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Morphogenesis of stems of Douglas fir (Pseudotsuga menziesii (mirb.) franco) Heger, Ladislav 1965

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The University of B r i t i s h Columbia FACULTY OF GRADUATE STUDIES PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR:OF PHILOSOPHY of LADISLAV HEGER Ing.(For.)» Brno, (Czechoslovakia)', 1949 M.F. Tlie University of B r i t i s h Columbia, . 1959 MONDAY, MAY 10, 1965 AT 2:00 P.M. IN ROOM 239, FORESTRY & GEOLOGY BUILDING COMMITTEE IN CHARGE Chairman: V. J . Okulitch External Examiner: J . L. Farrar A b i t i b i Professor of Forest Biology Faculty of Forestry University, of Toronto, Toronto, Ontario B. G. G r i f f i t h P. G. Haddock S. W. Nash J . H. G„ Smith R. W. Wellwood D. J . Wort THE MORPHOGENESIS OF STEMS OF DOUGLAS FIR (PSEUDOTSUGA MENZIESII. MIRB. FRANCO) ABSTRACT Widths of :22j,734 bands of earlywood and latewood have been measured systematically along the average r a d i i at the centres of the annual height increments of 18 Douglas f i r trees. Shapes of the annual growth layers of earlywood and of latewood, respectively, formed during an accrued growth period of 589 years were investigated: ( i ) using r e l a t i v e measures embodied i n diagrammatic computer outputs; ( i i ) using absolute measures by s t a t i s t i c a l and graphical tech-niques; ( i i i ) by computing Hohenadl !s form f a c t o r (lambda 0.9) for each year of growth of; (a) imaginary "earlywood stems" consisting'of layers of early wood; (b) imaginary "latewood stems" con s i s t i n g of layers of latewood; (c) actual stems cons i s t i n g of t o t a l annual l a y e r s . The form of earlywood layers d i f f e r e d markedly and consi s t e n t l y from that of latewood l a y e r s . The maximum width of earlywood layers -in i n d i v i d u a l trees occurred with-i n a zone located in. the upper portion of the l i v e crown; i n the stand i t was within a zone p a r a l l e l with the surface of the crown canopy. Width of earlywood was at i t s minimum at some.small distance above the stem base. This distance increased with tree age. Latewood layers were usually widest along the basal portion of the stems. As a.result, the form factors of "earlywood stems" were considerably higher than those of "latewood stems". The shapes of the growth layers, and hence the form of stems cons i s t i n g of these layers, could not be reconciled s a t i s f a c t o r i l y with the tenents of Schwendener-Metzger*s mechanistic, or Hartig's n u t r i t i o n a l , or Jaccard's water conductive, or hormonal theories of stem formation. There-fore, i t was suggested that the shapes of the annual layers of earlywood and latewood may r e f l e c t the respective spring and summer microenvironmental energy gradients. Then the. average form of trees from forests of the temperate l a t i -tudeswhichis that of a quadratic paraboloid, may be deter-mined by the average microclimatic structure p r e v a i l i n g i n these forests during the growing season. Form of open-grown trees, e c c e n t r i c i t y of stems, roots and branches, and other so far unexplained anomalies i n r a d i a l growth may be c l a r i f i e d s i m i l a r l y . Indirect and some preliminary d i r e c t evidence support-ing the proposed conceptual scheme of stem formation was presented- In • addition,, influence of some selected factors of macroclimate on the amount of r a d i a l growth expressed i n terms of the average widths of growth layers was analysed. Individual trees have been used as sampling u n i t s . The trends i n the growth series were removed by analysis of co-variance: average layer width indices were derived by c a l -c ulating deviations from the st r a i g h t l i n e s f i t t e d by l e a s t squares to the adjusted mean layer widths.. The degree of autocorrelation of both growth and weather series was l a r g e l y non s i g n i f i c a n t . Correlations between the growth indices of earlywood and latewood were nonsignificant or low. In the i n d i v i d u a l trees, s i x weather variables ac-counted for from 10 to 48 per cent of the t o t a l v a r i a b i l i t y observed i n the r a d i a l growth of latewood. Temperatures of the previous summer could not be rel a t e d to the amount of r a d i a l growth of earlywood of the current year. Since the approximate minimum true c o r r e l a t i o n i n the universe was zero the general influence of macroclimate was n o n s i g n i f i -cant . It appears that other studies have neglected the influence of physical microenvironmental factors on growth. There i s need for research on the means .by which d i s t r i b u -t i o n and amount of r a d i a l growth are c o n t r o l l e d by the net. flow of energy i n trees. GRADUATE STUDIES F i e l d of Study: Forest Mensuration Forest Mensuration J . H. G. Smith & J . W. Ker S i l v i c s P. G. Haddock Wood Anatomy R„ W„ Kennedy Forest Management I. C. MacQueen Related Studies: Biometry and F i e l d Design- J . Sawyer Plant Physiology. D. , J . .Wort Computer Programming H. Dempster PUBLICATION Smith, J.H.G., Ker, J„W 4, Heger, L. (1960). Natural and Conventional Height-Age Curves for Douglas-Fir and Some Limits to Their Refinement, Proc. F i f t h World For. Congress, pp. 546-551. MORPHOGENESIS OF STEMS OF DOUGLAS FIR (PSEUDOTSUGA MENZIESII (MIRB.) FRANCO) by LADISLAV HEGER Ing. (For.), Brno, (Czechoslovakia), 1949 M.F., University of B r i t i s h Columbia, 1959 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in 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 , 1965 In 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 of the requirements f o r an advanced degree at the U n i v e r s i t y of • B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that per-m i s s i o n f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood t h a t ; c o p y i n g or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission*. Department of The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada i ABSTRACT Chairman; Professor J . H. G. Smith Widths of 22,734 bands of earlywood and latewood were measured systematically along the average r a d i i at the centers of the annual height increments of 18 Douglas f i r t rees. Shapes of the annual growth layers of earlywood and of latewood, respectively, formed during an accrued growth period of 589 years were investigated; (i) using r e l a t i v e measures embodied i n diagramatic computer outputs; ( i i ) using absolute measures by s t a t i s t i c a l and graphical techniques; ( i i i ) by computing Hohenadl's form f a c t o r (lambda 0.9) f o r each year's growth of; a) imaginary "earlywood stems" consisting of layers of earlywood; b) imaginary "latewood stems" consisting of layers of latewood; c) actual stems consisting of t o t a l annual layers. The form of earlywood layers d i f f e r e d markedly and consistently from that of latewood la y e r s . The maximum width of earlywood layers i n i n d i v i d u a l trees occurred within a zone located i n the upper portion of the l i v e crown; i n the stand i t was within a zone p a r a l l e l with the surface of crown canopy. Width of earlywood was at i t s minimum at some distance above the stem base. This distance increased with tree age. Latewood layers were usually widest along the basal portion of the stem. i i As a r e s u l t , the form factors of "earlywood stems" were considerably higher than those of "latewood stems". - fbe shapes of the growth layers, and hence the.form of stems consisting of these layers, could not be reconciled s a t i s f a c t o r i l y with the tenets of Schwendener - Metzger's mechanistic, or H a r t i g f s n u t r i t i o n a l , or Jaccard's water conductive, or hormonal theories of stem formation. Therefore, a new scheme was proposed using the following concepts, (1) Heating of stems by solar energy constitutes a purely physical process; the rate of energy tra n s f e r between a tree and i t s environment determines the temperature of i t s cambial t i s s u e s . (2.) Because trees are not homoiothermous organisms, at a given time various parts of the cambial cylinder may possess d i f f e r e n t temperatures even i n an isothermal environment. (3) A pronounced s t r a t i f i c a t i o n of the environment due to gradients i n a i r temperature or i n length of time of posi t i v e net f l u x of energy has been observed i n fore s t s throughout the world. (4) Radial growth may proceed at varying rates f o r unequal periods of time within the d i f f e r e n t parts of the cambial cylinder, depending l a r g e l y on the l e v e l s of subcortical temperatures. (5) Consequently, the shapes of the annual layers of earlywood and latewood may r e f l e c t the respective spring and summer environmental energy gradients. (6) Then the average form of trees from forests of the temperate l a t i t u d e s , which i s that of a quadratic paraboloid, may r e f l e c t the average microclimatic structure p r e v a i l i n g i n these forests during the growing season. Form of open-grown trees, e c c e n t r i c i t y of stems, roots and branches, and other so f a r unexplained anomalies i n r a d i a l growth may be c l a r i f i e d s i m i l a r l y . Indirect and some preliminary d i r e c t evidence supporting the proposed conceptual scheme of stem formation was presented. In addition, influence of some selected factors of macroclimate on the amount of r a d i a l growth expressed i n terms of the average widths of growth layers was analysed. Individual trees have been used as sampling u n i t s . The trends i n the growth series were removed by analysis of covariance: average layer width indices were derived by ca l c u l a t i n g deviations from the straight l i n e s f i t t e d by least squares to the adjusted mean layer widths. The degree of autocorrelation of both growth and weather series was l a r g e l y nonsignificant. Correlations between the growth indices of earlywood and latewood were nonsignificant or low. In the i n d i v i d u a l trees, six weather variables accounted f o r from 10 to 48 per cent of the t o t a l v a r i a b i l i t y observed i n the r a d i a l growth of latewood. Temperatures of the previous summer could not be related to the amount of r a d i a l i v growth of earlywood of the current year. Since the approx-imate minimum true c o r r e l a t i o n i n the universe was zero the general influence of macroclimate was nonsignificant. It appears that other studies have neglected the influence on growth of microenvironmental factors and that there i s need f o r research on the means by which d i s t r i b u t i o n and amount of r a d i a l growth are controlled by the net flow of energy. V ACKNOWLEDGEMENTS Among the many people who gave me most constructive assistance i n preparation of t h i s thesis at various stages are: Dr. J.HoGo Smith, my chief advisor and chairman of. the exam-ining committee, Dr. R.W. Wellwood, Dr. P.G. Haddock, Dr. J.W. Wilson, Mr. J . Walters and Mrs. M.R« Lambden, a l l of the Faculty of Forestry; Dr. D o J o Wort, Department of Botany; Dr. SoWo Nash, Department of Mathematics; Mr. E. Klassen, Department of Metallurgy; Mr. A. E r i s a l u , Department of Buildings and Grounds; Dr« W.V. Hancock, Canada Department of Forestry; Dr. K. Westphal, Bedford Institute of Oceanography; Dr. J o C . Pennel, Cornell University; Mr. E.D. Berry; Mr. K. Dietz, University of Alberta. I am much indebted to a l l of them. Special acknowledgement i s due to the s t a f f of the Computing Center of the University of B r i t i s h Columbia, i n p a r t i c u l a r to Dr. J . R o H . Dempster, Mr. R . J . Henderson and Mr. E. Froese. Their u n f a i l i n g help made t h i s t h e s i s possible. I thank them a l l * The University of B r i t i s h Columbia awarded me Van Dusen's Fellowship i n Forestry, Queen Elizabeth Scholarship and University Forest Fellowship, I received additional support from Canada Department of Forestry and from the National Research Council of Canada* I thank a l l these agencies f o r t h e i r assistance. v i TABLE OF CONTENTS Page ABSTRACT * i ACKNOWLEDGEMENTS v TABLE OF CONTENTS • • O O * 9 C O « O » * O O * * « 0 O O * O O O 0 O O « * 9 * « * * a « VX LIST OF TABLES v i i i LIST OF FIGURES • o o o o o * o * « o o * * * » * o o o « o o o < i « * o « * o « o < » * o « * t t I X INTRODUCTION.. 1 GENERAL MENSURATIONAL CONSIDERATIONS 5 STEM FORM THEORIES - 1 15 STEM FORM THEORIES - 2 , 20 DISTRIBUTION OF RADIAL GROWTH - PAST WORK 49 MATERIALS AND METHODS 5g RESULTS • . • . . • • o . ? . . . o . « . « o . o . . . s . . . . . e . e o « « « . . o o . . « . . « £>3 PART ( A ) : DISTRIBUTION OF RADIAL GROWTH ALONG STEMS OF DOUGLAS FIR 63 Stem Form F a c t o r s 74 PART (B): IDENTIFICATION OF THE CAUSAL FACTORS DETERMINING THE FORM OF FOREST TREES 77 S u b c o r t i c a l Temperatures i n Douglas F i r .... 110 1 ** Bcix*lc Thickrisss • o » o o o o » « * o » » » « * « » © « » o » » « 112 2 - Moisture Content of Bark 112 3 — I n s o l a t e d Stems . . o « . . o . . o . . . o « . . . . . . . . . 112 4 - Stems of Forest-Grown Trees ............ 113 5 - Temperature D i f f e r e n t i a l 113 6 - Crown Shade 114 7 - A i r Temperature G r a d i e n t s 114 8 - Heat Propagation through Bark 114 V l l Page ConclllSlOnS (B) ©o©oo©o©oooeooo©©©©e©o©o©*©oe©oo DlSCUSSlOn (B) o e o o o © c o f i o o o o « e © o o e e © « « « o o o « o o e e 117 PART (C): CORRELATION AND REGRESSION ANALYSIS BETWEEN THE AMOUNT OF RADIAL GROWTH OF DOUGLAS FIR AND SOME SELECTED WEATHER FACTORS 126 Introducti On o © a o o o o o « o o o © o o « © o c o Q o o e o © © o « © o © o o 12& Msthods snd. Rssults oo©o©oo©©o©©©©o©o©o©©©©©©©©© 129 C one In s i on s (C) ©o©«o©ooo©o©o«*©o©o©©©©oo©o©o«©© 139 DlSCUSSlOn ( C ) o o o « o o o o « © o o c e « o o o « « e © o « o o « e o o © I/4.I CONCLUDING REMARKS o o o © o 0 o o o © o o o o 0 o o o « o o o o o o o o o « o o o e o o o e » o o 1/^2 LITERATURE CITED o o o o o o o o o o « © e o © © © o o © © o o o « o o © o © o « © o © © © © « © © © I/4-/4-APPENDIX0 DIAGRAMS 1 TO S3 © 0 © © © © * © © 0 © © © © © © © © © © © © © © © © © « 0 © © 177 v i i i LIST OF TABLES Table Page I Basic mensurational data of the sample trees 59 IT The averages of the c r i t i c a l widths of earlywood and latewood layers, and t h e i r average lon g i t u d i n a l p o s i t i o n i n the stem .. 67 III C o e f f i c i e n t s of v a r i a t i o n of the c r i t i c a l dimensions of growth layers ............ ........... 68 IV The averages of r a t i o s of the c r i t i c a l widths of earlywood and latewood layers ........... 70 V The c o e f f i c i e n t s of va r i a t i o n of the C 1*11 X C 3,1 ""diniSn S i On *""X*clt 1 O S * 0 « 4 « o o o 0 o 0 i > o o o c > 0 O 0 O O 6 « * e * *71 VI Simple co r r e l a t i o n c o e f f i c i e n t s between c r i t i c a l dimensions of annual layers of earlywood and latewood ... .<,.......... 72 VII Summary of covariance and autocorrelation analyses of earlywood layers 130 VIII Summary of covariance and autocorrelation analyses of latewood layers . 131 IX Von Neumann's r a t i o s (K) of the weather series from l ^ l O tO 19^2 o « 9 « o * « * o e o o o « e « o « « o « o o « o o o « e o « 9 « a o « * « X Summary of the simple c o r r e l a t i o n analysis: the average width of earlywood layers correlated with the average width of latewood layers within the S3.H16 y©3.1* • • • o o a * o « 0 9 « > O 0 O * « o e o e o o o e o o « o c e o o o o o o o o o « « 3-33 XI Summary of the multiple c o r r e l a t i o n analysis: mean width of earlywood layers correlated with mean monthly a i r temperature and with t o t a l monthly p r e c i p i t a t i o n of the current year 136 XII Summary of the multiple c o r r e l a t i o n analysis: mean width of latewood layers correlated with mean monthly a i r temperature and with t o t a l monthly p r e c i p i t a t i o n of the current year ......... 137 XIII Summary of the multiple c o r r e l a t i o n analysis: the average width of earlywood layers correlated with the mean monthly a i r temperatures of the previous S1HT1IT16T* o e o 0 0 » 0 0 0 0 « o 0 0 O O 9 « » « e 0 « t t 0 0 9 0 0 O 0 0 O 0 O 0 0 0 « 0 0 e o 0 13^ i x LIST OF FIGURES Following Figure Page 1 The sampling scheme ..............<<....... 6 l 2 Band of earlywood between two bands of latewood i n a s t r i p treated with oil-carbon suspension .. 6 l 3 Widths of earlywood layers, tree No. 1 , y©3,r*S 19 5 ^  ""-^ -9 ^ 2 o o © o o © © * o © o * © © e e © e o o © © © o © © © © © © e o &3 4 Widths of latewood layers, tree No. 1 , years 1 9 5 8 — 1 9 6 2 o . . . o « o . . « o o e » e e o . « . o . . e o . . » . . o » 63 5 Cross section areas of earlywood layers, tree No. 1 , years 195^~*1962 . . . . . . . . . . . . . . . . . . . . 63 6 Cross section areas of latewood layers, tree No. 1 , years 195^—1962 . . . . . . . . . . . . . . . . . . . . 63 7 The mid-internodal growth i n area of earlywood, "tr*©6 NO « X « o « o o o o o « o o o o o o o o o « e « o o o » « o o o o o © © « o o « 6 3 8 The mid-internodal growth i n area of latewood, "fc 2?6 @ NO O 1 O O O O O O O O O O O « O O 0 O © O O O « e © O O O » « O O O « O O O O © 63 9 Position of the maximum r i n g width i n r e l a t i o n to stem-apex of earlywood, and of stem-base, trees 1 3 M , 2 7 M , 3 2 M , 33M 6 6 10 Position of maximum rin g width of earlywood, and of the stem-base i n r e l a t i o n to stem-apex, trees No« 1 , 3? 4> 5 j 6 ....a.................. 6 6 11 Position of minimum and maximum r i n g width of earlywood, and of the stem-base, i n r e l a t i o n to the stem-apex, trees No. 8 , 9 . . . . . . o 6 6 12 Position of minimum and maximum r i n g width of earlywood, and of the stem-base, i n r e l a t i o n to the stem-apex, trees No. 1 0 , 1 1 6 6 13 Position of minimum and maximum rin g width of earlywood, and of the stem-base, i n r e l a t i o n to the stem-apex, tree No. 12 • 6 6 14 Position of minimum and maximum r i n g width of earlywood, and of the stem-base, i n r e l a t i o n to the stem-apex, trees No. 1 3 , 1 4 • • • • • • • • 66 X Following Figure Page 15 Determinants of form, tree No. 1 72 '(' 16 Determinants of form, tree No. 11 72 17 Schematic diagram of the longitudinal sections of average annual layers of xylem, tree No. 7 72 18-31 Values of lambda 0.9, trees No. 1 to 14, 32 Water content of outer bark as percentage of oven-dry weight, forest-grown Douglas f i r 112 33 Water content of inner bark as percentage of oven-dry weight, forest-grown Douglas f i r 112 34 Relationship between the ambient and subcortical temperatures at breast height within a stand of Douglas f i r , July 28 - September 11, 3-6 p.m. .. 113 35 V e r t i c a l temperature gradients i n a stand of Douglas f i r between 2-4 p.m. on sunny (S), cloudy (C), and overcast (0) summer days- 114 36 Heat propagation through the bark of Douglas f i r 114 37 Width of earlywood, tree No. 14 129 38 Width of latewood, tree No. 14 129 39-52 Values of average layer width indices of earlywood and latewood, trees No. 8 to 14, respectively .. 129 T h i s tree afforded anew an example of something I have observed i n several trees of good growth, i . e . that although at the butt, according to the number of annual rings, the trees had a greater increment than at a height of 9 feet, the size of the annual rings was often greater at a height of 18 than at a height of 9 f e e t . I have been unable to f i n d an explanation f o r t h i s , but i f I am not fortunate enough to discover the cause, i t i s my hope that others, now t h e i r attention i s c a l l e d to i t , may be able to do so. C.D.F. Reventlow (1748-1827) / INTRODUCTION The arboreal forms of pteridopsid gymnosperms were the f i r s t large plants which took hold of the land and succeeded i n an environment the true ferns never mastered. This was made possible by developing secondary thickening of t h e i r axes. The power to develop unlimited wood and bast by the a c t i v i t y of a perpetually young layer of d i v i d i n g i n i t i a l s arranged i n the cambial cylinder i s Nature's solution to the problem of support of vegetative and reproductive organs of woody plants. The cambial layer has been recognized as one of the most s i g n i f i c a n t progressive adaptations which, by making the tree habit possible, greatly advanced the evolution of the higher plants. When evaluated i n terms of i t s a c t i v i t y , the i n t e r f a s c i c u l a r cambium has also been considered to be one of Nature's most wasteful inventions because, i n contrast with herbs, the reproductive phase i n trees occurs much l a t e r and with f a r greater expenditure of materials f o r construction of t h e i r vegetative organs as compared with the amount of materials spend in the production of seed. V e r t i c a l axes several feet i n 1 2 diameter, of which only a few outermost inches function as conduction pathways and storage organs, are commonly formed i n a place where a hollow column would seem to be a more e f f i c i e n t way of solving the problem of conduction, storage and support. The basic pattern of c e l l u l a r structure of xylem and phloem i s contained i n the cambium. Any changes i n structure of these tissues, the number of c e l l s and also the kind and the arrangement of c e l l s formed during the processes of the second-ary thickening are based on the changes i n the cambial t i s s u e . The t o t a l tree volume of wood, i t s quality and also i t s techno-l o g i c a l properties are determined by the number, size, kind and arrangement of the xylem c e l l s deposited by the cambial cylinder and i t s ramifications. Within any one cross-section of the stem the number and size of the xylem c e l l s may vary considerably i f measured along opposing r a d i i and account f o r the eccentric po s i t i o n of the pi t h and f o r the general lack of c i r c u l a r i t y of the boles. The number and size- of the xylem c e l l s vary also with the distance from the stem apex accounting i n t h i s way f o r the gradual increase of the t o t a l cross-sectional areas and therefore also f o r the ultimate longitudinal shape of the stem and f o r i t s taper. Any other intermediate shape assumed by a tree during; i t s l i f e can be ascertained i n trees possessing d i s t i n c t annual rings-by a detailed investigation of the annual layers of xylem. The boles of coniferous trees i n the temperate l a t i t u d e s can be viewed as aggregates of layers of earlywood 3 and of latewood formed during a number of growing seasons. Any diameter at any point and at any age along the bole i s the sum of the thicknesses of these l a y e r s . Since i t i s known that the form of the tree stem varies during the course of i t s growth the thickness of the i n d i v i d u a l growth layers cannot be constant a l l the way along the bole. Therefore, the investigation of the dimensions of the annual layers of xylem i s the f i r s t step i n studying the morphogenesis of the stems of coniferous species. Any consistent pattern with respect to the amount of r a d i a l growth might help to i d e n t i f y the factors causing the cambium to produce such a pattern and, i n the end, to produce a bole of a given shape. The importance of such knowledge i s obvious. The y i e l d of timber sawn from a log depends l a r g e l y on the size, taper, and form of the log. C y l i n d r i c a l form would be the most economical one from the point of view of a sawmill operator. For a forester, both too r a p i d l y as well as too slowly tapering trees are uneconomical; the gain secured by improving the form of trees grown i n dense stands might be n u l l i f i e d by the l o s s i n the rate of growth. On the contrary, an increase i n volume of widely spaced trees might be offset by the deterioration of both stem form and wood q u a l i t y . The economical value of a stand i s therefore partly determined by the average form. This can be regulated by regulating the density of the stand. Growing space has been found to be related s i g n i f i c a n t l y to the rate of growth, to the stem form, and to the s p e c i f i c gravity of wood. The correct evaluation of t h i s r e l a t i o n s h i p 4 within a p a r t i c u l a r s o i l moisture regime can make more probable the largest y i e l d s , i n the shortest time, of wood of desired technological properties. The i n i t i a l spacing and a l l further measures modifying the stand density seem to be able to influence stem form and quality of wood more than the fix e d factors due to topography, macro-climate, s o i l and heredity. The present study i s concerned with the organization of the r a d i a l growth of some young plantation-grown and some unmanaged forest-grown Douglas f i r (Pseudotsuga menziesii (Mirb.) Franco.) I t i s an attempt to describe the d i s t r i b u t i o n s of the annual layers of earlywood and of latewood and to evaluate them as determinants of the stem form; to i d e n t i f y the factors responsible f o r t h e i r properties and, f i n a l l y , to use them i n a study of the e f f e c t s of weather on r a d i a l growth. 5 GENERAL MENSURATIONAL CONSIDERATIONS The term "form" r e f e r s t o the l o n g i t u d i n a l shape of a t r e e -which i s c o n s i d e r e d to be a s o l i d generated by r e v o l u t i o n of a diameter/height curve d e f i n i n g the stem p r o f i l e . The power index of any such curve determines the r a t e of change of the stem diameter with change i n h e i g h t and i s thus an exact c r i t e r i o n o f the stem form but not always of the stem t a p e r . Terms "form" and " t a p e r " are not synonymous. Boles d i f f e r i n g i n shape have a l s o d i f f e r e n t r a t e s of both absolute and r e l a t i v e t a p e r . Boles having the same form may have d i f f e r e n t r a t e s of absolute t a p e r but t h e i r r e l a t i v e t a p e r s are always the same. Terms such as " r a p i d t a p e r " or "slow t a p e r " do not c o n f e r any i n f o r m a t i o n r e g a r d i n g the t r u e form of the stems t o which they r e f e r . In t h i s study the terms form or shape of a stem, or b o l e , o r trunk, o r a s h a f t , o r of a t r e e are used i n t e r -changeably. They r e f e r t o the form of the v e r t i c a l a x i s of the f o r e s t grown c o n i f e r s of the n o r t h e r n temperate zone. By form f a c t o r i s understood the b r e a s t h e i g h t c y l i n d r i c a l form f a c t o r . The terms form q u o t i e n t , form c l a s s and a b s o l u t e form q u o t i e n t are the d i f f e r e n t d e s i g n a t i o n s of the Jonson's m o d i f i c a t i o n of S c h i f f e l ' s form q u o t i e n t (Spurr 1952). Unless otherwise s p e c i f i e d ^ by p a r a b o l o i d i s meant q u a d r a t i c p a r a -b o l o i d ; by diameter i s meant diameter at b r e a s t h e i g h t ; by height i s meant the t o t a l h e i g h t , by crown the l i v e crown. 6 The form of a geometric s o l i d has to be known i f i t s volume i s to be ascertained from measurements of i t s basal diameter and height. The early mensurational studies concerned with the evaluation of the volume of forest trees were conducted with recognition of t h i s fact and the form of the stems of trees received a great deal of attention. Form was c l a s s i f i e d soon as a variable which was highly unstable and also most d i f f i c u l t to assess. Simple mathematical expressions describing the exact p r o f i l e of the geometric s o l i d s could not be applied with the same degree of accuracy to the stems of a l l trees. This i s because tree stems are composites of a number of s o l i d s , each of which may have a d i f f e r e n t shape only approaching that of an i d e a l geometric s o l i d . Truncated n e i l o i d , frustum of a paraboloid, and cone are those most frequently encountered i n c o n i f e r s . They occupy portions of the stem of varying length and the rate of t h e i r absolute taper may d i f f e r (Newnham 195&S Altherr I960). Form may be considered also as a product of several components, namely: 1. shape of the main portion of the stem above the n e i l o i d a l base which can be n e i l o i d a l , conical or paraboloidal; 2. rate of taper; 3. amount of upward extension of butt swell, and 4« bark thickness (Behre 1927). 7 The l a s t two components are important i n that the reference diameter of most measures of form l i e s within a zone affected by the varying amounts of butt swell, which i s enveloped by a layer of bark of variable thickness. Influence of butt swell may be such that the various types of breast height form factors cannot be used as v a l i d c r i t e r i a of form. Form quotients may be affected by butt swell and bark thickness i n a s i m i l a r way, or i n a d i f f e r e n t way, depending upon whether t h e i r upper diameter i s measured within the rapidly tapering bole within the crown or whether i t i s measured within the slowly tapering bole below the crown. Thus, the amount of v a r i a b i l i t y i n form as indicated by standard measures of form may or may not agree with the actual amount of v a r i a b i l i t y present. V a r i a b i l i t y i n form within trees of the average diameter class was found to be about as great as the t o t a l v a r i a t i o n i n form i n the entire stand (Behre 1927) . D i f f e r -ences i n stand density, age, and s i t e q uality may cause more va r i a t i o n i n volume f o r a given size class than a difference of a thousand miles i n range (Behre 1927)• Individual trees of the same age, diameter and height, growing side by side i n the same stand, may d i f f e r by as much as 20 per cent or more in t h e i r cubic content (Clark 1902) . Trees of the same diameter and height growing on contrasting s i t e s were found to d i f f e r i n volume by as much as 30 per cent (Emrovic and Glavac 1 9 6 4 ) . Any disturbance of the stand density brings about changes i n the form of the residual trees and may a f f e c t profoundly the estimation of t h e i r volume* In the case of western yellow pine (Pinus ponderosa)« trees were found with form quotient as low as 0 . 4 5 0 and with volumes 30 per cent below the average. Also, trees were found having a form quotient as high as 0o850 and with volume 20 per cent above the average volume (Meyer 1931)» A range of form quotients from 0 .550 to 0.850 was not unusual i n an unmanaged red spruce and white pine forest (Behre 1932). Form fact o r s of 3248 Scotch pine (Pinus  s v l v e s t r i s ) stems from managed stands ranged from 0 . 3 1 0 to 0 . 5 5 0 , c o e f f i c i e n t of v a r i a t i o n being 7*5 per cent (Grochowsk I 9 6 0 ) . A range of form factors from O.34O to O.52O was found i n second growth Douglas f i r (Smith et, a l . 1 9 6 l ) . The form quotients measured on 751 spruce stems i n the eastern United States fluctuated between O.462 and 0 . 5 6 7 (Clark 1902). The true form factors of Hohenadl, using a reference diameter measured at a height equal to 10 per cent of the t o t a l height (Prodan 1951), were as low as O.38O f o r Scotch pine and as high as 0 . 