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Variation in lodgepole pine and its role in the genetic improvement of coastal forms Roche, Laurence 1962

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VARIATION IN LODGEPOLE PINE AND ITS ROLE IN THE GENETIC IMPROVEMENT OF COASTAL FORMS by LAURENCE ROCHE B.A., B.Agr. (Forestry), University of Dublin, 1960  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF FORESTRY IN THE FACULTY OF FORESTRY  We accept t h i s thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA March,  1962  In presenting  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 t h a t 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. f o r extensive  I f u r t h e r agree that permission  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  granted by the Head of my Department or by h i s  be  representatives.  I t i s understood t h a t copying 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 The U n i v e r s i t y of B r i t i s h Columbia, Vancouver &, Canada.-  iii  THE INLAND FORM OF PINUS CONTORTA  1.  A branch with staminate flowers  2.  Diagram of the involucre of the staminate flower  3.  A staminate flower  4.  An end of a branch with p i s t i l l a t e flowers  5.  A p i s t i l l a t e flower  6.  A scale of a p i s t i l l a t e flower, upper side, with i t s ovules  7.  A scale of a p i s t i l l a t e flower, lower side, with i t s bract  8.  A f r u i t i n g branch  9.  A cone from a tree of an intermediate form  10.  A cone scale, upper side, with i t s seeds  11.  A cone scale, l a t e r a l view  12.  Seeds  13.  V e r t i c a l section of a seed  14.  An embryo  15.  Tip of a leaf  16.  Cross section of a l e a f  17.  Winter  branch-buds  From Sargent (1897)  iii  THE INLAND FORM OF PINUS CONTORTA  iii  iv  ABSTRACT The thesis i s divided into two parts.  Fart one deals  with v a r i a t i o n i n a number of important s i l v i c u l t u r a l and taxonomic c h a r a c t e r i s t i c s of Pinus contorta.  Variation i n  bark and growth habit was studied i n the f i e l d and recorded by means of photographs. are  The data obtained i n t h i s manner  supplemented by information concerning v a r i a t i o n i n both  these c h a r a c t e r i s t i c s i n Lodgepole pine plantations i n Europe. I t i s concluded that the Shore form of Lodgepole pine i s extremely intolerant of shade, and i s not inherently a scrub tree, or i n f e r i o r i n form to the Inland v a r i e t y of the species.  The geographical p o s i t i o n of some superior coastal  stands i s given. The f i e l d study further showed that because of i t s shade intolerance the Shore form i s r e s t r i c t e d to the forests' edge, to ocean c l i f f s , sand dunes and muskeg.  There i t s p o t e n t i a l  growth habit and form are obscured by extremes of environment, and observed only when grown i n plantations, or i n i t s natural habitat when competing species are eliminated by f i r e . the  Under  l a t t e r conditions the Shore v a r i e t y of Lodgepole pine i s  a r a p i d l y growing tree, with normal growth habit and form, and i s seldom contorted either i n bole or branch. The Shore form has a c h a r a c t e r i s t i c bark type which i s  V  inherently d i f f e r e n t from the I n t e r i o r form. A study of v a r i a t i o n i n needle morphology was made on material obtained from trees of the Lodgepole pine provenance t r i a l at The I n s t i t u t e of Forest Genetics, P l a c e r v i l l e , C a l i fornia.  Needle width and length were measured, and i t i s demon-  strated that a c o r r e l a t i o n between these two measurements exists.  Because of t h i s c o r r e l a t i o n the Shore and the I n t e r i o r  populations  cannot be distinguished by either l e a f width or  length alone.  Therefore the mean r a t i o of width to length i s  used to separate the v a r i a t i o n i n l e a f morphology due to the place of o r i g i n of the trees from which the needles were c o l lected.  Analysis of variance shows that the mean r a t i o does  not d i f f e r s i g n i f i c a n t l y between trees representing a p a r t i c u l a r s i t e , between s i t e s the difference i s j u s t s i g n i f i c a n t , and between geographic regions highly s i g n i f i c a n t .  The Duncan  multiple range t e s t showed that the three major regions  (Rocky  Mountains, S i e r r a Nevada, Coastal) d i f f e r e d s i g n i f i c a n t l y from each other, but that there was no s i g n i f i c a n t difference between the mean r a t i o of the Coastal and the Mendocino White Plains material. Data concerning  the growth rate of the trees at Placer-  v i l l e , supplemented by data from European plantations, suggest that coastal Washington and Oregon provenances show the most rapid growth rate i n North Temperate regions. Specimens of seed and f o l i a g e c o l l e c t e d from natural  vi populations show morphological differences between the Coast and I n t e r i o r forms. A method of distinguishing Coast and Interior seed i s demonstrated. Germination tests show that under standard conditions of temperature  and humidity the rate of germination of the  Coast seed i s s i g n i f i c a n t l y d i f f e r e n t from Interior sources. Morphological differences i n seed c h a r a c t e r i s t i c s , can, therefore, be supplemented by germination data to e f f e c t i v e l y separate the I n t e r i o r and Coast forms of Lodgepole pine. Part two of the thesis deals with the selection and breeding of the Shore form.  The proposed breeding program  takes into account the t h e o r e t i c a l and p r a c t i c a l objections to the Scandinavian method of tree improvement.  Nevertheless,  i t incorporates t h i s method insofar as i t i s designed to produce large quantities of seed which i s not i n f e r i o r i n several desirable c h a r a c t e r i s t i c s , while simultaneously working for the genetic improvement of the species.  vii  TABLE OF CONTENTS PAGE TITLE PAGE  i  FRONTISPIECE  i i  ABSTRACT  iv PART I  INTRODUCTION  1  LITERATURE REVIEW OF VARIATION IN PINUS CONTORTA AND OTHER PINE SPECIES  4  GROWTH RATE  14  LEAF MORPHOLOGY  22  GROWTH HABIT  35  VARIATION IN BARK  44  SEED CHARACTERISTICS  54  SUMMARY OF CHARACTERISTICS DISTINGUISHING THE COAST FORM OF PINUS CONTORTA  60 PART I I  INTRODUCTION  61  POLLINATION IN RELATION TO BREEDING  67  NATURAL AND INDUCED MUTATIONS AND THE BREEDING OF PINE. . .74 CYTOGENETICS AND THE BREEDING OF PINE  77  viii PAGE SOURCES OF HEREDITARY VARIATION  79  SELECTION OF NATURALLY OCCURRING TREES WITH DESIRABLE CHARACTERISTICS  79  RECOMBINATION OF NATURALLY OCCURRING VARIATION BY MEANS OF HYBRIDIZATION  84  IDENTIFICATION OF TREES WITH DESIRED HEREDITY  91  SUMMARY OF BREEDING PROGRAM  95  BIBLIOGRAPHY  96  ix  LIST OF TABLES TABLE I.  PAGE MEAN HEIGHT OF TWENTY PROVENANCES OF SEVEN-YEAR OLD PINUS CONTORTA GROWING AT PLACERVILLE  II.  17  STATISTICS OF REGRESSION ANALYSIS OF NEEDLE LENGTH (X) ON WIDTH (X) FOR FOUR REGIONAL VARIETIES OF PINUS CONTORTA  III.  MEANS OF NEEDLE WIDTH AND LENGTH, AND RATIOS FOR FOUR GEOGRAPHIC REGIONS OF PINUS CONTORTA  IV.  27  29  ANALYSIS OF VARIANCE FOR DIFFERENCE IN LENGTH/ WIDTH RATIO OF PINUS CONTORTA NEEDLES BETWEEN TREES, SITES AND REGIONS  V.  GEOGRAPHIC ORIGINS OF TWENTY PROVENANCES OF PINUS CONTORTA SAMPLED AT PLACERVILLE  VI.  34  GERMINATION RATE OF FOUR SOURCES OF PINUS CONTORTA SEED AT VARYING PERIODS OF STRATIFICATION  VII.  32  58  GERMINATION RATE OF NINE SOURCES OF PINUS CONTORTA SEED FOLLOWING TWO WEEKS STRATIFICATION  59  X  LIST OF FIGURES FIGURE 1  PAGE  REGRESSION OF HEIGHT ON ELEVATION FOR 18 DIFFERENT PROVENANCES OF PINUS CONTORTA GROWING AT PLACERVILLE  2  18  RELATIONSHIP OF TOTAL HEIGHT AND ELEVATION FOR 18 DIFFERENT PROVENANCES OF PINUS CONTORTA GROWING AT PLACERVILLE  3  19  REGRESSION OF LENGTH ON WIDTH OF PINUS CONTORTA NEEDLES FROM 22 DIFFERENT PROVENANCES GROWING AT PLACERVILLE  4  26  DIFFERENCES IN RATIO OF NEEDLE WIDTH TO LENGTH FOR 20 PROVENANCES OF PINUS CONTORTA SAMPLED AT PLACERVILLE  5  33  DIFFERENCES IN RATE OF GERMINATION AT 25° C. BETWEEN COAST AND INTERIOR SEED OF PINUS CONTORTA  6  METHOD OF DISTINGUISHING INTERIOR AND COASTAL PINUS CONTORTA SEED  7  56  57  INCREASE IN LATEX YIELDS PER ACRE BY SELECTION AND BREEDING OF SUPERIOR STOCK  66  \  xi  LIST OF ILLUSTRATIONS ILLUSTRATION  PAGE  1  PINUS CONTORTA, PASSAGE ISLAND, HOWE SOUND, B.C. . . .39  2  PINUS CONTORTA. WHYTECLIFF, NEAR VANCOUVER, B.C. . . .39  3  PINUS CONTORTA. KITSAP PENINSULA, WASHINGTON  40  4  PINUS CONTORTA. KITSAP PENINSULA, WASHINGTON  40  5  PINUS CONTORTA. 4 MILES EAST OF OLYMPIA, WASH  41  6  PINUS CONTORTA. 5 MILES SOUTH OF OLYMPIA, WASH  41  7  PINUS CONTORTA. BLUE MOUNTAIN, OREGON  42  8  PINUS CONTORTA. EAST SIDE OF LAKE TAHOE, NEVADA. . . .42  9  PINUS CONTORTA. OLYMPIC PENINSULA, WASHINGTON  . . . .43  10  PINUS CONTORTA. LADNER, NEAR VANCOUVER, B.C  43  11  PINUS CONTORTA, CHINOOK PASS, WASHINGTON  49  12  PINUS CONTORTA. 4 MILES WEST OF OLYMPIA, WASH  49  13  PINUS CONTORTA, 20 MILES EAST OF PLACERVILLE, CALIFORNIA  50  14  PINUS CONTORTA. 5 MILES SOUTH OF OLYMPIA, WASH.  . . .50  15  PINUS CONTORTA. EAST SIDE OF LAKE TAHOE, NEVADA  . . .51  16  PINUS CONTORTA. 60 MILES NORTH OF VANCOUVER, B.C.. . .51  17  PINUS CONTORTA, NEAR PLACERVILLE, CALIFORNIA  18  PINUS CONTORTA, PLACERVILLE, CALIFORNIA. ORIGIN, SAMOA, CALIFORNIA  52  SEED 52  xii ILLUSTRATION  PAGE  19  PINUS CONTORTA. BLUE MOUNTAIN, OREGON  20  PINUS CONTORTA.  53  EAST COAST, VANCOUVER ISLAND, B.C.. .53  •  • a  XI LI  ACKNOWLEDGEMENTS Acknowledgement i s made to the University of B r i t i s h Columbia for f i n a n c i a l assistance, and f o r the laboratory and other f a c i l i t i e s which aided m a t e r i a l l y i n t h i s research. The writer greatly appreciates the academic advice  freely  given by Dr. P. G. Haddock, Mr. Oscar S z i k l a i , Dr. J . H. G. Smith, and Dr. V. C. Brink, and also the considerable a s s i s tance i n s t a t i s t i c a l analysis given by Mr. Antal Kozak and Mr. Jozsef Csizmazia. Acknowledgement i s also made to Dr. W. B. C r i t c h f i e l d , who f a c i l i t a t e d the w r i t e r i n obtaining material f o r the present study.  VARIATION IN LODGEPOLE PINE AND  ITS ROLE  IN THE GENETIC IMPROVEMENT OF COASTAL FORMS PART I INTRODUCTION In recent years there has been increasing interest i n the Lodgepole pine resources of the P a c i f i c Northwest.  