i t i v i t y , there are three types of black and white f i l m s : ortho-chromatic, panchromatic and infra-red. 1. Orthochromatic f i l m . Orthochromatic f i l m i s designed to record tone values corresponding to tones of nature. In practice i t i s used to designate a f i l m sensitive to blue and green, but not to red l i g h t . The f i l m i s sensitive to l i g h t s with a wave length of 560 millimicrons (Fig. JA) , with l i m i t s of s e n s i t i v i t y at klO - 590 millimicrons. Since the most forest d e t a i l s are green i n colour, orthochromatic films may be very useful i n tree species i d e n t i f i c a t i o n within a special circumstance. Despite t h i s , orthochromatic f i l m s are not used widely i n forestry i n comparison to panchromatic or infra-red f i l m , therefore they are discussed only b r i e f l y . 2. Panchromatic f i l m . a. S e n s i t i v i t y and use of the f i l m . The panchromatic fi l m s have been used i n photogrammetry only since 1939- They are sensitive to almost a l l colours of the v i s i b l e spectrum from wavelength 415-665 millimicrons (Fig. 7B), including orange and red i n addition to those colours recorded on orthochromatic f i l m . This kind of f i l m produces a picture i n black and white which appears normal to human eyes. The human eye distinguishes one colour from another, p a r t l y because some colours are brighter than others, some present more contrast, some may be illuminated more than others, and some d i f f e r i n degree of saturation. Various photographic fi l m s react somewhat s i m i l a r l y i n being not equally sensitive to a l l colours. To follow page 73 A S e n s i t i v i t y c u r v e o f o r t h o c h r o m a t i c f i l m a\u00C2\u00BB to 4x10\" 5 cms 5 6 Wave Length (cm) CO c 0 CO B S e n s i t i v i t y c u r v e o f p a n c h r o m a t i c f i l m 4xl0\"5 cms 5 6 Wave Length (cm) c CD CO C S e n s i t i v i t y c u r v e o f i n f r a - r e d f i l m 4xl0\" 5 cms 5 > 6 7 Wave Length (cm) 8 F i g - 7 S e n s i t i v i t y c u r v e s o f v a r i o u s t y p e s o f f i l m - Ik -The panchromatic f i l m comes as near as possible to responding to a l l colours that can be seen by human eyes. I t i s used i n a l l black and white photography when correct tone rendering i s desired. Most of the forest a e r i a l photographs are made with panchromatic f i l m . The f i l m contains smaller grains and therefore i s more sensitive than orthochromatic. I t s s e n s i t i v i t y i s about twice as f a s t as that of infra-red films (Schulte, 1951)- The maximum of i t s s e n s i t i v i t y curve i s at 635 millimicrons, which shows that i t i s very sensitive to red l i g h t . I t s higher s e n s i t i v i t y permits shorter exposures f o r the longer penetrating red wave lengths at high a l t i t u d e s . Advantage of panchromatic fi l m s with respect to illumination i s i t s a b i l i t y to use reflected blue sky l i g h t . The haze, however, i s the greatest disadvantage i n the use of panchromatic f i l m s . This d e f i n i t e l y l i m i t s the time when panchromatic f i l m can be used. b. Tone and texture of vegetation on panchromatic f i l m s . The photo-interpreter r e l i e s to some extent on the tone when recognition of species i s required. The eye can detect tone differences of no less than two percent on panchromatic f i l m s , but actually four percent i s more p r a c t i c a l i n recognizing trees (See page 50). During the summer, the leaves have more shades of green, varying from l i g h t to dark green, s i l v e r y , whitish, yellowish, or olive green. The s e n s i t i v i t y of panchromatic f i l m to the very closely related wave lengths of these shades i s unfortunately not very selective. The shades of green f o r a given species are rather constant, but with just enough va r i a t i o n to make the application of tone d i f f i c u l t as a r e l i a b l e - 75 -factor i n species i d e n t i f i c a t i o n . However, the over-exposure of hard-woods and under-exposure of conifers i s advantageous on panchromatic f i l m s , whereas i t i s disadvantageous on infra-red f i l m s , as i t causes loss of photographic d e t a i l s . Differences i n exposure may produce tonal contrasts which readily permit the photo separation of hardwoods from conifers. Generally, panchromatic f i l m gives better d e t a i l f o r low shrubby areas, grasses, rocks, s o i l s , etc., and the density of a forest also can be estimated more accurately, than on the two above mentioned ones. The texture of an object on a panchromatic f i l m i s more d i s t i n c t i n some respects than that given by infra-red or orthochromatic photographs. The differences are due to the fact that panchromatic f i l m i s not as contrasting as the forementioned ones. Panchromatic fil m s give more d e t a i l ; the larger the scale of the photographs, the more the det a i l s can be resolved, which i s a great advantage i n forest species interpretation. 3. Infra-red f i l m a. S e n s i t i v i t y and use of the f i l m . Before evaluating a e r i a l infra-red photography f o r the i d e n t i f i c a t i o n of plants, some fundamental points should be considered, regarding the nature of infra-red photography. Infra-red f i l m records radiations which are beyond the v i s i b l e spectrum. The average human eye i s sensitive, as i t has been mentioned above, to wave lengths i n the range from kOO to 700 millimicrons, which form the v i s i b l e spectrum. The Commercial type of i n f r a red f i l m used i n a e r i a l photography i s - 76 -sensitized between 4 l9 - 510 millimicron and 668 - 850 millimicron (Fig. 70). Infra-red wave lengths are not v i s i b l e to the human eye, and i t therefore\u00E2\u0080\u00A2cannot be shown by inspection how a given object w i l l be recorded on infra-red photographs. Techniques of using infra-red films do not d i f f e r from that of ordinary panchromatic and orthochromatic f i l m s . Two important modifications, however, must be s a t i s f i e d . The f i r s t i s that a corrected lens must be used. The lenses i n cameras using panchromatic f i l m are corrected so that wave-lengths i n the v i o l e t and yellow are both i n focus i n the same plane. I f the camera i s not equipped with a s p e c i a l l y corrected lens f o r use with infra-red f i l m , an acceptable p r a c t i c a l correction can be made by changing the f o c a l length about one percent (Spurr, 1949). The second modification i s the use of various f i l t e r s i f only infra-red radiations are required to be recorded, as infra-red f i l m i s sensitive not only to infra-red but also to v i o l e t , u l t r a v i o l e t and blue wave-lengths. In order to insure the transmission of only i n f r a -red waves through lenses, f i l t e r s are used to absorb the undesirable v i s i b l e and non-visible l i g h t s (Clark, 19^7). One of the chief d i f f i c u l t i e s i n obtaining good a e r i a l photographs by means of colour or other black and white photography 'is the haze i n the atmosphere. I