6 2 0 f o r Norway spruce (Picea abies) (Dittmar 1958; Al t h e r r 1953). The interspecies v a r i a b i l i t y i n form seems to be smaller than the intraspecies v a r i a b i l i t y . However, d i f f e r -ences i n volume between black and red spruces of the same diameter and height amounted to 12 per cent throughout the range of size classes (Spurr 1952). For the same diameter 9 and height, volume of Douglas f i r was, on the average, 10, 16 and 11 per cent less than that of Norway spruce, white f i r and Scotch pine, i n that order (Hausser and Bolsinger 1956). The under bark form of a l l important B r i t i s h conifers was sub-s t a n t i a l l y the same f o r the greater part of the length of t h e i r stems a f t e r the influence of the butt swell was elim-inated. It was only towards the t i p that marked differences began to appear (MacDonald 1932, 1933)» Fast taper combined with large butt swell was observed i n conifers on swampy s i t e s ; the trees from upland s i t e s and from the ridges showed the least amount of butt swell and also tapered l e s s (Spurr 1952)o Highly variable butt swell amounted to 5 per cent of the t o t a l volume i n some conifers over 16 inches i n diameter and could not be correlated with any of the variables analysed (Behre 1935) <• Butt swell was associated with crown development i n white pine; trees with long and wide crowns were found to have considerably greater butt swell (Gevorkiantz and Hosley 1929)« Root swelling affected the measurement of form of 472 Douglas f i r stems i n about 90 per cent of the cases; i n trees over 30 feet i n height, root swelling was found to extend as f a r as breast height i n almost every tree, and the amount of swell increased with the g i r t h (MacDonald 1933 )<> Butt swell extended frequently 12 feet and more above ground i n most conifers growing i n B r i t i s h Columbia (Claughton - Wallin and McVicker 1920) . Determination of the average form quotient was a more important source of error i n the estimation of volume than 10 e i t h e r the allowance f o r butt swell or bark thickness, but the l a t t e r was almost as s i g n i f i c a n t as the former i n the larger trees (Behre 1935)» No appreciable differences between form quotients calculated from measurements outside the bark, as compared with underbark form quotients, were found i n white pine (Gevorkiantz and Hosley 1929)» Differences i n volume as large as 40 per cent may occur i n some Australian species i f bark thickness i s disregarded i n t h e i r form assessment (Gray 1956)» Percentage of bark varied along the bole of B r i t i s h conifers i n a regular and consistent manner; i n the middle of the stem, i t was least variable and smaller than e i t h e r at the t i p or at breast height. The rapid increase i n bark percentage along the upper f i f t h of the bole was c h a r a c t e r i s t i c of a l l conifers investigated (MacDonald 1933)« White pine (Pinus  Strobus) trees of eastern U«S»A-» behaved s i m i l a r l y (Gevorkiantz and Hosley 1929)» Percentage of bark at breast height decreased with diameter or with g i r t h (Grochowski 1961; Korsun 1962; MacDonald 1933)p or was constant (Behre 1927). Consistent regional differences i n bark thickness at breast height i n trees of the same diameter were found i n pine by Wiedemann , (I.932) and Korsun (1962). I t i s evident that form of i n d i v i d u a l trees as measured by various methods varies considerably within any one .. specieso In spite of t h i s , modern methods of volume estimation do not regard measures of form as e f f i c i e n t s t a t i s t i c s . The stochastic r e l a t i o n s h i p e x i s t i n g between height, diameter and volume of stems i s usually determined empirically from a large 11 number of measurements of diameter and height* The r e s u l t i n g volume tables are thus based on a tree of an average form; because of t h i s they are not precise means of volume estimation of i n d i v i d u a l trees. The average form of most coniferous species of the northern temperate zone approaches c l o s e l y to that of a quadratic paraboloid. This fact can be deduced from a scrutiny of the r e s u l t s of volume studies conducted i n the past. As early as 1883 Strz e l e c k i suggested that there was a dir e c t p roportionality between the paraboloidal form fa c t o r and form quotient on one hand, and the form factor and form quotient of a tree bole on the other. Hence, there was a functional r e l a t i o n s h i p between the form f a c t o r and between the form quotient of tree boles (Gray 1943)• This r e l a t i o n s h i p was expressed by the equation form factor = (0.71) form quotient. Kunze's formula published i n 1891, form factor = form quotient - constant, i s a d i f f e r e n t formulation of the same r e l a t i o n s h i p . Average values of the- constant i n Kunze's equation, established empir-i c a l l y i n Europe, were 0 .21 and 0 .20 f o r Norway spruce and Scots pine r e s p e c t i v e l y . Those derived i n U.S.A. f o r f i r and spruce were 0.219 and 0.218 (Clark 1902; Belyea 1925). The t h e o r e t i c a l value'of the constant i s , i n the case of a paraboloid, 0 . 2 0 7 . Reynard (1884)j working with the concepts of S t r z e l e c k i , estimated the volume of tree stems i n Switzerland by the formula V = 0.555 d D H 12 where V = cubic volume, d = mid-point diameter, D = basal diameter, H - t o t a l height. Reynard's formula can be written as ' . . . . I . : ?.-?7l& , In t h i s form i t gives the volume of the paraboloid i n cubic feet and compares favourably with Spurr's rule-of-thumb f o r estimation of volume of standing trees v 100 4 which l a t t e r rule was derived by methods of regression analysis (Spurr 1952). S i m i l a r l y , 16 of the volume equations derived from 16 mostly broadleaved species of B r i t i s h Columbia averaged V = 0.22 + 1.3 (Smith and Ker 1957), nine equations f o r coniferous species could be combined to 2 V = 0.24 j[Q§ +-©.17 (Smith and Breadpn 1964). In the logarithmic volume equation of Bruce and Schumacher (1950), log V = a log D 4 b log H + l o g C the power of D equals 2.0 and that of H equals 1.0 i n the ease that i t i s applied to a bole which has a parabolic form. It holds i n a l l cases when the form fa c t o r of a population of trees i s constant f o r a l l size classes sampled and therefore independent of diameter and height. The respective values of the powers of D and of H based on analyses of 49 d i f f e r e n t .13 non-form volume tables i n the eastern and southeastern U.S.A. were 1.94 and 1.12 f o r pines and spruces combined, and 1.88 and 0.94 f o r spruces and f i r s combined. In f i v e sets of form class volume tables the slope exponents of D were, without exception, 2.0 (Spurr 1952). The value of Hohenadl Ts true form fa c t o r i s , i n the case of a paraboloid, 0.555* Average Hohenadl's form factor calculated f o r various species and numbers of stems were as follows: O.555 f o r 1,330 Norway spruces (Krenn 1944) 0.549 f o r 13,310 Norway spruces (Zimmerle i n Altherr 1953) O.55O f o r 543 European larches (Zimmerle i n Altherr 1953) O.55O f o r a "large number" of Norway spruces ( S c h i l l i n g i 9 6 0 ) . Recognition of the fa c t that, given a large mass of data, the majority of the conifers of the northern temperate zone has, very approximately, the same form from the top to the bottom i s r e f l e c t e d i n the dictum of Jonson: The percentile taper i s the same i n a l l "normal" spruce of the same form class notwithstanding the differences i n height and diameter. A large tree i s developed exactly as a small tree, providing that both have the same form quotient. (Claughton-Wallin and McVicker 1920) . The method of volume estimation developed by Jonson (1928), the new concepts of constructing the taper curve volume tables formulated by Baker (1925) and by Belyea (1931), as well as the method of Hohenadl (Krenn and Prodan 1944) are a l l based on the recognition of the f a c t that form i s , on the average, independent 14 of diameter and height. The method of Jonson i s further memorable i n that i t uses the external c h a r a c t e r i s t i c s of the crown i n the estimation of the form of the bole. I t s working hypothesis i s Metzger ts "wind pressure theory" or "girder theory" of bole formation. 15 STEM FORM THEORIES - 1 Most s c i e n t i f i c concepts have t h e i r o r i g i n i n experiment, or are supported by experiment to some extent. Other kinds of s c i e n t i f i c thinking are pure speculations; they may help to explain natural phenomena but t h e i r status should always be kept i n mind. Theories are schemes of thought with assumptions chosen to f i t experimental evidence; they may also contain speculative ideas. In examining any conceptual scheme i t i s necessary to separate i t s experimentally v e r i f i e d s c i e n t i f i c concepts from the speculative ideas which may accompany them. The concepts underlying the theories of stem form-ation were tested experimentally i n large trees under forest conditions i n only a few i s o l a t e d instances. This applies to the comparatively recent hormonal theory as well as to the n u t r i t i o n a l and mechanistic theories both of which were formulated more than 80 years ago. At present, the nature of the above theories, and also of the water conductive theory, i s thus lar g e l y speculative. This statement i s supported by the r e s u l t s of various researches, many of which may have only an i n d i r e c t bearing on the morphology of tree stems. The uneven d i s t r i b u t i o n of r a d i a l increment along the bole has been attributed to the uneven d i s t r i b u t i o n and u t i l i z a t i o n of elaborated foods within the cambial cylinder, not only by early writers but also by some contemporary investigators. 16 The quantity of foods available f o r growth at any point within the erown bole i s assumed to stand i n a dir e c t proportion to the quantity of f o l i a g e above the point i n question. In t h i s way the maximal concentration of photo-synthates i s supposedly reached at the base of the l i v e crown where maximal r a d i a l growth w i l l occur. Hardly any change i n the amount of r a d i a l growth takes place along the branchless portion of the stem. The boles of open grown conifers assume the conical shape of t h e i r crowns. Suppressed trees produce only a l i m i t e d quantity of foods, consumed i n the course of t h e i r basipetal transport, r e s u l t i n g i n depressed r a d i a l growth or, i n extremis, missing rings at the base. Accumulation of food substances near the root c o l l a r i n the early spring, ..and increased growth at the base, i s due to the delay i n r a d i a l growth of roots which, i n turn, i s caused by low s o i l temper-atures (Topcuoglu 1941; Onaka 1 9 5 0 a ) . Interpretation of H a r t i g ? s n u t r i t i o n a l theory by Paul ( 1 9 3 0 ) , and by Larson ( I 9 6 3 ) , d i f f e r s from that by Topcuoglu and Onaka. According to Larson, Hartig evaluated a l l the growth i n terms of an equilibrium between ass i m i l a t i o n and t r a n s p i r a t i o n . The i n t e n s i t y of t r a n s p i r a t i o n , considered by Hartig to be a function of the size of the l i v e crown, i s the chief f a c t o r conditioning the growth of conductive ti s s u e , i . e . , earlywood. Production of latewood i s due to increased assim-i l a t i o n , and i t s formation begins only a f t e r the t r a n s p i r a t i o n a l 17 demands are met* Any changes of the size of l i v e crown, such as i t s increase a f t e r thinnings, or i t s reduction by pruning, i s r e f l e c t e d i n an increased formation of earlywood i n the former, case; or i n a decreased formation of earlywood i n favor of latewood i n the l a t t e r case. Mechanistic "wind pressure theory" or "girder theory", conceived by Schwendener i n 1874 and subsequently implemented by Metzger, maintains that wind i s the prime mover shaping the boles of t r e e s . Force of the wind against the crown sets up bending stresses i n the stem. These stresses are assumed to be uniformly d i s t r i b u t e d along the branchless length of the stem and to act as cambial s t i m u l i . Amount of r a d i a l growth at any point along the bole beneath the l i v e crown i s proportional to the magnitude of stress developed at that point. Accordingly, the r e s u l t i n g shape of the stem i s that of a beam of uniform resistance to bending. Its p r o f i l e i s described by a cubic parabola having i t s vertex i n the center of gravity of the crown (Trendelenburg 1937; Hildebrandt 1954; Gray 1956) . Jaccard (1915> 1930) concluded, a f t e r determining the conductive capacity of the recent annual rings, that growth i n cross-sectional area between the roots and the base of the l i v e crown was such as to permit uniform and continued water transport to the crown. Dead branches remaining on the stem , reduce the cross-sectional area of the most recent rings and, therefore, t h e i r conductive capacity. Uniform conductive capacity could be maintained only when the cross-sectional area 18 of the most recent rings increased at the same rate at which i t was reduced by dead branches. Hence the commonly occurring increase of r i n g width with height. Every factor favoring the growth of the crown as a s i t e of t r a n s p i r a t i o n causes a corresponding increase of the roots. Increased growth of roots i s , however, possible only a f t e r they obtain foods from the crown. A tree can be v i s u a l i z e d as composed of two regions competing f o r carbo-hydrates . Growth of the upper part of the stem i s under the influence of the crown, whereas growth of the lower part of the stem i s dominated by roots. The minimum r i n g width of the annual layers occurs i n the zone between the two competing regions. S t r i k i n g differences i n date of resumption and cessation of c e l l d i v i s i o n observed i n branches, stems and roots of a tree can be explained i n s i m i l a r fashion. Gradual changes of form are probably accompanied by small changes of the height of the minimum width of the annual layer as i t moves upwards. The hormonal theory a t t r i b u t e s the uneven d i s t r i b u t i o n of xylem c e l l s along the bole to the gradients of the growth substances which can be detected i n the cambial meristems during the growing season and which, i n suitable concentration, stimulate p e r i c l i n a l d i v i s i o n s i n cambium (Soeding 1940, Onaka 1950 b). The elongating buds are con-sidered to be the chief producers of auxin and the sole d i s t r i b u t o r s of the cambial s t i m u l i . In t h i s way they control the architecture of the whole tree, including branches and roots (Larson 1962) . There i s a corr e l a t i o n i n time between the resumption of the cambial a c t i v i t y and renewal of bud growth. High auxin l e v e l s i n shoots i n spring cause wide vessel formation i n angiosperms. Mature leaves produce small amount of auxin, which may account f o r the continued production of latewood a f t e r extension growth stopped (Wareing 1958) . Auxin i s a c o l l e c t i v e name f o r a complex of phyto-hormones such as indole acetic acid, k i n e t i n and g i b b e r e l l i n s which are of absolute necessity f o r some fundamental reactions taking place i n the d i v i d i n g and growing c e l l s with c e l l u l o s e walls (Maskova 1948, Thimann 1952, Wort i 9 6 0 ) . Auxin i s sometimes assumed to loosen some linkages i n the c o l l o i d a l framework of the c e l l wall. This leads to a decreased wall pressure and to stretching of the cytoplasm and of the c e l l wall under osmotic uptake of water. The next step i s the formation of the new wall material and the growth by intussusception (Burstroem 1957) . Decrease or disappearance of auxin i s always associated with the cessation of the r a d i a l growth even i n cases when reserve foods abound. Auxin moves downward through protophloem and phloem in a wave l a s t i n g a few weeks. This movement i s followed clo s e l y by cambial d i v i s i o n (Avery et a l . 1937)* Due to gravity, auxin accumulates on the lower side of horizontal organs. Both kinds of reaction wood, namely "compression wood" on the lower side of i n c l i n e d coniferous trunks and "tension wood" on the upper side of hardwood stems are due to uneven concentrations or quantities of auxin (Wareing 1958; Wareing and Nasr 1 9 6 l ) . 20 STEM FORM THEORIES - 2 The common basis of the n u t r i t i o n a l , conductive, mechanistic and hormonal theories i s the l i v e crown. According to the "wind pressure theory", the in t e n s i t y of the wind attack i s proportional to the size of the l i v e crown, presumably at a l l wind v e l o c i t i e s and frequencies, and at a l l stand d e n s i t i e s . Therefore, the size of the l i v e crown i s an ind i c a t o r of the stem form. The size of the l i v e crown and the d i s t r i b u t i o n of the foliage i n the crown are also important f o r both the con-ductive and the n u t r i t i o n a l theories. Furthermore, i t i s also believed that The external fa c t o r s of climate and environment exert t h e i r influence d i r e c t l y on the growth of crown and only i n d i r e c t l y on the development of wood ... by a c t i v a t i n g physiological processes often quite f a r removed from the actual site of wood production (Larson 1963a).• Size of the crown i s , i n the majority of cases, loosely correlated with various measures of form (Gevorkiantz and Hosley 1929; Jonson 1928; Krenn 1944; Grochowski 1961). A more d e f i n i t e r e l a t i o n s h i p seems to exist between form and density of the stand (Wright 1927), which i n turn determines the depth of the l i v e crown i n stands with a closed canopy (Brown 1962). The most s t r i k i n g changes i n form were observed a f t e r the density of the stand was changed by thinnings and cuttings (Meyer 1931; Behre 1932; Pearson and F o l l w e i l e r 1927; Yerkes I 9 6 0 ; Myers I 9 6 3 ) . Such changes are usually explained i n terms 21 of the mechanistic theory,,i.e» they are commonly attributed to a heightened wind attack (Windirsch 1936, Assmann i960, Myers I963). I f the forces of wind are not important, e.g., i n the suppressed trees, then the nearness of crown as the source of building material i s considered to be s i g n i f i c a n t (Gevorkiantz and Hosley 1929). Both the n u t r i t i o n a l and the conductive theories correlate r a d i a l growth with food production and d i s t r i b u t i o n , as well as with.the water loss by stomatal t r a n s p i r a t i o n (Jaccard 1915, 1928, Topcuoglu 1941; Onaka 1950 a; Larson 1963c), A proportionality between the quantity and d i s t r i b u t i o n of f o l i a g e , and between rate and d i s t r i b u t i o n of r a d i a l growth along the bole, as well as the proportionality between the size of crown and quantity of water transpired, i s assumed by both theories (Fraser et a l . 1964, Jaccard 1915, 1930). Intensity of net a s s i m i l a t i o n of CO2 and the rate of stomatal t r a n s p i r a t i o n are determined l a r g e l y by factors governing size of the stomatal aperture. Apart from i t s d i r e c t e f f e c t s on the photosynthetic t i s s u e s , temperature i s believed to be a f a c t o r important i n stomatal control and, therefore, i n c o n t r o l l i n g the rate of the net photosynthesis, the rate of the stomatal t r a n s p i r a t i o n and, possibly, the rate of water'conduction and absorption. Curtis (1936) maintained that increased t r a n s p i r a t i o n i s due solely to a r i s e i n l e a f temperature, the vapor pressure gradient from l e a f to a i r being a f a c t o r of major importance. Indeed, tr a n s p i r a t i o n at 22 30°C i s nearly three times as fast as at 20°C (Meyer et alo I 9 6 0 ) . Transpiration followed very cl o s e l y net radiatio n received by a leaf as long as there was s u f f i c i e n t s o i l moisture (Gates 1962) . Leaves respond to t h e i r external environment i n accordance with accepted heat transfer theory. They tend to assume the temperature of the surrounding a i r . Leaves are heated by radiant energy and cooled primarily by conduction of energy to the a i r . Leaves i n sunlight are heated to a few degrees centigrade above a i r temperature f o r t h i n leaves to 30°C, or more, f o r very t h i c k leaves (Loomis 1965; Knoerr and Gay 1965) . The overheating of leaves i s l i n e a r l y related to the i n t e n s i t y of r a d i a t i o n . Temperature of the exposed top surfaces of leaves i n wind shadow can be, on the average, 10 times as high as the temperature of the a i r layer near the ground (Casperson 1957) . Leaves may reach temperatures as high as 37°C and be warmer than the a i r by 13 - 20°C (Fritzsche 1932) . Temperature increments due to the position of leaves may be more than 7 GC and may increase trans' p i r a t i o n by up to 230% (Konis 1950) . Exposed leaves may be 12°C warmer than shaded leaves; a leaf perpendicular to i n s o l -ation may be 3 ° to 8°C warmer than a l e a f p a r a l l e l to in s o l a t i o n (Waggoner and Shaw 1952; Wellington 1950) . These figures indicate c l e a r l y that d i r e c t proportionality between the size of a crown and between the quantity of water l o s t by t h i s crown may not exist i n the f o r e s t . 23 Most of the leaves during s t i l l weather and a l l leaves during a wind period lose large amounts of water i f the stomates are open so that photosynthesis may go on (Crafts .et a l . 1949)• Increased t r a n s p i r a t i o n , desiccation of leaves, closure of stomates, and r e s u l t i n g curtailment i n the production of foods, can also be caused by wind (Satoo 1957)• In t h i s , e f f e c t s of wind and e f f e c t s of temperature cannot be separated, just as gradients of a i r temperature cannot be separated from the wind gradients; they a f f e c t and determine each other (Best in Geiger 1950) . Rapid t r a n s p i r a t i o n caused by wind i s not harmful as long as the rate of water absorption balances the rate of water loss (Satoo 1957) . As a rule, the rate of absorption tends to l a g behind the rate of trans-p i r a t i o n so that water d e f i c i t s develop i n plants growing i n moist s o i l (Kramer i 9 6 0 ) or even i n plants with t h e i r roots i n water or nutrient solution (Kramer 1937) . Both saturated and dry s o i l s reduce the rate of apparent photosynthesis i n coni f e r s . A period of 30 to 60 hours was necessary f o r water to pass from the s o i l to the fol i a g e i n some coniferous seedlings (Clark I 9 6 I ) . Absorption l a g seems to be caused by the resistance offered by the c e l l membranes of the rooting system. Stem resistance i s probably a n e g l i g i b l e f a c t o r i n absorption i n woody species (Kramer 1938) . In coniferous seedlings tested without roots, a change i n absorption rate followed the change i n t r a n s p i r a t i o n (Satoo 1957)« Water entered more ra p i d l y from the s o i l through dead than through 24 l i v i n g roots (Kramer 1933)* Root pressure was denied any influence i n water transport i n plants (Braun 1 9 6 l ) , but rates of upward t r a v e l i n root-pruned trees were s i g n i f i c a n t l y lower than those i n normal trees (Greenidge 1 9 5 8 )e The phenomenon of time lag i n water absorption has an obvious bearing on the water conductivity theory of stem formation., Jaccard's concept of the "stem of uniform conductive capacity f o r water" i s i l l o g i c a l i f resistance to the passage of water through the roots rather than through the stem i s c r i t i c a l i n trees. As i s evident, the problem of water supply i n plants resolves into r e l a t i o n of the rate of absorption to water l o s s . : According to Crafts e_t a l . (1949), and contrary to the con-clusions of Curtis (1933)> water vapor i n the atmosphere profoundly a f f e c t s water movement through plants. Dif f u s i o n pressure d e f i c i t of water vapor i n the atmosphere i s a fa c t o r of primary importance i n stomatal cont r o l . Indeed, the water loss from leaves was an inverse l i n e a r function of the r e l a t i v e humidity (Thut 1939)« The capacity of atmosphere to hold water vapor approximately doubles f o r every r i s e of 20°F, but the influence of temperature at constant r e l a t i v e humidity i s small (Anderson 1936; Crafts et a l . 1949)* Relative humidity within stand i s governed p r i n c i p a l l y by the water output of the crown space f o l i a g e (Geiger 1950) . Transpiration, although estimated to be as much as the annual equivalent of 17 - 22 inches of r a i n i n an oak forest i n the eastern U.S.A« (Meyer et a l . 1960), was of secondary importance i n the dampening of the forest atmosphere of an oak forest i n the USSR; the physical evaporation from the s o i l was more important i n t h i s respect (Goryshina and Neshataev i 9 6 0 ) . Under laboratory conditions, the rate of evaporation from a water surface i s proportional to saturation d e f i c i t of the a i r above the surface from which i t i s taking place (Hammond and Goslin 1933)» However, evaporation from a water surface did not provide an index of evaporation from the s o i l (Kittredge 1954)° In the f o r e s t , the e f f e c t of water vapor pressure d e f i c i t i s masked by the influence of other micro-environmental factors (Selleck and Schuppert 1957; Heinrich 1950). Nevertheless, the c o r r e l a t i o n between vapor pressure d e f i c i t and rate of evaporation i s high and under a strong influence of the mass exchange (Goehre 1952). The mixing of a i r i s hampered by the closed canopy. In the crowns, the points of contact represent the zone of absence of turbulent exchange and have the most stable conditions of maximal humidity combined with minimal evaporation (Pogrebnyak e_t al« 1957). Any opening of the closed canopy activates increasingly the fac t o r s governing evaporation on which, i n the f i n a l analysis, the stomatal t r a n s p i r a t i o n depends (Niederhof and Stahelin 1942; Haddock 1961)0 Because of t h i s , the action of the moving a i r cannot be disregarded by eit h e r n u t r i t i o n a l or conductive theory. 2 6 The d a i l y wind movement i n crowns increased up to 4 times a f t e r heavy thinnings i n white pine; the d a i l y temperature i n crowns was also higher, the evaporation increased by 6 .2 per cent while the r e l a t i v e humidity decreased.. Crowns modified the temperature to 8 inches above the ground. At t h i s elevation the d a i l y wind movement increased up to 3 times and evaporation was higher by 24»5 per cent as compared with the unthinned stand (Adams 1930* 1935)* Wind at the periphery of crowns of broadleaved species was 8 times higher than i n the center of the crown. A wind of low v e l o c i t y caused greater difference i n the a i r movement between the center and the periphery of the crown than a strong wind (Hanson 1917)* Low wind v e l o c i t i e s were also most e f f e c t i v e i n increasing the rate of evaporation i n the f o r e s t . Wind as a component f a c t o r i n an analysis of c o r r e l a t i o n of evaporation rate to vapor pressure d e f i c i t decreased the variance i n evaporation unrelated to vapor pressure d e f i c i t by 54 per cent (Kucera 1954)• Apparently, the action of wind i n the forest i s not simply li m i t e d to the inducement of bending stresses i n the stems of the swaying trees, hence to a hypothetical stimulation of cambial layer. The existence of cambial stimuli caused by purely mechanical stresses has not been established. Therefore, the n u t r i t i o n a l and the conductive theories are linked by a common group of factors governing the rate of the net production of dry matter and the water 27 balance i n trees. Since i t i s believed that the hormonal theory provides a physiological basis f o r the f a c t s encompassed i n the n u t r i t i o n a l , water conductive and mechanistic theories (Larson 1963c) , none of the current stem form theories can be used separately to explain the form of t r e e s . The n u t r i t i o n a l gradients within the cambial cylinder or, a l t e r n a t i v e l y , the ageing of the cambial layer, as well as the p r i n c i p l e of competition by the growing c e l l s f o r photo-synthate, were a l l considered by some writers as being capable of explaining the d i s t r i b u t i o n of the r a d i a l growth of the c o n i f e r s . A stream of organic substances, envisioned as migrating along the v e r t i c a l axis, supplies the competing c e l l s produced by p e r c l i n a l d i v i s i o n with the necessary foods. The n u t r i t i o n a l status of the cambium deteriorated b a s i p e t a l l y , from one internode to another, owing to a steadily diminishing supply of elaborated foods associated with the increasing demand f o r them.. The gradual decline i n width of the xylem layer p a r a l l e l e d that of the metabolite l e v e l which, i n turn, probably was due to uneven ill u m i n a t i o n of the green foliage (Kienholz 1934; Duff and Nolan 1953, 1957; Farrar 1961) . Cambial ageing was ruled out as a f a c t o r c o n t r o l l i n g the r a d i a l growth, but the concept of the n u t r i t i v e gradients within the cambial layer was retained (Forward and Nolan 1 9 6 l a , b; 1962; Fraser et a l . 1964) . The existence of the n u t r i t i v e gradient i n the cambium or i n the phloem of the coniferous trees, such that i t would correlate with a gradient i n r a d i a l 28 growth, was never established. On the contrary, there seems to be a general lack of information i n t h i s respect. In one instance studied, concentration of sugar i n the phloem sap collected at d i f f e r e n t elevations along the bole of some broadleaved species during a part of one growing season, decreased b a s i p e t a l l y . Also, the concentration of the sap collected at 1.3 m above ground decreased with increasing height of trees (Topcuoglu 1941)» Radioactive tracers have shown that nutrients may be translocated i n the phloem i n opposing l o n g i t u d i n a l d i r e c t i o n s simultaneously (Biddulph et a l . i n Steward 1957) . The presence of d i r e c t p r o p o r t i o n a l i t y between the quantity of green f o l i a g e and amount of r a d i a l growth achieved i n the stem immediately beneath the point of attachment of t h i s f o l i a g e , as assumed by n u t r i t i o n a l theory, has not been proven. U n i l a t e r a l pruning of conifers did not a f f e c t the rin g width along the stem perimeter, nor did i t cause t h e i r stems to become eccentric (Burns 1920; Onaka 1950b). S i m i l a r l y , asymetric crowns did not produce eccentric growth i n the boles supporting them (Lodewick 1930) . However, impaired r a d i a l growth and discontinuous rings were observed on the branchless side of the boles of sequoia sprout clumps ( F r i t z and A v e r i l l 1925). The quantity of f o l i a g e stands apart from i t s e f f i c i e n c y (Schmidt 1953)• In the same way as the t o t a l size of l i v e crown may not be a v a l i d index of the rate of the t o t a l 29 r a d i a l growth (Lodewick 1930% Wadsworth 1942| Reukema 1 9 6 l ) , the quantity of green f o l i a g e born by i n d i v i d u a l whorls of branches may not have any bearing on the immediate dimensions of the xylem layers. Within a macroclimatic s i t e , the influence of a crown's microclimate was shown to be c r i t i c a l f o r the i n t e n s i t y of the gaseous exchange processes and there-fore f o r the rate of the net photosynthesis. For instance, top leaves of a young poplar tree i n the northern edge of the stand were more productive than the leaves at the base of the crown. They were also more productive than the t o t a l f o l i a g e of a s i m i l a r tree located a few yards away on the south edge of the stand (Polster and Neuwirth 1 9 5 8 K Suppressed Norway spruce trees produced more wood per unit of the crown area or per unit of foliage volume than the dominant spruce on the same macrosite (Neuwirth I 9 6 3 K The assi m i l a t i o n patterns of young Douglas f i r were strongly correlated with conditions promoting the saturation of the leaf t i s s u e s ; the mid crowns were most e f f i c i e n t photosynthetically (Gentle 1959)« Morphological and anatomical differences e x i s t i n g between the leaves i n the sun and shaded leaves within the crowns of some broadleaved species were greater than s i m i l a r differences reported f o r leaves of mesophytic and xerophytic forms of the same species (Hanson 1917)» At the same height i n the crown, the sun leaves were twice as thick as the shade leaves and t h e i r surface area was smaller (Talbert and Holch 1957)0 A gradual deformation of needles was observed i n crowns 30 of Norway spruce i n basipetal d i r e c t i o n . Three d i s t i n c t l y d i f f e r e n t types of needles could be recognized (Schoepfer 1 9 6 l ) . The morphology and anatomy of sun and shade needles has a d e f i n i t e bearing on t h e i r photosynthetic e f f i c i e n c y . Shade needles of white pine and balsam f i r assimilated about 150 per cent more CO2 than the sun needles at a l l l i g h t i n t e n s i t i e s . They also respired l e s s than the sun needles at a l l temperatures (Clark 1 9 6 l ) . The sun leaves of Ulmus americana l o s t 12 times as much water as did the shade leaves (Hanson 1917)• It i s generally known that the shape of boles and also t h e i r inner structure change a f t e r thinning and afte r pruning. This phenomenon i s explained by the n u t r i t i o n a l theory as follows; Since thinning increases crown size and tran s p i r a t i o n , a promotion of both earlywood and taper would be anticipated. Pruning, on the other hand, decreases crown size and trans p i r a t i o n , and one would expect a decline i n earlywood and taper but resurgence of latewood formation (Larson 1963c) . Thinning does not always increase the size of the crown immediately. On the contrary, branch elongation and crown surface may decrease i n released trees (Reukema 1964) . The r e d i s t r i b u t i o n of r a d i a l increment along the bole takes place, as a rule, immediately during the next growing season a f t e r release or af t e r crown reduction (Marts 1949, 1951; Lehtpere 1957; Forward and Nolan 1 9 6 l a , b; Reukema 1964)« Short-term changes and the t o t a l rate of elongation of red pine depended more on the immediate environment than on the inherent genetic 3 1 character of the t r e e . Branches did not d i f f e r from the main axes i n t h i s respect. Influence of the environment on growth of branches i n old trees was more important than that of the tree age (Forward and Nolan 1964)0 S i m i l a r l y , pruning does not necessarily promote growth of latewood. The reduction by 75 per cent of l i v e crowns of open-grown long l e a f pine depressed the r a d i a l growth d r a s t i c a l l y but the proportion of earlywood within the layer formed during the season following the season of treatment increased by about 3 0 per cent at BH (Marts 1951)• The verdict of Buesgen and Muench (1929) on n u t r i t i o n a l theory was as follows. A l l ... researches directed to explaining the d i s t r i b u t i o n of growth i n i n d i v i d u a l regions of the cambium by l o c a l differences i n n u t r i t i o n must be regarded as having miscarried .... A l l observations on the trees as on a l l other organisms agree that, i n cases of undisturbed development, growth does not take place where the materials flow i n , but the materials flow i n to the place where growth i s going on. The premises of Jaccard Ts water conductive theory of stem formation are based on the assumption of the cohesion-tension theory of water conduction through stems, i . e . , on a phenomenon which remains to be explained. In the words of Meyer et a l . (I960) It i s e n t i r e l y wrong to claim that water movement through plants requires occurrence of t r a n s p i r a t i o n . Translocation of water to the extent that i t i s used i n restoring c e l l turgor continues even during the periods when the t r a n s p i r a t i o n rate i s n e g l i g i b l e . 