In the  United States i n p a r t i c u l a r t h i s interest has been stimulated by increasing p r o f i t s from the u t i l i z a t i o n of the species. Lumber production i n 1956 was  sixteen times greater than that  i n 1933, and Rocky Mountain area stumpage prices between and 1956  increased by over 200 per cent (McMahon 1957).  1950 It  i s obvious, therefore, that i f present trends towards the u t i l i z a t i o n of small timber continue, Lodgepole pine, which i n acreage i s the t h i r d largest timber type i n the West, w i l l i n future years achieve the status of an important commercial species, and w i l l f a l l within the scope of a tree improvement program. Before a tree improvement program can be i n i t i a t e d for any species i t i s f i r s t necessary to study i t s v a r i a t i o n both i n nature and i n plantations. The v a r i a b l e characters studied may be purely taxonomic, or they may be characters which are p r i n c i p a l l y of interest to the s i l v i c u l t u r i s t .  2 The systematic botanist's objective i s to c l a s s i f y the species, and h i s approach i s , therefore, taxonomic.  The forester, on  the other hand, i s interested i n the species i n r e l a t i o n to i t s environment, and the edaphic, c l i m a t i c and b i o t i c factors which influence i t .  He i s also interested i n the vigour of  the species, and i n i t s general form, and h i s approach to the study of v a r i a t i o n , therefore, w i l l not be purely taxonomic, but also genecological. This thesis w i l l describe v a r i a t i o n i n Lodgepole pine primarily from a s i l v i c u l t u r a l point of view.  The approach  is., nevertheless, a synthesis of taxonomic and s i l v i c u l t u r a l observation which seems, at t h i s early stage i n the development of forest genetics, to be the approach which y i e l d s the most useful information to the p r a c t i c a l tree breeder. Growth habit and bark v a r i a t i o n were studied i n the f i e l d during the summer of 1961, p r i n c i p a l l y on the Coast of B r i t i s h Columbia, Washington and Oregon, but also i n the I n t e r i o r of these areas.  Parts of Nevada, Idaho and C a l i f o r n i a  were also v i s i t e d . Stebbins (1950) pointed out that v a r i a t i o n i n some charact e r i s t i c s of a plant species i s best recorded by means of photographs.  This i s the method used i n the present  study  to record v a r i a t i o n i n growth habit and bark type. In order to determine that provenance of Lodgepole pine which shows the most rapid growth rate i n North Temperate regions  3 a survey was made of the behaviour of the species i n plantations and provenance t r i a l s i n Europe; and p a r t i c u l a r l y i n England and Ireland.  Height measurements were made on the provenance  t r i a l of the species at The I n s t i t u t e of Forest Genetics, Placerville, California. The trees at P l a c e r v i l l e wece grown from seed collected i n twenty areas scattered throughout the range of the species. I n t r a s p e c i f i c v a r i a t i o n i n needle morphology was determined from needles collected at P l a c e r v i l l e from each of four trees representing twenty provenances of Lodgepole pine.  The  needles were two years o l d and c o l l e c t e d from the lower crown on the south side of each tree.  The mean width and length of  ten needles from each tree were obtained, and the r a t i o of width to length used i n determining the pattern of v a r i a t i o n associated with the place of o r i g i n of the trees. Foliage and seed specimens were c o l l e c t e d i n the f i e l d during the summer of 1961.  Seed, bark and foliage specimens  were also obtained from the B r i t i s h Columbia and Alberta Forest Services during the winter of 1961-62. Germination tests were c a r r i e d out on seed from nine d i f f e r e n t provenances of Lodgepole pine including four coastal sources i n order to determine whether s i g n i f i c a n t differences i n germination rate existed between the Coast and I n t e r i o r forms.  LITERATURE REVIEW OF VARIATION IN PINUS CONTORTA AND  OTHER PINE SPECIES  Though P_^ contorta was 1825 its  discovered and named as early as  there s t i l l exists considerable uncertainty taxonomic c l a s s i f i c a t i o n .  For a short time i t was known  as P^ inops (Mirov 1954), and i n 1852 was  concerning  the Sierra Nevada form  collected and named Pinus Murrayana.  This form i s s t i l l  considered a separate species by some American and European botanists. Sargent (1897), after considerable study of the species in  the f i e l d , concludes that the inland form (P. contorta var.  Murrayana, Engelm.) i s a v a r i e t y of the shore form (P. contorta, Loud.).  The drawings of the f o l i a g e , flowers and cones, of  both inland and shore v a r i e t i e s included i n Sargent's work are extremely accurate, and i n respect of foliage density c l e a r l y i l l u s t r a t e the difference between the two  types.  A few years l a t e r Jepson (1907) had t h i s to say "P. Murrayana i s treated by many authors as a v a r i e t y of Beach pine (Shore pine) of the coast  On the contrary  the t y p i c a l forms of the two are not only very d i s t i n c t and t h e i r habitats widely d i f f e r e n t , but the t y p i c a l form i s i n each case the only form throughout the main geographical region of that species."  He c l a s s i f i e d the inland form and shore  5 form as d i s t i n c t species, P_ Murrayana Balf., and P_  contorta  Loud, respectively. The following year Sudworth (1908) considered that d i f f e r ences i n thickness of bark, s i z e of cones and leaves, or size and form of the tree, are not too great to be merged i n one polymorphous species.  He described the P a c i f i c form as a tree  20 to 40 feet high and from 6 to 20 inches i n diameter, and the Inland form as a tree 50 to 100 feet high and from 12 to 24 inches i n diameter. In 1917  Davidson (1927) planted a single transplant of  the Inland form and one of the shore form i n the arboretum at the University of B. C.  Writing i n 1927  he stated that  for the f i r s t few years minor points of difference could be demonstrated, but a f t e r ten years the trees were i d e n t i c a l i n f o l i a g e , habit, and rate of growth.  He concluded that the  Inland v a r i e t y i s nothing more than an environmental form. The present writer has examined both these trees i n the University arboretum.  They are now  approximately 45 years old.  The following characters were studied:  l e a f length and  cone s i z e , closed cone habit, and bark type.  colour,  The r e s u l t s show  that, with the exception of bark type, the two trees are d i s t i n c t l y d i f f e r e n t from each other i n respect of a l l other characters.  There i s no noticeable difference i n the bark  type of the two  trees.  Kalela (1937) stated that the Inland and Shore forms are  6 separate species, respectively P_j. Murrayana and I\_ contorta, the former c o n s t i t u t i n g a continued series of climatic races within which a v a r i a b i l i t y similar to that i n Scots pine can be observed.  He considered the shore form to have a more rapid  growth; wider, firmer and more twisted needles than the Inland form.  However, Bowers (1942) agreed with Sudworth that P.  contorta i s a single polymorphous species. Harlow and Harrar (1958) considered P_^ contorta a species.  The coastal form was  dimorphic  described as a small tree, with  a contorted bole and dense i r r e g u l a r crown of twisted branches, 25 to 30 feet high and 12 to 18 inches i n diameter.  The Inland  form i s a medium-sized tree 70 to 80 feet high and 15 to 30 inches i n diameter, with a long, clear, slender bole and short, narrow, open crown. B u l l e t i n 61 of the Canada Forest Service (1956) treated Shore pine as a species, and the Inland form as a v a r i e t y of i t . Shore pine was  described as a small, usually shrubby tree 15  to 50 feet high and 12 to 18 inches i n diameter, with a crooked, often twisted trunk, and an i r r e g u l a r , open crown of large, twisted, generally much-forked branches. was  The I n t e r i o r form  described as a tree with a narrow crown, 50 to 100 feet  t a l l and one to two feet i n diameter at breast height. Generally speaking, the description of the growth habit of the Coastal form of P_j_ contorta as given i n the l i t e r a t u r e i s i n c o n f l i c t with the evidence now  being obtained from many  7 European plantations of t h i s form, and with the of the present writer.  observations  Sudworth (1908), however, noted that  i n close stands the Coastal form develops a t a l l ,  clean,  slender bole, with a short, small-branched crown. P. contorta has been planted extensively i n England and Ireland and i t s use i s increasing r a p i d l y i n current planting programs.  The climate over both these islands i s r e l a t i v e l y  uniform i n contrast to the extremes of climate which exist throughout the range of the species i n North America.  Many  d i f f e r e n t seed sources have been used and there i s considerable natural v a r i a t i o n which i s r e a d i l y observable under plantation conditions and the f a i r l y uniform climate.  In England seven  subtypes are distinguished, and i n Ireland three (Lines 1957). They are l i s t e d as follows: ENGLAND 1.  North coastal  2.  South coastal  3.  Alaska  4.  Alberta  5.  Skeena r i v e r  6.  North I n t e r i o r  7.  South I n t e r i o r  IRELAND 1.  South coastal  2.  North Interior  3.  Rainer Forest  Each type i s distinguished by i t s branchiness, bark colour and thickness, leaf colour and length, density of f o l i a g e , and growth rate. Lines  1  c l a s s i f i c a t i o n i s to a great extent a r b i t r a r y , f o r  many intermediate forms are found; nevertheless, i t i s useful to the p r a c t i s i n g forester and tree breeder, for the characters used to d i s t i n g u i s h the d i f f e r e n t provenances are important silviculturally.  To date there i s no major work which attempts  to c l a s s i f y natural forest types of P_^ contorta i n t h i s manner. Wood (1957) considered  contorta a polymorphic species,  d i f f e r e n t i a t e d into ecotypes which may form ecoclines ranging from the coast to the continental zone east of the Rocky Mount a i n s , and from 36 degrees north to 64 degrees north l a t i t u d e . C r i t c h f i e l d (1957) has carried out a major survey of v a r i a t i o n i n P^ contorta.  