t has been found that infra-red wave-lengths penetrate t h i n haze. Infra-red photographs can be taken s a t i s f a c t o r i l y when the haze i s too thick f o r panchromatic photography. Dense haze or fog, however, cannot be penetrated even by infra-red photography. Harrison (19 -^6 ) found that i f the haze i s so dense that - 77 -the v i s u a l range i s less than one-third of a mile, no satisfactory results can be expected beyond the l i m i t of infra-red photography. Hulburt (1935) made a series of photographs to determine whether objects could be photographed through fog by infra-red from a greater distance. His results showed that i t i s d i f f i c u l t to estimate v i s u a l l y the distance which infra-red w i l l penetrate. Generally the better the v i s u a l sight, the better the extent to which penetration can be increased by the use of infra-red f i l m . The chief disadvantage of infra-red f i l m i s that when the trees of a forest stand are i n the shadow of a h i l l or i n a dense stand, the shadow pattern and the crown form of i n d i v i d u a l trees cannot be seen. The most important use of t h i s f i l m i s i n s o i l mapping. Since water absorbs infra-red l i g h t waves, i t appears black on infra-red f i l m s . The more water i n the s o i l , the darker w i l l be i t s tone on a photograph. Because water greatly influences the quality of s o i l s , infra-red f i l m s are very useful i n s o i l mapping. b. Tone and texture of vegetation. One of the most important differences between infra-red and other black and white photography i s that the chlorophyll, the p r i n c i p a l colour substance i n the foliage of tree species, has a very high transparency i n infra-red and that infra-red radiation i s therefore ref l e c t e d by the leaf tissues instead of being absorbed by the chlorophyll (Clark, 1947). Infra-red radiations r e f l e c t e d by the leaf tissues registers i n l i g h t tones therefore, and foliages which absorb infra-red - 78 -l i g h t w i l l r egister i n dark tone on infra-red photographs. Generally, conifers register i n dark tones and deciduous trees register i n l i g h t tones. Certain types of vegetation r e f l e c t infra-red l i g h t better than others. Ives (1939) investigating the use of infra-red films for ecological surveys found that healthy grasses and immature trees were better r e f l e c t o r s than drying grasses and mature trees. An old tree appears darker on infra-red f i l m than a younger, assuming that they are of the same species, because i t has a more irreg u l a r crown which absorbs more infra-red l i g h t . Many f i l t e r s were used to experiment with infra-red f i l m to improve the tones by decreasing the contrast. I t has been found that most tonal variations between trees and other vegetation can be detected with infra-red f i l m s , i f they are used with minus blue f i l t e r . As a r e s u l t , the contrasts are softened so that thh deciduous trees, instead of appearing very l i g h t , display s l i g h t l y d i f f e r i n g tones of l i g h t grey. The conifers, instead of appearing black, display varying tones of dark grey to black. Sonley (19^6) reported that i n his Canadian tests infra-red with a minus blue f i l t e r produced more contrast than the red f i l t e r . This i s contrary to the results of other researchers i n the U.S. and also contrary to what he expected. At present, most of the infra-red f i l m s are used together with minus blue f i l t e r . The tone of Douglas f i r , western hemlock and western red cedar appears on infra-red photos with less v a r i a t i o n than on panchromatic photos, which i s due to the nature of the f i l m and minus blue f i l t e r . - 79 -Changes i n tone of Douglas f i r and western hemlock are varying between Medium and Medium Light, whereas that of western red cedar varies between Medium and Light ranges of the tone scale. Unfortunately, thorough study i n changes of tone of these species could not be made, because of lack of infra-red photographs. h. Colour f i l m s . a. S e n s i t i v i t y and use of the f i l m . In a l l of the f i e l d s of forest photogrammetry, conventional black and white photography has been applied with a f u l l scale. Application of a e r i a l colour photography, however, i s s t i l l very l i m i t e d . Although a e r i a l colour photography has proved by i t s unique q u a l i t i e s to be of superior value i n such f i e l d s as photo interpretation, reconnaissance, and management planning, i t i s not used as extensively as the black and white. Since World War I I , the quality of a e r i a l colour f i l m s has been improved constantly i n i t s colour f i d e l i t y , colour balance, s e n s i t i v i t y and fineness of grains. Many new colour films have also been developed. The most common colour fi l m s used i n the United States and Canada are Kodak Ektachrome Aero, Kodak Ektachrome Camouflage Detection, Kodak Aero Ektacolor, Anscochrome and Super Anscochrome. European colour f i l m s used in a e r i a l photography are: Agfacolor, Gevacolor and Ferranicolor. Colour f i l m s are sensitized to wave lengths not only i n the 400-500 millimicron band of the v i s i b l e spectrum, but also to larger wave lengths. They reproduce a l l the colours more or less f a i t h f u l l y as - 80 -the eye sees them. The colour f i l m l a c k s the g r a i n s of the \"black and white f i l m s . The absence of s i l v e r permits greater m a g n i f i c a t i o n s w i t h -out i n t e r f e r e n c e of g r a i n . Colour photography has inherent advantages over b l a c k and white, p a r t i c u l a r l y i n a p p l i c a t i o n s where p h o t o - i n t e r p r e t a t i o n i s dependent upon t r u e colour r e n d i t i o n . In b l a c k and white photography, the l i m i t a t i o n inherent i n reproduction of only monochromatic gray tones can be only p a r t l y overcome by s p e c i f i c f i l m and f i l t e r combinations t h a t increase t o n a l c o n t r a s t between t r e e species. b. Tone of v e g e t a t i o n on colour photographs. Colour photographs tend t o r e c o r d v e g e t a t i o n as i t n a t u r a l l y appears. This advantage i s very important when the d i f f e r e n t c o l o u rs recorded on the photographs can be a s s o c i a t e d w i t h d i f f e r e n t species. I d e n t i f i c a t i o n of t r e e species, f o r e s t and other v e g e t a t i o n types based upon co l o u r d i f f e r e n c e s o f f e r great p o s s i b i l i t i e s on good q u a l i t y c olour photos. With b l a c k and white photography, such d i s t i n c t i o n i s o f t e n ex-ceedingly d i f f i c u l t . Modern colour f i l m s are capable of rendering even f a i n t hues, making the i d e n t i f i c a t i o n of t r e e species more r e l i a b l e and e f f i c i e n t . Unfortunately, these modern colour f i l m s are very expensive, and t h e r e f o r e can h a r d l y be used i n p r a c t i c e economically. Changes i n f o l i a g e r e f l e c t i v i t y w i t h seasons