3 2 Decapitation of r i n g porous and diffuse porous hardwoods did not prevent the transport of water to the extremities of the stem. The r e s u l t s were s i m i l a r a f t e r a l l the water conducting pathways i n the bole were severed repeatedly by a series of overlapping cuts (Greenidge 1 9 5 5 > 1 9 6 2 ) o Toxic solutions were transported to above atmospheric heights (Slatyer i960). Solution of P 3 2 moved r a d i a l l y i n xylem towards and away from the p i t h (Kiselev 1962) . It i s believed that the t r a n s p i r a t i o n a l stream may be l i m i t e d to one or two outer annual rings (Chalk and Bigg 1956) . The demarcation of the water conducting pathways seems to be greatly complicated by the almost universal occurrence of s p i r a l growth the pitch of which varies with height i n tree, and with treatments such as release and crown reduction (Northcott 1957; Kennedy and E l l i o t 1957; Vite 1958) . The high l e v e l s of significance of correlations between measures of the size of l i v e crown and measures of form found i n Sweden (Jonson 1 9 2 8 ) do not seem to be generally reproducible. The s i m i l a r r e l a t i o n s h i p s i n the natural f o r e s t s i n Canada and U.S.A. were too poorly defined to be useful (Wright 1927; Gevorkiantz and Hosley 1929)<• The r e l a t i v e length of the l i v e crown was only loosely correlated with form i n managed stands of the continental Europe (Krenn 1944; Grochowski I 9 6 I ) . Form was not correlated with crown length i n plantation-grown conifers i n England (MacDonald 1932, 1933)* 33 These low or nonsignificant correlations are not i n accord with the concepts of the "wind pressure" theory. Trees were found which had the same height, diameter and form factor but very d i f f e r e n t crown lengths. This discrepancy was at t r i b u t e d to the strength properties of wood which are known to vary considerably within and between trees of the same species from one homogeneous s i t e ( L i t t l e f o r d 1961; Kommert 1964)0 Evidence was presented to the e f f e c t that the d i s t r i -bution of s p e c i f i c gravity i n stems was not f o r t u i t o u s but related to the stem form and crown length i n a fashion which agreed well with the tenets of Metzger's theory (Volkert 194l )« In the words of Larson ( 1963c) . It was recognized not only that stem form and wood density were intimately related but also that these values were i n turn strongly dependent upon crown size and development. The i n t e r r e l a t i o n s h i p between taper, s p e c i f i c gravity and length of crown such as shown by Volkert (1941) was not borne out by the researches of Pechmann (1954) and of Hildebrandt (1954)o The size of the crown i s usually not recorded i n studies concerned with s p e c i f i c gravity of stem wood. The r e l a t i o n s h i p between s p e c i f i c gravity and crown class, as well as that between s p e c i f i c gravity and rate of growth, were both investigated more frequently. Since the existence of a general c o r r e l a t i o n between the rate of growth and crown class may be j u s t i f i a b l y assumed (Ker 1953), the correlations between s p e c i f i c gravity and rate of growth should be of about the same 3 4 order as those which obtain between crown class and s p e c i f i c gravity. The length of the crown (Kramer I 9 6 2 ) , as well as width of the crown (Liebold 1963), were found to be correlated with crown c l a s s . I f so, then the above relationships bear on the r e l a t i o n of crown size to s p e c i f i c gravity. A degree of consistency would be expected to exist among the reported correlations between s p e c i f i c gravity on one hand, and rate of growth or crown class on the other, i f wood density depended strongly upon crown size and i t s development. Such i s not the case. The co r r e l a t i o n between s p e c i f i c gravity and crown class was low i n Douglas f i r (Wellwood and Smith I 9 6 2 ) , nonsignificant i n western hemlock (Wellwood i 9 6 0 ) and i n Douglas f i r (McKimmy 1959). Dominant Douglas f i r produced heavier wood than other crown classes i f r i n g width were held constant (Mozina i 9 6 0 ) . Also, dominant Douglas f i r produced wood of least s p e c i f i c gravity, while differences between crown classes were not s i g n i f i c a n t (Wellwood 1952). The r a t i o of crown length to t o t a l height accounted f o r an additional one per cent of the t o t a l v a r i a t i o n i n s p e c i f i c gravity (Stage I 9 6 3 ) . The rate of growth of Douglas f i r was not correlated with percentage of latewood (Wellwood and Smith I 9 6 2 ) . No co r r e l a t i o n , or weak correlations, were found between rate of growth and s p e c i f i c gravity of the same species by Harris and Orman (1958) and by Mozina ( i 9 6 0 ) , but a s i g n i f i c a n t c o r r e l a t i o n was obtained between strength and rate of growth (Harris and Orman 1958). S i g n i f i c a n t correlations between 35 rate of growth and s p e c i f i c gravity were found i n Douglas f i r by Knigge ( 1 9 5 8 ) , i n white spruce by Keith ( 1 9 6 1 ) , i n Japanese and European l a r c h by Pearson and F i e l d i n g ( I 9 6 I ) , i n Norway spruce by Schultze-Dewitz ( 1 9 6 1 ) ; nonsignificant ones i n l o b l o l l y and slash pine by Zobel et a l . ( i 9 6 0 ) , and i n Norway spruce by Hildebrandt ( 1 9 5 4 )• Specific gravity was lower i n wide-ringed as compared with narrow-ringed Douglas f i r having the same percentage of latewood (Paul 1 9 5 0 ) . V a r i a b i l i t y i n s p e c i f i c gravity or i n strength of wood between trees seems to be greater than that found within trees (Desh 1 9 3 2J Harris and Orman 1 9 5 8 ; Zobel and Rhodes 1 9 5 5 ; Kennedy I 9 6 I ) . With respect to s p e c i f i c gravity, the d i f f e r -ences between trees on the same si t e may be larger than differences between trees from d i f f e r e n t s i t e s or regions (Goehre 1 9 5 8 ; Schniewind 1 9 6 l ) . Differences between the poorest and the best s i t e s were less than differences due to spacing on the same s i t e (Jayne 1 9 5 8 ) ; wood of mountain-grown Douglas f i r or Norway spruce had lower s p e c i f i c gravity than that of trees from low a l t i t u d e s (Paul 1 9 4 6 ; Hildebrandt 1 9 5 4 ) . S p e c i f i c g r a v i t i e s of Douglas f i r planted across continental Europe showed a gradient decreasing from east to west (Knigge 1 9 5 8 ) o Basic density of Norway spruce decreased with increas-ing a l t i t u d e and l a t i t u d e within rings of a constant width (Ericson I 9 6 0 ) . Factors which cause the cambium of trees of the same species, growing on the same si t e and separated often by 36 only a few yards, to produce within an annual xylem layer of approximately the same dimensions s i g n i f i c a n t l y d i f f e r e n t proportions of earlywood and latewood were not explained. Some influence of microclimate (Glock 1955) microsite and heredity (Kennedy 196l) or heredity alone (Wellwood and Smith 1962) were suspected i n t h i s respect. Metzger's d3 rule was dismissed by Gray (1956) because the stems of trees are, on the average, quadratic and not cubic paraboloids. Gray (1956) formulated a general hypothesis as follows: The mechanical stress averaged over the whole section underbark i s constant along the length of the main stem and i f t h i s i s c i r c u l a r , the area of the section i s proportional to the stress on i t . As a rule, the cross-sectional areas of tree stems are very seldom c i r c u l a r , and eccentric growth, usually connected with n o n c i r c u l a r i t y , i s commonly encountered at any point along the bole (Kaburagi 1953)• It i s believed that eccentric r a d i a l growth i n trees represents an adaptation brought about by one-sided stresses caused by wind or, i n the case of leaning stems, by the force of gravity. The adaptive processes supposedly reinforce the stem i n a most e f f i c i e n t way and are, i n t h i s respect, comparable with s i m i l a r processes occurring i n the organs of animals (Trendelenburg 1937)• Pronounced eccentric growth of stems was observed even i n seedlings (Burns 1937) . This cannot possibly be explained, as i s customary f o r large trees, by a one-sided wind attack. Direction of pr e v a i l i n g winds was found to be i n 37 alignment with the major axis of the stem cross-section by M i l l e t (1944) and by Mueller (1958). Direction of p r e v a i l i n g winds did not agree with the orientation of the major axis i n Douglas f i r (Walters, -Kozak 1964)° In most reported cases the major axis was found to l i e i n the east-west d i r e c t i o n (Mussat; Grundner i n Chaturvedi 1926; Flemes i n Trendelenburg 1939; Heck i n Patterson and Colson 1952; Patterson and Colson 1952). The displacement of p i t h towards the southern perimeter of trees was observed and recorded by Leonardo da V i n c i (McMurrich 1930), displacement towards the north was reported i n 1735 by Buffon and Duhamel (Chaturvedi 1926)a A l l these reports seem to be based on measurements taken at one p o s i t i o n within the stem. Complete dissection of stems revealed that the s i t e of maximum r a d i a l growth may change i t s p o s i t i o n gradually along the bole following a s p i r a l course (Misra 1939? 1943)* Also, the maximum radius f o r any one year or group of years was not always i n the same v e r t i c a l axis (Adams 1928). Comparatively l i t t l e has been written about the magnitude and d i s t r i b u t i o n of mechanical stresses brought about by wind i n stems of trees. This i s understandable since The stresses and strains i n (a) log of timber are so complex that the problem has not yet been solved i n a manner that reasonably accords with the known strength of the beam as found by actual experiment (Claxton F i d l e r i n D'Arcy Thompson 1942). Bending stresses i n stems were eliminated by guying i n the experiments of Jacobs (1939, 1954)» Radial growth of trees prevented from swaying was d i s t r i b u t e d along t h e i r boles 38 i n a fashion which was more or l e s s i n accord with Metzger's hypothesis* The experiment of Jacobs seems to be commonly replicated, a f t e r a fashion, i n the t r o p i c a l r a i n forest where. ... trees are often bound together by the woody stems of l i a n e s so that they support one another very e f f e c t i v e l y <> •. a large tree i s often so strongly bound to i t s neighbors by lianes that even when cut right through at the base i t w i l l not f a l l (Richards 1952). Stems of many t r o p i c a l species are known to possess the buttressing habit. It would seem that the size, shape and p o s i t i o n of these structures present a strong case f o r the mechanistic theory. But there are reasons f o r doubting whether the advantages of buttressing are r e a l and valuable. buttresses are not developed where they are most "needed"; they are largest and most common i n trees i n sheltered v a l l e y s arid i n small trees i n sheltered undergrowth; they occur l e s s i n t a l l trees and l e s s i n trees growing on loose sandy s o i l s than i n trees on firm clays or i n trees on exposed ridges; i n the mountains they disappear altogether. Also, the buttressed trees may be more often blown down by wind than those without them. Since the buttressing habit depends on the systematic p o s i t i o n of the species ... they must be related to environmental conditions ... they are r e s u l t of the action of the habitat factors, any usefulness to the plant they may have being mainly i n c i d e n t a l (Richards 1952). In many t r o p i c a l regions v i o l e n t winds are l e s s common than i n temperate regions. Nevertheless, the buttressing habit i s f a r l e s s common i n e x t r a - t r o p i c a l trees. But i t i s not 39 absent i n them* The buttresses bn 46I Populus i t a l i c a trees i n Switzerland were most marked when the lower part of the trunk was i n shade and i n humid atmosphere. Their formation was stimulated near surfaces r e f l e c t i n g heat, sometimes i n a way which did not contribute to the s t a b i l i t y of the tree against overturning. In e f f e c t , i t could be detrimental to i t . Consequently, buttresses were not considered as functional structures but rather as accidental by-products of growth (Senn 1923) . Buttressing has been observed also i n l o b l o l l y and longleaf pine and was considered to be a protective reaction of trees to f i r e (Chapman 1942; Anderson and B a l t h i s 1944)* Formation of the enlarged bases of Fraxinus nigra i n Michigan bogs could not be r e l a t e d to wind attack (Gates and Erlanson 1925)o The character of buttresses i n Nyssa depended e n t i r e l y on the height and duration of flooding (Hadley 1926) . The enlargement of bases of Taxodium distichum was correlated with s o i l moisture regime. In streams and ponds the buttresses were of the same height regardless of the size of the tree (Harper I 9 O 5 ) . The development of buttresses i n cypress was a response to the simultaneous presence of water and a i r around the stem; prominent cone-shaped, bottle-shaped and bell-shaped buttresses were produced by varying depth and duration of the submersion (Kurz 1934) . In the opinion of Gray (1956), Metzger fs deduction was a rather a r t i f i c i a l one. only when a tree was embedded i n 40 a material s u f f i c i e n t l y strong would i t require the dimensions of a cubic paraboloid to o f f e r uniform resistance to l a t e r a l pressures. As trees are anchored i n weak material, Metzger's stem of uniform resistance was overdimensioned. Presumably, the s t a b i l i t y of trees against over-turning i s as important f o r t h e i r s u r v i v a l as that against breaking or s p l i t t i n g . In spite of t h i s , the current stem form theories pay l i t t l e or no attention to the problem of stem anchorage. Jaccard (1915) believed that every factor favoring the growth of the crown as a t r a n s p i r a t i o n a l organ caused a corresponding increase i n the roots. Forward and Nolan ( I 9 6 2 ) surmised,in the case of released trees, an increased production of hormone i n the root apices. The engineering p r i n c i p l e s encompassed by the mechanistic theory were applied to a study of root systems of Norway spruce by Fritzsche ( 1 9 3 3 ) * No influence of wind was found whatsoever on the development of deep-rooting systems, whereas the formation of shallow-rooting systems conformed with the precepts of Metzger (Fritzsche 1 9 3 3 ) . Stems of giant sequoias collapsed i n the absence of any wind action (MacDougal 1 9 3 7 ) , but i n Norway spruce the deductions of L a i t a k a r i , namely that the d i r e c t i o n of the p r e v a i l i n g winds and the size and position of the roots were correlated, have been upheld by Melzer ( I 9 6 4 ) . V e r t i c a l roots were of s l i g h t mechanical value to pine i n A u s t r a l i a and developed i n response to s o i l type and s o i l moisture; wind damage or windfirmness were not related 41 to crown size (Bryor 1937)• A r e l a t i v e l y small increase i n depth of rooting increased s i g n i f i c a n t l y the resistance to overblow of spruce i n peats over mineral s o i l s i n England (Fraser 1962)0 The orientation of the a e r i a l roots i n t r o p i c a l species agreed with the d i r e c t i o n of the p r e v a i l i n g wind attack (Navez 1930)o A e r i a l roots were also found to occur most frequently where they were least needed so f a r as the s t a b i l i t y of trees was concerned, i . e . , they occurred mostly i n small trees growing i n the sheltered and dense underbrush (Richards 1952)» Species otherwise buttressed tended to develop a e r i a l roots on a swampy s i t e and species not usually buttressed developed buttresses under swampy conditionso Aerial, roots were considered as an extreme form of response or adaptation to a high water table, and buttresses a moderate form (Beard 1948)o Depth of rooting was controlled by height of water table i n the case of partly submerged willow stems; the functioning roots occurred only i n the zone r i c h i n oxygen, i . e . , near the water l e v e l (Zimmerman 1 9 5 0 ) . Depth of rooting of white pine was r e s t r i c t e d by proximity of water t a b l e . A high water table resulted i n shallow root penetration. Deeper rooting was observed with lower water tables (Husch 1959)o High water table i n h i b i t e d the development of taproot of longleaf pine. Roots on an area with a water table 28 inches below the surface were 22 to 29 inches long compared with 3 to 6 feet on well-drained s o i l (Heyward 1933)» In sphagnum bogs the roots spread f a r more than those of the same 42 species growing i n mineral s o i l (Rigg and Harrar 1931)• Rooting habit of white spruce was modified by the periodic inundations which stimulated the production of adventitous roots (Jeffrey 1959)• The root system of black spruce was profoundly changed when the surface of a swamp was raised? formation of adventitous roots occurred above the root c o l l a r (Le Barron 1945)* Drainage increased the mechanical strength of s o i l , the depth of rooting and the resistance to overblow (Fraser 1962, Forestry Commission 1964) . On most mineral s o i l s , and i n the majority of species, the size of the rooting system may well be governed by the s o i l moisture regime according to t h i s r u l e : the greater the available moisture, the shorter the root and the greater the r a t i o between top and root (Haasis 1921) . Hence, p r i n c i p l e s of mechanical or conductive theories are not applicable to underground organs of trees under a l l conditions. A b r i e f survey of the l i t e r a t u r e w i l l show that r e s u l t s of a number of studies contradict the basic credos of the hormonal theory. It was maintained that only the dif f u s e porous species were e n t i r e l y dependent upon an exogeneous supply of auxin from extending shoots. In r i n g porous species, e.g., Fraxinus excelsior, another source of auxin was assumed to be available i n the i n i t i a l stages of the secondary growth (Wareing 1950) . In contrast with such findings, new xylem was found i n stems of debudded Prunus armeniaca. Radial 43 growth was largest at the stem base; none occurred i n the branches<> No abnormal tissues were detected i n trees without buds (Dvorak 1961). It i s well known that bark separates e a s i l y from the wood with the onset of growth i n the spring (Leeuwenhoek i n Commission of Dutch S c i e n t i s t s 1 9 6 l ; Bannan 1955)» Bark slippage was observed on f e l l e d , debranched and ringed stems of spruce and oak and was attributed to regener-ation of growth substances (Huber 1948) . Radial growth at the base of Monterey pine (Pinus ponderosa) continued f o r several seasons below a length of inactivated cambium (MacDougal 1943)• The cambial a c t i v i t y of young, vigorous, open-grown jack pine (Pinus Strobus) trees d e f o l i a t e d by insects was suspended f o r one year to be resumed again i n the basal region only<> The presence of a r i n g i n the basal portion of the stem, and i t s absence immediately above i t , could not be explained by eith e r n u t r i t i o n a l or hormone- theory ( 0 f N e i l 1963)'• Growth of defoliated l a r c h ceased over some parts of the cambial mantle while the other parts of i t were s t i l l active (Harper 1913 )<• Substances active i n bioassay, other than ind o l a c e t i c acid, were extracted from normal bark of Acer platanoides (Row 1 9 6 0 ) o It was maintained that cambia of trees contained growth substances, generated them, and moved them bas i p e t a l l y , without any stimulus o r i g i n a t i n g i n the upper reaches of tree (Soeding 1937; Jost 1940) . Similar conclusions were drawn from the studies of cambial tissue cultures; i n deciduous species, cambium or adjacent t i s s u e s contained a reserve of 44 growth substances even during the winter time, i n quantities permitting nearly optimum rate of growth at a certain temper-ature (Jacquiot 1949, 1950, 1951, 1952, 1957). I t was not necessary to add auxin to the culture medium i n order to i n i t i a t e a c t i v i t y of Picea and Abies cambial tissue cultures. Results were the same irr e s p e c t i v e of whether the tiss u e samples were removed from trees i n summer or i n winter. In the l a t t e r case d i v i s i o n might not occur even i f auxin was added (Jacquiot 1956) . Cambial tissue of Sa l i x capraea normally contained enough stimulants necessary f o r i t s d i v i s i o n ; the only indispensable substances from the beginning of i t s i s o l a t i o n was sugar (Gautheret 193$) . Slow p r o l i f -eration of cambial tiss u e of Crataegus monogvna occurred i n  v i t r o without any addition of growth substance (Morel 1946) . Evidently, the i n i t i a t i o n of the cambial growth might not depend on the export of hormones from elongating buds or leaves, or from the dormant buds. Radial growth may thus start long before height growth s t a r t s , and may not occur i n an orderly fashion following the wave of the b a s i p e t a l l y migrating auxin. I n i t i a t i o n of r a d i a l growth was not only completely divorced from extension growth i n some evergreen Indian species, but i t also occurred i n acropetal d i r e c t i o n (Chowdhury and Tandan 1950) . Radial growth i n pine started suddenly and uniformly i n the trunk and about a week before buds showed any elongation (Wight 1933)* No consistent pattern of cambial i n i t i a t i o n was 45 observed i n Douglas f i r (Kennedy 196l)«> Growth i n Larix began i n the middle of the stem (Knudson 1913)• New xylem formation i n pine began at some distance below the apex and then spread both b a s i p e t a l l y and aeropetally. As a r e s u l t , growth at the base began several weeks l a t e r than i n the crown (Brown 1915)• Resumption of growth i n roots of Douglas f i r started before growth i n stem (Goff 1898). In a number of coniferous species c e l l d i v i s i o n began 1 to 15 days before bud break (Ladefoged 1952) . In young Douglas f i r , substantial increases i n height began one month a f t e r the sta r t of comparable increases i n circumference at BH (Dimock 1964)0 Differences i n growth inception along the bole of forest-grown Douglas f i r were of 2 to 3 weeks, the top s t a r t i n g to grow before the base. Top and base of an open-grown ash started growing at the same time; the south side began to grow before the north side d i d . Environmental factors of each single tree were considered important i n t h i s respect (Ghalk 1930a) . Cambial a c t i v i t y of some exposed conifers began at the stem base at the same time as i t did i n the extremities of the upper branches (Mer 1#92). In apricots with bursting buds, there was always a more strongly developed layer of new xylem at the base of stem than i n the branches (Dvorak 1961) . Cambial a c t i v i t y of lowland spruce started one week e a r l i e r than apex elongation; subalpine spruce started 20 days e a r l i e r (Mork i 9 6 0 ) . The following conclusions by Giertych (1962) are e s p e c i a l l y valuable i n that they are based on a study of hormone d i s t r i b u t i o n i n large red pine (Pinus resinosa) trees: 46 It i s not e n t i r e l y clear whether the cambium generates i t s own auxins or depends on that trans-ported from the buds, but neither p o s s i b i l i t y can be excluded. It i s generally assumed that i n i t i a t i o n of cambial growth i n the spring depends on hormone transported from bursting buds. There i s l i t t l e evidence i n present data to suggest that xylem growth i s controlled by l e v e l s of hormones i n the buds .... The f a i l u r e of c o r r e l a t i o n between content of hormones and pattern of r a d i a l growth does not ... necessarily mean that auxin u t i l i z a t i o n by the cambium i s independent of i t s export from the buds, but no positive evidence that even the i n i t i a t i o n of cambial growth i n the spring depends on such export has been found. Reports concerning lon g i t u d i n a l p o s i t i o n and date of f i r s t appearance of the annual increment of latewood are not i n absolute agreement. Formation of latewood started f i r s t at the ground l e v e l and gradually spread upward (Young 1952) . Latewood was observed f i r s t i n young branches at a time when earlywood was s t i l l formed i n the stem (Ladefoged 1952) . Changeover from earlywood to latewood at the base of l i v e crown lagged about one week behind that at BH. The delay i n changeover was associated with delays i n s o i l moisture depletion (Zahner and O l i v e r 1962) . T r a n s i t i o n from normal earlywood to draught-induced latewood became more gradual with increasing height i n the stem of red pine (Larson 1963d). Latewood formation began f i r s t i n the upper part of the bole i n white and p i t c h pines (Brown 1915)• Formation of latewood began as early as i n l a t e May, or as late as i n early September (Kennedy I 9 6 I ) . Latewood appeared at ground l e v e l i n June, at the apex i n September (Young 1952) . Pine growing i n s o i l kept moist at f i e l d capacity formed earlywood from March to August (Zahner i n Kramer I 9 6 0 ) , 47 The q u a l i t a t i v e differences i n the formation of xylem elements were also explained i n the l i g h t of the varying moisture l e v e l s within the stem: a l l d r a s t i c increases i n the water content of xylem r e s u l t i n formation of earlywood regard-le s s of the time of vegetative period. Increases i n the water content of plants by the abscission of leaves have a si m i l a r effect on earlywood formation (Lutts i n Grudzinskaya 1957)• Decline i n s o i l moisture was considered as the possible cause of the t r a n s i t i o n i n xylem structure (Kraus and Spurr 1 9 6 l ) ; water supply was denied any influence i n t h i s respect (Bannan 1960b; Van Buijtenen 195$) . Decline i n hydro-s t a t i c pressure within the tree has, apparently, overriden the auxin f a c t o r i n determining c e l l size (Shepherd I 9 6 4 K A category of r a d i a l growth, standing apart from r a d i a l growth of trees, constitute so-called l i v i n g stumps. They represent a growth phenomenon which i s abnormal i n that i t takes place without the l i v e crown while the net product of t h i s growth may at the same time be that of the normal trees, namely l a y e r s of xylem d i f f e r e n t i a t e d into heartwood and sapwood (Lanner I 9 6 I ) . Covered with l i v i n g bark, without leaves or branches, l i v i n g stumps grow i n diameter even at heights more than 10 feet above ground. Secondary growth of xylem 12 to 50 mm thick was observed i n the moistest and densest Douglas f i r f o r e s t s (Lamb 1899)° Judging from the number of rings formed, Douglas f i r stumps were reported to l i v e f o r centuries (Munger i n Newins 1916) . A woody cylinder 48 30 to 60 mm thick exhibiting annual rings "was formed around stumps of some Tsuga canadensis and Pinus Strobus (Page 1927)• Radial growth i n stumps i s usually explained by root parasitism. But, according to P r i e s t l e y (1930), a la r c h stump a l i v e and active f o r 12 years was found by Th. Hartig i n the center of a beech wood with no other l a r c h near. 49 THE DISTRIBUTION OF RADIAL GROWTH PAST WORK Most studies concerned with r a d i a l growth, expressed predominantly i n terms of t o t a l r i n g width from basal portion of stems, belong to the realm of the t r e e - r i n g research. It was believed that It would be immensely h e l p f u l i f the e f f e c t s of known and recent climatic changes upon tree growth could be established, thus enabling us to eliminate t h i s broad climatic e f f e c t from the r i n g pattern, and so approach nearer to an understanding of the e f f e c t s of l o c a l and hereditary f a c t o r s which are of more p r a c t i c a l importance i n f o r e s t r y . U n t i l the tree r i n g record can be "broken down" i n t h i s way, the vast amount of information i t surely contains i s l i k e l y to remain locked up (Dobbs 1951)• Linear r i n g width was also considered to be the correct measure of the frequency of cambial d i v i s i o n and of the change i n form of stems (Topcuoglu 1940) . Amount of p r e c i p i t a t i o n , as well as s o i l water d e f i c i t , were found to influence the r e l a t i v e widths of the t o t a l xylem layers and also of the layers of early-wood and latewood along the stem (Topcuoglu 1940; Smith and Wilsie 196l) and, therefore, to influence the form. Since i t i s main-tained that the contemporary botanist i s no longer content to describe the form and structure of plants, but t r i e s to determine the nature of processes which give r i s e to the observed structure (Wareing 195&), the objectives of t r e e - r i n g studies and of morphological studies i n trees are not wholly unrelated. Furthermore, the frequently unsatisfactory outcome of comparisons between the amount of r a d i a l growth recorded by 50 tree rings at one l e v e l i n the stem on one hand, and of the weather records on the other (Sampson and Glock 1942), l e d to the r e j e c t i o n of ri n g width, measured at any one single l e v e l along the bole, as the v a l i d index of tree's true growth response (Burns 1929)« S i m i l a r l y , increment i n annual cross-sectional area at BH was not necessarily the true indicator of the t o t a l annual volume increment (Schober 1951) which l a t t e r quantity can be ascertained only by multiple sectioning of the bole o It was suggested that "a complete knowledge of relationships between tree growth and environment could be obtained by complete disse c t i o n of stems" (Glock 1941)• System-a t i c sampling of r a d i a l growth must be conducted i n any intensive inquiry into the form of stems. Hence any detailed study of form o f f e r s the information sought by t r e e - r i n g research workers i f variables other than r i n g width measured at one l e v e l are required. From the following excerpt i t i s evident that t h i s was the case: .... The question a r i s e s as to whether the width of a growth r i n g i s the most suitable measure of tree response to changes i n environmental f a c t o r s . Perhaps volume growth i s a better measure A thorough understanding of the d i s t r i b u t i o n of growth would help to answer these questions, and t h i s knowledge would be important i n sampling. Are expressions of growth i n the tree bole representative of t o t a l response? How many samples should be taken ...? Where should the sample be taken i n the tree? .... These consider-ations indicate that sampling i s a formidable task and that a large number of measurements i s needed f o r accurate estimate of either the thickness of the growth layer or the annual volume growth (Hormay i n Sampson and Glock 1942) . 