His approach was almost e n t i r e l y  taxonomic, for his conclusions were based on an analysis of several quantitative characters, i n samples of natural and c u l t i v a t e d populations of the species, such as leaf width, presence or absence of leaf r e s i n canals, cone angle and density. Macdonald (1958) i n a review of t h i s work was severely c r i t i c a l ; considering i t to be of l i t t l e value to the f o r e s t e r .  Insofar as  9 C r i t c h f i e l d s work was 1  an attempt at systematic  of the species t h i s c r i t i c i s m i s i n v a l i d .  classification  Nevertheless,  the  fact that i t could be made demonstrates the necessity of evolving a method of studying v a r i a t i o n i n forest trees i n which the genecologic rather than the purely taxonomic approach i s used. The forester must be interested not only i n those  charac-  t e r i s t i c s which are r e l a t i v e l y c e r t a i n clues to the i d e n t i t y of a species.  He must also amplify descriptive systematics  by a d d i t i o n a l data on the characters of forest trees which are important  economically, such as growth rates and  branching  habit and taper. C r i t c h f i e l d concluded  that J _ contorta exists i n several  regional forms, exhibiting geographic unit and h e r i t a b l e d i f ferences, and meriting recognition as four subspecies, which are l i s t e d below: 1.  Coastal region: P. contorta Douglas ex Loudon ssp. contorta  2.  Mendocino white p l a i n s : P. contorta ssp. bolanderi (Pari.) s t a t . nov.  3.  Rocky Mountains: P. contorta ssp. l a t i f o l i a (Engelm. ex Wats.) s t a t . nov.  4.  S i e r r a Nevada: P. contorta ssp. Murrayana (Balf.) s t a t . nov.  C r i t c h f i e l d stated that he found no v a r i a t i o n within the  10 Shore v a r i e t y of Lodgepole pine, which ranges from Southern C a l i f o r n i a to Alaska.  No single morphological  showed a clear-cut association with l a t i t u d e .  character studied This i s a sur-  p r i s i n g conclusion for such a wide-ranging form, and may due to his limited sampling.  be  For example between Baranof,  Alaska and Newport, Oregon, only three trees were sampled, two of which were i n the same area. mately 1,000  This i s a distance of approxi-  miles, and includes almost the t o t a l range of the  Coastal form of P^. contorta. From a s i l v i c u l t u r a l point of view i t would not be possible to assume homogeneity i n the Coastal form, for gradation i n growth rates, and other important exist (Macdonald 1954). apply:  characters, almost c e r t a i n l y  In t h i s instance Huxley s remarks may 1  "When gradation exists within a group, the mere confer-  r i n g of a subspecific name gives a f a l s e impression of the geographical homogeneity of the group." (Huxley, 1939.) Langlet (1957) stressed the importance of estimating the relationships between certain c h a r a c t e r i s t i c s (e.g., winter hardiness, growth rate, etc.) of a species and the factors to which adaptation has occurred and s t i l l occurs.  "The r i s k of  a seed transfer from a native stand to a s i t e with a d i f f e r e n t temperature must be judged i n r e l a t i o n to the v a r i a b i l i t y of the species.  Taxonomic subgroupings are then not only valueless,  but downright harmful, since they suggest a non-existent homogeneity within conventional units which are i n r e a l i t y mere  11 abstractions." The taxonomic c l a s s i f i c a t i o n  of forest trees without p r i o r  investigation of the broad pattern of v a r i a t i o n , and the relationship of that v a r i a t i o n to the l o c a l i t y and habitat i n which the tree grows, has led to considerable confusion, and to strong disagreement between d i f f e r e n t a u t h o r i t i e s .  For  example, Wright and Baldwin (1957) appear to have used previously described taxonomic v a r i e t i e s of Pinus s i l v e s t r i s as an a i d for grouping the species into geographic ecotypes.  But as Langlet  (1957) pointed out, "ecotype" i s not a taxonomic but a genecol o g i c term, and demonstrated conclusively that discontinuous v a r i a t i o n does not exist i n P_ s i l v e s t r i s , which - "A p r i o r i may  be expected to characterize any species with a large range  which shows evidence of inherited adaptation to the climate or other continuously varying natural conditions." Stebbins (1950) stated that the best example of c l i n a l v a r i a t i o n within plant species are those described by Langlet (1934, 1936)  i n Pinus s i l v e s t r i s .  Langlet measured percentage  dry matter content of the needles at beginning of dormancy i n 582 Swedish provenances of Scots pine, and, i n a smaller number of Swedish provenances, the chlorophyll content, length of mature leaves, hardiness, and r a p i d i t y of shoot development i n spring. He pointed out (1957) that dry matter content i s a very good measure of the plant's readiness for hibernation, and shows a remarkably close c o r r e l a t i o n with l a t i t u d e , the duration of the  12 period of vegetation, and the length of the f i r s t day of the year with a normal average 24-hour temperature of plus 6 degrees C. at the place of o r i g i n of the material examined. It w i l l be seen that Langlet's approach to the study of v a r i a t i o n i n P_j_ s i l v e s t r i s i s very d i f f e r e n t from that of Critchfield  (1957) i n his study of P. contorta.  Langlet's  study was designed to y i e l d as much information as possible which could be u t i l i z e d by the s i l v i c u l t u r i s t .  On the basis  of his r e s u l t s seed-collecting recommendations were drawn up for Scots pine.  These recommendations are i n common use i n  Sweden at the present time (Arnborg, 1960). F i e l d i n g (1953, 1960) studied v a r i a t i o n i n Monterey pine i n Australian plantations.  This study, l i k e Langlet's, was  designed to a s s i s t the s i l v i c u l t u r i s t and tree breeder, rather than the systematic botanist. important  V a r i a t i o n i n the following  c h a r a c t e r i s t i c s of the species was examined: 1.  Rate of growth  2.  Insect attack and disease  3.  Wood properties  4.  Form of the trunk  5.  Straightness and v e r t i c a l i t y of the trunk  6.  Crown c h a r a c t e r i s t i c s  7.  Flowering  8.  Cones and seed  9.  A b i l i t y to grow from cuttings  13 On the basis of the information thus obtained, F i e l d i n g was  able to draw up recommendations for the selection and  breeding of Pinus r a d i a t a . From a survey of the l i t e r a t u r e dealing with v a r i a t i o n i n P_ contorta i t must be concluded that there i s l i t t l e uniformity of opinion regarding the systematic of t h i s species.  classification  Despite C r i t c h f i e l d ' s suggested c l a s s i f i c a t i o n  the most recent publication dealing with the genus Pinus c l a s s i f i e d the i n t e r i o r form of Lodgepole pine as P_ Murrayana (Geussain, 1961), and Macdonald (1957) stated that the c l a s s i f i cation of recognisable features distinguishing important forest types of P_ contorta, both i n nature and i n plantations, has yet to be done. The l i t e r a t u r e also indicates that t h i s c l a s s i f i c a t i o n i s best achieved by a synthesis of s i l v i c u l t u r a l and taxonomic observation, amplified by c l i m a t i c and geographic data i n respect of the place of o r i g i n of the material studied.  GROWTH RATE Much information concerning the growth rate and habit of the Coastal form of Lodgepole pine i s now available from European plantations.  This information was not available to  e a r l i e r workers writing of t h i s form, and i s , perhaps, a further explanation for many of the contradictory opinions noted i n the l i t e r a t u r e . A systematic c l a s s i f i c a t i o n of a tree species should not be based only upon studies of v a r i a t i o n i n the f i e l d .  The  v a r i a b l e c h a r a c t e r i s t i c s measured i n natural populations should also be measured when a representative sample of the species i s grown under uniform conditions, such as i n provenances t r i a l s or plantations when the seed source i s known.  Only  then i s i t possible to separate out the e f f e c t s of environment, and to measure, with some accuracy, the extent of genetic variation. In 1934 an experiment to test the value of seven seed l o t s of Lodgepole pine of d i f f e r e n t origins was l a i d down at Clocaenog forest i n Great B r i t a i n .  The c o l l e c t i o n included  four l o t s from inland regions of B r i t i s h Columbia at medium elevations, one from Alaska and two l o t s from the coastal belt of the United States of America at elevations below 500 feet. The s i t e of the experiment i s exposed moorland at an elevation  15 of over 1,000 feet.  Edwards and Pinchin (1952) recorded that  the growth and appearance of the two coastal l o t s were very good and were, i n general, superior to the inland origins on this s i t e . Langlet (1934, 1938) carried out a small experiment i n Sweden involving three provenances:  Ocean Beach, Washington;  Summer Lake, Oregon; Klamath County, Oregon.  At the age of  f i v e years the mean height of the coastal provenance was greater than the inland provenances. The importance of the coastal provenances of Shore pine i n I r i s h s i l v i c u l t u r e was noted as early as 1928.  Even  at that r e l a t i v e l y early date i n the plantation h i s t o r y of t h i s country the Shore form had i n several situations i n a plantation i n County Wicklow reached a height of 60 to 70 feet (Forbes 1928).  Forbes stated that trees planted side-by-  side at Avondale c l e a r l y depict the c h a r a c t e r i s t i c s and r e l a t i v e growth of the Shore and Inland forms, the former being 50 per cent higher than the l a t t e r i n the course of 10 years. Mooney (1957), writing of Lodgepole pine i n Ireland, gave growth d e t a i l s concerning two 25-year-old plots of Inland and Shore forms growing on the same s i t e .  The Inland form, grown  from seed supplied by the Associated Foresters of Canada, i s 8 to 18 feet high on the higher, and 20 feet on lower, ground. Ground vegetation i s unchecked and woody Calluna i s waist-high. The Coastal form i s 16 feet from the Inland form described above.  16 This p l o t has a closed canopy which ranges from 25 to 30 feet, i n height.  