of the year can be advantageously used f o r d i s t i n c t i o n between t r e e species. Perhaps the greatest advantage of colour photography l i e s i n i t s use f o r s p r i n g and autumn f o l i a g e . However, as f o r any photography of v e g e t a t i o n undergoing - 81 -seasonal changes, the time and place are usually very l i m i t e d , especially when the uneven rates of colour change and the number of f a i r days for photography are considered. The disadvantages of colour photography i n comparison to black and white may be pointed out as follows: i Colour photography i s expensive. Wear and Dilworth (1955) re-ported a 20$ higher direct cost for colour photography than for similar black and white photography. i i Black and white films can be manufactured with both stable and uniform c h a r a c t e r i s t i c s . At present, colour films are s t i l l far from uniform. Colour balance and quality are the result of a complex interaction between the three emulsions that d i f f e r s l i g h t l y from one l o t to another. V a r i a b i l i t y of f i l m emulsions i s one of the main reasons why a e r i a l photo -graphy has achieved varying degrees of success or f a i l u r e . Under and over exposures w i l l affect the colour balance and the quality of colour photos considerably. i i i The problem of haze i s much greater for colour photography than for black and white. Weather l i m i t a t i o n s are also greater, and the chances of satisfactory results are never too good. i v Colour films are generally considered to be much slower i n s e n s i t i v i t y than comparable black and white f i l m s , p a r t i c u l a r l y i f they are used with correcting f i l t e r s . - 82 -v Colour f i l m s are more s a t i s f a c t o r y i f they are used as t r a n s -p arencies. S p e c i a l equipment i s needed when co l o u r transparen-cy i s stu d i e d , which creates problems i n f i e l d work. A study of changes of tone i n Douglas f i r , western hemlock and western red cedar could not he made w i t h i n the frame of t h i s work, because of l a c k of co l o u r photographs. F i l t e r s . F i l t e r s are a transparent m a t e r i a l used i n the o p t i c a l path of a camera l e n s t o absorb a c e r t a i n undesired p o r t i o n of the spectrum and prevent i t s reaching the s e n s i t i z e d photographic f i l m . F i l t e r s are us -u a l l y used i n photogrammetry t o minimize or cut out the b l u i s h haze gen-e r a l l y present i n the atmosphere, or t o accentuate t o n a l c o n t r a s t between d i f f e r e n t species and f o r e s t types. G e n e r a l l y , the choice of f i l t e r de -pends upon the amount of haze, the type of f i l m being used, and the de -s i r e d tone. The more blue l i g h t the f i l t e r cuts out, the b e t t e r w i l l be the haze p e n e t r a t i o n . Haze c o n s i s t s c h i e f l y of smoke, vapour and dust. To form a haze, these p a r t i c l e s must not exceed one micron i n diameter ( C l a r k , 19^7)\u00E2\u0080\u00A2 The e f f e c t of haze i s t h a t i t s c a t t e r s the blue l i g h t and thereby produces a blue-coloured haze. I n a e r i a l photography at 10,000 f e e t , haze can be con s i d e r a b l e , even though an observer on the ground does not perceive i t . Y ellow f i l t e r s are most commonly used i n f o r e s t photogrammetry w i t h orthochromatic, panchromatic and i n f r a - r e d f i l m s . Other c o l o u r s of f i l t e r s such as green and medium red are a l s o used w i t h b l a c k and white - 8 3 -f i l m . In order to reduce the effect of bl u i s h haze i n forest a e r i a l photography, panchromatic films are usually exposed through yellow f i l -t e r s . A l i g h t yellow f i l t e r , Wratten No. 3; cuts out most radiation shorter than ^50 m i l l i c r o n s . The medium yellow Wratten No. 12 (or min -us blue f i l t e r ) cuts out l i g h t shorter than 500 millimicrons, and the red Wratten 25 transmits l i g h t only longer than 58O millimicrons. Infra-red films are also exposed through f i l t e r s . There are various f i l t e r s used with infra-red f i l m s . The blue-green sensitive por-t i o n i s f i l t e r e d out with a medium red f i l t e r , Wratten No. 25. A \"deep\" red f i l t e r , Wratten No. 29, removes v i s i b l e red l i g h t below 680 m i l l i -microns. These f i l t e r s produce normal infra-red photography. Modified infra-red photography i s produced with the use of a l i g h t f i l t e r , which allows some blue-green l i g h t as well as the red i n infra-red radiation to reach the f i l m , giving normal tonal variations and cutting down the sharp contrast. On modified infra-red photographs the darkest and the l i g h t e s t trees can be registered with good d e t a i l s i n grey. I t i s achieved usually with medium yellow, Wratten No. 12 or min-us blue f i l t e r . Clark (19V7) S a v e a l i s t \u00C2\u00B0f s o m e f i f t y f i l t e r s that can be used with infra-red f i l m . A e r i a l colour photography also requires correcting f i l t e r s . The main function of a f i l t e r i s to improve the colour balance by afford-ing selective control of the wave-length admitted to sensitized emulsion layers. Becking (1959) recommended the use of two types of - Qk -f i l t e r s w i t h a e r i a l colour f i l m s , H F - f i l t e r s and E F - f l i t e r s . H F - f i l t e r s are used f o r haze c o r r e c t i o n , e s p e c i a l l y i f the photographs are taken from high a l t i t u d e , when the haze i n t e r f e r e n c e on the co l o u r balance i s very great. An orange or y e l l o w f i l t e r w i l l u s u a l l y compensate f o r the predominance of blue colour t h a t r e s u l t s from haze. The E F - f i l t e r s are used t o compensate d i f f e r e n c e s i n colour balance between f i l m l o t s . The proper E F - f i l t e r i s u s u a l l y s p e c i f i e d by the f i l m manufacturer. VALUE OF SEASON TO PHOTOGRAPHY The season of photography can g r e a t l y a f f e c t the value of photo-graphs f o r f o r e s t r y purposes, because of the nature of v a r i o u s t r e e spec-i e s . Deciduous species l o s e t h e i r f o l i a g e during the winter time, t h e r e -f o r e only the c o n i f e r s can be stu d i e d . In the s p r i n g and f a l l , t r e e f o l -iage changes i n colour and tone, w h i l e i n summer the f o l i a g e has normal c o l o u r . These f a c t o r s may determine the choice of f i l m and f i l t e r com-b i n a t i o n s used i n d i f f e r e n t seasons. a. Spring and f a l l photography The problems of s p r i n g and f a l l photography are the same. On photographs taken d u r i n g the s p r i n g or f a l l , deciduous t r e e s w i l l r eg -i s t e r w i t h l i g h t tone and conifer o u s w i t h dark tones. F o l i a g e of broad-l e a f t r e e s i s l i g h t yellow-green, while f o l i a g e of evergreen species i s dark green. This important f a c t helps us t o separate both of them e i t h e r i n pure or i n mixed stands. There are, however, some