51 T h e s a m p l i n g p r o b l e m u n s o l v e d , s t a t i s t i c a l m e t h o d s w e r e n o t a l w a y s a c k n o w l e d g e d a s a v a l u a b l e t o o l c a p a b l e o f s o l v i n g some o f t h e d i f f i c u l t i e s e n c o u n t e r e d i n t r e e - r i n g r e s e a r c h . A c o n c l u s i o n was r e a c h e d t h a t S t a t i s t i c s d o n o t t e l l u s t h i n g s we d i d n o t k n o w . A t m o s t , i t m i g h t j u s t i f y a g u e s s t h a t r a i n f a l l a n d t r e e g r o w t h a r e n o t e n t i r e l y u n r e l a t e d ( D o b b s 195l)o N e v e r t h e l e s s , t h e d i s c o u r s e o f H o r m a y ( S a m p s o n a n d G l o c k 1942) was r e i t e r a t e d m o r e r e c e n t l y a s f o l l o w s : T h e . . . c o m p l i c a t i o n i s c o m p o s e d o f t h e many p r o b l e m s o f u n i f o r m i t y w h i c h b e s e t t h e g r o w t h l a y e r s t h e m s e l v e s . I f v o l u m e r e p r e s e n t s t h e t r u e m e a s u r e o f g r o w t h i n a t r e e s t e m : (1) T o w h a t e x t e n t d o e s one r a d i u s r e p r e s e n t a s e c t i o n o r a w h o l e t r e e ? (2) T o w h a t e x t e n t d o e s o n e s e c t i o n r e p r e s e n t a t r e e ? (3) T o w h a t e x t e n t d o e s o n e t r e e r e p r e s e n t a g r o u p ? ( G l o c k a n d A g e r t e r I960), T h e o f t e n e n c o u n t e r e d s y s t e m a t i c v a r i a b i l i t y i n r i n g w i d t h s m e a s u r e d a l o n g t h e r a d i i w i t h i n one s t e m c r o s s s e c t i o n , f r e q u e n t l y c y l i c a l i n n a t u r e , h a s b e e n a t t r i b u t e d t o s u n s p o t a c t i v i t y ( D o u g l a s s 1919, 1920; S c h u l m a n 1942) . T h e r e c e n t d e m o l i t i o n b y G . B . T u c k e r ( M a d d o x 1964) o f t h e l i n k b e t w e e n c l i m a t e a t t h e s u r f a c e o f t h e e a r t h a n d b e t w e e n s u n s p o t a c t i v i t y i n v a l i d a t e d s u c h a s s u m p t i o n s . T h e l o n g a n d s h o r t r a n g e v a r i a b i l i t y i n r a d i a l g r o w t h o f c o n i f e r s o b s e r v e d , among o t h e r s , b y M i k o l a (1950) a n d D i n w o o d i e (1962), was a l s o a t t r i b u t e d t o c y c l e s o b s e r v a b l e i n c o n e p r o d u c t i o n ( B u r n s 1929) . S i g n i f i c a n t c o r r e l a t i o n s b e t w e e n t h e f o r m e r a n d t h e l a t t e r v a r i a b l e s w e r e o b t a i n e d , among o t h e r s , 52 by Holmsgaard (1955) and by E i s et a l . (1964); nonsignifleantz ones by Daubenmire ( i 9 6 0 ) . Eccentric growth was shown to constitute another source contributing to the t o t a l v a r i a b i l i t y i n r i n g widths measured at one l e v e l . The r e l a t i v e v a r i a t i o n was found to be approximately equal i n size on a l l sides of stems (Mikola 1950); but also so much discordance was found i n the sequences of thick and t h i n layers along opposite r a d i i of the same tree that no re l a t i o n s h i p between xylem formation and climate could be detected (Daubenmire 1955)* Maximum ring width did not always occur i n the longest radius and vice versa (Adams 1928). Also, r e l a t i v e v a r i a t i o n s of growth were approximately equal i n the average of two r a d i i and there was l i t t l e or no v a r i a t i o n i n the sequence of highs and lows f o r both r a d i i (Hansen 1941)• Increment cores from 6 to 8 trees were considered as s u f f i c i e n t to supply information about c l i m a t i c a l l y conditioned v a r i a b i l i t y within the i n d i v i d u a l stand (Holmsgaard 1955) . A population of 10 r a d i i from 5 trees appeared to provide an adequate record of growth f l u c t u a t i o n s i n groups of trees which showed climatic control of t h e i r diameter growth (Daubermire 1955)* C o e f f i c i e n t s of v a r i a b i l i t y of r i n g width measured at BH ranged from 30 to 40 per cent i n evenaged Norway spruce and Douglas f i r (Marsakova-Nemejcova 1954; Vins i 9 6 0 ) . V a r i a b i l i t y of r i n g width was found to be higher at 0.25 m above ground than at 1..30 m (Topcuoglu 1940); r i n g widths at the top of the bole of some hardwoods gave better correlations 53 with p r e c i p i t a t i o n than those near the base ( M i l l e r i n Tryon et a l . 1957) . A lack of uniformity i n the thickening of the same layer of xylem investigated at 5, 10 and 15 meter l e v e l s was reported by Shreve (1924). A study of 3 trees, dissected at 5-foot i n t e r v a l s , revealed that a single core taken at any point along the bole gave an accurate representation of the r e l a t i v e width of the growth layers (Marr 1943) . The v a r i a b i l i t y of r i n g widths measured at 6 l e v e l s within 8 trees was uniform at a l l heights and the r e l a t i v e magnitude of the v a r i a t i o n was the same (Holmsgaard 1955)• To c l a r i f y the developmental trends i n form observed and reported f o r various species (Dittmar 1953; Abetz I 9 6 0 ) , knowledge of the lon g i t u d i n a l p o s i t i o n of maximum r a d i a l annual increment i s important. In t h i s respect, the reasoning of Buesgen and Muench (1929) i s of some i n t e r e s t : If annual increase i n cross-sectional area of a stem i s the same everywhere throughout i t s length the l i n e a r breadth of the annual rings must increase from below upwards, because the circumference of the stem, which together with the breadth of the rin g determines the sectional area of the annual increment, diminishes i n an upward d i r e c t i o n . Consequently the annual rings are as a rule widest immediately below the l i v i n g crown. Inside the crown they f a l l o f f i n breadth with each branching. "Every stem analysis can show that the annual rings are widest d i r e c t l y below the l i v e crown", maintained Hildebrandt (1954), but according to Larson (1963b) The upward s h i f t of maximum tracheid diameter with age and the pos i t i o n of t h i s maximum during any one year may be related to the fact that maximum ri n g width occurs i n the v i c i n i t y of the branch whorl contributing most to stem growth. 54 The p o s i t i o n of the branch whorl contributing most to the t o t a l cross-sectional area was studied by Labyak and Schumacher (1954)« It was found that The average contribution of the single branch depends on i t s location and the number of i t s branchlets. A branch i n the top l / l O of the tree contributes most to main-stem growth just below i t s base; the production of lower branches i s evenly di s t r i b u t e d along the stem. Growth i n diameter at any given place along the lower part of the bole was a function of the size of crown above that place and was related to the distance from the crown (Young and Kramer 1952) . Trees were thought to be most active as regards wood formation i n the neighborhood of the l i v i n g crown; the diameter growth of the lower part of the stem takes place only to provide a minimum degree of reinforcement (Van Soest 1959)* In exposed trees, 1 the annual rings increased i n thickness from the base of the crown downward; i n suppressed trees, annual rings narrowed from the base of the crown downward and then increased again near the base of the trunk. The zone of increased diameter growth below the crown moved upward as trees increased i n height, thus tending to maintain c y l i n d r i c a l rather than conical form of trunks (Kramer and Kozlowski i 9 6 0 ) . In very old trees i n closed stands the diameter at about f o r t y feet was sometimes larger than a diameter at about twenty feet above the ground. An unexpected swelling was often found at 9/16 of the t o t a l height (Schenck I 9 O 5 ) . The thickest part of the annual rings before the release was i n the upper part of the 55 trunk inside the crown (Siren 1952). The maximal values of r i n g width as well as of r i n g area did not occur with any degree of consistency i n the immediate v i c i n i t y of the base of the l i v e crown (Berry 1964)« Total annual growth layer i n ponderosa pine was widest above or at the middle of the l i v e crown (Myers 1963) . The maximum ring width i n forest-grown young Pinus d e n s i f l o r a was i n the crown and near the roots, with a minimal r i n g width between the two maxima. The position of minimal ri n g width changed from year to year, generally tending to r i s e with increase i n length of the branchless portion of the stem (Onaka 1950a) . The r i n g area increased downwards at each branch l e v e l , hardly changed i n the branchless portion of the bole although sometimes i t decreased, and showed an abrupt enlarge-ment near the root c o l l a r . The maximal point of the r i n g area i n the crown appeared at a point l i t t l e lower than that of maximum r i n g width. The minimal point i n the branchless portion tended to be much higher than that of the minimum r i n g width (Onaka 1950a). Cross-sectional area increment was evenly d i s t r i b u t e d between b u t t - f l a r e and base of l i v e crown, but several l o c a l enlargements were observed i n the outer rings i n the basal t h i r d of the stem (Abetz i 9 6 0 ) . The r i n g area was greatest just below the l i v e crown and decreased both aero- and b a s i - p e t a l l y . Decrease i n area from the base of crown to the base of stem was more marked i n earlywood than i n latewood (Chalk 1930) . 56 The width of latewood i n v a r i a b l y increased i n descent while that of earlywood decreased. This meant that width of earlywood at a lower p o s i t i o n i n the bole could never exceed the width i t assumed at a higher position (Turnbull 1937; Green 1 9 6 l ) . S i m i l a r l y , the s p e c i f i c gravity or the percentage of latewood were found to increase downwards i n most reported cases (Young 1952; Siren 1952; Harris and Orman 195&; Hidlebrandt 1954; Wellwood i 9 6 0 ) , but a reverse s i t u a t i o n was also noted (Wellwood 1952; Smith and Wilsie I 9 6 I ) . Complete stem analysis by mid-internodal sectioning was conducted on a c e l l u l a r l e v e l i n Pinus Strobus by Adams (1928). The maximum r i n g width progressed upwards with each succeeding year. The time of the appearance of maximum r i n g width and the raUe of acropetal advance were conditioned by spacing. Similar conclusions, based on si m i l a r methods, were drawn by Misra (1943)« Complete stem analyses were repeated subsequently by Duff and Nolan (1953, 1957); Mott et a l . (1957); Low (1959); Mason ( i 9 6 0 ) ; Green (1961); Forward and Nolan ( I 9 6 l a , b); Smith and Wilsie (1961); Walters and Soos (1962), and by Fraser et a l . ( 1964)0 The r e s u l t s of these works suggest the following po s i t i v e conclusion which i s important f o r the present study, the width of t o t a l annual layers of xylem i n the stems of coniferous species i s d i s t r i b u t e d i n a s i m i l a r fashion regardless of the species or of the geographical area, but i t i s subject to modifications due to crown class and to changes i n stand density. The considerable lack of agreement between the resu l t of works reviewed i n t h i s chapter t e s t i f i e s that the position of maximum rin g width i n the stem i s not s u f f i c i e n t l y known or, a l t e r n a t i v e l y , that t h i s p o s i t i o n , l i k e that of r i n g width i t s e l f , varies considerably from tree to tree. Since the maximum r i n g width, or better the r a t i o between maximum r i n g width at the top of the stem and rin g width at the base of the stem within any one year, are the obvious determinants of the form of the annual xylem layers, and therefore of the stem form the present investigation regarding such data seems w e l l j u s t i f i e d . 58 MATERIALS AND METHODS The 18 Douglas f i r trees investigated i n the present study can be c l a s s i f i e d i n two groups! one consisting of 11 plantation-grown trees about 25 years old and another of 7 trees from unmanaged second-growth stands about .50 years old. The basic mensurational data pertaining to both groups are i n Tab. I. A l l the trees, with the exception of tree number 2 which was an open-grown tree, were forest-grown trees from the University of B r i t i s h Columbia Campus Forest. The one-acre plantation which supplied trees 13 M, 27 M, 32 M, 33 M and trees number 1, 3 , 4, 5, 6 and 7, i s located about 300 feet above and ha l f a mile away from the waters of the Gulf of Georgia at 49°15'N and 123°15 rW. I t was established i n 1937 on a rectangular parcel of cleared land moderately sloping to the south-west, beneath some young residual Douglas f i r , western red cedar (Thu.ia pli c a t a ) and western hemlock (Tsuga heterophylla). Specimen No. 1 i s an example of these residual t r e e s . Since 1958 the plantation has been disturbed on several occasions by the cutting of border trees, by clearing of the forested land around i t and by the subsequent windthrow. Trees number 8 to 14 grew approximately 3 miles away from the plantation i n natur a l l y established stands, rather heterogeneous as regards t h e i r composition, density, structure, depth of s o i l , and s o i l moisture regime. In these stands the Douglas f i r trees formed, as a rule, the upper story and grew TABLE I BASIC MENSURATIONAL DATA OF THE SAMPLE TREES Age at Height Stump above FINAL VOLUME FINAL FORM FACTOR Tree Height No. , » (yearsj 1 3 M 27M 32M 33M 1 2 3 4 5 6 7 8 9 10 11 12 13 14 20 20 20 20 24 22 24 23 23 23 33 46 48 48 48 49 48 50 ( f t . ) 51.2 51*7 51.8 52.8 60.1 48.I 56.5 57.5 57.9 63.O 74-4 108.2 116.0 116.6 114.2 123.8 111.2 122.2 D.B.H. Stump Live (LAMBDA 0.9) (i.b.) Height Crown Total Earlywood Latewood X (in.) ( f t . ) ( c u.ft. )(cu.ft.) (cu.ft.) Total Earlywood Latewc • 5.7 70 3.5 2.3 •1.2 .449 .491 .385 6.3 64 4.1 2.4 1.7 .470 .520 .410 5.9 53 4.1 2.6 1.5 .478 .523 .418 5.4 48 3.5 2.2 1.3 .495 .558 .408 8.9 1.5 47 10.8 7.1 3.7 .508 .556 .433 8.2 3.5 85 6.5 4.2 2.3 .454 .483 .407 7.4 0.8 52 7.3 4.9 2.4 .537 .607 .432 6.9 1.9 52 6.0 3.7 2.3 .493 .551 .416 6.8 1.7 47 6.5 4.1 2.4 .509 .529 .472 10.6 1.8 57 15.1 10.0 4.9 .509 .529 .469 12.7 3.2 63 24.I 15.5 8.6 .456 .524 .376 15.4 5.6 57 6O.4 31.9 28.5 .512 .511 .513 18.6 4.7 43 80.7 48.3 32.4 .488 .525 .442 15.7 6.3 53 65.I 37.8 27.3 .484 .529 .434 17.7- 3.1 53 91.0 61.6 29.4 ^.548 .583 .486 21.0 4.0 52 105.7 71.4 34.3 .485 .511 .437 20.6 2.6 40 87.8 61.0 26.8 .463 .483 .423 20.9 2.6 45 96.4 60.6 35.8 .490 .487 .496 xForm factors of trees 13M to 33M are based on 10 equidistant sections. vn 60 50 to 100 yards apart i n association with western red cedar and western hemlock i n the understory, and with undergrowth of red alder (Alnus rubra) on imperfectly drained s i t e s . The s o i l of t h i s area belongs to the Nicholson S o i l Series which i s considered to be acid, brown forest s o i l , mainly sandy loam with stones, a well-drained to poorly-drained, mixed g l a c i a l t i l l and outwash underlain by lenses or benches of marine clay or by sandy hardpan. The compacted g l a c i a l t i l l and the hardpan r e s t r i c t the depth of rooting and the whole area suffers from windthrow. In f a c t , a l l the large trees included in t h i s study, as well as the trees number 2, 3, 4 , 5, and 7 were uprooted i n the f a l l of 1962 by Typhoon Frieda, which t r a v e l l e d at speeds i n excess of 100 M.P»H<» The height of water table i n the natural forest was observed i n p i t s dug beneath the uprooted large stems. I t was found above the top of the mineral s o i l during the winter months and during early spring; during the summer i t retreated gradually to lower depths. On l e v e l ground i t was found 3«5 feet below the s o i l surface by the beginning.of June. In l o c a l depressions and ravines the water table did not retreat below 1.5 feet even during the summer. The climate of the area can be c l a s s i f i e d as a modified maritime one. The t o t a l annual p r e c i p i t a t i o n i s approximately 30 inches. The maximum r a i n f a l l occurs during the winter months, the minimum i n June and July. The a i r temperatures range from an average minimum of 31°F i n January to an average maximum of 12 F i n July, the extremes being zero and 92°Fo The average f r o s t - f r e e period i s 213 days (Canada, Dept. of Transport 1962). The r a d i a l growth of the 18 stems was sampled at the center of each annual height increment systematically from stem-apex to some variable small distance above ground as given i n Tab. I. A sketch of the sampling scheme i s i n Figo 1. In t h i s study the mid-internodal cross sections of the stem are known as l e v e l s . Their numbering i s always basipetalc Level number one coincides with the central cross section of the leader. A disc about 1.5 inches thick was removed at each l e v e l . An average radius was calculated from 4 r a d i i measured along the longest and shortest diameter and plotted into the d i s c . Then a s t r i p of wood 12 mm wide and about 0.8 mm thick was cut from the disc i n such a way that i t included the p i t h and that the center l i n e of the s t r i p coincided with the l i n e of the average radius. The following quantities were measured on the s t r i p s treated with an oil-carbon suspension (Fig. 2 ) : radius of p i t h , width of the primary wood, width of earlywood and of latewood bands within each annual ring, where discernible The primary wood as well as the bands i n which no latewood band could be distinguished under 5X magnification were c l a s s i f i e d as bands consisting of earlywood only. The bands were measured i n transmitted l i g h t to 0 .001 inch with a c a l i p e r and rounded o f f to the nearest 0.005 inch. The measurements obtained by t h i s method were, i n case of tree 32 M, compared with the I Figure I - The sampling scheme-F i g . 2 Band of earlywood between two bands of latewood in. a s t r i p treated with oil-carbon suspension. (approx. 2 0 X ) 62 corresponding measurements obtained f o r the same tree by Green (1961) who used Mork's d e f i n i t i o n of the latewood-earlywood boundary. Differences between the two groups of measurements were not s i g n i f i c a n t when tested by analysis of variance. The consistency of the measurements as well as the magnitude of the errors due to bias i n loc a t i n g the earlywood-latewood boundary and of the errors due to expansion of the s t r i p were tested during the course of work by comparing two or more sets of readings taken on the same s t r i p selected by chance. The average differences between readings were random and amounted to about 8 per cent i n the case of latewood and to about 5 per cent i n the case of earlywood. The maximum difference i n measurement of latewood was as high as 20 per cent and that i n earlywood about 13 per cent, both occurring, on the average, one time i n 40 measurements. 63 RESULTS PART (A) DISTRIBUTION OF THE ANNUAL RADIAL GROWTH ALONG THE STEM OF DOUGLAS FIR The o v e r a l l amount of r a d i a l growth achieved during f i v e growing seasons along the bole of tree No. 1 i s shown i n F i g . 3 and 1+ in terms of r i n g width and i n terms of ri n g area i n F i g . 5 and 6 . From these graphs i t i s evident that the annual increments of earlywood, i n width as well as i n area, were not di s t r i b u t e d along the bole of t h i s tree, during t h i s period, i n the same way as the corresponding annual increments of latewood. The same conclusion can be arrived at i f the cumulative ri n g areas of earlywood and of latewood respectively are plotted over height at which they were sampled; the plot, shown i n F i g . 1 and 8, w i l l y i e l d two imaginary stems, an "earlywood stem" and a "latewood stem", d i s t i n c t l y d i f f e r i n g i n shape. More complete information concerning the d i s t r i b u t i o n of r a d i a l growth can be found i n the diagrams included i n the appendix of t h i s work (Diag. 1 to 83)• In these diagrams the tri a n g u l a r matrix-of one-digit numbers portrays the right h a l f of an imaginary upright conical stem by i t s outline, and the r e l a t i v e rates of r a d i a l growth within t h i s stem by i t s contents. Only the successive arrays of numbers p a r a l l e l with the hypot-enuse of the tr i a n g l e are meaningful; they show the r e l a t i v e Figure 4- Widths of latewood layers.tree No-1,years 1958—1962-2 3 4 5 10 15 20 24 NUMBER OF INTERNODE FROM APEX CUMULATIVE RING AREA OF EARLYWOOD {SQ- INO 0 5 10 15 20 25 CUMULAT IVE RING AREA OP LATEWOOD (SQ- IN-) 64 r i n g widths, or r i n g areas, or percentages of l a t e wood by area, as the case may be, within the annual layers from the apex of the stem to i t s base or vice versa* Only the v a r i a b i l i t y of r a d i a l increment within the i n d i v i d u a l layers i s observed, the v a r i a b i l i t y i n r a d i a l increment between layers being eliminated. The number of horizontal arrays corresponds to the number of l e v e l s sampled. Therefore, the layer deposited i n the l a s t year of a tree's growth i s represented i n the matrix by the longest array of numbers which range i n every layer, the f i r s t one excepted, from zero to nine. Zero designates the p o s i t i o n of the minimum annual r a d i a l increment, the cipher 9 stands i n place of maximum annual r a d i a l increment. The remaining figures are the r e l a t i v e measures of the magnitude of r a d i a l growth within t h i s range and indices of i t s r e l a t i v e p o s i t i o n within the annual layer. The annual layer formed i n the f i r s t year of growth, indicated i n the headings of the diagrams, i s represented i n the matrix by a single zero. The s i t e s of the maximal r a d i a l growth or the s i t e s of maximal percentages of latewood are blocked out or crossed by l i n e s of varying thickness. The double c i r c l e around a number i n the array, representing the annual layer deposited i n the l a s t year of growth, points out the approximate po s i t i o n of the base of l i v e crown which was defined i n t h i s study as the lowest complete whorl of green branches. The singly e n c i r c led figure i s located i n the l e v e l which was closest to the BH position on the stem. 65 The information conveyed by the diagrams i s as follows? (1) The minimum values of a l l the various measures of r a d i a l growth portrayed occur at the stem-apex and along the p i t h . (2) The maximum ri n g width of earlywood occurs, i n most instances, at a short distance below the apex i n any one year. It i s , therefore, found within the l i v e crown, but i n tree No. 4 i t was below the most recent base of l i v e crown. (3) The zone of maximum increment of earlywood i s well defined and usually very narrow, but i t may be wide as i n the case of tree No. 13« (4) The width of earlywood decreases r a p i d l y i n basipetal d i r e c t i o n . (5) The maximum ri n g width of earlywood was not at the base of open grown tree No. 2, but higher up the stem. (6) The maximum ri n g width of latewood occurs within the stem at positions which are usually below those of maximal rin g width of earlywood and within a zone which was more or les s well defined only i n trees No. 32M, 5j> 8, 10 and 14• In the remaining trees the position of maximum ri n g width of latewood fluctuated widely along the lower portion of the stem. (7) In cases where r i n g width of latewood decreases b a s i p e t a l l y the rate of decrease i s small* (8) The zone of the maximal r i n g area of earlywood i s always higher than the zone of maximal rin g area of latewood. Its upper border was above the base of l i v e crown i n trees No. 1, 66 3 , 4, 5* l l * 12; i t was below the base of l i v e crown i n the remaining t r e e s . (9) The zone o f the maximal r i n g area o f latewood i s always below the base of l i v e crown; i n most i n s t a n c e s t h i s i s at the very base of the stem. (10) Consequently, the maximum percentage of latewood by area occurs always i n the lower p o r t i o n o f the stem. The a b s o l u t e p o s i t i o n o f maximum r i n g width of e a r l y -wood with r e s p e c t t o stem-apex i n the i n d i v i d u a l stems or i n groups of stems i s shown i n F i g . 9 to 14* An a d d i t i o n a l f e a t u r e of these graphs i s the p l o t o f the minimum r i n g width of e a r l y -wood i n t r e e s i n which i t was found t o occur c o n s i s t e n t l y over a number of y e a r s . A l l these graphs are based on moving averages c a l c u l a t e d f o r a l l growth l a y e r s w i t h i n any one t r e e by a v e r a g i n g 3 measurements of r i n g width o f earlywood o r latewood, r e s p e c t i v e l y , at a time. The mean valu e s o f the maximum and minimum r i n g width of earlywood, and the maximum r i n g width of latewood, as w e l l as t h e i r a b s o l u t e mean h e i g h t s i n the stem, are gathered t o g e t h e r with t h e i r standard e r r o r s i n Tab. I I . T h e i r c o e f f i c i e n t s of v a r i a t i o n are i n Tab. I I I . Since the v e r t i c a l p o s i t i o n i n the stem and a l s o the magnitude of the maximum and minimum t h i c k n e s s e s of the xylem l a y e r s of both types determine the shape of the i n d i v i d u a l growth l a y e r s and t h e r e f o r e , j o i n t l y and c u m u l a t i v e l y , the shape of the stem, the r a t i o s between the c r i t i c a l dimensions o f the l a y e r s were c a l c u l a t e d f o r each stem Figure I i • Position of minimum ond maximum ring width of earlywood,and of the stem-base, 1917 20 25 30 35 40 45 50 55 CO YFAR Figure 12- Position of minimum and maximum r ing width of early wood, and of the stem - b a s e , 1917 20 2C 3 0 35 4 0 4 5 5 0 55 6 0 YEAR YEAR YEAR TABLE II TREE OR GROUP OF TREES Emax (in.) M SE 1 3 M , ) 27M, ) 3 2 M , ) 3 3 M ) 0 . l 6 l O.Oi 1 , 3 , ) 4 , 5 , ) 6 )0 . 1 9 2 0 . 0 7 0 . 2 0 1 0 . 0 8 0 . 1 6 2 0 . 0 9 0 . 1 8 5 0 . 0 10 0 . 1 6 2 0 . 0 11 0 . 2 1 1 0 . 0 12 0 . 2 1 4 0 . 0 13 0 . 1 9 7 0 . 0 14 0 . 2 0 9 OoO THE AVERAGES OF THE CRITICAL WIDTHS OF EARLYWOOD AND OF LATEWOOD AND THEIR AVERAGE LONGITUDINAL POSITION IN THE STEM h(Emax) top ( f t . ) M. SE Emin (in.) M SE h(Ernin) bse ( f t . ) M':' SE Ebse (in.) Lmax (in.) M SE M SE h(Lmax) top ( f t . ) M SE LAYERS, h(Lmax) bse ( f t . ) M SE Lbse (in.) M SE H (in.) M SE N 9 . 2 O.35 0 .075 0 . 0 0 5 0 . 6 0.19 O.O78 O.OO5 0 . 0 7 0 0.003 2 2 . 4 1.6 11.4 1 » 7 6 0 ,058" C.OO3 3 2 . 8 1,68 58 .0.2 0.37 0 . 091 0.005 '.3.6 1 .29 0 . 108 0.009 .3.9 1.40 0 . 080 0 . 006 |0.2 1.05 0.097 0 . 0 0 4 '.5.5 1.87 O.O83 0 . 006 .4.1 1.11 0 . 108 0.004 !3*9 2.05 0.128 0 . 0 0 9 '.5.1 1.95 0.133 0.007 .1.3 0.76 0.115 0.007 1 . 4 0 . 3 7 0 . 0 9 5 0 . 0 0 5 0 . 0 7 9 0 . 0 0 3 2 9 . 1 1 .6 1 0 . 6 1 . 3 7 0 . 0 7 1 0 . 0 0 3 3 0 . 6 0 . 9 7 90 5 . 2 0 . 9 7 O . I 3 6 0 . 0 1 0 O .O85 0 . 0 0 6 3 3 . 0 3 * 4 4 1 1 . 2 2 . 2 2 O .O65 0 . 0 0 4 2 8 . 4 1 . 8 1 27 5 . 0 1 . 0 8 O .O87 0 . 0 0 6 O .O97 0 . 0 0 3 4 0 . 7 4 . 2 1 3 0 . 8 4-35 0 . 0 7 3 0 . 0 0 3 2 8 . 9 1 . 8 1 39 1 0 . 8 1 .16 0 . 1 1 0 0 . 0 0 5 O .O96 0 . 0 0 3 3 7 * 8 3 . 1 4 3 6 . 0 4 . 9 1 O .O84 0 . 0 0 3 29*6 1 .55 39 5 . 2 1.15 0 . 0 8 7 0 . 0 0 6 0 . 0 8 7 0 . 0 0 3 3 6 . 9 3*54 3 5 . 3 4 . 9 8 O .O73 0 . 0 0 3 2 8 . 8 1 . 5 9 44 4 . 9 0 . 3 0 0 . 1 1 4 0 . 0 0 4 O . O 8 3 0 . 0 0 3 42c6 4 . I 8 2 6 . 6 5 . 2 6 0 . 0 7 5 0 . 0 0 3 2 9 * 0 1 .52 42 9 . 3 2 . 0 0 0 . 1 4 1 0 . 0 0 9 O .O84 0 . 0 0 3 5 3 . 2 5«03 2 2 . 4 5 *08 O .O78 0 . 0 0 4 3 0 . 7 1*56 43 6 . 6 1 .23 0 . 1 4 5 0 . 0 0 7 0 . 0 7 4 0 . 0 0 2 58*6 4*71 1 2 . 8 3*30 O .O67 0 . 0 0 3 2 8 . 4 1 . 6 1 41 1 0 . 3 1 . 3 9 0 . 1 2 9 0 . 0 0 8 0 . 1 0 0 0 . 0 0 3 3 4 * 4 . 1 * 9 0 4 0 * 6 5 . 4 7 , 0 . 0 8 3 0 . 0 0 4 29*9 1-51 45 (Emax) (Emin) (Lmax) (Ebse) (Lbse) Maxim Minim Maxim Width n M s m ddth of earlywood layer ! tt tt tt tt ; » " latewood « earlywood layer at stem-base latewood layer " " " h(Emax) top h(Lmax) top h(Lmax) bse h(Emin) bse H . SE standard error, N - number of annual layers distance to (Emax) from stem-apex* " " (Lmax) «» " " " " (Lmax) " stem-base - " " (Emin) " " " annual height increment 0 TABLE III COEFFICIENTS OF VARIATION OF THE CRITICAL DIMENSIONS OF GROWTH LAYERS TREE OR GROUP OF TREES NO. Emax* h (Emax) top Emin h (Emin) bse Ebse Lmax h (Lmax) top h (Lmax) bse Lbse H N COEFFICIENT OF VARIATION (PER CENT) 13M, 27M, 32M, 33M 16.0 29-3 46.6 255.1 45.1 27.3 53.3 117.3 40.2 23.7 58 1,3,4,5,6 24.6 34-5 54.6 246.6 52.0 30.7 52.8 121.9 38.7 30.1 90 7 24.2 49-3 41.7 96.7 39.2 33.7 54.2 102.5 35.7 33.1 27 8 31.2 63.1 47.6 133.9 42.5 19.2 64.5 88.2 28.8 39.1 39 9 18.3 64.3 25.7 67.2 26.1 16.5 51.8 85.3 24.3 32.7 39 10 27-7 80.0 51.2 14.5 48.2 21.8 63.7 93.7 31.3 36.7 44 11 17.2 51.1 21.6 105.3 20.6 21.5 63.7 12.8 28.7 34-0 42 12 23.8 56.3 45.9 141.0 43 «4 21.3 62.0 I48.7 36.O 33-2 43 13 23.1 49-8 35.5 120.4 29.2 20.7 51.5 I64.8 25.8 36.2 41 14 23.6 45.0 43.4 90.9 43.2 18.3 37.0 9O.4 36.1 33-9 45 D e f i n i t i o n s of (Emax), etc. as i n Tab. II Non-normal d i s t r i b u t i o n s . 69 and year. The progression of the values of these r a t i o s as exemplified by trees No. 1 and No. 11 appears i n F i g . 15 and 16, together with plots of the positions of maximum r i n g width of earlywood expressed as percentages of the t o t a l tree height. The averages of the r a t i o s between the c r i t i c a l dimensions of the growth layers, t h e i r standard errors and t h e i r c o e f f i c i e n t s of v a r i a t i o n are i n Tab. IV and V. The various shapes which may be assumed by layers of earlywood and latewood are sketched i n Fi g . 17 f o r tree No. 7«.- In t h i s diagram shape ABDE i s the general shape of earlywood layers without minimal ri n g width; shape ABODE i s that of layers e x h i b i t i n g minimum rin g width. Shapes MNQR and MOQR are two average shapes which occur whenever growth of latewood i s larger at some distance above the base than i t i s at the base. The simple c o r r e l a t i o n c o e f f i c i e n t s . between the various combinations of c r i t i c a l dimensions of earlywood and latewood are i n Tab. VI. The above enumerated graphs and tables serve as the basis of the following conclusions. (1) The earlywood maxima appeared i n the stems a f t e r an i n i t i a l period of growth l a s t i n g from 5 to 10 years at distances ranging from 4 to 11 feet below the stem-apex. In most trees the maximum growth of earlywood occurred within a narrow zone located at a nearly constant average distance from the apex i n one tree and ranging between 9 to 25 feet i n 18 trees studied. In tree No. 12 t h i s distance increased s t e a d i l y with increasing age. A sudden downward s h i f t of the zone of maximal r a d i a l TABLE IV THE AVERAGES OF RATIOS OF THE CRITICAL WIDTHS OF EARLYWOOD AND OF LATEWOOD LAYERS TREE Emax Emin Lmax Emax Emax Ebse Emax H OR GROUP Emin Ebse Lbse Lmax Lbse Lbse (EbseMLbse) Emax N OF TREES NO. M SE M SE M SE M SE M SE M SE M SE M SE 13M,27M 32M,33M 2.68 0.19 0.97 0 .01 1.33 0.06 2.52 0.13 3.33 0 .21 1.66 0.18 1.30 0 .06 204.7 5.8 58 1 , 3 , 4 , 5,6 2.59 0.13 0.96 0 .01 1.17 0.03 2.60 0.09 3.00 0.12 I . 