Mooney stated that t h i s i s not an i s o l a t e d case, and  went on to say... "From what one can observe most South Coastal types of Pinus contorta give a s u f f i c i e n t l y high percentage of trees of good form and refined branch i n the stand to form a f i n a l crop, whilst at the same time giving f a r greater y i e l d s than the Inland type of Pinus contorta, and, of course, i t i s capable of suppressing the competing ground vegetation - p a r t i c u l a r l y Calluna - at an early stage." Mooney s conclusions concerning the South Coastal provenance 1  of Shore pine are supported by Macdonald (1954), who  said...  "Assessments of provenance c o l l e c t i o n s i n B r i t a i n indicate that as f a r as height growth i s concerned the coastal l o t s from Oregon and Washington are the t a l l e s t , and, at 14 years, even under wretched moorland conditions, have grown faster than q u a l i t y class 1 Scots pine could have grown on a completely suitable s i t e .  Although the evidence does not a l l appear on  these p a r t i c u l a r assessments i t i s almost certain that the height growth of coastal types increases from North to South." During the summer of 1961 the writer measured the height of a l l the trees i n the Lodgepole pine provenance t r i a l at Placerville.  The mean height for each of the provenances  measured, and the elevation of each seed source, are given i n Table I.  The elevation of the seed source was obtained from  C r i t c h f i e l d (1957).  The data were subjected to regression  17 analysis  to determine the c o r r e l a t i o n , i f any, between elevation  of seed source and the height of the progeny at P l a c e r v i l l e . A strong c o r r e l a t i o n was found to exist (Figures 1, 2). TABLE I MEAN HEIGHT OF TWENTY PROVENANCES OF SEVEN-YEAR-OLD PINUS CONTORTA GROWING AT PLACERVILLE  Site No.  Elevation of Seed Source i n Feet  Height of Progeny in Feet  Rocky Mountain and Intermountain Region 1 2 3 4 5 6 7  3,000 8,650 4,250 6,500 8,000 7,000 3,000  2.65 2.43 2.05 2.00 2.12 1.82 4.17  Cascade Mountain Region 8 9 10  4,700 8,250 5,550  2.26 1.70 2.50  Coastal Region 11 12 13 14 15 16 17  100 350 50 50 100 50 50  6.38 5.45 7.68 6.70 5.78 7.70 6.93  Mendocino Region 18 19 20  200 200 200  8.23 6.98 7.00  Fig-1 Regression of height on elevation for 18 different provenances of Pinus contorta growing at Placerville £  - 4 a>  0  1000  2000  3000  4000  5000  6000  7000  8000  9000  Elevation in Feet 2 Relationship of total height and elevation for 18 different provenances of Pinus contorta growing at Placerville  20 I t must be noted that the relationship between the height of these trees and the elevation of the seed source i s complicated by the fact that a l l the low elevation sources are of coastal o r i g i n .  Therefore, while a c o r r e l a t i o n between height  and elevation may e x i s t , the p r i n c i p a l conclusion i s that on t h i s p a r t i c u l a r s i t e at P l a c e r v i l l e the Shore pine i s much faster growing than any Inland provenance of the same age. The s i t e on which these trees are growing i s located between Sacramento and the summit of the S i e r r a Nevada at an elevation of 2,700 feet.  I t i s approximately 170 miles from  the P a c i f i c Coast, and has, during the growing season, a r e l a t i v e l y low r a i n f a l l .  Aspect i s south and southwest, and  the s o i l i s a deep, Aiken clay-loam (Liddicoet and Righter, 1960). This environment cannot be considered optimal for growth rate of the coastal provenances from B r i t i s h Columbia, Washington and Oregon.  For example, the Reedsport and Newport, Oregon seed  sources have an average summer temperature, and an average annual r a i n f a l l , of 57 and 54 degrees F., and 73 and 66 inches respectively.  The average summer r a i n f a l l i s 14 and 1? inches.  P l a c e r v i l l e has an average summer temperature of over 70 degrees F., and an annual r a i n f a l l of 34 inches, 86.5 per cent of which f a l l s between November and A p r i l . between July 1 and October 1.  Less than one-half inch f a l l s  Yet these coast provenances are  superior i n height growth to a l l inland forms, including those  21 seed sources r e l a t i v e l y close to P l a c e r v i l l e .  For example, the  V i c t o r i a , B r i t i s h Columbia; Umpqua, Washington, and the Newport, Oregon seed sources - respectively 800, 700, and 500 miles from P l a c e r v i l l e - are more than twice as t a l l as those samples from Lower Dinky Meadow, C a l i f o r n i a ; Huntington Lake, C a l i f o r n i a ; and Mineral, C a l i f o r n i a , respectively 220, 200 and 115 miles from P l a c e r v i l l e . This r a p i d growth rate of the Coast provenances cannot be explained i n terms of a "transfer e f f e c t " , for i n general pines show a decrease i n growth rate when transferred from a northern to a r e l a t i v e l y southern provenance (Arnborg, 1960). I t i s certain that i n the maritime climate of B r i t a i n and Ireland the Coast form maintains i t s superior growth rate over the I n t e r i o r form.  However, the same superior growth q u a l i t i e s  are maintained i n the Shore form, at least i n the juvenile stage, when i t i s grown i n an a l i e n environment.  I t i s suggested,  therefore, that the superior growth rate of the coast form i s genetically determined, and that within t h i s form the South Coastal provenances of Washington and Oregon are best adapted for growth i n the North Temperate  regions.  LEAF MORPHOLOGY Much of the l i t e r a t u r e dealing with the taxonomic c l a s s i f i cation of forest trees i s concerned with leaf morphology and anatomy, and many attempts have been made to delimit geographic ecotypes or clines within a species according to v a r i a t i o n i n leaf length, width, or thickness, and presence or absence of r e s i n canals.  Schotte (1905) found that northern sources of  Pinus s i l v e s t r i s . growing i n Sweden, had shorter needles than other areas.  This i s confirmed by Jaccard and Frey-Wyssling  (1935) and Langlet (1938).  Races of Pinus pinaster have been  distinguished by needle length, number of r e s i n canals per needle and f o l i a g e colour (Perry, 1940), (Rycroft and Wicht, 1948).  Schwarts (1934) stated that r e s i n canal number cannot  be used to d i s t i n g u i s h Scots pine, but that the number does increase with increase i n elevation.  D u f f i e l d (1951) found  that stomatal structure, and r e s i n canal number, w i l l d i s t i n g u i s h sources of Pinus  muricata.  Difference i n l e a f width was one of the p r i n c i p a l v a r i a b l e characters measured by C r i t c h f i e l d (1957) i n his systematic c l a s s i f i c a t i o n of Pinus contorta.  Because of the importance  of t h i s work i t w i l l be discussed separately and i n some d e t a i l . The conclusions of other workers with respect to v a r i a t i o n i n l e a f morphology of t h i s species were that the Coastal form i s  23 narrower than the Inland v a r i e t y , which includes the Rocky Mountains and the Sierra Nevada forms (Sargent, 1897), (Sudworth, 1908), (Laing, 1954); and also shorter (Lines, 1957), (Macdonald, 1954). C r i t c h f i e l d sampled a maximum of 12 trees i n each of 40 sites.  Approximately 60 per cent of the sampled areas are  confined to the Sierra Nevada region, and the coast of Oregon and C a l i f o r n i a .  Some samples were obtained from plantations  i n B r i t a i n and New Zealand, and others from the arboretum at Placerville.  Ten needles were collected from each tree, each  needle being obtained from a d i f f e r e n t branch.  The trees  sampled varied i n age from 6 to 600 years, and i n elevation from sea l e v e l to 10,000 feet.  The t i p and basal portions  of the needle were removed, and the mid-portion, between one-half and one inch long, was preserved. Width was determined by measuring the mid-section of the retained portion. Leaf length was also measured, but f o r a separate sample. Needle length was not considered a r e l i a b l e c h a r a c t e r i s t i c i n delimiting subtypes:  "Only a b r i e f survey of geographic v a r i a -  t i o n i n needle length i s included i n t h i s study because of the probable influence of non-genetic factors on the expression of t h i s c h a r a c t e r i s t i c ; i n p a r t i c u l a r because of the doubtful comparability of needles c o l l e c t e d i n d i f f e r e n t regions at d i f f e r e n t seasons."  ( C r i t c h f i e l d , 1957.)  On the basis of l e a f width C r i t c h f i e l d found i t impossible  24 to separate the coastal and inland populations:  "The range of  l e a f width i n the coastal region coincides rather c l o s e l y with the range of t h i s feature i n the Intermountain-Rocky Mountain region.  Further, none of the samples from this, part of the  inland region has a mean leaf width s i g n i f i c a n t l y greater than that of the wider-leaved coastal samples.  These facts emphasize  the absence of any v a l i d taxonomic d i s t i n c t i o n i n l e a f width between the inland region as a whole and the coastal region" ( C r i t c h f i e l d , 1957).  He concluded that the most important  regional difference i n l e a f width within Pinus contorta i s the difference between the Sierra-Cascade group and the remainder of the species. There i s no c l e a r l y defined pattern of v a r i a t i o n i n l e a f length observable from C r i t c h f i e l d ' s data.  Plantation samples  representing inland sources are longer than coast plantation samples, but the former are represented by 8 samples and the l a t t e r by 4, and many of the inland, high elevation samples from natural populations are shorter than the coastal samples. For the purpose of the present study of v a r i a t i o n i n l e a f morphology of Lodgepole pine needle samples were obtained from 84 trees representing 23 provenances growing on the same s i t e at P l a c e r v i l l e , C a l i f o r n i a .  1  The geographic location of 20 of  1 This provenance t r i a l was established from the seed samples c o l l e c t e d by Dr. C r i t c h f i e l d . The trees are even-aged.  25 the provenances i s given i n Table V. geographic region are represented:  Three major and one minor these are the Rocky Mountains,  the S i e r r a Nevada and the Mendocino White P l a i n s , and  the  Coastal region from B r i t i s h Columbia to Northern C a l i f o r n i a . The Mendocino White Plains i s the minor region, being only a few square miles i n area.  