great drawbacks a l s o i n photography f o r both seasons. The sun i s h i g h i n the s p r i n g months, t h e r e f o r e i t - 85 -reduces the shade of i n d i v i d u a l t r e e s and thus decreases the use of some d e t a i l s produced \"by shade. The number of photographic days i s small i n both seasons. \" I f photographs are taken too e a r l y i n the f a l l some of the deciduous may not have changed t h e i r c o lour and may be confused w i t h evergreen. I f photographs are taken too l a t e other species may have l o s t t h e i r leaves and w i l l not be r e s o l v e d i n the photographs .. \" (Spurr, 1948) < S i m i l a r t r o u b l e s may occur i n springtime a l s o , because broad-l e a f species begin t o \"blossom at d i f f e r e n t times. The same species may r e g i s t e r on the same p i c t u r e w i t h e n t i r e l y d i f f e r e n t tones. For s p r i n g and f a l l photography, panchromatic f i l m s w i t h y e l l o w f i l t e r or co l o u r f i l m s are used. M o d i f i e d i n f r a - r e d technique w i l l a l s o give s a t i s f a c t o r y r e s u l t s . \"b. Summer photography Most f o r e s t photography i s c a r r i e d out during the summer, when f o l i a g e i s at normal c o l o r a t i o n . The number of f l y i n g days i s l a r g e r than In any other season and the p i c t u r e s c o n t a i n a maximum of i n f o r -mat i o n . A l l types of f i l m and f i l t e r s are used i n summer, \"but the most common ones are panchromatic f i l m s w i t h y e l l o w or green f i l t e r s . The former give a b e t t e r appearance and r e s o l u t i o n , and the l a t t e r give sharp c o n t r a s t . M o d i f i e d i n f r a - r e d f i l m s are used a l s o w i t h a great success. Summer photographs w i t h panchromatic f i l m s are o f t e n taken at summertime t o give an RF of 1 : 10,000. - 86 -c. Winter photography. The d i f f e r e n c e s between deciduous and coniferous t r e e s are the sharpest on p i c t u r e s made i n wi n t e r , t h e r e f o r e i t i s most o f t e n used i n separation of deciduous and evergreen stands. The p o s i t i o n of the sun i s low i n the sky i n w i n t e r , t h e r e f o r e the shadows are long, d i s t i n c t , and are a v a i l a b l e f o r accurate height determination by the shadow method. The great drawback of p i c t u r e s taken i n winter months i s t h a t the species i d e n t i f i c a t i o n of deciduous t r e e s i s very d i f f i c u l t . Where hardwoods and other deciduous species are common, and have r e a l economic importance, the winter photography must be considered. P i c t u r e s taken i n t h i s seas-on are most o f t e n used i n topographic mapping, because the topography and other d e t a i l s of the area can be seen w e l l through bare t r e e s . Orthochromatic, but mainly panchromatic f i l m s , a r e used f o r winter photography w i t h green or minus blue f i l t e r , producing a good t o n a l c o n t r a s t between species. - 87 -EVALUATION OF DIFFERENT PHOTO SCALES IN INTERPRETATION OF TREE SPECIES 1. Advantages and disadvantages of various scales i n species recognition. The scale of photography imposes one of the most serious l i m i t a t i o n s on the results to he obtained from any study. There i s no standard scale which w i l l s a t i s f y the many users of a e r i a l photography. There i s one basic fact only: i t i s impossible to have both a large area coverage and a large scale In the same single \"9 x 9\" p r i n t . Because of t h i s f a c t , a compromise i s necessary -- one must be adjusted or even s a c r i f i c e d at the expense of the other. A RF varying between 1 : 3,000 and 1 : 4,000 may be excellent f o r i d e n t i f i c a t i o n of minute d e t a i l s , such as the study of crown de t a i l s of a tree, or any other small part of an object. But such a scale i s f a r too large f o r general forestry purposes because the forest interpretations, including species i d e n t i f i c a t i o n , are contingent on the study of a l l parts of an area and not only on the minute d e t a i l s and the r e l a t i o n e x i s t i n g between them. Since large scale photos cover less area than smaller ones, the economic requirements are only accomplished with d i f f i c u l t y . Hence there i s required a great number of prints for area coverage, therefore the wide use of t h i s scale of photos for p r a c t i -c a l study of forest stands and i t s r e l a t i o n to the t e r r a i n are precluded. Mechanical d i f f i c u l t i e s are of considerable importance. Such items as re-cycle time of the camera, low a l t i t u d e , image motion, and shutter speed must be considered. The most important factor for i d e n t i f i c a t i o n of a tree on the large scale photos i s the texture (location and the arrangement of - 88 -the branches on the bole) rather than the tone or crown shape. The tone cannot be a r e l i a b l e recognition factor i n t h i s case, because the minute de t a i l s are so great that there may occur variations i n tone within one object, e.g., a tree. Neither can the shape of a tree be used e f f e c t i v e l y , because the interpreter sees the arrangements of the branches rather than the whole shape i t s e l f . In other words, the interpreter i s too close to the tree and therefore the enlarged branches of the tree hinder correct v i s i o n of the true crown shape. The application of these scales i s very l i m i t e d . Generally they are used only for study of very small d e t a i l s of an object f o r a special project. RF's varying between 1 : 7,000 and 1 : 9,000 provide an excellent working range for i d e n t i f i c a t i o n of Douglas f i r , western hemlock and western red cedar. Since the minute d e t a i l s are reduced the combina-t i o n of tone and texture can be applied with considerable r e l i a b i l i t y . Some minute d e t a i l s of a tree may be l o s t for intensive study, but the general arrangement of branches and density of the crown i s not influenced. The locations of branches i n most cases are s t i l l c l e a r l y v i s i b l e . The shape of the crown i s also better v i s u a l i z e d and can be applied more e f f e c t i v e l y i n recognition of a tree, since the branches are reduced and the tree i s seen from greater distance than i n smaller scale photos (provided that both photos were made with same focal-length camera). The impression of a form i s always better from a distance than from a point too close to the object. Good stereo r e l i e f representation and depth perception of the trees are e a s i l y possible, the photographic position as well as slopes can be evaluated, and therefore the tree can be much - 89 -more e a s i l y studied i n r e l a t i o n to i t s environment than on smaller scale photos. Information obtained from smaller scales i s more important i n species determination than the minute d e t a i l s obtained from large scales. The area coverage per p r i n t i s also greater (almost four times less photo prints