4 6 0.10 1.26 0.04 I 6 4 . 6 5.5 90 7 2.18 0.22 0.83 0 .04 1.34 0.07 2.61 0.17 3.43 0.26 2.26 0 .20 1.09 0.09 139.5 6.2 27 8 2.22 0.10 0.91 0.02 1.40 0.06 1.72 0.10 2.31 0.12 I . 2 4 0.08 1.04 0.04 176.1 6.4 39 9 1.99 0.07 0.89 0.02 1.21 0.06 1.95 0.05 2.34 0.11 I . 3 6 0 .06 1.00 0.04 158.3 6 . 8 39 10 2.32 0.18 0.94 0 .01 1.24 0.03 1.86 0.05 2.26 0.06 1.16 0.05 1.08 0.05 179.3 7.54 44 11 2.01 0.06 0.95 0 .01 1.15 0.04 2.62 0.09 3 .00 0.12 1.62 0.08 1.14 0.03 137.8 6.53 42 12 1.86 0.07 0.91 0.02 1.14 0.04 2.61 0.10 2.92 0.13 1.89 0.12 1.02 0.03 143.4 4.82 43 13 1.57 0.05 0.90 0.02 1.11 0.02 2.73 0.11 3.05 0.14 2.23 0.11 0.94 0.02 142.2 4.86 41 14 2.03 0.09 0.89 0 .02 1.34 0.06 2.10 0.07 2.72 0.11 I . 5 8 0.08 1.07 0.04 143.8 5.84 45 x D e f i n i t i o n s of (Emax), (Emin), (Ebse), (Lmax), (Lbse), etc., as i n Tab. I I . TABLE V THE COEFFICIENTS OF VARIATION OF THE CRITICAL-DIMENSION-RATIOS OF GROWTH LAYERS TREE Emax* Emin OR GROUP Emin Ebse OF TREES Lmax Emax Lmax Emax Lbse Ebse Emax H Lbse Lbse COEFFICIENT OF VARIATION (PER CENT) rse'j + (Lbse) Emax -3M, 27M, >2M, 33M 55 .1 10 . 1 32.2 39.9 48 .7 84.9 32.8 21.6 -> 3,4» 5,6 46 • 4 10.6 22.4 34.6 37 . 1 62 . 0 30 . 6 31.4 7 51.4 24.6 28.3 34 . 7 39.8 45.4 42.1 22.9 8 27 .7 15.0 27.2 36.4 31.0 40.3 23.8 22.7 9 23.5 10.8 29 .3 17.4 29 . 1 28.8 23.O 27.0 10 50.2 9.8 18.4 18.8 18.6 30 . 7 29 . 2 27.9 11 19.8 7.2 21.3 21.7 26 .0 33.3 17.8 30 . 7 12 25.9 13.2 24.1 25.6 29.9 43 . 1 18.6 22.0 13 I808" 12.8 12.8 26.0 29 .2 31.4 15.5 21.9 14 29.8 11.5 30.6 21.8 26.7 32.9 26.3 27.2 * D e f i n i t i o n s of (Emax), (Emin), etc. as i n Tab. I I . TABLE VI SIMPLE CORRELATION COEFFICIENTS BETWEEN CRITICAL DIMENSIONS OF ANNUAL LAYERS OF EARLYWOOD AND LATEWOOD* TREE OR GROUP OF Emax Emax Emax CORRELATED WITH Emax Lmax N TREES Emin Ebse Lmax Lbse Lbse 1> 3 > 4* 5,6 0.663 0.680 0.296 0.306 0.841 90 "M"-TREES 0.377 O.378 0.000 0.257 0.771 58 7 0.662 O.447 0.021 O.O56 0.781 27 8 0.820 O.694 0.050 0.292 0.509 39 9 0.316 0.137 0.498 0.476 0.602 39 10 0.744 0.728 0.772 0.831 0.876 44 11 0.472 0.452 0.253 0.348 0.845 42 12 O .84I 0.844 0.439 0.559 0.516 43 13 0.868 O.83O 0.455 O .38I O.898 41 14 0.820 0.743 O.486 0.725 0.822 45 ^Autocorrelations and trends of the series were not investigated. - 0 Figure 15- Determinants of form,tree No-1 Figure 16- Determinants of form,tree No- II-Figure 17- Schematic diagram of the longitudinal sections of average annual layers of xylem,tree No- 7-Scale of heights, I "= 10' Scale of widths, l"=0- l " 73 growth of earlywood to a new position about 30 feet f a r t h e r away from the apex was observed i n trees No. 10, 11 and 13• Maximal r a d i a l growth continued at t h i s new position f o r about 20 years i n tree No. 13, and f o r about 10 years i n trees No. 10 and 11, to return suddenly to the previous position about 10 feet below the apex. (2) The earlywood minima appeared early i n trees from the natural forest at the average distances ranging from 5 to 11 feet from the base. They did not appear consistently every year and t h e i r p o s i t i o n fluctuated considerably, the general trend over the years being an acropetal one. (3) In plantation-grown trees d e f i n i t e earlywood minima were observed only i n trees No. 6 and 7* In both these trees they could be detected f o r the f i r s t time i n layers only about 15 years o l d . (4) The v a r i a b i l i t y i n maximum r i n g width of earlywood i s about one-half of that observed i n the minimum ring width of earlywood or that i n the maximum r i n g width of latewood. (5) Maximum ring width of earlywood can be, on the average, more than twice as large as minimum r i n g width of earlywood or maximum ring width of latewood; i t was, on the average, about as large as the t o t a l r i n g width at the stem base. (6) The r a t i o between maximum ri n g width of earlywood and t o t a l r i n g width at the base was the least variable one. 74 (7) In most stems, the correlations between the c r i t i c a l dimensions within the i n d i v i d u a l layers were s i g n i f i c a n t at P = OoOl i n both types of la y e r s . (8) The correlations between maximum r i n g width of earlywood and maximum ring width of latewood were non-significant or s i g n i f i c a n t but low. (9) The average annual increment i n height can be more than 200 times that of maximum r i n g width of earlywood. Stem Form Factors Three types of Hohenadl's true form factor, lambda 0.9, were calculated f o r each year of growth of trees 1 to 14, namely: (1) a series of form fact o r s measuring the form of the "earlywood stem", i . e . of an imaginary stem consisting of layers of earlywood, (2) a series of form f a c t o r s measuring the form of the "latewood stem", i . e . of an imaginary stem consisting of layers of latewood, (3) a series of form factors measuring the form of the stem consisting of the t o t a l annual layers, i . e . , of the actual stem. Three series of three d i f f e r e n t types of form fact o r s are portrayed, f o r each tree separately, i n F i g . 18 to 31« More important conclusions derived from these graphs are as follows: 75 (i) The form factors of "earlywood stem" are the highest ones, those of "latewood stem" the lowest ones. The form factor of the actual stem assumes approximately intermediate values between these. In a few instances the values of a l l three types of form factors were nearly the same f o r a period from 3 to 6 years (trees No. 2 and 8). "Latewood stem" form factors were higher than the remaining two i n the l a s t seven years of growth of tree No. 14* ( i i ) Values of a l l three types of form factors increased with age. ( i i i ) The flu c t u a t i o n s i n the stem form were due primarily to the s i m i l a r f l u c t u a t i o n s observable i n the form factors of "earlywood stem". (iv) Within the same year, the "latewood stem" form factor may vary independently of the "earlywood stem" form f a c t o r . I94S 1950 I9SS I960 Y E A H 6 0 0 r F i f l u r e 20- Values of A ,tree No- 3 •550 •500 01 xP •450 •400 •350 "Latewood Stem" J L J 1 I L 1945 1950 1955 I960 YEAR . 5 5 0 | _ Figure 21- Values of Xog,tree No-4 •500 "Earlywood Stem" •450 01 6 •400r-•350 •300--^Latewood Stem 1945 J L 1950 J I L YEAR 1955 J L I960 •550r F ' 9 u r e 2 7 • Values of X ,tree No IO-•350 - J •300-. 2 5 0 - I I I I I I I I I 1 I I I I 1 I 1 I I I I I I i I i i I I I i l l I I i I l I 1 I I 1920 25 30 35 40 45 50 55 60 YEAR Y E A R Plants are not homoiiO-thermous organisms and plant physiologists, unlike human and animal physiologists, have not been much concerned with the ef f e c t s of excessive heat, though of course plant c e l l s , l i k e animal c e l l s , are r e a d i l y k i l l e d or inactivated by high temperatures. P.W. Richards (i960) L i f e i n both the forest and the sea i s di s t r i b u t e d i n horizontal l a y e r s . The students of the sea have always been keenly aware of t h i s , but the students of the forest paid l e s s attention to the problem of depth. To study the forest man must climb. Marston Bates (1961) 77 PART (B) IDENTIFICATION OF THE CAUSAL FACTORS DETERMINING THE FORM OF FOREST TREES The systematic pattern observed i n longitudinal d i s t r i b u t i o n of r a d i a l growth of earlywood and, i n contrast to t h i s , the consistently d i f f e r e n t pattern of r a d i a l increment of latewood cannot be reconciled s a t i s f a c t o r i l y with any of the e x i s t i n g theories of bole formation. Since i t i s desired to i d e n t i f y the causal relationships that would make sense of the phenomena encountered, a d i f f e r e n t theory i s needed. Structures such as buttresses and enlarged bases have already been appraised. Their formation i s occasioned by i n t e n s i f i e d r a d i a l growth manifesting i t s e l f by wide annual rin g s . The r a t i o between r i n g width within the enlarged base and that within the "normal" trunk (Gates and Erlanson 1925) i s comparable with the average r a t i o s between the maximum and between the basal widths of the layers of earlywood found i n t h i s work. Whereas the position i n stem of the maximal annual r a d i a l increment of earlywood i s not stationary, and therefore not detectable from the outward appearance of the stem, the position of the increased r a d i a l growth within the enlarged or buttressed bases does not change l o n g i t u d i n a l l y with time. Hence the r e a d i l y recognizable abnormal phenomenon of the atrophied stem bases which has i t s analogy i n the normally occurring butt f l a r e s . The o r i g i n of the l a t t e r structures i s to be sought, as shown in the present study, i n the greater 78 width of latewood layers which are widest, rather consistently, within the basal portion of the stem. As already stated, the mechanical value of buttresses as supporting structures was questionable i n t r o p i c a l trees (Richards 1952) . Experience has shown that the majority of breakages i n stems of spruce and beech occur high above ground even i n trees without prominent butt swell (Ursprung 1913, Hildebrandt 1954)» A conclusion was reached that the r e i n f o r c e -ment of the basal portion of stems, which tend to be over-dimensioned even i f unbuttressed, had a function other than that of support (Ursprung 1913)» I t was also stated that factors of environment, other than the mechanical influence of wind, rather than heredity have been suspected as those respons-i b l e f o r the formation of buttresses i n both t r o p i c a l and ex t r a t r o p i c a l species (Richards 1952; Senn 1923) . S i m i l a r l y , factors causing the formation of enlarged bases were i d e n t i f i e d as those belonging to the environmental complex (Kurz 1934)* I f so, then i t can be assumed with some l o g i c that the longitudinal p o s i t i o n of maximum ri n g width of both earlywood and latewood i n the "normal" stems of forest grown trees i s due primarily to extraneous physical factors of the environment. This assumption w i l l be adopted as a working hypothesis i n explaining the notably consistent differences i n shape of the annual xylem layers encountered i n Douglas f i r . Factors of environment have been pointed out by some authors as d i r e c t agents causing noteworthy q u a l i t a t i v e and 79 quantitative changes i n wood structure. In fact, s p e c i f i c gravity and the h i s t o l o g i c a l c h a r a c t e r i s t i c s of wood from the atrophied bases d i f f e r e d remarkably from those of wood from the upper portion of stems of normal outward appearance (Gates and Erlanson 1925; Penfound 1934; Paul and Marts 1934)• It was believed that Stems of plants i n general had become variably modified to meet the exigencies of climates i n which they l i v e . Roots, on the other hand, due to l e s s exacting environment surrounding them, have changed but l i t t l e through ages and represent a r e l a t i v e l y conservative organ i n most plants (Andrews 1947)* Nevertheless, xylem of roots exposed to the influences of the atmosphere acquired rapidly the character-i s t i c s of the normal xylem from stems (Kny i n Brown 1915; Wieler in Morrisson 1953; Morrisson 1953)« Length of tracheids, t h e i r thickness, as well as percentage of latewood i n Pinus contorta from bogs d i f f e r e d substantially from the corresponding a t t r i b u t e s of wood of Pinus contorta on lava beds (Kienholz 1931)• Thickness of earlywood tracheids varied i n the same species according to the habitat (Groom 1914)* Average length of tracheids increased by up to 25 per cent i n P i n u s ' s y l v e s t r i s aft e r thinnings (Savina 1956); i t was reduced a f t e r thinnings i n western hemlock (Wellwood and Smith 1962) . Average diameter and length of tracheids i n jack pine increased with an increase i n spacing. There was no c o r r e l a t i o n between length of tracheids and length of internode i n which they were formed (Adams 1928). 80 The f i r s t law of Sanio (in the stems and branches the tracheids everywhere increase i n size from within outward, throughout a number of annual rings, u n t i l they have attained a d e f i n i t e size, which then remains constant ....) (Bailey and Shepard 1915) could not be applied to some con i f e r s . F a i r l y regular cycles in tracheid length were observed to occur with age at one l e v e l i n the stem (Bailey and Shepard 1915)° It was suggested that the dimensions of tracheids may r e f l e c t the influence of climatic factors (Bailey 1920) . The second law of Sanio (the ... size (of tracheids) increases from below upward, reaches i t s maximum at a d e f i n i t e height and then diminishes toward the summit ....) was applicable i n red spruce and Scots pine. However, a fact unnoticed by Sanio i s that the maximum average tracheid length occurs higher from the ground i n rings nearer to the bark. This probably bears a r e l a t i o n to the fact that each successive increment i s ... farther from the ground (Bailey and Shepard 1915). Presumably, tracheid length within the same annual layer exhibits longitudinal trends comparable with similar trends i n r i n g width.. This assumption i s hard to reconcile with the reports of various authors who found that an inverse r e l a t i o n s h i p e x i s t s between r i n g width and tracheid length. Greater growth i n diameter was correlated with a shorter tracheid i n Douglas f i r (Lee and Smith 1916). In the same species, tracheid length decreased along longer r a d i i of eccentric trees (Wellwood and Smith 1962) . The longest tracheids i n any one ri n g were from the narrowest part and the shortest from the broadest part of a r i n g . i n Sitka spruce (Chalk 1930b). In white spruce the maximum c e l l length appeared to be associated with the p a r t i c u l a r r i n g width which marks the lowest point to which r a d i a l growth may drop without bringing about an increase i n frequency of m u l t i p l i c a t i v e d i v i s i o n s (Bannan 1963). This inverse r e l a t i o n s h i p between tracheid length and rin g width was found also i n Thu.ia o c c i d e n t a l i s ; among trees of si m i l a r diameter mean c e l l length i n the peripheral wood was greater i n trees with the narrower r i n g s . A similar r e l a t i o n s h i p was observed i n Pinus Strobus (Bannan 1960a, 1962)0 No rel a t i o n s h i p between tracheid length and r i n g width was found i n slash pine. It was assumed that tracheid length was under r i g i d genetic control (Echols 1955)• This assumption and f i n d i n g of the same author (Echols 1955) that a l i n e a r r e l a t i o n s h i p exists between f i b r i l a r angle and length of tracheid i n latewood of a l l rings and at a l l l e v e l s , are at variance with the finding of Vite (195$) who reported that f i b r i l a r angle increased i n suddenly released Pinus taeda. The f i r s t law of Sanio was confirmed i n western hemlock; age was found to have the strongest e f f e c t on tracheid length (Wellwood i 9 6 0 ) . Trees with shorter or longer than average tracheids retained t h i s feature. This was considered as a genetic e f f e c t (Wardrop and Dadswell 1953; Wellwood i 9 6 0 ) . • . It was maintained that Growth i s controlled primarily by genetic makeup of the plants, importance of environment i s completely dependent upon r i g i d i t y with which genetic factors control the plant. S i l v i c u l t u r a l treatments have been shown to be i n s u f f i c i e n t to produce wood f o r specialized uses (Zobel and Bruce i n McKimmy 1959)• 82 It was also maintained that the ef f e c t of environment may completely mask any genetic v a r i a b i l i t y (Hoist I960). The res u l t s of one of the oldest provenance experiments speak f o r the l a t t e r arguments with respect to growth, the behaviour of various provenances of Norway spruce was b a s i c a l l y that of trees of one common o r i g i n (Fisher 1949)• Also, i n Fraxinus  excelsior, the existence of d i s t i n c t l y d i f f e r e n t " s o i l races", assumed to exi s t by Muench, has not been proven (Weiser I 9 6 4 K Furthermore, study of hybrid seedlings of corn was unable to demonstrate any differences i n water loss between various strains (Craft et a l . 1949) . Environmental factors masked completely the hereditary influences i n various strains of cotton (Simpson 1946) . Ninety-eight v a r i e t i e s of apple trees, segregated into 16 groups according to t h e i r assumed optimal temperature requirements, possessed much greater capacity f o r adaptation to varied summer temperature than had been assumed. Climatic conditions favouring one group favoured a l l groups regardless of t h e i r temperature optima (Caldwell 1928) . Formation of lammas shoots was found to be governed more by environment than by heredity (Walters and Soos 1961) . A general lack of c o r r e l a t i o n between wood quality and external features was noted i n Douglas f i r trees (Wellwood and Smith 1962) . No secure conclusions could be drawn from the outward character-i s t i c s of Norway spruce f o r the purposes of the breeding work (Blossfeld and Haasemann 1964) . Ring porosity could be brought about i n normally diffuse porous species by environmental stress (Barner I 9 6 3 ) . $3 The appearance of annual rings i n the Jurassic epoch i n response to inclement seasonal conditions . correlated with the appearance of tangential p i t t i n g and of true parenchymateous storage elements ... has been the most important factor i n the evolutionary development of plants from the e a r l i e r epochs to the present (Jeffrey 1917)• Annual rings were considered as a s t r u c t u r a l adaptation to a r i d and semi-arid environment. They support geological evidence pointing to well developed dry or monsoonal climates i n temperate l a t i t u d e s during the Mesozoic (Barghoorn i n Shapley 1953)• Nevertheless, a feature as old as that of annual ri n g was not found to be gen e t i c a l l y f i x e d : The fact that i n a controlled environment there was no va r i a t i o n i n lumen diameter and c e l l wall thickness across the growth ring demonstrates that the normal pattern of ear l y - and latewood development i s subject to environmental rather than genetic control, a conclusion drawn by Fry and Chalk (1957) from t h e i r examination of Pinus patula grown i n Kenya (Richardson i 9 6 0 ) . Both wind and adverse s o i l moisture conditions brought about anatomical and morphological changes which were considered as adaptive. It was established that plants possess a "compensating mechanism", i . e . a b i l i t y of a genotype to react to i t s environment producing advantageously modified phenotypes (which) must be of importance i n determining survival i n nature; i t was further maintained that The variety, extent and physiological significance of compensating mechanism has yet to be determined but they may be of greater importance i n ecological selection and competition than i s r e a l i s e d at present (Venning 1949? Whitehead and-Luti 19631 Whitehead 1963) . 84 The rough-barked specimens of Betula verrucosa were shown to form s i g n i f i c a n t l y longer f i b r e s i n rings which were also wider as compared with similar trees of the same species with smooth bark (Newall and Gardiner 1963) . Specific gravity of wood formed on the side of longer r a d i i of some Douglas f i r and western hemlock stems was consistently higher than s p e c i f i c gravity of wood sampled along shorter r a d i i of the same stems (Wellwood and Smith 1962) . A similar phenomenon was observed within the opposing sides of the stem of one and the same phenotype. This "curious feature long known to former workers" was e s p e c i a l l y prevalent i n stems of Pinus r i g i d a investigated by Brown (1912). the density of xylem was l e s s on the south side of t r e e s . This was due to a greater proportion of latewood on the north side as compared with the south side. This d i s p a r i t y i n wood formation was not marked i n young trees. As to the cause of t h i s lessened density on the south side, no reasonable conclusion was attained i n these investigations, nor has i t ever been s a t i s -f a c t o r i l y accounted f o r . It i s without doubt correlated with i n s o l a t i o n i n some way, but further study i s necessary to determine t h i s d e f i n i t e l y (Brown 1912). In a more recent investigation by Liese and Dadswell (1959), i t was found that sun and shadow can have a pronounced influence i n modifying the length of tracheids i n open grown coni f e r s . Fibers of trees which grew north of the equator were shorter on the south side of t h e i r stems, f i b e r s of trees from the southern hemisphere were shorter on the north side of t h e i r stems. Differences i n length of tracheids between the insolated 85 and shaded side corresponded roughly to the differences i n length of earlywood and latewood types of tracheids from within one annual r i n g . The authors offered the following explanation of t h i s phenomenon, the heating of the bark by the sun stim-ulates the cambial a c t i v i t y ; therefore within an annual ring, the tracheid length and the growth i n t e n s i t y stand i n an i n d i r e c t proportion to each other. The d i f f e r e n t a t i o n of xylem elements on the warmer sides of the stem occurs f a s t e r than on the cooler northern side. Therefore, tracheids on the insolated side have le s s time f o r t h e i r extension growth and, consequently, they are longer on the shaded side of the stem. The two l a t t e r investigations are of especial interest to t h i s study f o r two reasons. F i r s t l y , out of the whole complex of environmental factors, temperature was selected as the key fa c t o r adjudged to be able to influence both tracheid length and c e l l wall thickness. Secondly, the temperature d i f f e r e n t i a l affected wood qual i t y within the opposing sides of the same stem d i f f e r e n t l y . It i s well known that a l l the growing tissues, and sex c e l l s , are very sensitive to temperature extremes and to temperature f l u c t u a t i o n s (Belehradek i n Precht e_t a l . 1955) • In higher organisms, growth means an increase i n size and i s always connected with m u l t i p l i c a t i o n of the c e l l s . The influence of temperature has to be considered separately f o r the increase i n size and f o r the increase of the numbers of newly-formed c e l l s (Christophersen i n Precht et a l . 1955)* 86 The size of the c e l l s i n the secondary xylem i s determined by the size of the cambial i n i t i a l s and by changes that take place i n t h e i r derivative c e l l s during d i f f e r e n t i a t i o n into tracheary elements (Bailey 1920) . Temperature seems to exert some influence during the l a t t e r stage; i n roots c e l l wall t e n s i l i t y decreased i n d i r e c t response to increased temperature (Burstroem 1956) . The roots of peach and apple, succulent and mechanically weak at 65°F or le s s , were found to be t y p i c a l l y woody and of considerable mechanical strength at 75°F (Nightingale 1935) • I n t e n s i f i e d l i g n i f i c a t i o n i n parts of a tree with a sunny aspect was recorded by Fisher (in Morrisson 1953)• C e l l d i v i s i o n within the cambial layer of Fraxinus and Acer was favored at 60°F, l i g n i f i c a t i o n was accelerated at temperatures above 70°F (Hanson and Branke 1926) . Maximum d a i l y temperatures of about 70°F were optimal f o r diameter growth of ponderosa pine. Higher temperatures depressed the r a d i a l growth (Mace and Wagle I 9 6 4 ) . The numbers of xylem c e l l s produced by a cambial layer within one season showed the same tendency as annual r i n g width, nor was there always a c o r r e l a t i o n between the maximal number of c e l l s and maximum ri n g width. Ring width depended not only on a number of c e l l s but also on t h e i r size (Adams 1928). Increase i n ri n g width i n trees from a humid habitat, or i n rings from within the crown, was due i n part to an increase i n diameter of tracheids but more to the number of tracheids l a i d down (Kienholz 1931; Zahner and O l i v e r 19,62; Shepherd 1964) . 87 The increase i n width of the swollen bases was due to a great increase i n the number of c e l l s of latewood (Gates and Erlanson 1 9 2 5 ) o Greater size of the basal portion of trees was due primarily to greater number and only secondarily to a larger size of the xylem c e l l s (Penfound 1934) , It can be concluded that i t i s l a r g e l y the number of c e l l s which determines the width of the annual layers of xylem; the r e l a t i v e r i n g width may be, as already mentioned, subject to the dir e c t influence on the stem of factors from the environmental complexo Temperature was found to be important i n t h i s respect; the enormously stimulated one-sided r a d i a l growth i n stems of Ficus repens was attributed to influences of atmosphere. E f f e c t s of l i g h t , or temperature, or humidity were suggested (Massart i n Ursprung 1913)« Radial increment on the south side of stems of Norway spruce growing 1350 m above sea l e v e l was, on the average, 1.5 times that found on the north side of the stems. This r a t i o was exactly opposite i n trees growing 230 m above sea l e v e l (Kern i 9 6 0 ) . Grafts of f r u i t trees healed f a s t e r on the southern side than on the northern side of trees (Braun i 9 6 0 ) . Trees on a southern slope increased i n radius more rapidly during the early part of the season. However, by the end of the season trees on the northern slope made the largest increases (Cantlon 1953)* The length of the growth period was d i r e c t l y related to the amount of r a d i a l growth of both earlywood and latewood and p consequently, to the percentage of latewood (Chalk 1927? Savina 1956; Mikola I960; Kennedy 1961). The length of the period of the cambial a c t i v i t y i s determined by the date of i t s inception and by the date of i t s cessation. Both these data were found to be cl o s e l y related to temperature. Vernal ambient temperature was assumed to be the chief f a c t o r responsible f o r c o n t r o l l i n g the rate of enzymic reactions associated with secondary growth; vernal increase i n ambient temperature, rather than physical transport of auxin from developing buds, was considered to be responsible f o r i n i t i a t i o n of cambial a c t i v i t y (Steward 1957)• High temperature was the main f a c t o r i n i n i t i a t i n g diameter growth i n the spring (Larsson et a l . I964K The co r r e l a t i o n between rate of cambial a c t i v i t y and temperature was positive up to 60°F, but negative f o r temperatures above 60°F (Hanson and Brenke 1926). Prelim-inary changes i n the cambial tissue of branches were observed i n March at average a i r temperature of 40°F, the maximal temperature not exceeding 53°F (Ladefoged 1952). Formation of f r o s t rings was observed i n a year i n which unusually warm weather i n March was followed by a s p e l l of cold weather i n A p r i l (Glock and Agerter 1963)0 Frost rings i n f r u i t trees were found mostly on the south side of the stem (Tingley 1936). Beginning and con-tin u a t i o n of cambial a c t i v i t y depended on the a l t i t u d e (Kern I960). More than a three-month v a r i a t i o n i n the inception date of r a d i a l growth was observed i n tupelo gum tr e e s . This was ascribed to the e f f e c t s of temperature (Eggler 1955)* 89 Prolonged high temperature was assumed to be the cause of cessation of r a d i a l growth at a time when a l l other environ-mental factors were not l i m i t i n g i n t h i s respect (Jacquiot 1950; Eggler 1955; Mace and Wagle 1964) . Site quality was not correlated with the time of cessation of growth ( G r i f f i t h I960; Kern i 9 6 0 ) , yet the less the tree grew i n thickness the e a r l i e r in summer the wood formation declined (Ladefoged 1952). In stem bases of trees i n a stand, having an increment of 1 mm or less, cambial a c t i v i t y ceased l a t e i n July or early i n August. In open-grown trees with annual ring wider than 2 mm c e l l d i v i s i o n occurred as late as September (Bannan 1955)• Frost damage i n crotches of apple trees was due to the prolonged cambial a c t i v i t y i n t h i s region. The acuteness of the branching was correlated with the amount of injury; the rings were widest i n narrowest crotches (Horsfau 1932; Potter 1938) . Continued cambial a c t i v i t y and root growth was observed i n root stocks overwintering i n the greenhouse (Hoist 1956) . According to Brown (1915), the r a p i d i t y of vernal growth i n white pine depended on the amount of reserve foods, moisture and temperature. The f i r s t two were always at the optimum. The t o t a l temperature e f f e c t derived from temperature of a i r , from the dire c t i n s o l a t i o n and from the temperature of s o i l water. The f i r s t two factors were dismissed as e n t i r e l y n e g l i g i b l e or minor in t h i s respect because of the thick layers of bark. I r r e g u l a r i t i e s i n dimensions of xylem tissue and i n the number of new xylem elements, observed a l l along the stem, were due to i r r e g u l a r cycles i n cambial a c t i v i t y . 90 The following generalizations applied with respect to time of cessation of r a d i a l growths growth i n t e n s i t y f a l l s off f i r s t i n the upper parts of the bole, more t a r d i l y below; cessation of xylem formation does not follow the same law but growth p e r s i s t s sluggishly i n a l l parts of the bole. The d i s p a r i t y i n growth along the bole was assumed to be due to "conditions of temperature". Temperature changes become operative f i r s t where the primary cortex s t i l l p e r s i s t s ; they are l e s s e f f e c t i v e i n the basal portion of stem because of t h i c k layers of bark. Therefore, r a d i a l growth i n white pine was retarded f i r s t along the upper stem but went on vigorously along the lower stem f o r a much longer period. Contrary to Brown (1915), Adams (1935) believed that i n s o l a t i o n i n the spring was responsible f o r the inception of cambial a c t i v i t y i n t r e e s . Cambial a c t i v i t y may start sooner i n the upper part of a tree because bark i n t h i s region i s thinner and more exposed to d i r e c t sunlight than the thicker bark i n shade of the lower stem. The increasing width of xylem layer i n the upward d i r e c t i o n may be due to proximity of the source of foods or i t may be due to the response of the cambium to a greater heat stimulus e a r l i e r i n the season and thereafter. There are no data to support the l a t t e r hypothesis but the f a c t remains that stands which have been thinned show greater diameter growth i n the iower part of the stem ... the nature of the ef f e c t of the differences i n a i r temperature on the physiological a c t i v i t y of the various parts of the tree can only be assumed since s u f f i c i e n t data are not available to warrant d e f i n i t e statements (Adams 1935). 