Ten, two-year-old needles were randomly  taken from the lower crown, on the south side of each tree. The width and length were determined for each needle, the former by ocular micrometer, and the l a t t e r by hand r u l e r scaled i n millimeters.  I t was  therefore possible to determine  whether a c o r r e l a t i o n between width and length of needle existed.  Needles from two trees representing each s i t e were  f i r s t measured (Lot 1).  A preliminary analysis showed that a  c o r r e l a t i o n between width and length existed i n the needle samples representing the Rocky Mountain region.  The measurements  were then repeated for two more trees representing the same s i t e s (Lot 2). processed  The complete data for each geographic region  separately by Alwac III-E computer.  was  The r e s u l t s of  t h i s analysis are given i n Figure 3, and i n Table I I . A c o r r e l a t i o n between width and length of needle was  found  for the three major geographic regions, but not for the Mendocino White Plains region. The curves for the Rocky Mountain and Coastal samples c l e a r l y i l l u s t r a t e the d i f f i c u l t y of separating the two populations by width alone; the mean width being almost i d e n t i c a l for  Mean  •£ 30+ c a> _J a>  "O CD  1-3  CONTORTA  Y = 37 83 + 0 30 X  LATIFOLIA  Y=-8-44+l43 X  MURRAYANA  Y= 18-20 + 0 58 X  1-4 I Needle Width in Mm  16  17  1-8  1-9  Placerville  Fig 3 Regression of length on width of Pinus contorto needles from 22 different provenances growing at  N> ON  TABLE I I STATISTICS OF REGRESSION ANALYSIS OF NEEDLE LENGTH (Y) ON WIDTH (X) FOR FOUR REGIONAL VARIETIES OF PINUS CONTORTA No. of Samples  SD  48.04  279  0.015  10.6  - 8.4  0.5713  8.74  1.64  43.34  142  0.014  7.6  18.2  0.2935  7.34  Contorta  1.36  48.85  301  0.016  7.5  37.8  0.1800**  7.41  Bolanderi  1.34  54.93  121  0.012  11.8  51.3  0.0248  Variety  X  Latifolia  1.39  Murrayana  Y  **  X  b  SD  r  SE  £  11.85  Highly s i g n i f i c a n t  A l l measurements are i n millimeters  to  28  both regions.  I t i s also clear that the nature of the r e l a t i o n -  ship of width and length i s d i f f e r e n t f o r the two populations. The Sierra Nevada samples are s u f f i c i e n t l y d i f f e r e n t i n width to be able to distinguish  t h i s population from the Rocky  Mountain and Coast forms by width alone. of the correlation precisely  Nevertheless, because  of width and length, the populations are more  distinguished by the use of the r a t i o .  Table I I I gives the means of needle length and width, and the r a t i o s f o r the four regions.  C r i t c h f i e l d ' s data for both  measurements for the same regions, excluding the Intermountain samples, are also given i n t h i s t a b l e .  The Intermountain  samples are excluded for the purpose of comparison, as only two sampled s i t e s of t h i s group are represented i n the Placerv i l l e material. I t w i l l be seen that there i s considerable uniformity i n the r a t i o s representing the three major regions, although  there  i s a d i s t i n c t difference i n length and width between each separate group of measurements.  For example, C r i t c h f i e l d has a  mean width for the Rocky Mountain group of 1.57 mm.  This i s  much higher than the mean of the P l a c e r v i l l e material for the same area, which i s 1.39 mm. for both Lots one and two. However, the length for the same geographic group, as given by C r i t c h f i e l d , i s 50.80 mm., which i s also greater than the P l a c e r v i l l e data, and thus the r a t i o of width to length for the two measurements i s the same.  The r a t i o s for the Mendocino White Plains group are quite d i f f e r e n t for each set of measurements.  This same population  showed no c o r r e l a t i o n between length and width of needles. However, i t i s not u n l i k e l y that such a r e l a t i o n s h i p does exist.  For example, when a l l three means for width and length  are taken into consideration (Table III) i t i s obvious that even for t h i s population the longest leaves are also the widest. TABLE I I I MEANS OF NEEDLE WIDTH AND LENGTH AND RATIOS FOR FOUR GEOGRAPHIC REGIONS OF PINUS CONTORTA Width m.m. Lot 1 Lot 2 Critchfield  Mendocino White Plains  Coastal Region  Rocky Mountains  Sierra Nevada  1.30 1.38 1.28  1.32 1.41 1.41  1.39 1.39 1.57  1.64 1.54 1.76  47.08 62.16 35.00  48.04 49.66 48.76  46.31 44.63 50.80  44.88 39.76 48.78  0.028 0.022 0.030  0.027 0.028 0.028  0.030 0.031 0.031  0.036 0.038 0.036  Length m.m. Lot 1 Lot 2 Critchfield Ratio Lot 1 Lot 2 Critchfield  Using the mean r a t i o calculated for each sampled s i t e an analysis of variance was c a r r i e d out to determine differences  30 between trees, s i t e s and regions. between trees was  found.  No s i g n i f i c a n t difference  Difference between s i t e s was  just  s i g n i f i c a n t , and between regions highly s i g n i f i c a n t (Table IV). When these data were subjected to the Duncan Multiple Range Test (Steel and T o r r i e , 1960)  i t was  found that the three major  regions d i f f e r e d s i g n i f i c a n t l y from each other, but there  was  no s i g n i f i c a n t difference between the Mendocino White Plains and Coastal forms.  The difference between s i t e s i s concentrated  p r i n c i p a l l y i n the Coastal and Mendocino forms (Figure 4)•  For  example, i n the former group the mean r a t i o for sample 14 (Bandon, Oregon) i s s i g n i f i c a n t l y d i f f e r e n t from sample 17 (Mouth of Noyo River, C a l i f o r n i a ) ; and i n the l a t t e r group the mean r a t i o f o r sample 18 (Fort Bragg, C a l i f o r n i a ) i s s i g n i f i c a n t l y d i f f e r e n t from sample 19 (one mile east of Mendocino White Plains). The f o l i a g e of the i n t e r i o r sources at P l a c e r v i l l e i s yellow green i n colour, while the coast i s dark green. l a r difference i n colour was  observed i n the coast and  A simiinterior  foliage samples c o l l e c t e d i n the f i e l d and obtained from the B r i t i s h Columbia and Alberta Forest Services. The establishment of a correlation between width and length does much to explain the very large discrepancies i n the estimations of both measurements for Lodgepole pine needles as given by d i f f e r e n t a u t h o r i t i e s . I t i s often stated that leaf length i s more prone to environmental influences than width, which i s  31 under stronger genetic control ( C r i t c h f i e l d , 1957).  There i s  l i t t l e doubt that l e a f length does vary considerably with changes i n environment.  Nevertheless, l e a f length, at least  i n Lodgepole pine, w i l l p o s i t i v e l y influence leaf width, and because of t h i s the r a t i o of the two measurements i s a much more r e l i a b l e comparative measurement.  I t i s l i k e l y that a  s i m i l a r relationship between width and length exists i n other pine species. The r e s u l t s lend support to C r i t c h f i e l d ' s view that the coastal form i s a separate subspecies, though, as already noted, C r i t c h f i e l d did not f i n d any s i g n i f i c a n t differences i n length or width of needles between the coast and i n t e r i o r forms.  However, the r e s u l t s do not support h i s conclusion  that the Mendocino White P l a i n s form i s a separate subspecies. This population was subdivided p r i n c i p a l l y because of the absence of r e s i n canals.  But some authors state that there are  no r e s i n canals i n the shore form (Keng and L i t t l e , 1961), and i t i s certain that they are absent i n the southern regions ( C r i t c h f i e l d , 1957).  F i n a l l y , r e s i n canals are present i n one  of the Mendocino White Plains l e a f samples measured for the present study. I t i s suggested that the Mendocino White Plains population i s merely the southern extremity of the d i s t r i b u t i o n of the Shore form of Lodgepole pine, for neither leaf morphology nor absence of r e s i n canals support the view that i t i s a separate  32 subspecies. TABLE IV ANALYSIS OF VARIANCE FOR DIFFERENCE IN LENGTH/WIDTH RATIO OF PINUS CONTORTA NEEDLES BETWEEN TREES, SITES AND REGIONS Source of Variation  DF  Region Within Region  F(table) 0.05 0.01  SS  MS  F  3  .001092  .000364  16.55  2.78  4.16  **  16  .000803  .000050  2.27  1.83  2.35  *  Trees  3  .000126  .000042  1.91  2.78  4.16  NS  Error  57  .001272  .000022  Total  79  .003293  ** s i g n i f i c a n t at 0.01 p r o b a b i l i t y  level  * s i g n i f i c a n t at 0.05 p r o b a b i l i t y  level  Remarks  Mean Ratios for Each Sample I  Significantly different from values at foot of arrow  Not significantly different from values at foot of arrow  Sample Number  •021  18  •023  17  024  20  024  13  •027  7  028  12  028  16  •028  2  •029  15  030  19  031  II  032  8  032  14  032  3  033  6  033  5  034  4  034  I  •039  10  040  9  Fig 4 Differences in ratio of needle width to length for 20 provenances of Pinus contorta sampled at Placerville  34 TABLE V GEOGRAPHIC ORIGINS OF TWENTY PROVENANCES OF PINUS CONTORTA SAMPLED AT PLACERVILLE Sample No.  Elevation i n Feet R  1 2 3 4 5 6 7  Rocky Mountain and Intermountain Region  6 miles NE of McLeod Lake, B r i t i s h Columbia Fraser, Colorado Exshaw, Alberta 2 miles North of Basin, Montana Georgetown, Colorado 3 miles NE of Gardiner, Montana Meacham, Blue Mountains, Oregon R  8 9 10  0  Cascade Mountain Region  M i l l Creek, Mineral, C a l i f o r n i a 3 miles East of Huntington Lake, C a l i f o r n i a Precise o r i g i n unknown R^  11 12 13 14 15 16 17  4,700 8,250  Coastal Region  15 miles West of V i c t o r i a , B r i t i s h Columbia Maltby, Washington Umpqua Lighthouse, Reedsport, Oregon Bandon, Oregon Newport, Oregon Crescent C i t y , C a l i f o r n i a Mouth of Noyo River, C a l i f o r n i a R^  18 19 20  3,000 8,000 4,250 6,500 8,800 7,000 3,000  100 350 50 50 100 50 50  Mendocino Region  2 miles East of Fort Bragg, C a l i f o r n i a 1 mile East of Mendocino, C a l i f o r n i a 1 mile East of Mendocino, C a l i f o r n i a  200 200 200  GROWTH HABIT The o r i g i n a l Shore pine was f i r s t described from coastal areas i n the southern part of the entire range of P^ contorta (Edwards, 1957), where i t i s scrub-like i n appearance.  