are needed for coverage of the same area), therefore the number of prints required for general area coverage i s not considered excessive. RF's varying between 1 : 14,000 and 1 : l6 ,000 and beyond provide an excellent area coverage i n the broadest sense. Major physiographic d e t a i l s are e a s i l y seen, studied, and a l l o t t e d boundaries. Land forms can be delineated only when great contrast i n pattern occurs. Slopes associated with various land forms are not seen as e a s i l y as on 1 : 9,000 photos, and on very small scale photos, cannot be distinguished at a l l . The species i d e n t i f i c a t i o n on these photos i s very d i f f i c u l t or cannot be resolved on photos showing no differences i n recognition factors of species. Texture appears more or less equally fine for each species. Shape of crown cannot be distinguished because of excessive reduction i n size . The only applicable photo factor i s tone, which can be used only on that scale of photos. Mechanically they are easy to obtain; however, such factors as haze, crab and t i l t may become of great concern during the f l i g h t . 2. Test of best photo scale i n species recognition The value of scale i n i d e n t i f i c a t i o n of species was tested by an experiment. Three scales of photographs were tested. Photographs with large scale were 1 inch to 330 feet (RF 1 : 4,000); photos with medium scale 1 inch to 730 feet (RF 1 : 8,700 ) and f i n a l l y photos with small scales 1 inch to 1,500 feet (RF 1 : 16,000). - 90 -There were three interpreters. Interpreter A with almost no experience i n species interpretation, interpreter B, s l i g h t l y more experience, and interpreter C, had two years of experience i n the f i e l d of species i d e n t i f i c a t i o n . Ten Douglas f i r , ten western hemlock and ten western red cedar trees were examined. Every tree was studied i n d i v i d u a l l y and separately on each scale of photos which amounted to 90 steps to be i d e n t i f i e d . Results of th i s survey are shown i n Table 30, where the errors are expressed numerically and i n percentages for each scale of photos, then summarized i n d i v i d u a l l y by interpreters. I t can be seen i n Table 30 that fewer errors were committed on the medium scale ( l : 8,000) p r i n t s , which was as expected, while more errors were made on the larger as wel l as on the smaller scale photo pr i n t s . Most of the f a u l t s were committed i n separation of Douglas f i r and western hemlock. This may be attributable to the sim i l a r appearance of these two species on a e r i a l photos. Fewer errors were made i n separation when these two species were close together on the ground and the differences i n appearance could be recognized more e a s i l y . The least number of errors was committed i n i d e n t i f i c a t i o n of western red cedar, which i s due to i t s e n t i r e l y d i f f e r e n t shape, texture and appearance i n comparison with Douglas f i r and western hemlock. I t can be concluded from the table that, with experience, species i d e n t i f i c a t i o n may be improved considerably. Stellingwerf (1961), also has carried out a more or less similar experiment. His examination involved the photo-interpretation of TABLE 30 Committed Errors i n species recognition by different interpreters on various scales of photos. Inter-preters \u00E2\u0080\u00A2 Total No. of Trees to be i d e n t i -f i e d No. of steps i d e n t i -f i e d cor-r e c t l y E r r o r s Total No. of errors Total No. of errors i n per-centage S c a l e o f p h o t o g r a p h s L A R G E M E D I U M S M A L L Species N * Species N Species N Df. Wh. Wrc. Df. Wh. Wrc. Df. Wh. Wrc. A 90 i n 6 7 3 16 53 k 6 2 12 ko 7 8 5 21 70 1+9 54 B 90 kk 5 8 2 15 50 5 5 k 11 36 6 8 6 20 66 k6 51 C 90 Qk 3 2 0 5 16 1 1 1 3 10 3 3 2 8 26 16 18 Number of errors Percentage of errors Le gend. N i -- 92 -stands w i t h d i f f e r e n t age-classes, and i d e n t i f i c a t i o n of v a r i o u s t r e e species. His r e s u l t s are presented i n Tables 31 and 32. Table 31\u00E2\u0080\u00A2 Percentage correctness of p h o t o - i n t e r p r e t a t i o n f i g u r e s f o r species Species estimated on photographs Spruce Douglas f i r Deciduous species T o t a l under 30.6 48.3 15-1 31-3 r i g h t 44.2 40.5 45-3 43.5 over 25-2 11.2 39-6 25.2 T o t a l 100.0 100.0 100.0 100.0 Table 32. Percentage correctness of p h o t o - i n t e r p r e t a t i o n f i g u r e f o r species i n d i f f e r e n t age c l a s s e s Species estimated Old Middle Young T o t a l on photographs aged aged under 23.5 33-3 35-2 30.6 r i g h t 62.6 38.6 35-3 46.5 over 13.9 28.1 29.5 23.9 T o t a l 100.0 100.0 100.0 100.0 - 93 -THE VALUE OF HUMAN FACTORS IN PHOTO-INTERPRETATION \"The airphoto i s the window through which the viewer projects his background to determine what i s i n the view.\" (Frost, 1953)- Photo-interpretation i s an art rather than a science. I t happens often that the interpreter knows what characteristic points he has to look for on the object to be i d e n t i f i e d , but he i s completely unable to v i s u a l i z e them. I t i s we l l known that stereoscopic v i s i o n i s a basic requirement for photo-interpretation. Moreover, there are additional other needs, which are at least as important to a photo-interpreter as stereo accuity. I f any\of these a b i l i t i e s i s missing, the interpretation w i l l not be complete, i n most cases. The human factor i n photo-interpretation may be subdivided into v i s u a l accuity and mental accuity (Colwell, 1954). ( l ) Visual accuity When a pa i r of a e r i a l photographs i s looked at through a stereoscope, the instrument lenses take care of the focusing for the eye-to-photo distance. I f the prints are oriented properly, the eyes do not converge. This v i s u a l position i s the same, despite the nearness of the photographs, as i f i t would be necessary to search for a small object at a far distance. In such cases the interpreter works with such small d e t a i l s d a i l y f o r long periods of time. Therefore the interpreter's ocular mechanism must be able to maintain v i s u a l e f f i c i e n c y through a whole work period. - 9k -Another requirement i s the a b i l i t y to perceive small differences i n parallax. This allows exploitation of the exaggerated stereo e f f e c t , which i s caused by long \" a e r i a l eyebase\". (Actual ground distance between p r i n c i p a l points of two consecutive photos). This a b i l i t y can be increased to a certain l i m i t by experience. Local conditions a f f e c t tree i d e n t i f i c a t i o n very much on a e r i a l photographs. An interpreter working with a photograph of a new l o c a l i t y may have l i t t l e d i f f i c u l t y i n separating various forest stand types. He may have, however, great d i f f i c u l t i e s i n determining the species, age classes and condition of the dif f e r e n t i a t e d stands. General recognition rules and techniques of the photo i n t e r -pretation provide the basic information necessary, but the