91 Deductions of Brown (1915) and Adams (1935) are supported by findings of Hartig (in Brown 1915) and Knudson (1913)» Disparity of r a d i a l growth along the stem was also reported by Topcuoglu (1940) and by Mer (1892); upper portion of trunks of forest grown trees grew f a s t e r i n diameter during the spring months than the basal portion. Conditions were reversed during the summer. In open grown trees on bare s o i l the basal portion was observed to start growing i n diameter four weeks before the bases of trees i n the closed stand with humus lay e r . This d i s p a r i t y was attributed to temperature (Hartig i n Brown 1915). Indeed, f a l l plowing i n orchards i s known to increase the incidence of sun-scald injury at the base of f r u i t trees (Mix 1916)° Rings formed during a hot and dry summer were exceptionally narrow along the lower portion of the bole; they were more nearly normal within the crown (Schober 1951)o Both the amount of r a d i a l growth, at one l e v e l or a l l along the bole, and the quality of wood were frequently related to the bark thickness and bark character, which l a t t e r two variables were, i n turn, correlated with factors of environment. Solar r a d i a t i o n and a i r humidity were the most important fac t o r s i n t h i s respect. For example, bark on the edges of buttresses of t r o p i c a l trees was 2.5 times thinner than the bark higher up on the stem (Francis I924). Bark thickness was well correlated with stem diameter i n trees from the temperate zone; no such 92 c o r r e l a t i o n existed i n trees from t r o p i c a l r a i n forest and they showed also l i t t l e v a r i a t i o n i n bark thickness along the bole (La Rue 1932/3 F u l l e r 193$) • In trees from temperate l a t i t u d e s percentage of bark increased with height i n stem and could be larger at the upper l e v e l s than i t was at the ground; slowly tapering stems had less v a r i a t i o n i n bark percentage as compared with rapid l y tapering stems (La Rue 1932). Trees of systematically related species growing i n savannas were thick-barked; those from the r a i n forest were thin-barked (Richards 1952)« Pine from the coastal regions was t y p i c a l l y thin-barked; that from dry regions possessed t h i c k layers of bark (Wiedemann 1932). Cypress growing along fresh water had s i g n i f i c a n t l y thinner bark than that from pools of stagnant and therefore warmer water (Mattoon 1915; Demaree 1932). In eccentric branches of T i l i a , bark was twice as t h i c k on sides of the longer radius than on the side of the shorter radius (Krabbe 1882) <> Bark was rougher on the south side of trees where the growth was also more active (Leonardo da V i n c i i n McMurrich 1930) . Abrading dead bark and s l i t t i n g the cortex longitud-i n a l l y promoted growth from the cambium; li g a t u r e s around the stem decreased the number and size of xylem elements (Sachs 1887; De Vries; Krabbe; P f e f f e r i n Newcombe 1894, 1895; Knight l803 ) o Prominent widening of annual rings under the f i s s u r e s occurs commonly i n species with deeply fi s s u r e d bark (Huber i n Ursprung 1906)o Growth i n thickness of cambial layer may be 93 favored under crevices of Robinia (Braun 1955)• The wider the cambial layer the more rapidl y were the new xylem elements formed i n Fraxinus and Acer(Hanson and Brenke 1926) . Crevices were found on the convex side of bent T i l i a trees while t h e i r concave side was smooth-barked (Karzel 1906) . Thickness and/or character of bark were related to the amount, or to the duration of r a d i a l growth, or to the wood quality i n poplar (Joachim 1954); i n western yellow pine (Dunning 1922); i n southern cypress (Mattoon 1915)j i n redwood (Luxford 1930); i n Norway spruce (Blossfeld and Haasemann 1964); i n Scots pine (Dengler i n Joachim 1954); i n alpine f i r (Kennedy and Wilson 1954a, b); i n bi r c h (Newall and Gardiner I 9 6 3 ) ; i n oak (Kirst I 9 6 3 ) ; i n beech (Svoboda 1964) . With respect to texture and color, bark of the l i v i n g stumps sometimes bore l i t t l e resemb-lance to the bark of normal trees (Lamb 1899; Page 1927) . Bark character was related to the degree of bark slippage (Huber 1948) . Aspen from high a l t i t u d e s had a thicker corky layer than that from lowlands (Shope 1927)• The r e l a t i v e volume of cork i n bark of Douglas f i r was higher than that of any other North American conifer studied (Chang 1954) and ranged from 20 to 45 per cent i n the oven dry bark (Grondal 1942) . The t h i n layer of cork i n the bark of trees from the t r o p i c a l r a i n forest was due to the e f f e c t s of humidity (Whitford 1906; Schimper i n Francis 1924)* Excessive moisture suppresses suberization; i n s o l a t i o n hastened formation of deep cork (Esau 1958; de Zeeuw 1941)* With respect to the uniformity of 94 a c t i v i t y , cork cambium behaved as the vascular cambium, i t could be active i n some parts of stem while s t i l l r e s t i n g i n other parts of the same stem ( G r i l l o s and Smith 1959) . The values of the c o e f f i c i e n t of d i f f u s i v i t y of ground cork and of water are exactly the same (Carslaw and Jaeger 1959), but the prevention of water loss from stems was considered the primary function of the corky layer (de Zeeuw 194l)<> On the other hand, i t was shown that layers of bark are not impermeable? l i q u i d s could reach the cambial layer from outside as well as from i n s i d e . For example, ar s e n i c a l solutions penetrated by l e n t i c e l s and by f i s s u r e s i n the old bark (Swingle and Morris 1 9 1 7 ) ° O i l s of low v i s c o s i t y penetrated through the cork into the cambium of apple twigs (Ginsburg 1931)» Radioactive fluorochrome was translocated from vessels through the sclerenchyma r i n g into the bark (Heinrich 195$) . Radio-active phosphorus moved through bark into wood of branches; i t was concluded that nutrients may be supplied to trees v i a the bark (Kiselev 1962) . Absorption of water by the bark and not by the roots provided the necessary stimulus f o r l e a f formation i n o c o t i l l o (Lloyd I9O5) . The conclusion of Brown (1915), namely that reserve foods are not l i m i t i n g i n the beginning of cambial a c t i v i t y , seems to be i n agreement with more recent findings; carbohydrate reserves were adequate at any pos i t i o n i n the stem to support growth i n that l o c a t i o n once i t started (Wilcox i 9 6 0 ) . Depletion of starch was considered to be proportional to the amount of 95 r a d i a l g r o w t h i n c a s e s o f d e f o l i a t i o n , b u t u n d e r n o r m a l c o n -d i t i o n s p r e s e n c e o f s t a r c h was n o t c a u s a l l y c o n n e c t e d w i t h r a d i a l g r o w t h ( W i g h t 1933)* R o o t a n d s t e m b a r k o f h e a l t h y t r e e s r e a c h e d a m i n i m u m i n s t o r e d f o o d i n t h e e a r l y f a l l a n d m a x i m u m , 2,5 t i m e s t h e m i n i m u m , i n e a r l y s p r i n g ( H e p t i n g i n J a c k s o n a n d H e p t i n g I 9 6 4 K T h e a m o u n t o f s t a r c h s t o r e d i n s a p w o o d o f D o u g l a s f i r was a t i t s maximum d u r i n g l a t e w i n t e r a n d e a r l y s p r i n g ( C h a p m a n e_t a l . 1963) . W i n t e r p h o t o s y n t h e s i s was shown t o a c c o u n t f o r u p t o 25 p e r c e n t o f t h e t o t a l n e t a n n u a l g a i n o f p h o t o s y n t h a t e i n D o u g l a s f i r ( H e l m s I 9 6 4 K I n N o r w a y s p r u c e some a c c u m u l a t i o n o f p h o t o s y n t h a t e was p o s s i b l e e v e n d u r i n g t h e t e m p e r a t u r e s b e l o w f r e e z i n g p o i n t ( P a r k e r 1953)• P h o t o s y n t h e s i s c o u l d o c c u r i n b a r k o f s t e m s o f m a t u r e a s p e n t r e e s o B a r k f r o m t h e n o r t h s i d e o f t h e s t e m c o n t a i n e d m o r e c h l o r o p h y l l p e r u n i t a r e a t h a n b a r k e x p o s e d t o s u n a n d i t c o n t a i n e d a l s o m o r e c h l o r o p h y l l p e r u n i t a r e a o f s u r f a c e t h a n a n y o f t h e l e a v e s ( P e a r s o n a n d L a w r e n c e 1958) . A n o t h e r o f B r o w n T s (1915) c o n c l u s i o n s , n a m e l y t h a t b a r k i s t o o t h i c k t o p e r m i t t h e w a r m i n g u p o f t h e c a m b i a l l a y e r i n t h e s p r i n g , m i g h t n o t b e w h o l l y t r u e . I n l a r g e f r u i t t r e e s t h e s u b c o r t i c a l t e m p e r a t u r e s , d u r i n g t h e w i n t e r , r e a c h e d 7 1 ° F . I n t a r r e d t r e e s s u b c o r t i c a l t e m p e r a t u r e s r o s e t o 9 2 ° F c ( S e l b y 1897) . C a m b i a l t e m p e r a t u r e s o n t h e s o u t h s i d e o f o p e n g r o w n s p r u c e r e a c h e d 131°F ( H a r t i g i n P r e c h t e_t a l . 1955)j i n f r u i t t r e e s t h e y a t t a i n e d 100 t o 113°F d u r i n g t h e summer ( F e r k l i 9 6 0 ) , a n d 80°F d u r i n g t h e w i n t e r ( E g g e r t 1944)• S u b c o r t i c a l 96 temperatures 30 feet above ground reached1 90°F at a i r temperature of 108 F (Reynolds 1939) . Temperature of the' canibium on the south-west side of an old f i r tree was 90°F at BH at a i r temperature of 75°F (Gerlach i n Geiger 1950) . Cambial temp-eratures fluctuated as much as the a i r temperatures i n old basswood trees under a 6 mm-layer of bark lacking corky layers (Kuebler and Traber 1964) . Temperature of xylem midway between p i t h and bark of the shaded side of Pinus radiata infested by Sirex was always higher than that of a i r i n shadow by 1 to 5°C; healthy trees were always cooler by 2 to 5°C than the a i r . Temperature of trees of d i f f e r e n t crown classes d i f f e r e d (Jamieson 1957) . Temperature of dead trees was up to 18°F higher than that of l i v i n g trees (Rameux i n Mason 1925) . Subcortical temperatures i n logs fluctuated more than the a i r temperatures and varied d i r e c t l y with i n t e n s i t y of solar r a d i a t i o n (Graham 1925) . They were highly variable within the same log as well as i n logs of the same species, and s t i l l more i n logs of d i f f e r e n t species (Graham 1922) . The temperature d i f f e r e n t i a l , i n the cambium or under the bark, between insolated and shaded sides of the same trunk was between 35 and 55°F during the winter time (Selby 1897; Eggert 1944) and between 15 and 36°F during the summer (Gerlach i n Geiger 1950; F e r k l and Ferkl 1 9 5 4 ) . Evidently, temperatures which can be transmitted to subcortical tissues through the layers of bark are high enough to be considered as c r i t i c a l i n inception and maintenance of 97 r a d i a l growth because, i n plants, the optimal temperatures of most types of growth are generally lower. This fact can be shown by the inspection of the r e s u l t s of tissue culture studies. It was believed that a growing undifferentiated mass of c e l l s such as a c a l l u s culture or a culture of excised roots exhibiting a l i m i t e d amount of d i f f e r e n t i a t i o n should possess fewer i n t e r n a l variables and should also permit control of the external variables at w i l l (White 1943)» A rigorous control of temperature was shown to be e s p e c i a l l y important i n t h i s respect; a maintained increase i n temperature from 28 to 30°C caused a 20 per cent increase i n growth rate of excised tomato root t i p s . A further increase from 30°C to 31°C caused a 30 per cent decrease i n growth rate (White 1937a, b). The range between optimum and l e t h a l temperatures i s very narrow. A maintained r i s e of 5°C above optimum w i l l k i l l the cultures. Cultures w i l l endure maintained low temperature without injury and w i l l resume normal growth at temperatures more nearly optimal (White 1943)» Temperature of tissues growing i n the dark was that of the a i r temperature. Illuminated tissues were always warmer than a i r due to intercepted radiant energy transformed into heat (de Capite 1955; Gautheret 1961) . The optimal temperatures of the cambial tissue culture of S a l i x capraea was about 60°F (Gautheret 1938) . Cambial tissue of various species p r o l i f e r a t e d i n v i t r o at 77°F (Jacquiot^, 1950, 1951; Gautheret 1938); tissue of Pinus banksiana 98 grew well at 72 °F (Loewenberg and Skoog 1952)o Callus culture of Sequoia sempervirens was maintained at 70°F (B a l l 1950) , that of Helianthus annuus at 68°F during the day and at 79°F during the night (de Capite 1955); that of sunflower at 76 to 83°F (Hildebrandt e_t a l . 1945)* Excised tomato root t i p s grew well at 86°F, a temperature of 95°F being lethal:(White 1937 a). Excised root t i p s of pea, sunflower, corn and cotton had temperature optima at 50°, 68°, 77° and 7 7 ° , respectively (Galligar 1938)» Asparagus root i n i t i a l s kept growing at 77°F (Galston 1948); asparagus excised stem t i p s at 79°F (Loo 1945)• Total increment and also the largest number of l a t e r a l s i n i s o l a t e d roots of Pinus s y l v e s t r i s were produced between 63 and 66°F (Slankis 1949)» Maximum growth of apple and peach roots was observed at 65°F (Nightingale 1935)* Callus formation i n apple cuttings and g r a f t s was optimal at 68°F; i t occurred within the range 32 to 104°F. Oxygen, even below the a i r concentration was not l i m i t i n g (Shippy 1930)o It was maintained that Tissue cultures of the cambium are derived from complexes of l i v i n g c e l l s , which include, i n addition to cambial i n i t i a l s t issue c e l l s that are known to be capable of d e d i f f e r e n t i a t i o n and subsequent d i v i s i o n . Furthermore, when parts of the cambium are removed from a tree and are grown i n tissue cultures, the i n i t i a l s cease to function normally and form c a l l u s (Bailey 1952) . It was also reported that periods of growth of the c a l l u s cambium are not i n v a r i a b l y i d e n t i c a l with those of normal cambium (MacDougal 1943) <» Nevertheless, the above survey makes 99 i t clear that the optimal temperatures of cambial tissue cultures are not substantially d i f f e r e n t from those of c a l l u s tissue cultures. The range of both of them i s from about 60°F to 79°F and i s therefore considerably lower than the upper l i m i t of the subcortical temperatures found i n tre e s . It i s well known that The temperature r e l a t i o n s of physiological processes do follow certain t y p i c a l curves which seem to be i d e n t i c a l or nearly r e l a t e d f o r processes of the same fundamental nature i n d i f f e r e n t organisms (Krogh i n Leitch 1916). Therefore, temperatures optimal f o r growth of plant tissue i n v i t r o may well be i n d i c a t i v e of temperatures optimal f o r the rate of the r a d i a l growth i n trees. Conversely, temperatures found to be supra-optimal i n tissu e cultures may be c r i t i c a l f o r cambial growth i n trees because the optimal temperatures of tissue cultures are higher than those usually observed i n growing intact plants (de Capite 1955; Gautheret 1961). In the absence of any inquiry which would evaluate the influence of cambial temperature on the processes of r a d i a l growth i n trees the phenomenon of heating of stems merits further attention. Results of r e l a t i v e l y few studies seem to be available i n t h i s respect. The more important fac t o r s governing the l e v e l s of the subcortical and xylem temperatures can be l i s t e d as follows: (1) i n t e n s i t y , a l t i t u d e and angle of incidence of solar r a d i a t i o n ; (2) thickness, surface texture, inner structure and color of bark; 100 (3) amount of shading; (4) moisture content of bark and of xylem; (5) a i r temperature and a i r movement; (6) proximity of other r a d i a t i n g and absorbing surfaces; (7) the cooling e f f e c t of the t r a n s p i r a t i o n stream deriving i t s temperature from the s o i l ; (8) size of the stem. (Selby 1897; Graham 1922; Mason 1925; Ferkl and Ferkl 1954) . During the winter the maximum heating e f f e c t takes place on the part of trunk oriented towards south and culminates between noon and 2 pm. During the summer bark of trees i s nearly p a r a l l e l to the d i r e c t i o n of the sun rays at noon. Maximum underbark temperatures were found during second h a l f of July on the sides of stems oriented towards west between 3 pm and 5 nip. During a sunny day, i n trees i n the open, there are not two s i t e s within the cambial cylinder which would have the same temperature ( M i l l e r 1931; F e r k l and F e r k l 1954) . Trees leaning to the northeast were most severely injured by solar r a d i a t i o n ; the injury was confined almost e n t i r e l y to the southwest side of the trunk (Mix 1916) . The e f f e c t of i n s o l -ation which was equal to 100 per cent i n branches perpendicular to the d i r e c t i o n of sun's rays, decreased to 30 per cent i f the angle of incidence was 50 degrees (Ferkl and Ferkl 1954) . Bark thickness was, by f a r , the most important f a c t o r determining the r e l a t i o n of a i r temperature to sub-c o r t i c a l temperature. In trees with a t h i n layer of bark the 101 subcortical temperature corresponded closely to a i r temperature; shadow or wind caused immediate and rapid drop i n subcortical temperature; r e f l e c t i o n from snow had an opposite ef f e c t (Harvey 1923a.; Beal 1934) . With a surface temperature of 135°F i t took 9 minutes to reach 122°F at the cambium shielded by 0 . 2-inch layer of bark. With t h i c k e r bark and higher external temper-ature the cambial temperature continued to r i s e a f t e r the heat was removed; the cooling period was considerably prolonged (Kayll 1963b). Mortality due to freezing i n western pine beetle varied inversely as the thickness of bark protecting the brood. This r e l a t i o n s h i p held only f o r bark layers more than 0 .5 inch thick (Keen and Furniss 1937) . Stems of smooth-barked trees were warmer than those having rough bark (Russell 1889). Fissures occupied as much as 44 per cent of the circumference of a 15 inch pine. When a temperature of 500°C was applied at the bottom of a f i s s u r e 0 .5 inch deep a temperature of about 1000°C was recorded on an adjacent plate (Kayll 1963b). Black bark may be 8°F warmer i n sunlight than white bark (Harvey 1923b). In trunks of f r u i t trees painted black the sun scald injury was confined e n t i r e l y to the blackened part of stem (Mix 1916) . In la r c h , growth did not begin f i r s t i n those regions with the thinnest bark and best i n s o l a t i o n but i n the middle region of stem because, supposedly, there the bark was of the same color as that of the basal regions and only h a l f as thick (Knudson 1913). 102 Exchange of energy between plant and a i r by free or forced convection transfers energy from the plant i f i t i s warmer than the a i r and transfers energy to the plant i f the a i r i s warmer than the plant. In the steady state the exchange of energy between plant and a i r w i l l result i n the plant having an equilibrium temperature (Tibbals et a l . 1964) . The rate of energy tr a n s f e r between the plant and the environment determines the temperature of the plant. Various parts of a plant may possess d i f f e r e n t temperatures because of varying rates of energy transfer (Gates I 9 6 5 ) . Temperature of parts of stems in shadow are always i n an approximate agreement with the temper-ature of a i r i n shadow (Gerlach i n Geiger 1950; Ferkl and Ferkl 1954)• The temperature i n the base of seedlings was l a r g e l y influenced by the amount and position of the shade cast by the cotyledons and by the true f o l i a g e (Baker 1929)• C o n f l i c t i n g evidence e x i s t s on the e f f e c t s of moisture content on heat tolerance (of cambium). Thermal conductivity of wood increases with increasing moisture content, and bark may react i n the same manner .... Conversely, the e f f e c t s of an increase i n thermal conductivity may be offset by an increase i n thermal capacity. However, i n importance of effect on high temperature heat tolerance, moisture content i s probably fourth, following bark thickness, temper-ature of applied heat, and i t s duration (Kayll 19o3a). Bark of some deciduous species contained 2 to 7 times as much moisture as bark of Tsuga canadensis, depending on species and. position above ground. Bark of any i n d i v i d u a l tree was several times as moist near the base as i t was 6 feet above s o i l l i n e ( B i l l i n g s and Drew 1938) . The absorptive 103 capacity of bark f o r water d i f f e r e d among the species. Action of wind was assumed to be the cause of differences i n moisture content i n bark of d i f f e r e n t trees of the same species (Young 1937)« Water content of bark was lower i n winter and at the end of the summer; i t fluctuated more than that of wood (Gibbs 1957)» Phloem of southern pines contained consistently over 200 per cent of moisture on a dry weight basis, whereas the outer bark showed an average of l e s s than 30 per cent at temperatures of about 10°F (Beal 1933)« Water content of seedlings grown under uniform conditions.ranged from 100 to 250 per cent (Kayll 1963a) <> Water content of xylem i n young poplar saplings was maximal i n June, minimal i n September. From A p r i l to September moisture content rose from the base to the apex; the gradient was reversed during the dormant season (Butin 1957) <> Severance of l a t e r a l s did not a f f e c t noticeably the moisture content i n stems of Douglas f i r (Chalk and Bigg 1956). Regional differences i n moisture content of sap wood in Abies balsamea could not be explained (Clark and Gibbs 1957). Temperatures of overwintering cambium under insolated bark were brought down to a i r temperature by a 50 feet/minute breeze i n 2 to 3 minutes. The height to which the cambial temperature rose depended on v e l o c i t y and d i r e c t i o n of wind (Harvey 1923a). A warm wind t r a n s f e r r i n g energy to a plant may bring about the same plant temperature as would a d e f i n i t e f l u x of incident radiation (Gates 1965) . 104 Long wave radiation of earth and reflected solar radiation can be more important sources of the energy, for a body above ground, than the direct solar radiation (Precht .gt .al. 1955)• The energy content of plants i s moderately coupled to the incident sunlight, but strongly coupled to the infrared thermal radiation from the surrounding surfaces (Gates 1962, 1965). Growth may go on in date palms even when minimum temperature of a i r i s below freezing, provided the maximum temperature of the day i s well above 50°F. Differences i n the interior temperature from the a i r temperature have ranged from 26°F warmer on the coldest morning to 32°F cooler on the hottest day, but the daily range of interior temperature was rarely above 7 to S°F. The stabilizing of temperature of the meristematic tissues of the date palm i s believed to be due to a protective envelope around the phyllophore, and to the ascending sap current with temperature acquired from the s o i l (Mason 1925)« The cooling effect of transpiration stream in trunks of forest trees was found to die out rapidly above ground level (Mayr in Baker 1929)• Trees with a trunk diameter of less than a foot suffered from sun scald more than larger trees. Rarely, i f ever, was sun scald observed on large old trees.(Selby 1&97)• In bringing the cambial temperature to 65°C, 7**inch DBH balsam f i r withstood an external temperature of 300°C longer than a 12-inch DBH beech; 9-inch DBH hemlock was almost twice as 105 r e s i s t a n t to heat as 15-inch DBH balsam f i r . These differences were attributed to character of bark ( S t i c k e l i n K a y l l 1963b). Width of the bark layer was considered a factor important i n heat transfer to cambium. Bark width i s d i s t -ributed along the bole i n a fashion which i s d i r e c t l y opposite to that of t o t a l r i n g width or of r i n g width of earlywood, but which resembles that of r i n g width of latewood. It follows that the i n s u l a t i o n of the cambial layer i s least e f f e c t i v e i n the upper reaches of the bole i f the influence of shading and in s o l a t i o n are disregarded. E f f e c t s of temperature thus might be f e l t f i r s t within a part of the cambial cylinder protected by thinnest layer of bark even i n case that the temperature p r o f i l e within the forest would be isothermal at a l l times, discounting the e f f e c t s of i n s o l a t i o n . Existence of v e r t i c a l temperature gradients i n the forest, and also i n the open, during the growth season, or part of i t , during the day and/or night, supports the concept of d i s p a r i t y of r a d i a l growth of xylem along the stems. It i s known that a forest tree extends through a series of temperature regimes from the microclimate of a root t i p , where the largest temperature differences during the growing season might not be over 15°F, to that of a twig where temperatures may range from -40 to 100°F (Fraser 1957). The v e r t i c a l gradients i n summer a i r temperature between s o i l surface and crown region of an oak stand were as high as 36°F (Goryshina and Neshataev i 9 6 0 ) . A similar gradient i n a 106 natural stand of Norway spruce was only 2 to 4°F (Kautu 1952)» Temperature i n crown space during the day was proportionate to the:density of the stand which, together with height and area, determined the whole microclimatic structure of the stand (Goehre and Luetzke 1956). In t h i s respect, even the s p a t i a l d i s t r i b u t i o n of trees i n the forest was considered to be important: temperature conditions i n plantations with regular spacing might d i f f e r from those with random spacing to such a degree as to a f f e c t the rate of growth (Selleck and Shupert 1957), Three types of diurnal microclimatic temperature gradient were observed during the growing season: under heavy shade the temperature was higher i n the crown space than at the ground; a complete reversal of t h i s gradient was observed in stands with small openings; under medium,shade v e r t i c a l temperature gradients disappeared (Cantlon 1953)• Canopy tended to increase temperature at higher elevations above ground during the summer. The lowest temperatures were at 20 cm above ground throughout the year; microclimatic structure of three habitats was pronouncedly d i f f e r e n t during various seasons of the year (Sparkes and Murray 1955)* The crown space of an old stand was the space of highest a i r temperatures and of the most unsettled condition. The layer 3 m high above the ground showed uniform temperature. Sinking cold a i r i n a stand of low density resulted i n a temperature minimum at the forest f l o o r (Geiger 1950). Higher maximum and lower minimum 107 a i r temperatures were found in crowns and within the space below the crowns i n thinned stands of pine (Adams 1935)• "Secondary temperature maximum" was observed during the day at some small distance above the ground; i t s v e r t i c a l p o sition varied and depended on l o c a l conditions (Vujevic 1909, Geiger 1950). Mean monthly temperatures within the microclimatic layer are not independent of height. Differences as much as 13°F were observed between maximum a i r temperature at 2 m and 5 cm above ground (Baum 1949 > Cantlon 1953)» It was recognised that meteorological variables such as a i r temperature and a i r humidity confer only a l i m i t e d amount of information regarding the processes which bear on the heat and water economy of a forest stand: they are meteor-o l o g i c a l elements the knowledge of which may only lead to a p a r t i a l comprehension of a phase of microclimatic processes taking place i n plant community. In f a c t , the a i r temperature may be very misleading as an environmental parameter by i t s e l f (Bates I962). Both the microclimatic and the physiological processes within the plant community depend on the radiat i o n balance, i . e . on the radiation-reradiation d i f f e r e n t i a l . The radiati o n balance i s the v a l i d expression of the energy con-version occurring within the various zones of the stand p r o f i l e ; the heat budget, which i n the end determines the microclimatic structure of a stand, depends upon i t . Heat budget can be estimated by evaluating radiat i o n balance and by determining the rate of exchange of heat and of water vapor going on between forest atmosphere and the space above the canopy. The energy and raoisture budget of a forest are inseparable: a l l the variables entering thero must be measured at the same time at various heights within the stand and above the stand. The measurement of r a d i a t i o n balance showed that the radiant energy received by a young Norway spruce stand during the height of summer amounted to, on the average, 615 cal/em 2 per day; of these only 29 were re-radiated during the night. The remainder was converted into other forms of energy which was u t i l i z e d by the stand. Up to 60 per cent of the t o t a l energy received was retained within the zone of tree tops, i . e . within the rtsun crown". This f a c t was considered as rather surprising because the wood volume i n t h i s zone i s much smaller as compared with the volume of wood within the zone of "shade crown" ( i . e . of the crown beneath the point of contact of the neighbouring crowns) .... Therefore, the active surface i n the l i f e - o f the forest i s not the crown space but the space of tree tops ...» The height of the "zone of tree tops" decides about the quantity of the energy received by r a d i a t i o n and about i t s further conversion .... In the space between the upper l i m i t of shade crown and between tree apex every decimeter of the height by which a tree tops i t s neighbour s i g n i f i e s a substantial gain i n energy. (Baurogartner 1952, 1957) . A marked s t r a t i f i c a t i o n i n the environment was produced i n stands of pine by ^ the combination of a Jaeat sink at the cool ground surface and of a heat source i n the trees above. As the sun heats the trees, the l e v e l of highest temperature migrates from 50 feet downward to 30 feet and lower. For several hours t h i s middle l e v e l i s warmer than the a i r either above or below i t , and heat flows both upward and downward from i t . This heat 109 source, evident i n temperature p r o f i l e s i n the forest . . o cannot be explained except as a result of absorption of sunshine by the fo l i a g e of the trees ( M i l l e r 1956). There i s no doubt that similar phenomena should occur i n coniferous f o r e s t s through-out the world (Gates 1962) . The "physical gradients" i n "fol i a g e climate" from a crown's periphery toward a tree trunk are, e s p e c i a l l y i n conifers, miniature r e p l i c a s of the more intense v e r t i c a l gradients i n the atmosphere from the forest f l o o r to the canopy. In both situations the fo l i a g e modifies patterns of evaporation, convection and radiation, and therefore of temperature (Wellington 1950) . Temperatures within wide ranges did not affect s i g n i f i c a n t l y the rate of translocation of organic nutrients i n stems of some small plants (Curtis 1929; Crafts 1932; Curtis and Herty 1936; Went and Hu l l 1949) . 110 Subcortical Temperatures i n Douglas F i r The i n t e r n a l temperatures of stems of forest trees were studied, among others, by Hunter, Schoepf, de Candolle, Hartig and Wieler i n 1775» 1783, 1832, 1874 and 1889, i n that order (Mason 1925; Liese and Dadswell 1959)• There seems to be a general s c a r c i t y of works dealing with t h i s type of problem af t e r the beginning of t h i s century. Apparently no research on subcortical temperatures was ever done i n Douglas f i r . In order to gain some knowledge about the l e v e l s of temperatures which can be reached within the tissues of the phloem-xylem boundary i n stems of Douglas f i r an inquiry was conducted i n t h i s respect during the growing season of 1964° Working i n the unmanaged, naturally established stands of the University Campus Forest, an attempt was made to f i n d : (1) the average thickness of bark at BH, i t s v a r i a b i l i t y and the degree of i t s c o r r e l a t i o n with DBH i n trees from stands about 50 years old; (2) i n trees from the same stands, and separately i n the border trees, the amount and the seasonal fluctuations of water content of the outer and of the inner bark at BH: (3) the l e v e l of subcortical temperatures attainable at BH i n the insolated stems; (4) the range and the seasonal trend of subcortical temperatures at BH of trees growing i n the stands of normal density; (5) the temperature d i f f e r e n t i a l at BH between insolated and shaded part of the same stem; temperature d i f f e r e n t i a l at BH between l i v i n g and between dead tre e s . (6) the e f f e c t s of own crown's shade on the temperature at the stem surface of young open grown trees; I l l (7) the v e r t i c a l a i r temperature gradient i n a stand of Douglas f i r ; (8) the r e l a t i v e importance of bark thickness and of i t s water content on the rate of heat propagation through the bark. The temperatures were measured during June, July, August and the f i r s t h a l f of September. The year 1964 was generally rainy and cool with the annual mean temperature le s s than h a l f a degree above the all-time low. The mean temper-ature f o r every month except January and February was below normal. A l l the summer months were d u l l e r , cooler and wetter than usual, July being the wettest and d u l l e s t on record, as •f well as one of the coolest. Bright sunshine was not much above the all-time low. The maximum a i r temperature, 8 l . 