Thus  at a very early date i t became known as Scrub pine (Sargent, 1897), and p r a c t i c a l l y a l l subsequent l i t e r a t u r e , even the most recent, follows the early description, which i s summed up by Tackle (1959), who stated that i t i s a "low scrubby tree of the P a c i f i c coast". The early description of Shore pine from the contorted scrub phenotypes of i t s southern extremity has been extended to the whole coastal form of the species. not  This has occurred,  merely because of r e i t e r a t i o n i n the l i t e r a t u r e of the  early account, but also because of the refuge status of Lodgepole pine west of the Coast Mountains.  I f the species i s  studied i n the f i e l d i t i s immediately clear that i t i s the most shade-intolerant tree of the major coast species.  Thus  i t i s relegated to s i t e s which cannot support any other competing  species, and i s found i n abundance on muskeg, rocky,  coastal outcrops ( I l l u s . 1, 2), and on poor, dry s i t e s where f i r e i s frequent.  The severity of the environment of these  areas greatly modifies i t s form, and i t s scrub-like appearance, though environmentally determined, i s then frequently considered  36 to be an inherent c h a r a c t e r i s t i c of the species. Occasionally the incidence of f i r e w i l l enable Shore pine to become established on Douglas fir-hemlock s i t e s . early growth, and precocious i n such areas.  I t s rapid  flowering give i t the advantage  On these better quality s i t e s Shore pine w i l l  grow r a p i d l y , and can reach a height of 70 feet i n a l i t t l e over 50 years ( I l l u s . 6).  In form i t w i l l compare favourably  with the I n t e r i o r v a r i e t y of the species. There are extensive stands of t h i s kind on the east coast of Vancouver Island, along the coast of Oregon and on the Kitsap Peninsula i n Washington ( I l l u s . 3, 4). This capacity for height growth on good s i t e s has been noted by some botanists who  have had the opportunity to study  the species both i n i t s natural habitat, and i n arboreta plantations.  and  Elwes and Henry (1910) stated that the coastal  form w i l l grow to 70 feet on good s i t e s , and Dallimore  and  Jackson (1923) described i t as "a tree varying greatly i n stature and habit according to s i t u a t i o n , from a stunted bush, or a small tree 10 - 30 feet high, with short, twisted branches, to a tree 70 - 200 feet high". As with a l l tree species, i n f e r i o r phenotypes, g e n e t i c a l l y determined, w i l l be found, both i n the Shore and Inland forms ( I l l u s . 5, 7, 8).  Though growing on r e l a t i v e l y good s i t e s they  produce heavy, f a s t i g i a t e branching and frequently a short bole. On i n f e r i o r , i s o l a t e d s i t e s , where the species has been established  37 for a long time, there may  be some s e l e c t i v e pressure for fitness  to exist under extreme environmental  conditions. Selection  which w i l l adapt the species for growth on bog could produce an ecotype unsuitable for commercial planting.  The Lulu Island  Lodgepole pine, which i s an ancient population (Hansen, 1947), appears to be such an ecotype.  In extensive planting i n England  and Ireland the s t r a i n has shown i t s e l f i n f e r i o r to other provenances of the Shore form. Unfortunately the Lulu Island stands, and similar stands at Long Beach, Washington, and near the v i l l a g e of Rainer, Washington, have long been the source of seed supplied to B r i t a i n and Ireland because of the a c c e s s i b i l i t y and abundance of cones.  However the progeny of such seed sources, though  they vary considerably i n desirable s i l v i c u l t u r a l characteri s t i c s , have not shown the scrub-like growth of Shore pine as described i n the literature. Studies by Heusser (1960) and Hansen (1947) of p o s t - g l a c i a l forest succession i n the P a c i f i c Northwest support the conclusion that Lodgepole pine i s the most shade-intolerant of the coniferous coast species, and c l a r i f y i t s present status i n the ecology of the P a c i f i c Slope forests. Lodgepole pine was  the predominant species over most of the  P a c i f i c Coast during early p o s t - g l a c i a l times.  I t s advance was  favoured by i t s a b i l i t y to p e r s i s t under conditions of physiographic i n s t a b i l i t y following g l a c i a t i o n .  However, following  38 land s t a b i l i t y , the proportion of pine greatly declined, and occupied only those locations "where s u r v i v a l was not endangered by competition for l i g h t by other conifers" (Heusser, 1960). During the l a t t e r part of the p o s t - g l a c i a l period there was a climatic change to wetness and coolness.  The species which  were competing with Lodgepole pine were unable to survive, and the pine, free of competition for l i g h t , again spread over vast areas. The climate i n h i s t o r i c times again favours species other than Lodgepole pine, and once again i t i s relegated to the forests' edge, to ocean c l i f f s , sand dunes, and muskeg.  There  i t s p o t e n t i a l growth habit and form are obscured by extremes of environment, and are observed only when grown i n plantations, or i n i t s n a t u r a l habitat when competing species are eliminated by f i r e .  1  Under the l a t t e r conditions the Shore v a r i e t y of  Lodgepole pine i s a r a p i d l y growing tree, with normal growth habit and form, and i s seldom contorted either i n bole or i n branch ( I l l u s . 9, 10).  1 Seed c o l l e c t e d from "dwarf" Lodgepole pine growing on the Mendocino White Plains i n C a l i f o r n i a , and planted with 22 other provenances at P l a c e r v i l l e , has produced the t a l l e s t trees i n the p l a n t a t i o n .  I l l u s . 2.  Pj. contorta. Whytecliff, near Vancouver, B. C  I l l u s . 2.  Pj. contorta. Whytecliff, near Vancouver, B. C.  Illus. 3.  P. contorta, Kitsap Peninsula, Washington  I l l u s . 4.  Pj, contorta. Kitsap Peninsula, Washington  I l l u s . 3.  P^ contorta. Kitsap Peninsula, Washington  I l l u s . 4.  Pj_ contorta. Kitsap Peninsula, Washington  41  I l l u s . 5.  I l l u s . 6.  P. contorta, 4 miles west of Olympia, Washington  P. contorta, 5 miles south of Olympia, Washington  41  I l l u s . 5.  JVj. contorta. 4 miles west of Olympia, Washington -  I l l u s . 6.  Pj. contorta, 5 miles south of Olympia, Washington  I l l u s . 8.  P_ contorta, east side of Lake Tahoe, Nevada  I l l u s . 8.  P. contorta. east side of Lake Tahoe, Nevada  I l l u s . 9.  P. contorta. Olympic Peninsula, Washington  I l l u s . 10.  P. contorta. Ladner, near  Vancouver, B r i t i s h Columbia  OJ  VARIATION IN BARK Bark Thickness There are extremely few studies concerning v a r i a t i o n i n bark within a forest tree species, and of these most are concerned with determining bark thickness i n r e l a t i o n to the volume of the tree.  To the writer's knowledge there i s no  major study which attempts to r e l a t e v a r i a t i o n i n bark thickness, texture and colour to ecotypic or c l i n a l v a r i a t i o n within the p r i n c i p a l coniferous species. In order to check the a p p l i c a b i l i t y of e x i s t i n g Lodgepole pine volume tables, Parker (1950) measured bark thickness of Lodgepole pine on four one-tenth-acre plots at Kananaskis Forest Experiment Station, Alberta.  This study showed that  bark thickness varies with age and s i t e quality, being thicker on poor s i t e s than on good ones, and on older trees than on young ones; though the r a t i o of thickness to the diameter of the tree decreases with increasing age. I r i s h volume tables for the Shore form of the Lodgepole pine express bark as a percentage of over-bark volume (Joyce, 1961).  I t i s clear from these tables that the r a t i o of bark  thickness to diameter of the Shore form also decreases with increasing age. Jentsch (1954) examined bark thickness i n f i v e i n t e r i o r  45 and one coastal source of Lodgepole pine growing i n Germany. Measurements, which were conducted on eighteen-year-old trees, f a i l e d to show any d i s t i n c t i o n i n thickness between the coastal and i n t e r i o r forms. Bark Texture and Colour Sudworth (1908) stated that Shore pine bark i s rough, furrowed and ridged, and purplish red brown i n colour; though older trees have smooth, fined scaled bark, pale brown with a greyish tinge, which i s also t y p i c a l of the Interior form. According to Harlow and Harrar (1958), the Shore form i s deeply furrowed and transversely fissured, and the bark of high elevat i o n trees consists of t h i n , loosely appressed scales, orangebrown to grey i n colour. In Ireland the Shore form of Lodgepole pine i s distinguished from the Interior form by bark texture.  The bark of coastal  trees i s rough and dark, and v e r t i c a l l y fissured; while the Inland form has smooth bark which i s pale grey i n c o l o u r .  1  However, Lines (1954), w r i t i n g of Lodgepole pine i n Ireland, stated that bark i s not a good diagnostic feature.  This i s also  the opinion of C r i t c h f i e l d (1957). In 1955 and 1957 an investigation was c a r r i e d out i n England to determine the general properties of the timber from  1 Communication  from the I r i s h Forest Service.  46 Lodgepole pine plantations.  The 1955  out on the Shore form and the 1957 the trees was  investigation was carried  on the Inland.  examined i n both years.  I t was  The bark of  recorded  that  there i s a d i s t i n c t difference i n both types (D.S.I.R. 1960). The nature of t h i s difference i s c l e a r l y i l l u s t r a t e d by photographs i n the progress reports r e l a t i n g to t h i s study.  The  Shore form i s deeply f i s s u r e d and dark i n colour, the I n t e r i o r form i s light-coloured and smooth i n texture. I t i s apparent from the l i t e r a t u r e that there i s considerable v a r i a t i o n i n thickness, texture and colour of Lodgepole pine bark.  There i s also considerable evidence to show that  v a r i a t i o n i n bark thickness i n this species, both i n the Shore and I n t e r i o r form, i s to a large extent influenced by such environmental factors as stand density and s i t e q u a l i t y , and also the age of the tree.  