above-mentioned problem cannot be solved u n t i l the knowledge of interpreters i s supplemented by l o c a l f i e l d reconnaissance. The interpreter's a b i l i t y to i d e n t i f y objects on a e r i a l photographs i s related to his f a m i l i a r i t y with the shape and dimensions of similar or i d e n t i c a l objects. The a b i l i t y to i d e n t i f y an object w i l l be related to the number of times the interpreter has seen and correctly i d e n t i f i e d similar objects. I f the interpreter knows the variations i n appearance of an object examined, i t enables him to i d e n t i f y the object correctly. Such knowledge i s indispensable when i t i s necessary to determine tree species from a e r i a l photographs. On the basis of what a photo-interpreter must do, i t can be said that he should be able, at l e a s t , to: a. See wel l at a distance, b. See wel l close up, - 95 -c. Maintain v i s u a l e f f i c i e n c y throughout the workday, d. See stereoscopically. (2) Mental accuity Besides good v i s u a l a b i l i t y , the interpreter should have certain intelligence and personality c h a r a c t e r i s t i c s . When photo-interpretation i s analyzed i n terms of v i s u a l requirements, i t may be seen that an in d i v i d u a l can perform we l l i n an interpretation t e s t , despite the fact that his ocular mechanism may be r e l a t i v e l y unsuitable f o r photo-interpretation. Conversely, an i n d i v i d u a l who f a i l s such a test might have eyes which are suited to the art . In the f i r s t case, the interpreter has been mentally f i t , i . e . , he was patient, his imagination was good, and he was able to judge correctly despite the fact that his v i s u a l a b i l i t y was defective. In the second case, despite the interpreter's good v i s u a l a b i l i t y , he was not able to judge what he saw on photos. Both defects might be improved with a strong w i l l and patient study. A very essential requirement i s that an interpreter have s u f f i c i e n t l o c a l experience i n the area to be examined. The interpreter might have excellent v i s u a l a b i l i t y and might be mentally f i t , but i n the absence of l o c a l experience his results may e a s i l y turn out wrong. For ef f e c t i v e interpretation of tree species the interpreter must have a good memory, interest i n his work, and must possess background i n forestry, and related f i e l d s . He must have a p a r t i c u l a r knowledge of the ecological relationships of the forests i n the s p e c i f i c region with which he must deal. I t i s necessary for him to know chara c t e r i s t i c features of each tree species, i n order to d i f f e r e n t i a t e among them on photos. He also has - 96 -to know how these characteristics appear on different kinds of photographs, and i n different seasons of the year. In addition to the above requirements the interpreter should be physically capable of persistent study i n a leaning position. He should work with good l i g h t i n g f a c i l i t i e s . Glare should be avoided. Stereoscopic accuity i s only one of the v i s u a l s k i l l s needed for photo-interpretation. Other requirements include good distance v i s i o n , acceptable near v i s i o n , good reserves f o r accommodation and convergence, good ocular muscle balance and the v i s u a l capacity to maintain an exacting search f o r small d e t a i l s . The interpreter should also have professional background, l o c a l experience and keep himself mentally f i t . - 97 -KEY TO AERIAL IDENTIFICATION OF DOUGLAS FIR, WESTERN HEMLOCK, AND WESTERN RED CEDAR There are many types of keys which the interpreter may use i n proceeding to i d e n t i f y and analyze either natural or c u l t u r a l conditions i n an area. The purpose of any key or series of keys i s to point out or to c a l l attention to objects or features of a pattern which w i l l guide i n co l l e c t i n g data from an area examined. B a s i c a l l y there are two types of keys: (a) positive keys, and (b) inference keys (Simontacchi, 1955)- Positive keys permit d i r e c t i d e n t i f i c a t i o n of objects, c h i e f l y those with which the reader i s already f a m i l i a r or those which lend themselves we l l to pic t u r i n g and description. Keys based on inference are those requiring use of l o g i c , deductive reasons, and detailed analysis of regional and l o c a l environment. Such a key pictures and describes situations, either natural or man-made, occurring i n one area assumed to be t y p i c a l and then suggests, often by association, that analogous situations can e x i s t elsewhere, provided that natural and environmental conditions are s i m i l a r . The development as well as the use of such keys i s based on a n a l y t i c a l procedures. An inference key w i l l be presented for Douglas f i r , western hemlock, and western red cedar, grown i n the v i c i n i t y of Vancouver and Haney. The key i s most suited to large-scale photos and i s based primarily on the tree's ground c h a r a c t e r i s t i c s , such as shape, branching habit, l o c a l i t y , etc., as wel l as on t h e i r photo-characteristics, such as tone - 98 -and texture. I t i s , however, emphasized that the keys should be v e r i f i e d and revised by study of l o c a l forest regions. 1. (a) Tone i s dark or medium dark and crowns are coniferous i n appearance 2 (b) Tone i s medium or very l i g h t and crowns are coniferous i n appearance 6 2. (a) Trees are found i n mixed stands, where they may occur as dominant or codominant trees occupying rocky w e l l drained s i t e s 3. 3. (a) Dominant trees have medium tone and usually pyramidal crowns k (b) Trees are usually codominant, with medium dark, or dark tone and have long pyramidal crown with drooping tops 5 k.(a) Trees grow with sharp pointed crown on south dry-rocky, but well drained middle and upper slopes. The middle and upper branches are tending upward, having long hanging side branches, giving uniformly coarse texture. The lower branches are straight Douglas f i r (b) Trees occur mostly on lower lands, tone i s medium dark, the branches are long and trending upward. The trunk i s clear and the top i s less pointed, and the crown usually appears wider than i n h.(a). Texture i s coarse Douglas f i r (c) Trees have flattened or \"broom l i k e \" dead top. The trunk i s straight, with i r r e g u l a r gaps between - 99 -branches. Texture i s very coarse Douglas f i r 5.(a) Trees have short and narrow c o n i c a l crowns. The branches are slender and tend to droop. The top t w i g leans g r a c e f u l l y . The f o l i a g e i s dense causing a dark tone. Texture i s medium or \"feathery\", and tr e e s occur u s u a l l y on a c i d s o i l s Western hemlock (b) Tone i s dark, crown shape i s pyramidal. The top i s narrow, but s h o r t e r than i n 5-(a), and the crown i s wider. Texture i s coarser Western hemlock (c) Crown shape i s mostly dome l i k e . Branches are l o n g , f l a t , or p o i n t i n g downward. Long i r r e g u l a r gaps occur between whorls and branches Western hemlock 6 .