4°F, was recorded on the 11th of August (Canada, Dept. of Transport 1964) . Both the subcortical and the a i r temperatures were measured and recorded e l e c t r i c a l l y ; two single-channel portable recorders and two kinds of thermistor probes were used; the tubular probe used i n measurement of subcortical temperatures was 11.5 cm long and 3*95 mm i n diameter; i t s time constant was 3«7 seconds. The extended disc type of probe was used f o r measurement of a i r and stem surface temperatures; i t s time constant was 0 . 8 seconds. Both types were of stain l e s s s t e e l . Temperatures could be recorded continuously at 2-second i n t e r v a l s within the range from 40 to 115°F with an accuracy of 1.5°F. 112 1 - Bark Thickness The average bark thickness at BH of I63 Douglas f i r trees having an average DBH of 15-5 inches was 0 . 9 7 inches, the c o e f f i c i e n t of v a r i a t i o n being 31 per cent. Only about 54 per cent of the v a r i a b i l i t y i n bark thickness was accounted for by the concomitant v a r i a b i l i t y i n DBH. 2 - Moisture Content of Bark Altogether, 64 forest-grown trees and 26 border trees were sampled at BH between June 12 and August 1 4 . Average water content of the outer bark of the forest grown trees was 85 per cent, c o e f f i c i e n t of v a r i a t i o n being 30 per cent. Corresponding values f o r border trees were 64 and 40 per cent. Average water content of the inner bark of the forest grown trees was 132 per cent, c o e f f i c i e n t of v a r i a t i o n being 10 per centj the corresponding values f o r border trees were 125 and 10 per cent. Scatter diagrams, prepared f o r forest grown trees only, are given i n F i g . 32 and 3 3 • 3 - Insolated Stems The highest temperatures at the phloem-xylem boundary were measured at BH of trees which grew along the southeast border of a stand which was opened by clear cutting several years ago. They were as high as 102°F on sunny days between 9 to 11 am under 0 . 7 to 0.8 inches of bark i n 10 to 1 4-inch DBH trees, where the temperature of the a i r i n shadow was 65 to 67 F. In insolated 17 to 2 0-inch DBH trees the subcortical temperature rose by 5 to 6 . 5°F i n about 60 to 75 minutes under o o x» 6/12 6/15 6/22 7/1 7/3 7/12 7/17 8/1 8/14 O a> o PERCENTAGE OF WATER (DW) o 0> o S 2 (0 (fi <n O J a* 3? s» * S *? o o ? W ~ O *? J T a w 3 a n o o < <0 6/121— 6/ ls l— 6/22 7/1 7/3 o 3> 7/12 7/17 8/1 o o T " = PERCENTAGE OF WATER (DW) 5 O O Z Z II II U l o o o • • • • • • 8/141 113 layers of bark 0 . 8 to 1.2 inches thick, when the a i r temperature one inch above the surface of the exposed side of the stem was 7'5°» Temperatures at the surface of insolated stems were commonly i n excess of 115°F when the surface of bark i n shade registered 60 to 65°F. Temperature of the xylem of the f i r s t ring, counting from the bark, about 70 feet above ground i n a forest-grown tree about 100 feet high, reached 81° on August 11. 4 - Stems of Forest-Grown Trees Subcortical and a i r temperatures were measured simultaneously on r a i n l e s s days i n the afternoon during August and the f i r s t h a l f of September at BH, f o r 82 stems selected at random i n a f u l l y stocked stand about 50 years old. The rela t i o n s h i p between the ambient and between the subcortical temperatures i s portrayed i n F i g . 34« 5 - Temperature D i f f e r e n t i a l The subcortical temperature:of the insolated side of border trees was commonly 11 to 12°F higher than the temperature of the shaded side, the l a t t e r side assuming the temperature of a i r i n shadow. The highest temperature d i f f e r e n t i a l was 30°F i n a 14-inch DBH tree under 0 . 6 inches of bark. Temperature of xylem of dead insolated trees was 1 1 ° to 12° higher than that of l i v i n g insolated trees of a similar diameter. 114 6 - Crown Shade Temperature of a i r i n shadow at the bark surface of stems of open grown trees was as much as 25°F lower than the a i r temperature at the insolated t i p of branches 4 to 6 feet long whenever the l a t t e r temperature reached about 90°* 7 - A i r Temperature Gradients The v e r t i c a l a i r temperature gradients were measured in a fully-stocked stand of Douglas f i r , about 90 feet high, between the elevations of 2 and 80 feet above ground* The measurements were taken on 6 sunny and 6 cloudy afternoons during August and the f i r s t h a l f of September; they are plotted in Fig* 35° The largest difference observed was 15°F on August 11* The average temperature d i f f e r e n t i a l was 6*5°F on cloudy days or on days with overcast sky; i t was 8*7°F on sunny days* 8 - Heat Propagation through Bark The propagation of heat from the surface of bark through i t s i n t e r i o r to phloem-xylem boundary was studied i n blocks of wood with bark cut out from Douglas f i r stems at d i f f e r e n t elevations above the ground. The blocks were about 5 inches wide, 9 inches long and 2 to 3 inches t h i c k . As a source of heat an in f r a r e d lamp was used; the heat at the surface of bark was 100°F i n every case tested. Moisture content of bark was determined at the end of each run. Some re s u l t s of t h i s phase of the work are shown i n F i g . 36; temperature under the bark 0 .4 cm t h i c k rose by about 20° i n f i r s t 15 minutes of the t r i a l when the water content of bark _™ I , I I 1 1 1 55 6 0 65 70 75 80 85 AMBIENT TEMPERATURE (°F) 115 was 13 per cents temperature rose by 15° under the bark of the same thickness at a water content of 105 per cent; the temper-atures under the "wet" bark did not a t t a i n the l e v e l s reached under the "dry" bark. Temperature under 2»2 cm of bark rose by about 10° a f t e r one hour of heating; temperature under 1.7 cm of bark rose by about 13° during the same time, the moisture content being 60 per cent i n both cases. Temperature under 1.45 cm of bark rose by about 16° i n one hour, at a moisture content of 38 per cent. 116 CONCLUSIONS (B) (1) No pronounced seasonal trend was evident i n the water content of the outer as well as of the inner bark of both forest-grown trees and border trees. Border trees had, on the average, a lower water content of the outer bark. Hence, sun and wind exert some drying e f f e c t i n t h i s respect. The average water content of inner bark of both groups of trees was about the same; i t was much higher than the water content of the outer bark and f a r le s s v a r i a b l e . (2) In large trees, having t h i c k layers of bark, i n s o l a t i o n brought about subcortical temperatures which were high enough to be considered as supra-optimal f o r r a d i a l growth, i f i t i s assumed that the optimal cambial temperatures are between 65 to 75°F. (3) Temperature of a i r i n shadow determined the sub-c o r t i c a l temperatures of the shaded side of insolated t r e e s . (4) The r e l a t i o n s h i p between ambient and between sub-c o r t i c a l temperatures at BH of forest-grown trees was well defined and c u r v i l i n e a r . Subcortical temperatures were always lower than the ambient temperatures; the difference was about 2° at the ambient temperature of 55° and 7° at the ambient temperature of 70°F. (5) The v e r t i c a l temperature gradients were most pronounced on sunny afternoons. Temperatures i n the crown space were always higher than those i n the stem space. (6) The heat-conducting properties of bark depended more on i t s thickness than on i t s water content. 117 DISCUSSION (B) The importance of temperature as a fa c t o r influencing profoundly the functioning of l i v i n g systems i s well recognized. The range of temperature at which c e r t a i n physiological processes may occur at a l l i s r e l a t i v e l y narrow. Slight temperature changes a f f e c t markedly the speed even of processes having more extended ranges. L i t t l e i s known about the e f f e c t s of temp-erature on the a c t i v i t y of the cambial layer i n trees i n general. V i r t u a l l y nothing i s known about the ranges of cambial temp-eratures as regards inception, rate and cessation of the r a d i a l growth of earlywood or latewood i n Douglas f i r . Nevertheless, i t i s agreed that the general shape of the growth-temperature curve does apply to various kinds of growth of diverse organisms. It follows that the behaviour with respect to temperature of cambial tissue cultivated at maintained temperatures i n v i t r o may be i n d i c a t i v e of the respective behaviour of the cambial layer i n the growing trees, i f the rate of temperature change i s not s i g n i f i c a n t as compared with the degree of temperature i t s e l f . Knowledge of the r e l a t i o n s h i p between growth and maintained temperature may constitute only an incomplete basis f o r i n t e r p r e t a t i o n of growth under conditions of natural environment, i . e . , among other things, under temperature conditions which are i n a state of continuous f l u x . Heating of stems was found to constitute a purely physical process unaffected by the l i f e processes of t h e M i v i n g stem t i s s u e s . 118 Subcortical temperatures under t h i n layers of bark fluctuated almost as much as did the a i r temperatures. On the other hand, subcortical temperature of stems i n shadow was a function of the a i r temperature i n shadow and was stable f o r longer periods of time. Furthermore, sub-c o r t i c a l temperatures i n insolated basal parts of stems, under r e l a t i v e l y thick layers of bark, reached l e v e l s which may be safely considered as supra-optimal f o r any type of growth. It i s probable that subcortical temperatures caused by i n s o l a t i o n under t h i n layers of bark along the upper portion of boles are even higher. Consequently, the growth processes within some parts of the cambial cylinder may slow down, purely l o c a l l y , to a certain degree, or they may stop completely f o r some time, depending on the degree and duration of temperature reached by the cambial tissues, i r r e s p e c t i v e of the rate of temperature change. Hence the phenomenon of d i s p a r i t y of r a d i a l growth along the bole as regards i t s po s i t i o n , rate, and date of cessation. The phenomenon of d i s p a r i t y i n time and position within the cambial cylinder of the inception of r a d i a l growth may be explained s i m i l a r l y : ambient temperatures and/or dire c t i n s o l a t i o n of the stem, and not other appurtenances of growth, such as carbohydrates, water and hormone, were, reportedly, the fa c t o r s l i m i t i n g i n the start of the vernal r a d i a l growth. Cambium may not begin to function uniformly a l l along the bole at the same time, but some parts of i t may be active at a time 119 when other parts are s t i l l dormant. It follows that the t o t a l period of the seasonal cambial a c t i v i t y anywhere within the cambial cylinder may vary. Consequently, the amounts of annual r a d i a l increment produced at d i f f e r e n t points along the stem during a certain length of time may also vary i f the rate of growth at the points i n question during t h i s time period i s about the same. It i s not known to what degree the t o t a l length of time during which a p a r t i c u l a r portion of the cambial cylinder i s active agrees with the length of time of optimal rate of growth. Nevertheless, the annual r a d i a l increment of both earlywood and latewood, usually expressed i n terms of r i n g width at breast height, was found, by a number of workers, to be p o s i t i v e l y correlated with the length of the growing season. It seems reasonable to expect that t h i s d i r e c t proportionality between width of r a d i a l increment and length of time of growth found at one l e v e l i n a stem holds also for a l l other l e v e l s of the same stem. I f so, then the variable widths of both earlywood and latewood layers at any one l e v e l i n a stem are a function of a time period during which the r a d i a l growth was i n progress at these l e v e l s , notwithstanding the eventual d i f f e r -ences i n rate of growth. As already mentioned, the length of the t o t a l period of seasonal cambial a c t i v i t y was found to be governed, primarily, by the l e v e l s of the ambient temperature and therefore, supposedly, by the l e v e l s of the cambial temperature. I f so, 120 then the shape of the i n d i v i d u a l layers, and therefore the shape of tree steins, i s determined, primarily, by the seasonal v e r t i c a l temperature gradients of the l a t e r a l meristematic t i s s u e s . The available experimental evidence suggests that cambial temperature gradients i n stems of trees derive from v e r t i c a l temperature gradients of a i r around the stem and from the amount and d i s t r i b u t i o n along the stem of d i r e c t i n s o l a t i o n , depending on the position of the sun above the horizon and on the available growing space. In t h i s respect, the thermal properties, as well as thickness of bark protecting the cambial layer exert a powerful modifying influence. Nothing i s known concerning the significance of free and of bound stem water on the functioning of cambium. Therefore i t i s assumed that seasonal temperature gradients within the cambial cylinder are r e f l e c t e d i n the d i s t r i b u t i o n of annual r a d i a l increment along the bole. In t h i s study, the layers of earlywood were, without exception, widest at some short distance below the stem apex once the period of open growth was over. They narrowed very gradually downwards to stem base and abruptly to stem apex. In contrast to t h i s , most of the latewood layers were widest at the base; i f not there then at a position which was, i n the vast majority of cases, below that of maximum growth of earlywood. Narrowing of the earlywood and latewood layers occurred within the zone of tree tops, i . e . , within a stratum receiving the largest amount of solar radiation throughout the 121 year. Cambium along the top portion of the boles i s protected by a t h i n layer of bark, and f a r removed from any hypothetical cooling e f f e c t s of the t r a n s p i r a t i o n stream; the mass of xylem contained within the tops of stems i s small and may be subject to d i r e c t i n s o l a t i o n at any hour during sunny days. Consequently, cambial temperatures along the upper portion of boles may be supraoptimal f o r growth of earlywood and of latewood as well, at least during the warm weather. In most of the i n d i v i d u a l trees the maximum width of earlywood was observed, once i t started appearing above the stem base, at some short distance below the apex. This distance varied with year and tree, but, i n a group of trees, the maximum growth of earlywood always occurred within a r e l a t i v e l y narrow and well-defined zone. This zone was located immediately below the zone of tree tops and was more or le s s p a r a l l e l with the general canopy l e v e l . There were few exceptions to t h i s r u l e . Warming of masses of cool forest atmosphere occurs from the top only during the early spring when the ground i s s t i l l cool - a process not unlike that of warming of masses of sea water. In the f o r e s t , the upper and the lower boundaries of the zone of maximum growth of earlywood coincide, probably, with the upper and lower l i m i t s of an a i r layer which may reach and maintain, because of i t s position, a cert a i n temperature l e v e l early i n the spring. Temperatures of t h i s layer of a i r may be optimal f o r the s t a r t i n g and continuation of cambial a c t i v i t y along the portions of stems passing through t h i s a i r 122 layer at a time when the lower masses of a i r are s t i l l too cool to exert a si m i l a r e f f e c t along the lower portions of stems. The long period of cambial a c t i v i t y afforded by the temperatures p r e v a i l i n g during the day within the top layer of a i r may explain the position of maximum ring width of earlywood i n the Douglas f i r stems studied. Gradual decrease i n width of earlywood layers towards the stem base may be explained by correspondingly gradual heating of the lower layers of a i r with the advancing season. Consequently, cambial a c t i v i t y may sta r t progressively l a t e r along the lower stem. Earlywood layers tapering o f f i n thickness b a s i p e t a l l y may be formed during the correspondingly shorter periods of growth i f the differences i n time of t r a n s i t i o n from earlywood formation to latewood formation are not s i g n i f i c a n t i n t h i s respect. The phenomenon of earlywood-latewood t r a n s i t i o n has not been s a t i s f a c t o r i l y c l a r i f i e d . It i s known to occur commonly during the warmer part of the growing season. Temperature conditions within the forest and, presumably, within the cambial cylinder, p r e v a i l i n g during the time of latewood formation may d i f f e r from those p r e v a i l i n g during earlywood formation. The d i f f e r e n t character of cambial temperature gradients e x i s t i n g during the summer i s , perhaps, r e f l e c t e d i n the shape of latewood layers. These were widest, i n most of the trees studied, along the stem base, i . e 6 , under r e l a t i v e l y thick layers of bark which are, i n forest-grown trees, 123 seldom exposed to prolonged d i r e c t i n s o l a t i o n ; the mass of xylem contained within t h i s stem region i s lar g e r than e l s e -where i n the stem, while cooling e f f e c t s of the tra n s p i r a t i o n stream, i f any, are most pronounced here. Consequently, cambial a c t i v i t y may be optimal or nearly optimal along the stem bases even during hot summer periods at a time when growth i s i n h i b i t e d along more elevated, and therefore warmer, portions of stems. The range i n the long i t u d i n a l p o s i t i o n of the maximum width of latewood which was, as compared with that of earlywood, much wider, i s at t r i b u t a b l e , conceivably, to the general lack of s t a b i l i t y i n summer temperature regime within f o r e s t s of i r r e g u l a r s p a t i a l organisation. The phenomenon of "minimum r i n g width of earlywood" found i n t h i s and i n other studies, may be ascribed, perhaps, to the depressing e f f e c t s on cambial a c t i v i t y of the "secondary temperature maximum". This peculiar feature of the temperature gradients, already mentioned, was observed i n the open. It i s not known whether a "secondary temperature maximum" occurs i n the forest, but "subnormal diameters", due to l o c a l l y depressed r a d i a l growth, have been reported f o r a number of forest-grown species, including Douglas f i r . Sudden and also gradual long-time changes i n longi t u d i n a l p o s i t i o n of the maximum, as well as of the minimum, ri n g width of earlywood were observed i n trees from the natural f o r e s t . These changes are, probably, caused by correspondingly 124 gradual or abrupt changes i n growing space and, consequently, in microclimate of i n d i v i d u a l trees. Density of a natural forest decreases slowly with age, while abrupt changes are caused usually by natural calamities. Density of managed stands may also be changed by s i l v i c u l t u r a l treatments. An explanation of the o r i g i n of the frequently dr a s t i c and always immediate changes i n stem form a f t e r thinning and pruning i s to be sought i n the changed microclimatic structure of the treated stand which i s r e f l e c t e d i n the cambial temperature gradients of the i n d i v i d u a l trees composing the stand. The shape of stems of open-grown trees, e c c e n t r i c i t y of stems, roots and branches and other anomalies i n r a d i a l growth may be explained with the help of si m i l a r concepts. Often expected or hoped-for correlations between the temperature and ... growth did not show up and, in f a c t , i n many cases i t would have been surprising i f they had .... I t i s not s u f f i c i e n t to measure just the a i r temperature .... It i s absolutely e s s e n t i a l to evaluate the flow of energy when considering the i n t e r a c t i o n of organisms with t h e i r environment. The response of the organism may have very l i t t l e to do with the a i r temperature. D.M. Gates (1962) 126 PART (C) CORRELATION AND REGRESSION ANALYSIS BETWEEN THE AMOUNT OF RADIAL GROWTH OF DOUGLAS FIR AND SOME SELECTED WEATHER FACTORS Introduction Systematic sampling of the two types of r a d i a l growth seems to provide more r e l i a b l e information concerning the amount of r a d i a l growth achieved by the i n d i v i d u a l tree than similar information based on sampling of the t o t a l r i n g width at one le v e l o The t o t a l r i n g width, or a l t e r n a t i v e l y the percentage of latewood, might not be s a t i s f a c t o r y variables f o r use i n s t a t i s t i c a l analysis where the two components of the t o t a l r i n g width, namely the width of earlywood and the width of latewood are not correlated. Only a few studies consider the two types of r a d i a l growth separately. Information about the nature of the r e l a t i o n s h i p between earlywood and latewood layers or widths within the same annual layer or ri n g i s even scarcer. S i g n i f i c a n t correlations between earlywood and latewood widths were obtained i n Sweden (Eklund 1957)• In l a r c h from high a l t i t u d e s the fl u c t u a t i o n s i n ri n g width of latewood followed the f l u c t u a t i o n s i n t o t a l r i n g width (Jazewitseh 1961) . Ring width of latewood did not agree well with the t o t a l r i n g width i n Douglas f i r (Knigge 1958) . The v a r i a b i l i t y i n earlywood was responsible f o r almost a l l v a r i a t i o n i n t o t a l r i n g width i n Corsican pine (Low 1959) and i n Douglas f i r (Berry I 9 6 4 ) . 1 2 7 The annual increment of latewood or the proportion of latewood was shown to be p o s i t i v e l y correlated with the amount of available s o i l moisture and/or the amount of p r e c i p i t a t i o n (Paul and Marts, 1931; Chalk 1951; Mammen 1952; Savina 1956; Green 1 9 6 l ; Smith and Wilsie 1 9 6 1 ; H a l l I962). A i r temperature was found to influence negatively the formation of both latewood and earlywood i n Douglas f i r (Chalk 1930; Green I96I; H a l l 1962). Temperature was p o s i t i v e l y correlated with the widths of both earlywood and latewood i n Norway spruce (Eklund 1957)* Results of these and other s i m i l a r reports are based, as a r u l e , on sampling of r a d i a l growth at one position i n the stem, usually at BH. Using t h i s method, only 3 to 12 per cent of the t o t a l v a r i a b i l i t y i n annual r a d i a l growth were a t t r i b -utable to fl u c t u a t i o n s i n weather (Schumacher and Day 1939)« Since the b i o l o g i c a l unit of r a d i a l growth i s the layer of xylem l a i d down on every part of the stem (Farrar 1961), i t was decided. (1) to use the average width and the average cross-sectional area, respectively, of the xylem layers i n a l l the analyses; (2) to f i n d the degree of c o r r e l a t i o n between the two components of the t o t a l annual layers and, i n case that they are not related, treat them separately i n a l l subsequent analyses; (3) to f i n d what f r a c t i o n of the t o t a l v a r i a b i l i t y i n r a d i a l growth can be accounted f o r i n multiple regression 128 analysis by a few selected weather factors of the current and of the previous year, respectively; (4) to f i n d the degree of simple c o r r e l a t i o n between the amount of r a d i a l growth and between the various factors of macroclimate used i n multiple regression an a l y s i s . Current annual p r e c i p i t a t i o n and temperature are shown by most authors to be the most important independent variables i n studies of r a d i a l growth i n t r e e s . Correlations between t o t a l annual r a d i a l growth and p r e c i p i t a t i o n were posit i v e (Hansen 1941; M i l l e t 1944; Koch 1958"; Kern I960; G r i f f i t h i960) or, i n trees from high a l t i t u d e s , negative (Koch 1958"; Kern i 9 6 0 ) or, i n high l a t i t u d e s , nonsignificant (Eklund 1957)• Correlations between temperature and r a d i a l growth of xylem were negative ( D i l l e r 1935; Coile 1936; Hansen 1941; G r i f f i t h i 9 6 0 ; Kern I960; Rudakov 196l) or p o s i t i v e (Ladefoged 1952; Eklund 1957; Koch 1958; Mikola I 9 6 0 ; Jazewitsch 1 9 6 l ) . A l l these positive correlations were obtained f o r trees from high l a t i t u d e s or from high a l t i t u d e s . The measurements on t o t a l r i n g widths within one cross-section were found to be autocorrelated i n England (Chalk 1927) and i n Sweden (Eklund 1957)« In the l a t t e r case t h e i r s i g n i f -icance increased considerably with l a t i t u d e . Nonsignificant s e r i a l correlations were found i n coastal Douglas f i r by E i s et a l . (1964)• 129 Methods and Results (1) The secular trends exhibited by the series of the average widths of earlywood and latewood layers respectively, exemplified by tree No, 14 i n F i g . 37 and 3$, were removed by analysis of covariance. The s e r i a l number of the r i n g from p i t h within each annual layer was a basis f o r the regression adjustment of data, thereby removing the eff e c t of the gradient i n r i n g width within the l a y e r . The regression equations employed were of the following form: (A) lny = a(lnx) f bx t c where y = r i n g width of earlywood and x = s e r i a l number of the r i n g from p i t h , (B) lny = a + b (lnx) where y - r i n g width of latewood, x having the same meaning as above. The summaries of the covariance analyses are i n Tab. VII and VIII. (2) A straight l i n e was f i t t e d to the i n d i v i d u a l series of the adjusted mean r i n g width of earlywood and. latewood, respectively, by the method of least squares. (3) Deviations from t h i s l i n e were mu l t i p l i e d by the square root of the number of observations of r i n g widths within the i n d i v i d u a l l a y e r . The r e s u l t i n g r i n g indices are shown i n F i g . 39 to 52. 01 I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I 1 I I I I I I I I I I I I 1917 20 25 30 35 40 45 50 55 60 YEAR Y E A R Figure 39- Average layer width index of earlywood,tree No-8 - H 2 r - F i 9 u r e 40- Average loyer width Index of latewood, tree No- 8 Figure 41- Average layer width index of earlywood,tree No-9-YEAR I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 1 I I I I I l l l I I I 1920 25 30 35 40 45 50 55 60 YEAR + .20r- Figure 43- Average layer width index of earlywood,tree No 10 YEAR + 121- f igure 44- Average layer width index of latewood,tree No-10 + 08 I I I I I I I i I I I I I 30 35 40 Y E A R 45 50 55 60 Figure 46 ' Average layer width index of latewood, tree No- 1I-Y E A R YEAR + •20. Figure 49- Average layer width index of earlywood,tree No- 13-+ 10 S oh z - I O r •201/ ±-L± i i i i I I, I I 1 i i i i I i i i i I i M | I I I I 1 J_J 1920 25 30 35 40 Y E A R 45 50 55 60 +-20r- Figure 51- Average layer width index of early wood, tree No-14 4 . | 2 r Figure 52- Average layer width Index of latewood, tree No-14 + 08 h TABLE VII SUMMARY OF COVARIANCE AND AUTOCORRELATION ANALYSES OF EARLYWOOD LAYERS Tree Years of D.F. No. Growth Error Year 8 1920-1962 1030 42 .9 1918-1962 1123 44 10 1918-1962 1123 44 11 1918-1962 1123 44 12 1917-1962 1171 45 13 1918-1962 1123 44 14 1916-1962 1220 46 * A l l s i g n i f i c a n t at P = 0.001 ** A l l nonsignificant at P = 0.05 R 2 px K** • 392 24.71 1.592 .468 9 . 6 8 1.552 .509 21.92 1.611 .517 4.53 1.463 .586 19.16 1.622 .682 24.70 1.708 .484 12.96 1.837 K = von Neumann's r a t i o T A B L E V I I I SUMMARY OF COVARIANCE AND AUTOCORRELATION A N A L Y S E S O F LATEWOOD L A Y E R S T r e e Y e a r s o f D . F . N o . G r o w t h E r r o r Y e a r 8 1920-1962 1030 42 9 1918-1962 1124 44 10 1918-1962 1124 44 11 1918-1962 1124 44 12 1917-1962 1172 45 13 1918-1962 1124 44 14 1916-1962 1221 46 * A l l s i g n i f i c a n t a t P = 0.001 A l l n o n s i g n i f i c a n t a t P = 0 .05 K = v o n N e u m a n n ' s r a t i o r 2 p3€ K3€3€ .505 4 .68 1.424 .587 7.78 1.755 .447 9.61 1.917 .569 5.87 1.594 .526 8.53 I .84O .591 10.83 1.757 .476 7.97 1.819 132 (4) The degree of autocorrelation within the r a d i a l growth series was evaluated by von Neumann's r a t i o (Ezekiel, Fox 1959)* The calculated values of these r a t i o s are i n Tab. VII and VIII. (5) The average cross-sectional areas of the annual layers of earlywood and latewood were treated i n the way outlined i n steps 1 to 4» (6) A straight l i n e was f i t t e d by least squares to each monthly series of observations on average a i r temperature as recorded at the Vancouver City weather station between 1910 and 1962 and the deviations from these i n d i v i d u a l l i n e s were calculated. (7) Of necessity, and despite the recognition of the fact that large p r e c i p i t a t i o n variations e x i s t i n g over the short distances i n the area of study make any combining or c o r r e l a t i n g of records of two weather stations impractical or impossible (Canada, Dept. of Transport 1962), s a t i s f a c t o r y regressions were developed f o r t o t a l monthly p r e c i p i t a t i o n series measured between 1938 and 1962 at Vancouver C i t y on the one hand and those measured at Vancouver Airport on the other hand. These regression equations were used i n correcting the Vancouver City p r e c i p i t a t i o n series f o r the period 1910 to 1938. The corrected series was then pooled with the 1938 to 1962 series recorded at Vancouver A i r p o r t . (8) Straight l i n e s were f i t t e d to pooled monthly precip-i t a t i o n series by least squares and the deviations from these l i n e s were calculated. 133 (9) The autocorrelation within the i n d i v i d u a l weather series was then evaluated (Table IX). (10) Degrees of c o r r e l a t i o n between the average widths of earlywood and latewood layers was investigated within i n d i v i d u a l annual layers f o r trees No. 8 to 14« Results of t h i s analysis are shown i n Tab. X. (11) Relationships between r a d i a l growth and weather of the current year were studied by means of multiple c o r r e l a t i o n and regression analyses conducted separately f o r earlywood and latewood. The summaries of the c o r r e l a t i o n analyses,are i n Tab. XI and XII. (12) Information about the influence of the weather factors of the previous summer on formation of earlywood i s contained i n Tab. XIII. (13) The series developed f o r average cross-sectional area of the xylem layers of earlywood and latewood, respectively, were found to be autocorrelated and t h e i r analysis was discontinued at step No. 4« TABLE IX VON NEUMANN'S RATIOS ( K ) x OF THE WEATHER SERIES FROM 1910 TO 1962 MONTH MARCH APRIL MAY JUNE JULY AUGUST Aver. Monthly A i r Temperature 1.555 1.711 1.867 I.644 1.618 1.807 Total Monthly P r e c i p i t a t i o n 1.937 1.772 1.948 I.848 2.101 2.039 The s i g n i f i c a n t values of K at P = 0.05 are less than I.5856 or larger than 2.4914. TABLE X SUMMARY OF THE SIMPLE CORRELATION ANALYSIS'. THE AVERAGE WIDTH OF EARLYWOOD LAYERS CORRELATED WITH THE AVERAGE WIDTH OF LATEWOOD LAYERS WITHIN THE SAME YEAR Tree No. N r r 8 43 - 0 . 0 3 4 N * S o 9 45 - 0 . 1 5 4 N e S a 10 45 0 . 3 2 9 * .1082 11 45 0 . l 6 6 N o S o 12 46 0 . 3 8 4 * * .1475 13 45 0.316* ' .0999 14 47 0 . 1 5 7 N o S * TABLE XI SUMMARY OF THE MULTIPLE CORRELATION ANALYSIS: MEAN WIDTH OF EARLYWOOD LAYERS CORRELATED WITH MEAN MONTHLY AIR TEMPERATURE AND WITH TOTAL MONTHLY PRECIPITATION OF THE CURRENT YEAR SIMPLE CORRELATION COEFFICIENTS  TEMPERATURE PRECIPITATION  NO. MARCH APRIL MAY JUNE MARCH APRIL MAY JUNE 8 43 - 0 . 0 3 9 0.115 -0.125 -O.O84 -0.014 -O.O43 0.045 0.104 0.101 9 45 0.094 0.061 0.037 - 0 . 0 4 1 -O.I85 0.289 0.031 0.006 0.150 10 45 - 0 . 0 1 6 0.081 -O.O95 -0.123 -0.173 -0 .033 - 0 . 0 5 8 0.062 0.107 11 45 0.308 O.329 O.I38 0.259 -O.O83 0.011 0.132 -0.105 0.154 12 45 0.128 0.225 -0.053 0.108 -0 .188 O.O65 0.166 -0 .106 0.140 13 45 0.246 0.339 O . I 6 4 0.284 O.O46 0.135 0.206 - 0 . 