I t must be concluded that thickness i s  not a very r e l i a b l e variant for p r e c i s e l y delimiting i n t r a s p e c i f i c v a r i a t i o n . However, t h i s l a t t e r consideration does not apply to bark texture and colour, on the contrary, evidence from plantations i n England and Ireland suggests that major differences i n both these c h a r a c t e r i s t i c s of bark are associated with the p r i n c i p a l regional forms of Lodgepole pine. The present  study deals p r i m a r i l y with the texture  colour of the bark, and was  and  c a r r i e d out with the object of  determining to what extent the differences i n these bark charact e r i s t i c s i n plantations are p a r a l l e l e d by s i m i l a r differences  47 i n natural populations.  No measurement of thickness was made at  any of the s i t e s v i s i t e d . The study showed a d i s t i n c t difference i n bark texture and colour between the Inland and the Shore form of Lodgepole pine. Differences i n bark texture are given i n I l l u s t r a t i o n s 11 to 18, which are representative of each stand v i s i t e d .  I l l u s t r a t i o n 18  depicts the bark of a Lodgepole pine tree grown at P l a c e r v i l l e , C a l i f o r n i a from seed c o l l e c t e d on the coast.  The bark of the  Shore form i s fissured v e r t i c a l l y and h o r i z o n t a l l y , and i s dark i n colour.  The Inland form i s fine-scaled and l i g h t grey or  cinnamon i n colour.  No deeply fissured, black bark was observed  on any of the Inland trees, though on occasion f a i r l y t h i n , very l i g h t l y fissured bark was observed i n coastal areas, p a r t i c u l a r l y on young trees.  However, no o l d trees of the Shore form had  bark even remotely similar to that of the Inland form. There i s considerable v a r i a t i o n within each major geographic region, for example, the high elevation sources from northern Alberta are much l i g h t e r and smoother than the bark from lower elevations i n Alberta.  Nevertheless, t h i s v a r i a t i o n i s s l i g h t  compared to the obvious, and consistent, d i s t i n c t i o n between the Inland and the Shore form. The difference i n bark texture and colour, sometimes observed i n plantations, between the Inland and the Shore form of Lodgepole pine i s p a r a l l e l e d i n natural populations. I t i s suggested, therefore, that t h i s c h a r a c t e r i s t i c i s h e r i t a b l e  48 and can be legitimately taken into consideration intraspecific variation.  in classifying  Illus.  12.  P_j_ c o n t o r t a ,  4 miles  west  of  Olympia,  Washington  I l l u s . 12.  P. contorta, 4 miles west of Olympia, Washington  50  I l l u s . 13.  I l l u s . 14.  c o n t o r t a . 2 0 m i l e s east o f P l a c e r v i l l e ,  California  Pj, c o n t o r t a , 5 m i l e s south of Olympia, Washington  50  I l l u s . 14.  contorta, 5 miles south of Olympia, Washington  I l l u s . 15.  I l l u s . 16.  P_i_ contorta, e a s t side of Lake Tahoe, Nevada  contorta, 60 miles north of Vancouver, B. C  I l l u s . 16.  P. contorta, 60 miles north of Vancouver, B. C  I l l u s . 17.  P.  contorta, near P l a c e r v i l l e ,  California  I l l u s . 18. P_ contorta, P l a c e r v i l l e , C a l i f o r n i a Seed o r i g i n - Samoa, C a l i f o r n i a  I l l u s . 20.  P_j_ contorta. East Coast, Vancouver Island  53  SEED CHARACTERISTICS A microscopic study of i n t e r i o r and coastal Lodgepole pine seed, similar to that of A l l e n (1960) f o r Douglas f i r , showed that certain morphological c h a r a c t e r i s t i c s may be used to d i s tinguish the seed from each source.  These c h a r a c t e r i s t i c s  are i l l u s t r a t e d i n Figure 6. A preliminary investigation was made to determine the behaviour of seed incubated without s t r a t i f i c a t i o n .  I t was  found that the Coast form i s extremely sluggish i n rate of germination r e l a t i v e to the I n t e r i o r seed sources (Figure 5). Four sources, two Interior and two Coast, were then incubated following naked s t r a t i f i c a t i o n as devised by A l l e n and Bientjes (1954), f i f t y seeds of each l o t being incubated after two, four and s i x weeks' s t r a t i f i c a t i o n .  The results are given i n  Table VII. I t w i l l be seen that the longer the s t r a t i f i c a t i o n period the more rapid the germination rate of the Coastal seed l o t s . Nevertheless, whatever the period of s t r a t i f i c a t i o n , the Coastal l o t s are slower to germinate than the I n t e r i o r .  Increasing the  period of s t r a t i f i c a t i o n does not noticeably increase the germination rate of the I n t e r i o r l o t s .  After two weeks' s t r a t i -  f i c a t i o n the germination per cent i s almost as great i n three days' incubation as i t i s f o r the same l o t s s t r a t i f i e d s i x weeks.  55 In order to test the v a l i d i t y of the above r e s u l t s , nine seed l o t s , including four of coastal o r i g i n , were germinated following naked s t r a t i f i c a t i o n for two weeks. of v a r i a t i o n was observed (Table V I I I ) .  The same pattern  (Lot A i s taken  from a tree of I n t e r i o r o r i g i n growing i n the arboretum of the University of B r i t i s h Columbia.)  I t i s suggested, therefore,  that i n t e r i o r and coastal seed l o t s may be r a p i d l y distinguished by t h i s method, and that the optimum period of s t r a t i f i c a t i o n for such a test i s approximately two weeks. Following  the practice of Haasis and Thrupp (1931) the  germination percentage for a l l tests i s calculated as a percentage of the t o t a l number of seeds germinated. temperature was 25 degrees C. i n a l l cases.  The  incubation  Number of Days  Fig- 5 Differences in rate of germination at 2 5 ° C between coast and interior seed of Pinus contorta ON  INTERIOR FORM Pointed protuberance at funicular  COAST  FORM  Protuberance usually absent  end of seed Usually over 3 mm in length  Usually under 3 mm in length  Prominant ridge on upper surface  Ridge not usually prominant  Fig- 6 Method of distinguishing interior and coastal Pinus contorta seed-  58 TABLE VI GERMINATION RATE OF FOUR SOURCES OF PINUS CONTORTA SEED AT VARYING PERIODS OF STRATIFICATION  Period of Incubation - Days:  1  2  3  4  5  6  7  16 73  72 78  100 100  64 77  8 35 100 100  70 58 88 66  85 75 72 100  100 85 100  100  84 52  88 68  94 89  100 100  2 Weeks S t r a t i f i c a t i o n 1. 2. 3. 5.  Lulu Island Sechelt Rocky Mountain House Lot A  13  4 Weeks S t r a t i f i c a t i o ni 1. 2. 3. 4.  Lulu Island Sechelt Rocky Mountain House Lot A  32  28 16 64 63  6 Weeks S t r a t i f i c a t i o ni 1. 2. 3. 4.  Lulu Island Sechelt Rocky Mountain House Lot A  8 89 77  74 49 100 97  1, 2 are of coastal o r i g i n 3, 4 are of i n t e r i o r o r i g i n  100  59 TABLE VII GERMINATION RATE OF NINE SOURCES OF PINUS CONTORTA SEED FOLLOWING TWO WEEKS STRATIFICATION  1  Chemainus  2  Lulu Island  Days 4 5  Elevation i n Feet 1  Seed Lot  100  20  80  100 100  25  8  16  70  100  34  70  100  14  79  100 100  3  Sechelt  4  Mount Finlayson  1,000  5  Edson  3,150  30  94  97  6  Kananaskis  4,900  16  86  100  7  Rocky Mountain House  3,245  62  100  8  Lot A  13  91  100  9  Grande P r a i r i e  32  100  2,000  1, 2, 3, 4 are of coastal o r i g i n 5, 6, 7, 8, 9 are of i n t e r i o r o r i g i n  60  SUMMARY OF CHARACTERISTICS DISTINGUISHING THE COAST FORM OF PINUS CONTORTA Growth Rate and Habit Normal t r e e - l i k e growth habit on f a i r to good s i t e s , reaching 70 to 80 feet i n 50 years. Foliage C h a r a c t e r i s t i c s Dark green i n colour.  Ratio of needle width to length  usually less than .03. Seed C h a r a c t e r i s t i c s Usually l e s s than 3 mm. i n length.  Distinguished from  i n t e r i o r seed by absence of pointed protuberance at funicular end, and i n d e f i n i t e ridge on upper surface.  Germination rate  for s t r a t i f i e d or u n s t r a t i f i e d seed d i s t i n c t l y slower than i n t e r i o r seed. Bark Type Dark i n colour and f i s s u r e d both v e r t i c a l l y and horizontally. Tolerance Extremely shade i n t o l e r a n t .  PART I I THE GENETIC IMPROVEMENT OF THE SHORE FORM OF PINUS CONTORTA INTRODUCTION Research i n forest tree breeding i s now proceeding at an increasing rate i n many centers i n Canada and the United States.  However, a r e l a t i v e l y small proportion of t h i s research  i s applied to the actual commercial production of improved forest tree seed, and i n no part of North America, except, perhaps, i n the Southern United States, has t h i s aspect of forest tree breeding reached the proportions i t has i n Sweden and Great B r i t a i n .  In f a c t , remarkably l i t t l e attention i s  given i n the main centers of research to the study of the techniques involved i n producing and marketing improved v a r i e t i e s of forest tree seed. Forest tree breeding i s e s s e n t i a l l y applied research, and i t s p r i n c i p a l purpose i s the economic and rggular product i o n of large quantities of seed superior i n q u a l i t y to that c o l l e c t e d casually i n the f o r e s t , which i s often d e f i c i e n t both i n quality and i n quantity.  The resources  of B r i t i s h and  Swedish tree breeders are directed p r i m a r i l y to t h i s objective, with the r e s u l t that i n a r e l a t i v e l y short period a l l the seed  62 required f o r the planting program of some of the main species w i l l be obtained from seed orchards.  B r i t a i n i s producing  large quantities of hybrid l a r c h (Larix eurolepis) i n t h i s way,  and by 1963 w i l l also have established the seed orchards  required to produce i t s t o t a l annual needs of Scots pine (Pinus s i l v e s t r i s ) seed, which i s 2,000 pounds annually.  Plans are  now being drawn up to produce similar quantities of Lodgepole pine seed.  Sweden has already established 350 hectares of  seed orchards, which i s h a l f i t s t o t a l requirements f o r the whole country (Arnborg, 1960). I t i s true that those countries have large planting programs.  I t i s equally probable that within the next few years  there w i l l be a very rapid increase i n planting i n North America.  I f planting i s to be the p r i n c i p a l method of regene-  r a t i o n then i t i s simply a further r a t i o n a l i z a t i o n of the regeneration program to supply the seed from seed orchards. There are a number of reasons which explain why many North American tree breeders are reluctant to adopt f u l l y what has now become known as the Scandinavian method of tree improvement, but the most important may be stated as follows:  first,  i t i s considered too expensive, and secondly, i t i s pointed out that trees selected and registered as plus trees i n t h i s manner, and propagated i n seed orchards, w i l l r e t a i n the status of plus trees permanently even though at a l a t e r date progeny w i l l have proved them otherwise.  