(a) Trees have pointed narrow or l e s s narrow c o n i c a l crown shapes, l i g h t or very l i g h t tone, and l a c y t e x t u r e . Branches are slender and a l l curve upward. Trees grow u s u a l l y on a c i d s o i l s , and u s u a l l y are e i t h e r dominant or codominant Western red cedar (b) The crown i s sho r t e r than i n 5'(a), and l e s s narrow, but s t i l l p o i n t e d . The top i s more or l e s s rounded i f t r e e s are grown i n a dense stand. Tone i s l i g h t Western red cedar (c) The crown i s lo n g and not uniform, w i t h a lo n g dead spike l i k e top. Long i r r e g u l a r crooked limbs hang downward, but branches i n the upper p o r t i o n of the crown may tend s l i g h t l y upward Western red cedar - 100 -(d) Tops are rounded, dome l i k e often with two or more leaders. Tone i s very l i g h t , and texture i s f i n e r than i n 6(c) Western red cedar - 101 -CONCLUSION A e r i a l photographs have already proved to have wide-spread application i n Forestry, and i t seems that they w i l l be put to even greater use i n t h i s f i e l d i n the future. The needs of a forest-interpreter d i f f e r s i g n i f i c a n t l y from those other photo-interpreters. The forester must be able not only to measure and evaluate various timber stands, but also to disti n g u i s h them, and to recognize i n d i v i d u a l species. He must be able to recognize t h e i r minute components, i . e . , i d e n t i f y species, whether they are growing i n the open or i n dense stands. From the data and facts presented i n t h i s study the following conclusions can be drawn regarding the process of species i d e n t i f i c a t i o n : 1. Components of a tree crown change with tree age, 2. Percentage of l i v e crown of Douglas f i r , western hemlock, and western red cedar trees are c h i e f l y influenced by basal area and height/crown width, 3- The crown shape of Douglas f i r i s influenced by elevation, k. Among the p i c t o r i a l q u a l i t i e s there are a few forms of information available f o r forest interpreters, among which the tone i s the most important, but t h i s should be used i n combination with other factors. 5- In the series of photos studied, the smaller the scale the l i g h t e r was the tone, 6. Among the many factors influencing the texture of a tree image on a e r i a l photographs, the age and the scale are the most important. - 102 -7- The best photo-scale f o r the recognition, of Douglas f i r , western hemlock^, and western red cedar has been found to be about RF 1 : 8,700, 8. Of the three films used i n the i d e n t i f i c a t i o n of the tree species, v i z . , panchromatic, infrared, and colour films are used, infrared p o t e n t i a l l y i s preferable, 9. Colour films are least used, because of cost. They are preferable for recognition of special problem areas,such as caused by certain rusts and other tree diseases, 10. The f i l m - f i l t e r - s c a l e combination i s a l o c a l problem and i s dependent on the nature of vegetation and the s p e c i f i c objectives desired, 11. I t i s dangerous to generalize concerning the sp e c i f i c a t i o n of photography from one region to another. The writer of th i s study hopes that some of the information presented here w i l l prove to be of value i n the future, yet appreciates that much more research i n t h i s f i e l d i s required. - 103 -REFERENCES CONSULTED Aldred, A.H. 1959- I d e n t i f i c a t i o n of tree species on a e r i a l photographs. Thesis for the B.S.F. degree, Faculty of Forestry, The University of B r i t i s h Columbia, Vancouver, B.C. Andrews, G.S. 1934. A i r Survey and Forestry Developments i n Germany. For.Chon., 10:91-107. Andrews, G.S. 1940. Notes on the Interpretation of V e r t i c a l A i r Photo-graphs. For.Chon. l6:202-215-Baker, F.S. 1950. P r i n c i p l e of S i l v i c u l t u r e . McGraw-Hill Book Co., Toronto, Ont. Bauman, H. 1957- Forstliche Luftbild-Interpretation. (interpretation of Forest A e r i a l Photos). Selbsverlag der Forstdirection, Sudwurtemberg-Hohenzollern, Tubingen-Bebenhausen. Becking, R.W. 1959- Forestry Applications of A e r i a l Color Photography. Photogram. Eng. 25(4):559-565. Benninghoff, W.S. 1950. Use of A e r i a l Photographs i n Mapping Vegetation and S u r f i c i a l Geology i n Subarctic Regions. Photogram. Eng., 16(4):428-429-B i l l i n g s , W.D., and R. J. Morris, 1951- Reflection of V i s i b l e and Infrared Radiation from Leaves of Different Ecological Groups. Amer. Jour. Bot. 38:327-331. Bradshaw, K.E. 1950. Use of A e r i a l Photos by the Forest Survey i n C a l i f o r n i a . Photogram. Eng. l6(4):315-317-Burks, G.F., and R.C. Wilson, 1939- A Vegetation Inventory from A e r i a l Photographs. Photogram. Engin. 5(l):3 0 - 4 2 . Chapman, H.W.(l). 1949- Forest Reconnaissance by Helicopter Empire Forestry. Rev. 28:340-342. Chapman, V.J.(2). 1949- The Application of A e r i a l Photography to Ecology as Exemplified by the Natural Vegetation of Ceylon. Indian Forester. 73:287-314. Clark, W. 1947- Photography by Infrared. Second Edition. John Wiley and Sons. New York. Colwell, R.N. 1946. The Estimation of Ground Conditions from A e r i a l Photographic Interpretation of Vegetation Types. Photogram. Eng. 12(2):151- l6l . Colwell, R.N. 1948. A e r i a l Photographic Interpretation of Vegetation f o r M i l i t a r y Purposes. Photogram. Engin. l4(4):472-481. - 10k -C o l w e l l , R.N. 1950- New Techniques f o r I n t e r p r e t i n g A e r i a l Color Photography. Jour. For. 48(3):204-205. C o l w e l l , R.N. 1952. Report of Commission V I I . (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. Photogram. Eng. 18(2):375-451. Col-well, R.N. 1956. Determining the Prevelance of C e r t a i n C ereal Crop Disease by Means of A e r i a l Photography. H i l g a r d i a 26(5):223-286. D i l w o r t h , J.R. 195&. The use of A e r i a l Photographs i n C r u i s i n g Second-Growth Douglas-Fir Stands, U n i v e r s i t y of Washington, Ph.D. Thesis. F o r e s t Survey D i v i s i o n Consolidated Manual. 1959' B r i t i s h Columbia F o r e s t S e r v i c e , V i c t o r i a , B.C. F r o s t , R.E. 1952. D i s c u s s i o n of Photo R e c o g n i t i o n , A n a l y s i s and I n t e r p r e t a -t i o n , and Photo Keys. Photogram. Eng. 18(3):502-505\u00E2\u0080\u00A2 F r o s t , R.E. 1953- Factors L i m i t i n g the Use of A e r i a l Photographs f o r A n a l y s i s of S o i l and T e r r a i n . Photogram. Eng. 19(3):427-436. G r i f f i t h , B.G. i960. Growth of Douglas f i r a t the U n i v e r s i t y of B r i t i s h Columbia Research F o r e s t a t Haney as Related to Climate and S o i l . F a c u l t y of F o r e s t r y , The U n i v e r s i t y of B r i t i s h Columbia, Vancouver, B.C. pp. 15-19. Harlow, W.H. and E.S. Harrar, 194l . Textbook of Dendrology. McGraw-Hill Book Co., pp. 555-556. H a r r i s o n , G.B. 19^ -5\u00E2\u0080\u00A2 The S c a t t e r i n g of L i g h t i n the Atmosphere. Photo Jour. 85 (B):57-62. Hexter, H.J.H. 195\u00C2\u00B0. The Use of A e r i a l Photographs i n Timber C r u i s i n g on the N a t i o n a l F o r e s t s . Photogram. Engin. 