0 6 6 0.197 14 45 - 0 . 0 4 2 0.100 - 0 . 1 8 8 0.031 -0.107 0.244 0.104 -O.O97 0.223 O N TABLE XII SUMMARY OF THE MULTIPLE CORRELATION ANALYSIS. MEAN WIDTH OF LATEWOOD LAYERS CORRELATED WITH MEAN MONTHLY AIR TEMPERATURE AND WITH TOTAL MONTHLY PRECIPITATION OF THE CURRENT YEAR SIMPLE CORRELATION COEFFICIENTS TREE NO. TEMPERATURE PRECIPITATION R2 N JUNE JULY AUG. JUNE JULY AUG. 8 43 -0.073 -0.355 - 0 . 0 9 4 0.09$ O.48O - 0 . 1 4 8 0.267 9 45 -0.259 -0.045 0.023 0.235 0.209 0.211 0.255 .10 45 0.080 -0.144 0.202 0.170 0.294 - 0 . 0 8 7 0.214 11 45 -0.017 -0.17$ -0 .017 0.300 0.458 0.273 0.3$3 12 45 0.164 0.032 -0.147 0.035 - 0 . 0 2 8 0.173 0.106 13 45 -0.159 -0.275 -O.O47 0.450 0.337 0.228 0.409 14 45 0.060 -0.127 0.136 O.446 O.462 0.110 O .48I - 0 TABLE XIII SUMMARY OF THE MULTIPLE CORRELATION ANALYSIS: THE AVERAGE WIDTH OF EARLYWOOD LAYERS CORRELATED WITH THE MEAN MONTHLY AIR TEMPERATURES OF THE PREVIOUS SUMMER SIMPLE CORREL. COEFF. TREE NO. MEAN MONTHLY AIR TEMP. R 2 N JUNE JULY AUG. 8 43 -0.182 -0.218 0.087 0.1253 9 43 -0.146 -0.118 -O.OI4 0.0287 10 43 - 0 . 0 2 7 - 0 . 0 3 0 0.209 0.0750 11 43 O .I65 0.028 0.285 0.1277 12 43 0.098 0.124 0.240 O.O585 13 43 0.277 0.233 0.320 0.1358 14 43 0.015 0.047 0.087 0.0099 139 CONCLUSIONS (C) The conclusions based on the r e s u l t s of the foregoing procedures and analyses are as follows: (1) The correlations between the average widths of earlywood and latewood layers were nonsignificant, or when s i g n i f i c a n t , low. (2) Only a nonsignificant degree of autocorrelation was found within the series of mean widths of both earlywood and latewood la y e r s . (3) Low s e r i a l c o r r e l a t i o n was detected only i n the monthly temperature series f o r March. (4) In the i n d i v i d u a l trees, eight variables of climate included i n the multiple regression analysis accounted f o r from 10 to 22 per cent of the t o t a l v a r i a b i l i t y observed i n r a d i a l growth of earlywood. The simple c o r r e l a t i o n c o e f f i c i e n t s between weather factors and r a d i a l growth of earlywood were mostly nonsignificant and not consistent with respect to sign. The approximate minimum true c o r r e l a t i o n i n the universe was zero. (5) In the i n d i v i d u a l trees, s i x weather variables i n the multiple regression analysis accounted f o r from 10 to 48 per cent of the t o t a l v a r i a b i l i t y observed i n the r a d i a l growth of l a t e -wood. The simple c o r r e l a t i o n c o e f f i c i e n t s between the l a t t e r variable and between monthly p r e c i p i t a t i o n were consistently p o s i t i v e only i n the case of June p r e c i p i t a t i o n . The e f f e c t of 1 4 0 temperature on formation of latewood was mostly negative. The approximate minimum true c o r r e l a t i o n i n the universe was zero. ( 6 ) In the i n d i v i d u a l trees, temperature of the previous summer accounted f o r from 1 to 13 per cent of the t o t a l v a r i a b i l i t y i n growth of earlywood. Most of the simple c o r r e l a t i o n c o e f f i c i e n t s derived i n t h i s analysis were nonsignificant. The approximate minimum true c o r r e l a t i o n i n the universe was zero. 141 DISCUSSION (C) The o v e r a l l l e v e l of significance of correlations between the variables of macroclimate and amount of r a d i a l growth of the i n d i v i d u a l stems was low even when the average widths of growth layers were used instead of simple r i n g widths. The highest pos i t i v e simple c o r r e l a t i o n c o e f f i c i e n t s were those obtained between growth of latewood and r a i n f a l l of the current summer months f o r trees growing i n small depressions and ravines c o l l e c t i n g water by l a t e r a l seepage (trees No. 1 1 , 1 3 , 1 4 ) • The high water table during the spring months was probably respons-i b l e f o r the observed lack of c o r r e l a t i o n between macroclimate and growth of earlywood. Phenomena such as winter and f a l l photosynthesis, as well as the absence of c o r r e l a t i o n between the rate of current photosynthesis and amount of current r a d i a l growth (Helms I 9 6 4 ) . seem to have a d e f i n i t e bearing on the problem of the type discussed. In any^case, p r e c i p i t a t i o n seems to be, along with the a i r temperature, a l i m i t i n g factor i n growth of Douglas f i r even i n the humid coastal zone of B r i t i s h Columbia. In t h i s respect, the r e s u l t s of the present study based on a few trees sampled intensively, agree with the r e s u l t s of growth studies based on a large number of trees sampled extensively (Eis 1 9 6 2 , G r i f f i t h I960), 1 4 2 CONCLUDING REMARKS The concept of d i s p a r i t y i n time, rate, and position along the bole of the r a d i a l increment i s used i n t h i s study to explain the shape of i n d i v i d u a l growth layers and, therefore, of stem form i n Douglas f i r . I t i s suggested that microenvironment of i n d i v i d u a l trees determines the form of t h e i r boles and that the microclimatic structure of a f o r e s t stand determines the average form of stems i n t h i s stand. This and also other studies have shown that the average form of forest-grown trees from the northern temperate zone.is exactly, or very nearly, that of a quadratic paraboloid. It follows then that the average shapes of annual layers i n stems of forest-grown species from the northern temperate zone are, approximately, those described i n t h i s study. It can be safely assumed that microclimatic structure within the conif-erous f o r e s t s i s of about the same nature throughout the world. Hence the explanations with respect to morphological phenomena observed i n stems of Douglas f i r may not be r e s t r i c t e d s o l e l y to t h i s species. Since there was l i t t l e d i r e c t f a c t u a l evidence which would support the conceptual scheme of stem formation evolved i n t h i s study, i n d i r e c t evidence was sought i n l i t e r a t u r e . Findings of other workers have been used as a basis of a l l important assumptions. The most important of them i s that concerning the character of the- seasonal cambial temperature 143 gradients i n the growing trees. This assumption can be readily-tested. Such a test might prove to be much simpler than those necessary f o r t e s t i n g of n u t r i t i v e or hormone stem form theories. The present explanations concerning the shape of annual growth layers are t h e o r e t i c a l i n that t h e i r experimental basis i s slender. However, they are not wholly speculative and, above a l l , they are not t e l e o l o g i c a l . In t h i s respect the scheme proposed i n t h i s study has a d e f i n i t e advantage over the mechanistic and water conductive theories because: Science r e j e c t s purpose as a sa t i s f a c t o r y explanation of natural phenomena. The a c t i v i t i e s of l i v i n g organisms ... are now considered to be r e s u l t s of the operation of the same fundamental laws which describe the properties of matter and the transformations of energy which are known to apply to nonliving systems. 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Rep. 11, 32 pp. 1 A P P E N D I X D I A G R A M S 1 TO 83 r-i O r-l fM O ;—I fNJ [\l I—I t iM H rf( H O O . o <r ; o l A o o LU • < z u • — — sx a cx v- : jr; b -o ^ ^ * •O <f cn m (<"i rr> ,n - t >t (\l m m sf i ~ -O O H H r H H H r \ J H r \ J H i n OOOOO—•'-•'-'^ -(^ Oi-trM o o o o o o o o o o o o o o o : •;)•> i < "1 id • ON - .-v: o <-. < ^  o e> ii, •* 2 2 2 i 2 5 2 2 0 0 0 1 2 1 3 1 0 i 0 1 6 5 5 5 6 5 7 6 ^ \ 7 / 6 7 7 7 7 6 7 " 7 y / 7 7 g^v a a 3\, 7V> 9\,fa b b 6 7 7 r r ^ T T T X q _ (K? ?VSg 9 9N£ 5Ng 9 9 9 9 9 9 9 9 DIAG.6 RING WIDTH OF EAKLYWOOJ TREE N0.27M '" YEARS 193»-1^5< j DIAG .7 RING WIDTH OF LATEWOOu TREE NG .2 7 M V EARS 1939-1956 DIAG.9 RING AREA OF LATEWOOD IKtE N 0 . 2 / M YEARS 1939-1956 DI AG-6 KING AREA OF EAkLYWOOl) T,<EE N0.27M " YEARS 1939-195(3 DI AG•10 r-LRCENTAGc Ur uATEWOOO T K E E N 0 . 2 7 M Y E A R S 1939-1958 2 2 DI AG. 11 R I N G WIDTH OF EAKLYWV/JL) T R E E N0.32M Y E A R S 1939-1958 DI AG. 12 •-. IiMG WIDTH OF LATEWOOD T'<EE N0.32M Y'ARS 1939-1958 DI AG.13 " R I N G A R E A O F EAKLYWOOD T:%FF N0.32M Y E A R S 1939-1958 DI AG.14 RING AREA OF LATEWOOD 1 vcE N0.32M YEA;>S 1939-1958 o r A G . i s " " PERCENTAGE OF LATEWOOD [SEE -N0.32M Y E A h"; S 1939-1958 0 2 7 b \ g \ 6 6 6 4 3 4 O S J N A 2 2 ONg 9 N 6 7 4 3 3 5 4 1 1 0 2 3 3 0 ^ 9 9 l \ 7 3 3 3 3 2 0 1 1 2 0 5^ 2 0 0 U 0 0 O O P 0 0 0 0. 0 4 4 6 7 0 0 4 5 6 6 4 2 2 2 3 1 0 0 0 3 3 1 1 1 N 9 8 \ 4 4 2 3 4 2 0 0 2 3 1 1 D I A G . 1 6 R I N G WIDTH OF EARLYWOOD T R E E N 0 . 3 3 M  Y E A R S 1 9 3 9 - 1 9 5 8 UrSG"."T7 R I N G WIDTH OF LATEWOOD T R E E N 0 . 3 3 M y E A R S " ! 9 3 9 - 1 9 5'8~ "D TAG", I S " " • " R I N G A R E A O F E A R L Y W O O D T R E E N 0 . 3 3 M Y E A R S 1 9 3 9 - 1 9 5 8 " " " 0 0 0 0 0 0 0 0 0 0 0 6 4 3 4 0 0 4 4 3 3 v9Nft 5 7 5 4 5 0 0 4 4 6 5 5 0 4 3 3 3 5 5 0\5Sft 5 6 4 3 3 2 4 3 4 4 0 0 6 4 4 5 3 5 4 6 5 0 3 4 4 4 5 4 4 3 6 6  0 2 5 5 6 5 5 4 5 7 6 6 6 0 0 6 ^ ^ ^ 4 5 4 0 5 5 6 6 5 5 4 Q-Sg 9 9N4N9 9 9" 0N9N5. 5Ng 9 8 8 9 9 D I A G . 1 9 R I N G A R E A O F LATEWOOD T R E E _ N 0 . 3 3 M _ Y E A R S 1 9 3 9 - 1 9 5 8 D I A G . 2 0 P E R C E N T A G E OF LATEWOOD T R E E N 0 . 3 3 M  Y E A R S 1 9 3 9 - 1 9 5 8 o o o(&) 1 1 1 2 1 0 6 3 6 d\3S6 7 3 5" 0 0 0 7 6 6 0 !?vX'?tSiNv7 6 ^ DIA6.21 RING WIDTH Of EARLYWOOD IK - i N O . l YEARS 1939-1962 DIAG.22 RING WIDTH OF LATEWOOD. TREE" NO. l" YEARS 1939-1962 UI AG.23 RiNG AREA OF EARLYWOOD I REE NO.1 TEARS 1939-1*62 D l A G . 2 4 RING AREA OF LATEWOOD TREE N O . l YEARS 1939-1962 D l A G . 2 5 PERCENTAGE OF LATEWOOD T R e r w o . : " ~ ~ VEARS 1939-1962 0 0 0 0 0 6 6 1 6 7 X 9 6 6 6x7 6 7 7 6 5 6 0 7 7 4 7 7~o \3\6 6 6 5 6 6 6 6 6 0 5 6 X 9 9 X 3 7 4 6 7 5 4 5 5 6 7 5 6 0 3 /S$S^ ! 2 5 2 6 4 7 6 4 6 7 7 b 6 0 4 3 2 6 7 5 2 3 3 7 . £5N6 5 7 ^ ^ 6 5 (gj) OVg 9 $ 9 ^ 4 4 ^jNg 7 6 6 6 4 6 6 6 4 6 0 X 9 X 6 7 5 1 1 3 6 X g \ 7 3 2 3 4 4 4 6 5 6 5 ^ 0 0 0 0 0 0 0 0 0 0 0 0 5 2 4 0 2 4 4 f 0 2 4 5 5 0 0 1 2 4 3 2 5 0 0 2 3 4 5 3 ^ N 6 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 0 1 2 2 2 0 0 1 1 2 3 3 0 0 1 2 2 3 3 0 0 1 2 2 3 4 4 4 4 0 0 1 2 4 4 4 4 4 4 0 0 1 2 3 4 3 4 5 5 6 0 1 1 2 3 4 5 4 4 5 5 6 0 0 1 2 3 4 4 6 5 5 6 5 6 . 0 0 1 2 3 4 3 4 5 5 6 7 6'\fr\, 0 0 0 1 2 3 4 3 J^SVjJ 5 6 5 7 0 2 1 2 2 6 4 5 6 5 7 6 6 6 6 7 0 3 5 3 3 4 7 6 6 6 6 7 6 6 7_ 0 1 4 7 7 3 4 6 5 7 6 5 7 6 0 1 ZX9X7 7 2 4 4 6 0 1 1 rSg~9N6 _3 3 6 0 5 7X? 9 9 8 0X9 9 9 * ^ 01 AG.26 _ ^ RING WIDTH OF EARLYWOOD TREE NO.2 YEARS 1943-1962 D1AG.27 RING WIDTH Or LATEWOOD TREE NO.2 YEARS 1943-1962 PI AG.2 8  RING AREA OF EARLYWOOD TREE NO.2 YEARS 1943-1962 0 0 0 0_0_ 0_ 0 0 0 0 0 0 0 0 0 b o o 0 0 0 0 1 1 1 0 0 0 1 1 1 1 0 0 1 ~T~1 2 2 1 0 3 3 6 4 0 0 1 1 1 2 1 2 3 4 0 0 1 1 2 2 2 4 4 4 5 0_ 0 2__2 4 3 4 3 5 6 ~0 0 1 1 " l 2~ 3 4 3 "4 3 6 4 0 0 1 1 2 1 2 2 5 4 4 4 5 5 0 0 0 2 2 2 1 3 2 4 5 4 4 6 7 0 2 0 4X9 8 \ 4 \ 9 8X2 0X9 9X7X9 0 0 0 0 0 0 o o o o 0 0 7 4 4_ 0 7 6 5 0 5 6 b 0 0 2 2 4 3 3 6 0 0 3 4 5 4 3^^^. 0 5 5 4 3 5 3 5 6 6 C^NA 4 5 6 6 j^b*7 6 6 0 0 5 6 6 5 7 7 7 6 6 7 0 0 4 4 4 4 7 7 6X8X6 7 T ~ O ^ ^ b 4 5 4 6 5X.8 8\6 6 6 5 0 0 6 7 6 6 4 ^ ^ 4 5 7 7 7 7 7 DIAG.29  RING AREA OF LATEWOOD TREE NO.2 YEARS 1943-1962 DIAG.30  PERCENTAGE OF LATEWOOD TREE NO.2 YEARS 1943-1962 6 5 7 6 4 _ S N K , 5 7 4(j(p 6 3 6 4 6 5 4 5 6 4 6 4 5 4 5 4 4" 3 4 3 3 4 5 4 4 3 5 2 4 5 3 3 2 2 3 ~3 5 4 3 3 2 1 2 2 3 2 3 2 2 1 1 1 2 3 2 2 1 1 2 0 1 1 1 2 i 1 0 0 1 0 0 0 4 2 1 0 1 1 2 0 0 0 0 1 5 2 3 5 2 3 5 3 3  3 3 1 2 3 2 2 4 1 1 3 3 3 2 2~7 1 0 2 0 0 0 0 1 1 9 . 01 AG.31 RING WIDTH OF EARLYWOOD ~TRE~E NTDTT YEARS 1939-1962 DIAG.32 RING WIDTH OF LATEWOOD "TREE NO.3 YEARS 1939-1962 DIAG.33 RING AREA OF EARLYWOOD TREE NO.3 YEARS 1939-1962 0 0 0 _0_0_0 0 0 0 0 0 0 0 1 0 0 0 1 T 1 O T T T T T T 0 0 1 1 1 1 1 2 0 0 2 1 2 1 2 2 2 0 " 1 2 3 2 3 3 T T 5 0 1 1 2 3 2 2 3 3 3 0 1 2 4 4 5 3 ^ V 4 4 0 - l ~2~2"4~3" 7 " 5 T T 0 0 2 3 3 4 4 7 5 2 0 0 0 1 4 4 6 6 7 4 4 3 3 6 5 \ 7 4 6 4 7 4 0 1 2 3 4 6 5 6 5~7 5 \ 6 \ 7 6 6 4 0 1 1 5 5 2 t^ N5 5 X ^ ^ 7 7 6 5 5 0 0 2 2 3 5 5 6 6 7 7 6 5 4 6 5 5 4 0 1 1 4 4 5 5 T~rS£ ii frsg"" E T J T S 7 0 2 3 3 3 4 6 5 5 ^ S 6 7 6 6 6 5VJ 9 \7 6 0 1 4 3 5 5 4 7 5 6 7 6 7 7^gS6 \9 \7 6 6 5 8 9 9 9 8 8\6 5 9"^7^TN6 % X V " 7 T ~ 6 ~ 4 0 0 0 0 0 0 0 0 1 3 0 0 0 7 0 2 3 3 4 3 3 0 0 4 3 4 3 4 0 3 3 4 3 3 2 0 2 6 3 3 2 3 0 3 3 5 3 4 4 4 4 4 0 4 2 4 4 3 2 3 3 3 5 0 6 5 5 4 5 4 7 5 4 5 0 5 5 3 4 3 6 4 3 4 3 5J 0 3 4 4 4 4 4 6 6 2 6 5 0 3 1 2 3 4 4 4 5 4 3 6 4 7 7 7 6\£v 5 7 6 ? S 2 \ 0 5 6 4 5 4 5 4 5 6 6 6 0 4 4 6 5 2 5 6 3 4 6 4 0 4 5 4 4 5 4 5 5 5 6 6 6 4 7 5 6 7_ Q ^ £ l \ 5 6 6 5 4 4 4 6 6 6 7 7 6 6 6_ 5 4 6 6 5 5 5 6 6 7 6^7 5 0 4 7 5 7 6 6^N6 5 7 7 6^ DIAG.34 RING AREA OF LATEWOOD TREE NO.3 YEARS 1939-1962 D1AG.35 PERCENTAGE OF LATEWOOD TKEE. NO.3 YEARS 1939-1962 0 0 0 0 0 0 cfo 0 0 0 0 0 4 o o o o 4 0 4 0 0 0 3 3 2 5 0 0 2 2 2 3 4 3 0 2 3 2 3 5 4 4 3 0 2 3 T~5~T~T~5-5~b 0 4 5 4 4 5 1 3 3 3 4 0_1 6 4 5 5 5 2 2 3 5 3 S 3 3 4 4 4" 5 5 3 5 5 5(g)) 5^Sft 4 5 6 0 0 1 0 0 1 0 0 1 2 0 1 2 2 2 0 0 2 2 4 3 0 0 2 3 3 4 3 0 0 1 2 3 3 3 0 1 1 3 3 5 5 3 4 4 1 2 4 5 6 6 7 5 5 1 2 4 6 6 6 7^Nj 7 1 2 3 5 0 0 2 2 4 5 0 1 1 4 5 6 0 2 3_3_6_' 5 "0 2 "5 5 2~7" 0 3 4 7 7 6 0 1 5 £ \ ^ S J 0 2 4 6 7 7 7 7 6 0 2 6 4 \9 9 6 ~ 0 5 6 7 ^ 9 6 ^ DIA6 .36 RING WIDTH OF EARLYWOOD TREE NO.4  YEARS" 1940-1962 D i AG.3 7 RING WIDTH OF LATEWOOD TREE NO.4 YEARS" : 9 4 0 - l ? 6 ? " 15 I A G . 36 RING AREA OF EARLYWOOD TREE NO.4 YEARS 1940-19752 0 0 0 O O P 0 P 0 0" 0 0 0 1 0 0 0 0 1 0 1 0 0 0 1 1 1 2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 1 0 0 1 1 F T 1 1 2 2 "" 0 1 1 1 1 2 1 1 1 2 2 0 0 1 1 2 2 2 1 1 2 3 2 0 1 1 2 2 3 2 2 1 2 2 2 2 0 1 1 1 2 2 3 3 3 2 3 3 3 0 1 2 2 2 3 3 4 6 4 3 4 4 0 1 1 2 2 3 ~4~~3~ 5 4 4 0 1 3 3 4 3 4 5 4 6 6 0 1 2 4 3 4 4 6 6 4 7 0 2 3 2 4 5 6 4 "5" 0 2 ^ \ t g^ Nfr 7 7 7 6 o 3 5 \ g \ t e v - ^ 7 4 \4 DI AG.39 RING AREA OF LATEWOOD TREE NO.4 ' YEARS "T9"W-r96"2 DI AG.40 PERCENTAGE OF LATEWOOD TREE NO.4 YEARS 1940-19"62 ?N8 9X5 6 2 5 7 6 7 5' 9 9 9NT 4 "2 5 6 4 5 3 5 2 3 4 4 2 4 5 3 6 4 4 0 2 3 1 3 5 4 3 5 2 4 4 4 1 3 3 3 2 2 1 4 4 0~"4^ Nff 3 0 " 5 T T T T 1 2 3 1 2 1 0 0 0 0 0 0 0 5 4 5 0 3 5 4 5 0 1 3 7 7 7 7 5 2 2 "5" 5 3 7 4 2 7 7 3 6 3 2 3" 5 6 2 4-7 5 6 6 3 6 4 3 5 5 2 3 4 5 4 1 2 2 ~ r 4 3 4 4 2 .2 2 3 4 2 1 5.1 3 3 3 3 1 1 4 2 2 4 2 1 2 '6 5 0 1 0 3 4 1 0 4 5 4 4 0 1 1 1 3 1 0 7~4 0 2 2 1 2 1 z~r~r 3 4 1 0 3 2 1 0 0 2 3 "DTAG741 RING WIDTH OF EARLYWOOD TREE NO.5 YEATR3~l?4T>-="r3T2^ ' DI AG.42 RING WIDTH OF LATEWOOD TREE NO.5 YEARS 1^40-1962 : "DIAG.43 RING AREA OF EARLYWOOD TREE NO.5 T EAR'S - I940-iy6"2 ^ 4 2 7 5 6 5 6 4 5 7 1 7 7 6 7 6 7 3 5 5 7 5 5 6 4 6 5^ 5\? \7 5^3\6 7 6 5 ^ X 5 7 7 5 0 0 0 0 0 0 0 0 0 1 0 0 1 1 1 0 0 1 1 2 3 0 0 1 3 2 3 4 0 0 1 2 4 2 2 0 0 1 2 1 5 3 2~7 0 1 0 1 0 1 0 0 1" 0 0 1 0 1 2 4 T ~ 5 -2 2 3 2 2 6 2 6 3 5 5 2 3 3 5 % 3 5 i _ 3 3 4 4 4 3 5 5 6 7 4 5 5 4 3 5 5 5 T l 2 2 3 4 5 4 D l A G . 4 5 PERCENTAGE OF LATEWOOD TREE NO.5 YEARS 1940-1962 DI AG.44 RING AREA OF LATEWOOD TREE NO.5 YEARS 1940-T97o2 DIAG.46 RING WIDTH OF EARLYWOOD TREE NO.6 YEARS m"0-l'9B2 " DIAG.47 RING Wl iTn Or LATEWOOu TREE NO.6 YEARS 1940-1962 "DIAG.48 RiNG AREA OF EARLYWOOD TREE NO.6 YEARS 1940-1962 01 AG.49 RING AREA Or LATEWOOD TREE NO.6 YEARS" 1940-1962 DI AG.50 PERCENTAGE OF LATEWOOD TREE NO.6 YEARS" T9"40"-l9'&"2 0N9 >v5 DIAG.51 RING WIDTH OF EARLYWOOD TREE NO.7 YEAR"5~T^T0-1962 5 6 7 7 w. 4- 7NJX5 3 3 6 5 7 7 6 5 5^ RSwf 6^BVf "2 4 5 5 6 5 5 6 3 5 6\£ DlAG.52 " RING WIDTH OF LATEWOOD TREE NO.7 YEARS19'30-1*6 2 "" >£>| - . r ~ - r v O (NI C O v O * x n -3" v O C M i n co c o : co \D m ' c o co c o - d -i | <r m ico r o < M < J -A o CO CO m m v O >£> <r m <J- m CNJ C M C M C M C M I i — I j r H i — I C M H H J H ( \ J ( M • O i — I >—I ! • — I C M i — l r H | r — I O O o o o <t in [ C O ro C O J - C O C O C M C O C O <J" co -d- < f : < f <-> C M I C O C O < T ! < f C O C O C M |r—( C M C M i — I r - H O O O r — I Ii—( i—i r - l O O 0 | 0 O d o O O IO O O i I j o o o i o o o j o o o o o o  C O C O C M C  C M C O C M C M i — l i —1 r - l • — I r H O o o o o O o o o o in in r- in v O m <*• m < J -7 <J- J C M v O C O C M r ~ C O C M r - m ( M v O r -n v O r- r~ <r r - r -in r-in <r in <r m <r C O C O C O m C M <»- <r C M co C M C O C M C M C M C M i - H O O o O O o O O j O O O O O O 0 0 0 ooo o_o o o 0" do 0 0 0 0 0 0 0 1 0 0 0 0 1 1 1 0 0 0 1 1 O i l 0 0 0 0 1 0 1 1 1 0 0 0 0 0 1 1 1 2 2 0" 0' 0 0 1 2 1 T 1 "1 2 0 0 0 0 1 1 1 1 1 1 3 2 0 0 1 1 1 1 1 2 2 2 2 2^_3 0~0 0 1 1 1 2 3 4 7 5 4 3 3 0 0 0 1 1 2 2 2 2 1 2 2 2 2 3 0 0 1 1 2_ 2 2 2 3 3_ 5 5 2 2 3 3 0 6 0 1 "1 " " l 2 3 " 4 " 4 4" 6 2 3 3 4 4 0 0 0 1 1 2 2 3 3 5 4 3 7 7X5x7 5 6 0 0 0 1 1 2 2 4 4 3 3 3 4_7 7 4 3 4 3 0 0 1 1 1 1 2 3 3 3 2 4 " 2 6 \ & X 3 3 T T C T 0 1 1 2 1 2 3 2 3 4 4 3 4 3 6 7 X 8 X 3 4 5 4 0 1 2 2 5 2 2 3 4 4 4 5 3 5 5 5 6 7 5 3 3 4 0 0 2 3 1 4 2 4 3 4 "5 4 7 4 6 5 5X8 9 9X6 5 6" 0 0 1 2 4 2 4 2XlN4 4 6 5 6 5 5 5 5 5 6 5 6 4 5 0 0 0 2 2 4 2 4 2 6 4 4 6 5 7 6 6 6 6 6 6 4 6 6 5 0 1 1 2 3 4 5 3 6 3 4 4 4 5 7 6 4 5 5 6- 7 7 5 4 4 5 0 1 1 2 3 4 5 7 2 5 3 3 3 4 6 6 7 6 7\8 9 X 7 ffiNj 6 7 0 0 1 2 1 3 5 7 2 4 3 4 7 6 7 6 5 ^ 8 X 4 4 X f l X 6 5 0 2 1 2 4 4 4 5 5 X 8 X 4 7 X 9 9 9 9 9 X ? V ^ 6 X 9 9 " 8 ^ " ~ 6 '6VNj~"5 0 0 4 2 4 4 6 3\j i 9 ^ V t 7 5 X 9 X 7 6 ^ X f l X ^ V X ^ 7 \ f f X 7 5 5 7 0 4 3 4 2 3 4 5 5 5 5X\3 5 3 6 4 6 6 5 6 4 6 6 i X B 9 8 9XjNs>X 0 ^V8 9 * 9 S . 6 X c N 5 x 8 9 9X7X9X4^X9X^9X6 7 6 5^X9\6 5 7 X 9 X 6 4 6 6 ' 5Xg 0 (Tv9 9X^X8 9 9 9 9 X 7 7 X 9 X 3 X 5 X 3 5 4 5 7 6 5 5 6 5 5 X 9 X 6 X 8 8 9" DIAG.54 RING A R E A OF L A T E W O O D TREE N O » 7 YEARS 193 0 - 1 9 T 2 <tfaj r o ir-T--.. '-n r o v£><T ico iO. co ; ro r o j^o r o r\j m c o -cyrjoyin r o c o f a y r o i^.(Nip3/flo L O <J-rO|<j-poo <|-/^j'\JrtTi :<|- r— r o co r f r a j c s j rsj roI-o| <)-.<)• ;vO <t <j" r o •o :r\j CNI <f>^ ) <f r o m r o <f <f r o (Ni r o <f <f ir\ <j- :ro <f <f - <t CO r\j (\iJO-l t r o jro m r o j ro in <f /oJ <)• Lrv<r r o <r»^ > r o r o :ro (Nj <(• i <)-<)- rsj O^O r o if\ IvO r o ;co f\l (NJ "CNJ r o i ro r o CNI O O io I-I r o i-d- •£> r o |<f r o r o !ro --i i n ;r\i r\j CNJ I I i ! ; •.O O O JO O O : 0 r\j <}• <ro r o \0 iCN) (Nj <—i j r o (NI r o 1 , I i ' o o o o o o o io o o 'o o o !o o o ' o o o a o o ."2 U J I— < LL. < U J < cc — . L U a a (NI c* | - H I o r o LO L U C C U J < CC L U r- >-i_ O f—i x 1 s» — J Q * o »—< tr-• LD <T. LU <3 «—• 1—1 •Y ' J j >' <— > C J O O O — ' O O O O O O O ic >• -1 a: <t rsj UJ u . 1 .^ —i UJ • 0-CO O .—1 < 7^ t o O >L! CC < z UJ <t t—< t—< UJ Q y r- > —1 -1 - o -o o -.—1 -o o o o o o o o o o o o -o o o o o o o o o o o a o o o o o o o ^ —* rsj ^ —< i—i rs i f \ i r\j i\j ."sj (^i i-Ti J—^ •—i o -™ O O O O —i O O O O O —< o o a o o o o o o o o o c o o o t> o o o o d O D .s : J J t— <l M _l O <T LL —j a 1 LU • o cc a IO < • LO o UJ TC < UJ < *—• a LU > s T <M -r .-NJ <r O i r o -r O J >r o j r o r o O J •J- r o r\j (M - •s- r o rsj r o O ) *r\ r O r\ l rr\ r o r\ l rsj (M r o o j r o OI r\ l r o -r m - O J r o - r o r\J r\j r l O J r\j o j rsj ^ (NJ * rsj r o - o O J —< r—1 o j r\ l fM •—I rsj r - r o r o - —4 1—1 o j <—( r\J r \ l r o - o r o r o O J OI O J >r - o - -« -- -- -> <N ^ r o <• - o o rH —« F—1 - -> ,—t pH »—< (\J •si rsj r o r o -< - o —« o -< o i—i —4 O J O J r O .—t -or o o —« o o o —< o O —< - < O J rs] •—t H O J o o o o o o o o o o O o o r o O J o o o o o o o o o o o o o O o o o o o • o o o o o o o o O o o o o o o o o o o o o o o o o O o o o i rs i j—i ' jo O O CT-< j—i O O —i O — • jrH r\l O O O o o o o o o jo O O O O O j o o o o o 0 1 1 l ' 3 4 6 73 ~ 2 C 0 5 > ^ 5 3 C 3 DIAG .60 RING WIDTH OF EARLYWCUD TREE NO.9 0 0 0 0 0 0 C 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 c c 0 0 0 0 0 5 3 0 0 0 3 0 0 3 4 4 4 6 3 5 4 6 6 0 6 5 3 4 0 0 6 6 4 0 0 6 5 5 o o o \ 0 0 0 0 0 0 0 0 D I f l G . 6 1 RING WIDTH CF LA I tKliliU TREE N0.9_ YEAR S 1915-1362 0 0 0 0 0 1 0 0 11 0 0 11 0 0 0 0 0 0 0 0 0 0 C I 0 1 0 0 0 1 0 1 0 0 1 1 1 1 1 1 1 1 1 2 2 1 1 DI AG.62 RING AREA UF EARLYWOGO TREE NO.9 0 0 0 1 1 1 1 2 2 3 2 3 0 0 1 1 1 2 2 2 2 2 3 2 3 0 0 1 1 1 1 2 2 2 2 2 3 3 4 0 0 1 1 1 1 2 2 2 2 2 2 3 3 4 0 0 0 1 1 1 1 2 2 2 2 3 3 4 3 4 0 0 1 1 2 1 2 2 3 3 4 4 3 3 5 4 5 YEARS 1915-1962 o o o o o o o o o o CJ o o o o 3 o a .2 •3. rsi _l LL H a in '-i LU « O •CO ac o •—' so <. z. • 00 o o LU z LU < Ir— t—1 c LL' a > | u i 'ji -r HJ I o -r LO -c CM <T O ro LH ^ ^ r o in in rsj -o LO >o in jro so rsj j j i f ' sj- ,o v-r <• -cr i-o rs j i n LO . n c n -r in LO m ;>,o in -o sT -T^ ^ ^ -or NT -r LO. 'sj ! i n LO LO -J- ~a <t!LO LO LO r-/ JD «O -O -r ' A -o -o , ! ! / i / / / m u T ^ s r r \ i > r | { < i j ) ^ i n j ' j , \ O J i ^ - o ^ J > i r i i r > ' j - ' B ' - o - o p ' ! •4-; u s -j- .4- rsi JO -j- !>r -cr i n -cr LO LO '.O Jr^r -o LO . n L n -o i n o -£> - n -o v l - r o in CS.I -t -r <r :ro -1- -4- IO sT -c V •D 'JO / •o LO ft« JO LO o O r o O I r O <r rsj «r r o sT m LO -r -r LO LO in -o LO 'J\ LO in uo •O -o JO -0 •O r o m rsj <r 00 - T - o r o r o •r h r o •r- -O ro :.o <r ' .O •LO '•JO ; o •J~. 'JO •o ;LO -0 LO .NJ o» OJ rs i rsj fSI rsj n ro ,-r, .-o r LO ^ -J- rO r rO LO I- JO r sT LO JO •C' C\ • o O J - o OJ rsj r H r o r o rsj rsj -J - r o r o m / i i ,o N!" :rO •-o .•o LO LO •c s r s t sT .o xT LO -0 o OJ ISJ -< O J r H - ,o rsj •Ni r o <SJ rsj rsj 1 rsi •JO • j - ro •T LO :LO LO. rsj O J - O J i—l —1 OJ O J *-* rs i rsj OJ r o r o k %o r o >r r o m m r o m - T LO <r <- >r ro LO •n JO —4 r o H —4 r H —4 rsj - •—I rsj rsj rsj O J rsj r o r o -o "I ro •O rO •M rO r o -J- -cr •'O s f s T IJN : s T iO LO tsj r-4 r H »—1 - H i—4 rsj - rsj r H rsj rsj - rsj r o | o j iO rsj r o ro CSJ |OJ O J -< r o - o - o .rO rO - T NT -1- LO <r r-4 —4 r-i - H - - - H r H -< O J r 0 rsj - 1 r -o .-o IM - Ni i-rsi - - •*Sl .-0 NT 'rsi r o •M -r r o ro -r >r —4 H - r H o —t - H - —i - H - - o - - - h — rsj - I—» |--• --rv rsj ;<—1 rsj rsj •o rsj rv l-o 1 sT <r —1 o o o o - o #—4 r H O o r-4 O —4 i-4 O J -h —4 - - i—i - —4 O J rsj rsj -r~4 OJ LO ;ro r o >T o o o o o o o - H o O a o O O o o - i o j o - 4 O —i i—l —4 O - •—4 .—I r-l i o r-4 -•—I r-l r - l j r o rsj r o o o o o o o o o o o o o O O o o O o 1° o o .—i O o H O o r-4 r-l - 1° r-4 r-4 —^ —1 —4 1 |rsj rsj r o o o o o o o o o o o c o o o o o O o 1 CJ CJ o CJ o jo O o o o o jo o O •—I o o ;0 rsj r v o o o o o o CJ o o O CJ CJ o CJ o o o CJ o u o C J i jo o o o o o jo o o o o o o O o I! 3 3 a .s >-< C J >o :y L L —^ a 1 O s —4 —H U J * a c-4 • v D < • L 5 O < ~Z U J < t or Q c£ >-I M ( N i O O O O o o o o o —i —4 < M i f , „ 4 —i - 4 —4 f \ j < M »^  —' —I - 4 f \ | c-4 .—( —4 —4 c-4 O O O c-4 —I O O O O —I o o o o o o o o o o o o rr, < M C M r s i —4 ^ m ^  f \ J rr, rr, I M rr, rr, CSI CM ( M r v j ( M rr, r\i C N j r s j I M ( M I M - i o o o o o - 4 O O o o o o o o o o o o o o o o o o o o o o o o o o o o o o < rt UJ • r- or o < Z t O O UJ < z i u or O *-4 O r-4 i-^ O cH O o o o — o o O O O O O O o o o o o o o o o o o o CM CNI CM (M CM CM fSJ f\J CNJ CNJ rt rt CM CM CM H H H r\j r\j r\j •-4 rt CNJ rr\ CM CM rt -4 -4 rt -4 rsi C^i ^4 ^ ^4 O rt —4 rt —4 rt O rt O O rt O o o o o o o o o o o o o o o o o o o Q f-t ^ ^ ^* ^ C*) ~4 <-* ~4 —* O O O rt o o o o o o o o o o o o o o 0 I AG .5 8 RING WIDTH OF EARLYWOOD TREE NO.11 YEARS 191-3-1962" 6 5 3 6 \ 5 5 3 4 6 6 4 b 4 "3 b 3 4 4 2 b b A 4 6 3 5 5 3 6 b 'J 4 4 b 3 <t 4 3 4 6 6 6 5 f) 4 6 6 5 4 6 6 4 b 3 3 5 b 5 4 6 b 5 4 7. b 3 f) 6 4 4 4 4 <i 5 5 4 u 4 •) 3 b 2 4 4 4 4 6 4 5 5 5 6 3 b 3 3 3 4 4 3 4 4 4 4 j '^ 4 2 3 3 4 4 4 5 5 4 4 3 4 2 i. 4 3 4 3 6 4 4 4 4 3 3 4 3 2 4 3 3 3 3 4 4 3 4 3 4 2 3 3 4 2 4 3 4 1 2 3 3 4 1 2 '+ 3 4 2 b b 2 I 4 4 4 4 3 1 3 4 4 i 4 3 2 2 3 3 3 4 2 4 ? b 3 i H 2 b i> 0 o o o o <o o o o o o o 0 G C C C C C 0 1 1 1 11 0 0 0 1 1 1 C 1 G 0 C U C 0 C 0 0 0 0 0 C 0 0 0 1 I 1 3 2 2 2 2 3 2 4 3 2 2 4 5 5 4 4 6 4 6 6 2 1 1 1 I 2 1 1 1 2 1 1 2 2 1 2 2 2 1 2 2 2 1 1 2 1 2 2 2 1 2 2 2 2 2 2 3 1 2 2 2 1 1 1 2 T r T 2 1 2 2 2 2 2 2 3 1 2 1 2 2 3 3 3 2 3 3 3 2 3 3 4 3 3 3 3 3 4 3 •f A 5 4 5 3 4 5 2 3 4 4 5 4 5 3 4 4 4 5 6 6 4 6 6 6 5 6 6 5 "5 3 6 2 4 4 5 r> b 6 5 5 5 6\ 5 6 5 6 4 5" 01 A G . 7 0 R I N G Ai<bA O F r A R L Y V U J G D T R E E NO.11 Y E A R S 1915-1-J62' -J .;j »— <i _j u . rt a 1 rt <r rt rt UJ » CT a rt • <J3 UJ a ; <; < or LU »— >• O r t O O O O r t O r t o o o o o o o o o o o o o o O O O O O O O O O O O C J O o o u o c j . v j o o ' a o c j o o o r M r t r t r v j ^ - f l u o i j - J - r o , " " ^ - ^ rtOrt^rtfl|ror\jf\jrnrn O O r t r t r t f \ i ! f \ J r t r S j r \ ) ^ J N J , i ' o a o o r t O | O r t r t ( N j _ i r v j - _ . u j a o a o o o b o u o o / . PSI M I N o o o o o o o o o o o o a x f\J r - - I O • ^ M • r- i 7. • O O UJ < z u i Q -x: t-— ' o o o o o o o o o o o o o rt O rt o rt o rt o o o o o o o o o o o o o o o o o o o o o o o 0 C 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 1 I 1 1 1 1 1 DIAG.75 RING AREA CF LATLWGOD TREE NO.12 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 1 0 0 1 1 1 1 1 1 1 YEARS 1914-1962 1 1 1 1 1 1 1 1 2 1 1 2 1 2 2 1 12 2 1 10 11 1 1 1 1 1 0 1 1 1 1 1 0 1 1 12 2 1 1 1 1 1 1 1 1 1 1 2 1 3 3 0 0 0 0 2 I 1 1 I 1 1 1 1 1 1 1 0 0 0 1 0 0 11 0 0 11 0 0 0 1 0 0 0 0 O i l 1 1 1 1 2 2 5 7 5 5 3 3 3 4 3 4 4 4 6 4 5 5 4 3 3 3 4 4 3 4 5 4\5 4 4 3 4 4,4 "X 6 * 5 X * 1 1 1 1 1 1 1 12 2 1 2 4 3 3 3 4 4 4 5 4 5 6 4 6 4 5 6 5 6 4 5 4 4 5 4 5 4 3 5 6 5 6 5 5 3 5 4 3 4 5 5 4 4 3 3 5 4 5 5 4 5 4 4 5 5 5 6 5 5 4 6 6 5 6 5 5 3 4 4 3 4 5 4 6 5 5X 6 5 5 5 4 5 6 5 5 4 6 5 5 6 6 5 \5 X X X . 6 5 6 5 4 6 5 4 6 6 5 >8y6 5 4 6 6 5 5 5 6 5 5 5 4 4 5 5 6 5 6 5 5 6„ 445 6, 6X^-ilX 6 t \ 6 5 5 5 5 5 4 5 4 6 5 6 5 5 6 4 5 5 4 4 5 4 5 6 5 6 6 4 6 4 5 5 4 X 5 5 5 4 5 4 5 6 6 6 4 5 6 6\6 5 5 6 5 5 X X X X 6 566. 6. 5 5 5 5 5 5 5 6 5 5 6 6 6 6 6\5' 5 6 6 5 0 14 4 6.5 4 6 . _ XXNS. an a _s _) < LU rsj vO LL Lr* CJ »-i X ro 1 LO i—. —4 —4 3 » <? •—i i—l r- . 7 ' • </> O OJ Of < 'XI <l •—1 M Of. LU CI Y 1— > vf i"0 vf J3 - o -o */<rf^ -o v r LO ,r o <r _> LO LO n ' O v u o -r u -j- •_> o sr -J. o o*' -cr .o -o LO to ..o <- «o -o -o m m >r / ;0 JO '.O O LO 4- .JO . O J O JO • o jo ...O O o -o "O -o -o +/» 'O .^O rO o -.C -O rsj -j-•4" LO ;0 •JO ^ 'uo rsi <f *-! O 4" <r -3- o ro -o vT .jo. •J- -o '.jo -o - / 4 5 rO ••O .0 sf IO -jo. <r LO -T <r <r _o '"0 O -O LO '..O ro i.o^ »C -j- -n ro vO ro 4" :0 0 ro 'jo JO .4-<• p/_0 iO sT .0. <r o, 0 o c o sr -t LO^ JO -j- 0 -o 'jo •U 'JO JO. o o o o o o o o o o o o o o o o o;o o o o o o|o o o o o o o o o o o oo o o o o o o o o o o o o o • a-— a j o u -t: <i :<r '.LI < o. or: — > C M U N -cr ir> J N sr U N in uV^ '•r -t -r J) •iJ^ rj/! ' 'JT. \ jo sr J~I sr ^2 ^ r. - - o sr sr ay£<~*x j^f, u> S 3 so Jc C M sr O i j C M ST ;-i in rt rri rvi sr sr r o UN o r o rvj C M sr C M sr Oor\j : rtrtrsJsrrN / ro!Lri;N | r trvi O O —i r v i o o rt sr fNi rNijtNj U N — • - * rt o o ; r t rt CNJ CNJ rvj sr rvi 0 0 0 O 0 0 O C ^ O C J 0 0 0 i o ' : 5 0 0 O O 0 O 0 O ' J O . < _ ) U N s.7 ^ ^ ^ ^ " J " r o ' T V JN ^- sr ;ST C M r o UN r o -\j —i o sr C M r o *.r\^f un U N r o ( M r o r o C M C M r o o j ^ / C M sr C M C O sr sr ^ ( M in c O rt rvj r o - o r o i C M ^ 1 C M U N sr e^^'.u r o C M s3 —< C M C M r o r o -0 sr C M ro C M M j C J O L J O O O O O O O O ' O O rt. in rt ^ j^-^ rt—irvUNrMCMrMOrtCMNj-fMOOCMsrCM c <~, C: o c . C o O o c o a o o r> o o o o 1—' t— rt rt O — o o — c-I V rv L J i V r v r v rvi rt rt r v IV. I V r o - INJ r v rt r v U ! J > ( V I V »— rv r v FV t v .jv J > |V u U J I V rv I V i» J > u- t v U > cv v r I J J Lf> rv! .V j> J": V ' J > ' . V J > U - r v o V*. U"! •J"' j > V- U". 0* V-*l 1^  vr- j > <T Ct v" v < j > o cr o A vm J > C- c i.T J > o-, o o c. o o o cr. o o o o c o o o • o o o <-. o O O O O O C a O O O O O O O O l O O O O o c c o o c, c o o o o o o a c v o o o — r c n c o o a o o o o o c i o c i - i - o c r - rr - - o c o o c i— o o r ~ C V I — rt rvj rv) »— r— V ) r v cv; IV) v.- J > r v J > v ~ J> ( V ; I — f— rt >— r — r-j rv r - i— .v — CV rt f V r - V ; r v "v- v rt r v r v r v f v ; rv-U J r v - v r v rv> r v r -r v i -^ > ^ u u-— ; j o T> r n X —« » — < > m .Tl o <r. o o • > rt O -0 • m rt rt Cl u; o -n STJ : a i rr. r v ; j> r -s. o o "1 o c o Li ' J J < CNJ •0 I/O UL 1—I o 00 1 LO t _ J r H • —4 O "ON a r H * - l z • c/> o ' J J ac < z U J <t r-t *—4 oc L U a >-o o C J o C J o o o o o o C J o c_> C J C J C J C J C J o c j O C J O C J O O —1 r o - o rs i OJ r o r - l r o - o rsj r o r H rsi r o r o rsj r o - i rsj rsj - o r o OS rsj .—1 rsi r o r o oo rsi rsi r o - rsj rs j ,*r> rs, •O rsj r o r o rsj r v 'NJ rsi r o rsj - O .-o - o - - 1 rsj rsj r\j rs; r o r o rsj r o r - l r\j — H rsj rsj rsi rsj rsj O i rsj r o • n rsj — H CNJ CNJ r - l —i rsj rsj O j r\ i CNJ r o o —i OJ rsj rsj •rsi rsj r H r v oo r o r o o • H - r - l -— - 00 —< rsj rsi oo r o rsj CJ -—i --- - i r - l - rsj -rsj rsj rsj rsj o -- -- • H r—1 r H — H r o r o rsj rsj OJ CNJ - H —1 r-1 r - l - • H —4 r - l r H rsi rsj r - l rsj OJ r H CJ -r H r H o o r H •-4 -,—1 —1 -r H r-H (V -' o 3 r—1 o o o o _ r - l _. _ i .—i _ _, r H o r j o o o - J - - O —— -o o o C J 13 o o o o o o CJ C J o o o o o o o O C J CJ o o C J o o o o CJ o -o o o O o o o o o C J o o o o C J o o o o C J O C J o o C J CJ o C J o C J o o o C J O C J O C J O C O U O O O O O O — I o o o o o o o o X • * I 1 Q • >-i a CO J E z • C_> O U J < Z J J - . —. or LO in vO «t «i in N vr rg m * i f i -j- m <\i r o >o O J <o - J o i o o o »H o o o o o o o o 0 •0 .o ^ sj- r*. v?- --r -T - 0 r-O '.j 'O ^ <\ O 4- fl -r*. -\ Nt ^ fl O st ^ vr ^ c -T ^ >r A sr no fl fl fl ^ f i s* n ^ r , . r fl NJ- -4- fl m fl fl A tr* fl 'Ni s * .^n -0 xi fl ^ ^ ^ rv s f ] o ^ vt s r s f l fl u"\ ^ :^ >j- fl f\t LT\ Nf fl A - j - -n <r v? J - . . n ' A i n r\j A >r A -0 -4" A k/> A 4- ^ -c o m * f H lA CM O N o n^yS <sj © o f \ J ( V J O O o o ^  o o o O © O O U O ' ^ s f v f .O ^ \ f ^ ro vO ^ - A - 0 ] - f fl NT f M -3" v t fl xT NT jd" . -T ^ f t IT '(1 «f O -t | ^ ^ vT A I ' - T v t ^ j F ' . n - J - I - j - fl vj- u"> u*\ \ t '.p "*\ LA j . y un :\* >r i -T fl .n 4" i n <r:*T fl -n O '.r\ ^  <r <T r\ /<T -4* fl A >J- 1 fNJ sj- sT '-T\ fl^xf LT-. <T , n - 0 fl -o i ^ i n - j - - f fl >^ s f fl!LO '.rv vj- ir* fl s f .'.n s t <j* 9 * -4" ir*t ' i n -o c ir* «\ *o ^ ^ \f\ ijr*\r<^ ^ <f -J- -C s\ *f xn - s O f l ^ i r s i r o s O <t ^ ^ n ' r\ <r <r r\ <r ^ «o -r i n *-n t f l ^ f l u ^ i L n f l i n s T s r ^ i i n - f i n ^ v O - r i u ^ o ^ i '.n -o -o .n jffir^ >r - u - j - -r\ ^ -4- <; -r>yf -4* V-M r f K M o r r , m o i CNJ «o r o o j O i oj r g o j -t o j PH 0 0 0 0 0 0 fll H f y (\J CM "J OJ CM CO OJ OJ OJ o j -< r o (NJ o j —1 H m H H H ^ 0 0 0 0 0 0 O i o j CNJ r o o j r o OJ O O OI INJ >}• r v O H H i N H OJ O O —> O OJ o o o o o C J ro 10 ro o j o j ro <NJ o j o j r \ i rsi i n rsj no r o JNJ r o _i O O O O O O MO LO •0 -O ao r r m sr J J m <3 o- m >f CM 01 o m r o in 10 r o uo r H —1 r o o j PO O O O O O O CO & -4" sj-fsj fl O 1 o O i J E i > 1 _ ) ! X. < ;CM LU ! -o :t_r> a ! i ..r j f l LU • • ' 0" CM « a ~ i oo < 2 • < u j i n —I OC :UJ J J »<- >C Xl N<f u -\ ,.<•> o o 5 ^ //// C M — I — i rt —< O O O O O ; O O O O <_> O O O o o o a o o. r r rt >• s 0 •o •a •JN U"> ' O -o U N XI - O J N / - o J N o - o s r / s 0 L O ' J N s r 1 U N s r // ' J N U N s r - r " ' J N >cr J N i ) U N i n s r U N J N U N J N •/\ 'JN, U N ' J N U N JN U N J N ' J N s r • o s r s r U N - c S T J N LCN •J- J N fl J N ' J N / <r s r - J N J N • s r •J- fl s r J N J, sO i J I f s r IJN fl s r U N - c •o U N sO fl r o J N fl ; f l s r r o >r -cr so * >r\ ' J N U N U N s r C M s r r o • o s r <M s r j - LCN • J N : v n -cr i n s r sr r o C M fl r o fl fl'llM fl s r - r U N -cr r o J N •v- TIN U N r\j C M r o • o r o fl . v j . r o s r • J N U N -cr fl r o fl fl sT U N C M rt r o r o O J r o rt C V C M s r s r fl fl s r fl fl fl s r i n —1 (M r o r\j rt rt C M C M r o s r A rvj r o fl r n fl fl r o U N rt C M rt C M -rt C M fl : . f l r o C M fl fl C M fl fl fl s r s r rt -rt rs i rt rt C M CM fl ! C M C M fl fl CM CM C M C M fl -cr s r --rt rt rt rt C M C M C M ; r t C M C M C M C M rt C M C M C M fl r o o rt -rt rt C M rt r o rt C M ! rt C M CM rt C M —1 , C M r v C M CM C M o o o rt rt rt O rt rt w r rt rt -rt C I r t C M rt C M C M o O o rt —1 rt O o o o o o o O o o o o o j o O o o o o j o o o o O o o o o o o o o o o j o o o o o c_) ; c j O O O O o o o o o o o a o o a o a a o o —i o a o o O O O O O O O O O O O O O O O O O O O O O O O O 

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