16(4):317-321. Hindley, E., and J.H.G. Smith, 1957- Spectrophotometrie A n a l y s i s of Fo l i a g e of Some B r i t i s h Columbia C o n i f e r s . Photogram. Eng. 2 3 ( 5 ) : 8 9 4 - 8 9 5 . Hulburt, E . 0 . 1953- A t t e n u a t i o n of L i g h t i n the Lower Atmosphere. Jour. O p t i c a l Soc. Amer. 25:125-130. Ives, R.L. 1939. I n f r a r e d Photography as an A i d i n E c o l o g i c a l Surveys. Ecology 20:433-439-Jensen, A.A., and R.N. C o l w e l l , 19^ -9\u00E2\u0080\u00A2 Panchromatic versus I n f r a r e d Minus Blue A e r i a l Photography f o r F o r e s t r y Purposes i n C a l i f o r n i a . Photogram. Eng. 15(2):201-223-Johson, E.W. 1952. Using A i r c r a f t i n Checking Forest P h o t o - I n t e r p r e t a t i o n . Jour. For. 50:853-855. - 105 -Katz, A.H. 195\u00C2\u00B0- Contributions to Theory and Mechanics of Photo-Interpreta-t i o n from V e r t i c a l Photographs. Photogram. Eng. l6(2):339-386. Landen, D. 1952. History of Photogrammetry i n the United States. Photogram. Eng. 18(5):881-884. Leighton, E. 194l . How Many Tones? Photo Technique. Journal, December 1941, pp. 37-39-Losee, S.T.B. 1951- Photographic Tone i n Forest Interpretation. Photogram. Eng. 17(5):785-799-Losee, S.T.B. 1952. The Applications of Photogrammetry to Forestry i n Canada. Photogram. Eng. 18(4):742-757. Manual of Photographic Interpretation, i960. American Society of Photo-grammetry. pp. 457-517-Middleton, W.E.K. 1950. The Attenuation of Contract by the Atmosphere. Photogram. Eng. 16(5):663-672. Moessner, K.E. 1953- Photo Interpretation i n Forect Inventories. Photogram. Eng. 19(3):496-507. O'Neill, H.T. 1953- Keys for Interpreting Vegetation from A i r Photographs. Photogram. Eng. 19(3):422-424. Pope, R.B. 1957. The Effe c t of Photo Scale on the Accuracy of Forestry Measurements. Photogram. Eng. 23(5):869-873. Raup, H.M., and CS. Denny, 1950. Photo Interpretation of the Terrain along the Southern Part of the Alaska Highway. Geological Survey B u l l e t i n . 963-D. 103-133-Rohmeder, E., and H. Schonbach. 1959- Genetic und Zuchtung der Waldbaume. Verlag Paul Parey. Hamburg und B e r l i n , pp. 34-33-Ryker, H.C. 1933- A e r i a l Photography: a method of determination of timber species. Timberman 43(5):H-13-Schulte, O.W. 1951- The Use of Panchromatic Infrared and Color A e r i a l Photography i n the Study of Plant D i s t r i b u t i o n . Photogram. Eng. 17(5):688-717-Sigafoos, R.S. 1950. Some Botanical Problems i n the Interpretation of A e r i a l Photographs of Tundra Areas. Photogram. Eng. l6(4)-429-431. Simontacchi, A., G.H. Choate, and D.A. Bernstein, 1955- Considerations i n the Preparations of, Keys to Natural Vegetations. Photogram. Eng. 21(4):582-587. Smith, J.H.G. 1957. Forest History from A e r i a l Photographs. For. Chon. 33(4):390-392. - io6 -Smith, J.H.G., and J.W. Ker. i960. Growing Douglas f i r and Western Hemlock at Desired Rates. Research Note 24, The Faculty of Forestry, The University of B r i t i s h Columbia, Vancouver, B.C. Smith, J.H.G., J.W. Ker, and J . Csizmazia. 1961. Economics of Reforestration of Douglas f i r , western hemlock and western red cedar i n the Vancouver Forest D i s t r i c t . Faculty of Forestry, The University of B r i t i s h Columbia, Vancouver, B.C. Sonley, G.R. 1946. Interim Report on Experimental A i r Photography f o r Forest-Cover C l a s s i f i c a t i o n . For. Chon. 22(2):157-158. Spurr, S.H., and CT. Brown, 1946. Specifications f o r A e r i a l Photographs Used i n Forest Management. Photogram. Eng. 12(2):131- l4l . Spurr, S.H. 1948. A e r i a l photographs i n Forestry. Ronald Press Co. New York. pp. 4 l . Spurr, S.H. 1949- Films and F i l t e r s for Forest a e r i a l Photography. Photogram. Eng. 15(3):473-481. Spurr, S.H. i960. Photogrammetry and Photo-Interpretation. The Ronald Press Co. New York. pp. 295-331-Steen, W.W., R.E. Pippin, and A. Shapiro, 1957- Quantitative Evaluation of Photo Interpretation Keys. Photogram. Eng. 23(5):858-864. Stellingwerf, D.A. i960. Methods and Results of a Forestry Photo-Interpretation. International Training Centre for A e r i a l Survey, Delft-The Netherlands. Stoeckeler, E.G. 1949- I d e n t i f i c a t i o n and Evaluation of Alaskan Vegetation from Air-Photos with Reference to S o i l , Moisture and Permafrost Conditions. U.S. Dept. Army Corps, of Engineers, pp. 103. Stone, K.H. 1950- A e r i a l Photographic Interpretation of Natural Vegetation i n the Anchorage Alaska Area. Geographical Review, 38:465-474. Sudworth, G.B. 1908. Forest Trees of the P a c i f i c Slope. U.S. Department of Agriculture, Forest Service. Tarkington, R.G. 1953- An Aspect of Color Photography and Interpretation. Photogram. Eng. 19(3):4l8-420. Thelen, R. 1919- A e r i a l Photographs and National Forest Mapping. Jour. For. 17:515-522. Tupper, J.C., and W. Clark. 1944. Characteristics of Photographic Materials. Manual of Photogrammetry, American Society of Photogrammetry. pp. 208-225. - 107 -University of B r i t i s h Columbia Research Forest Committee. 1959- The F i r s t Decade of Management and Research - U.B.C. Forest. 19^9 - 1958. Faculty of Forestry, The University of B r i t i s h Columbia, Vancouver, B.C. Waldo, C.E. 1950. Application of Color Photography. Photogram. Eng. l6(4):327-228. W a l l i s , I. 19^3\u00E2\u0080\u00A2 How Reflection Changes Appearance. American Photography. Jour. August 1943. 20-24. Wear, J.F., and J.R. Dilworth. 1955- Color Photos Aid Salvage. Lumberman, December, pp. 88-89, 132-133-Wieslander, A.E., and R.C. Wilson. 19^2. C l a s s i f y i n g Forests and other Vegetation from A i r Photographs. Photogram. Eng. 8(3):203-315' - 108 -A P P E N D I X cl - 1 1 0 -APPENDIX I 4 5 6 F i g 2 V a r i a t i o n s in C r o w n S h a p e s o f D o u g l a s f i r F i g - 2 c o n t ' d V a r i a t i o n s in C r o w n S h a p e s o f D o u g l a s f i r 2 c o n t ' d V a r i a t i o n s in C r o w n S h a p e s o f D o u g l a s f i r k I F i g - 3 V a r i a t i o n s in C r o w n S h a p e s o f W e s t e r n h e m l o c k c d 80 50 70 90 MO 130 Age in Years 3 D Graph I Average top angles over age for Douglas fir Age in Years G r a p h 3 A v e r a g e t o p a n g l e s o v e r a g e f o r W e s t e r n r e d c e d a r A S e n s i t i v i t y c u r v e o f o r t h o c h r o m a t i c f i l m CO c a> co 4 X l O \" 5 cms- 5 6 Wave Length (cm) 7 B S e n s i t i v i t y c u r v e o f p a n c h r o m a t i c f i l m CO c CO CO 4 x l 0 \" 5 cms 5 6 Wave Length (cm) C S e n s i t i v i t y c u r v e o f i n f r a - r e d f i l m CO c a> co 4 x l O ~ 5 cms 5>6 7 Wave Length (cm) 8 F i g - 7 S e n s i t i v i t y c u r v e s o f v a r i o u s t y p e s o f f i l m "@en . "Thesis/Dissertation"@en . "10.14288/1.0075433"@en . "eng"@en . "Forestry"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "Study of crown shapes of Douglas fir, western hemlock, and western red cedar as an aid in the identification of these species on aerial photographs"@en . "Text"@en . "http://hdl.handle.net/2429/39988"@en .