trials  Workers w i l l be reluctant to  r e j e c t them because of the very heavy expense incurred i n the i n i t i a l selection and propagation i n seed orchards.  Finally,  there i s a t h e o r e t i c a l objection to the Scandinavian method of i n d i v i d u a l tree s e l e c t i o n .  I t i s stated that the amount of  genetic gain obtained by i n d i v i d u a l tree selection i s not worth the cost incurred.  For example, J . W. Wright estimated that i f  h e r i t a b i l i t y of a character such as height/increment i s 25 per cent, then the selection d i f f e r e n t i a l would have to be one i n ten thousand to obtain an increase of 2.2 1 at 25 years.  feet i n height growth  I t i s argued from examples such as t h i s that the  cost of inspecting 10,000 trees to obtain one tree with such a small increase i n growth p o t e n t i a l i s much greater than the value of the genetic gain. This argument i s based on an equation drawn from the work of animal breeders, which may  be stated as follows:  Estimated genetic gain = H e r i t a b i l i t y x Selection D i f f e r e n t i a l H e r i t a b i l i t v «= * d i t i v e Genetic Variance Total Phenotypic Variance A<  y  Selection D i f f e r e n t i a l = X selected - X unselected  trees,  where X i s the mean of a single character measurement of the selected and unselected trees. I t w i l l be seen that i f the h e r i t a b i l i t y of a p a r t i c u l a r character i s high there i s less need for a high selection d i f f e r e n t i a l i n order to obtain genetic gain. 1 Unpublished material, L i b r a r y , Faculty of Forestry, U. B.  C.  In Australian C a p i t a l T e r r i t o r y , the techniques applied to obtain superior Pinus radiata are similar to those applied to Pinus s i l v e s t r i s and Picea excelsa i n Sweden, and i t i s considered that a ten per cent increase i n monetary returns i n a r o t a t i o n i s a very conservative estimate.  This increased  expectation value allows an a d d i t i o n a l 21 Australian pounds per 1,000  plants to be spent to produce superior stock without  any loss being sustained.  The present cost of producing  planting stock i n A u s t r a l i a n C a p i t a l T e r r i t o r y i s 2 pounds per 1,000 pounds per 1,000  plants.  Thus any expenditure  approximately less than 23  plants (or 11 times the amount now  spent) i n  producing such superior stock, would r e s u l t i n a f i n a n c i a l gain ( F i e l d i n g , 1957).  Perry and Wang (1958) showed that a  genetic improvement of as l i t t l e as one per cent more than j u s t i f i e s the extra costs of programs of seed orchard e s t a b l i s h ment, or of harvesting seed from seed-producing areas, besides preventing severe losses due to the use of seed of improper geographic o r i g i n , or i n f e r i o r genetic q u a l i t y . D u f f i e l d (1962) estimated that an expected genetic gain of one-half of one per cent i n Douglas f i r w i l l j u s t i f y a 47 per cent increase i n seed investment. In the late t h i r t i e s the natural rubber industry of Malaya r e a l i z e d that i t s p o s i t i o n was  about to be seriously  menaced by the development of synthetic rubber. the industry decided that, i f the industry was  The leaders of to survive,  production per acre must be greatly increased, and cost per pound of latex greatly reduced.  An intensive drive aimed at  the development of high y i e l d i n g trees was  launched.  r e s u l t s of that e f f o r t are shown i n Figure 7. acre was  The  Production per  increased by no less than 260 per cent (Swan, 1955).  I t must be concluded that the weight of the evidence j u s t i f i e s a program of forest tree improvement, and that genetic gains can be achieved by the f u l l u t i l i z a t i o n of the knowledge already obtained by workers i n t h i s f i e l d . In drawing up the proposed program for the breeding of Shore pine, the t h e o r e t i c a l objections to the Scandinavian method of tree breeding, as stated, have been taken into account.  Nevertheless, the program does incorporate certain  aspects of the Scandinavian method insofar as i t i s designed to mass produce seed which i s not i n f e r i o r i n certain important c h a r a c t e r i s t i c s while simultaneously working for a g e n e t i c a l l y improved v a r i e t y .  ol  I 5  10  I  I  I  I  I  I  1  I  15  20  25  30  35  40  45  50  Years after Year of Planting Out  7  after Swan, 1955  increase in latex yields per acre by selection and breeding of superior stock  POLLINATION IN RELATION TO BREEDING Natural Method of P o l l i n a t i o n In Pinus, ovulate s t r o b i l i develop during a period of three to four weeks from a t i n y bud to a conelet ready for pollination.  Both the I n s t i t u t e of Forest Genetics at Placer-  v i l l e , and the North Idaho Forest Genetics Center f i n d i t usef u l to c l a s s i f y the various stages of female flower development as follows:  (1) buds small, (2) buds large, (3) buds opening,  (4) flowers p a r t l y open, (5) flowers maximum, (6) closed, and (7) cones enlarging.  flowers  Stages 1, 2, and 3 are deter-  mined by the s i z e or condition of the bud.  Stages 4, 5,  6,  and 7 are determined by the p o s i t i o n of the cone scales r e l a t i v e to the axis of the conelet. receptivity.  Stage 5 i s the optimum period of  In Stage 6 the cone scales are t i g h t l y closed  so that p o l l i n a t i o n i s no longer possible (Cumming and  Righter,  1948). There i s considerable v a r i a t i o n i n the time of shedding of pollen.  Trees at higher elevations and l a t i t u d e s w i l l normally  shed pollen l a t e r than those of lower elevations and l a t i t u d e s . There i s also genetic as w e l l as annual v a r i a t i o n i n t h i s characteristic.  Thus i t i s always necessary to determine for s p e c i f i c  areas the average period of pollen-shedding, of optimum r e c e p t i v i t y of female s t r o b i l i .  besides the period  68 D u f f i e l d (1947, 1953) showed that at l a t i t u d e 39 degrees N., longitude 120 degrees W., the mean date over a three-year period for the Inland form of Pinus contorta i s June 22, for the Coast form at Point Arena, C a l i f o r n i a , June 9. In common with a l l the pines, Lodgepole i s an anemophilous species.  Wind carries the pollen to the upright female s t r o b i l u s .  The pollen grain r i s e s through the droplet i n the micropylar o r i f i c e and contacts the nucellus with the p r o t h a l l i a l c e l l side of the grain away from, and the pollen tube side towards, the nucellus (Doyle and O'Leary, 1935).  F e r t i l i z a t i o n , however,  does not occur immediately, f o r the pollen tube ceases growth and l i e s quiescent over summer and winter.  The following year  the pollen tube again starts to grow and the egg i s f e r t i l i z e d during early summer (Stanley, 1958).  Thus i t takes three  seasons from the i n i t i a t i o n of the f l o r a l primordia to seed maturation. The Coast form w i l l normally shed i t s seed at maturation, but the Inland v a r i e t y tends to produce serotinous cones, and the seed i s often retained u n t i l a r t i f i c i a l heat i s applied (Crossley, 1956).  Seed from the Inland form i s mature i n  August and September, that of the Coast i n September and October (Publication No. 654, U. S. D. A.).  69 The E f f e c t of Inbreeding There i s some evidence that several species of pines are self-compatible, and that s e l f i n g i s accompanied by reduced f e r t i l i t y and loss of vigour i n the progeny.  Bingham and  Squillace (1955) showed that s e l f - p o l l i n a t i o n i n Pinus monticola resulted i n a 50 per cent reduction i n seed y i e l d s , though cone y i e l d s were almost i d e n t i c a l with the cross-pollinated control. Seed germination and seedling height for the f i r s t three years were also below that of the cross-pollinated seed.  Mergen  (1954) found a reduction i n height growth i n s e l f - p o l l i n a t e d Pinus e l l i o t t i i . ing  Johnson (1945) recorded the r e s u l t s of s e l f -  i n Pinus strobus, Pinus s i l v e s t r i s and Pinus resinosa.  In P_j_ strobus eleven out of f o r t y - s i x seedlings of selfed o r i g i n showed pronounced chlorophyll deficiency.  Pinus strobus  and  Pinus s i l v e s t r i s were at four years of age s i g n i f i c a n t l y smaller than comparable seedlings derived from open and i n t r a s p e c i f i c cross-pollination.  S e l f i n g had also an unfavourable e f f e c t on  seed set and seedling emergence i n P^ s i l v e s t r i s . and on seed set  i n Pi. resinosa.  Similar r e s u l t s have been obtained when  other coniferous species have been selfed (Orr Ewing, 1954), and i n general i t can be concluded that the s e l f i n g of Lodgepole pine w i l l r e s u l t i n a loss of vigour, and a deterioration i n other c h a r a c t e r i s t i c s i n the progeny.  A f u l l account, therefore,  must be taken of t h i s phenomenon i n the breeding of the species.  70 Most a g r i c u l t u r a l plants are annuals, and many are d i f f i c u l t to reproduce vegetatively.  Therefore, i n order to produce a  desirable hybrid type i t i s necessary to develop pure l i n e s by selfing.  These pure l i n e s can be maintained i n d e f i n i t e l y and  crossed each year to produce the hybrid.  Trees on the other  hand are perennial and there i s no need to develop a pure l i n e i n order to maintain a p a r t i c u l a r genotype as i s necessary i n the case of an annual.  Furthermore, the most important coni-  ferous species can be maintained i n d e f i n i t e l y by g r a f t i n g or from cuttings.  Thus, i f the progeny of a cross between two  trees has proved desirable that same cross can be repeated i n d e f i n i t e l y , and one of the major reasons f o r s e l f i n g i n an a g r i c u l t u r a l crop does not apply i n r e l a t i o n to forest trees. I t i s sometimes suggested that several desirable characters may be incorporated i n a single s t r a i n by crossing a number of pure l i n e s , each homozygous f o r a p a r t i c u l a r character. There are three major objections to t h i s p r a c t i c e . would take a considerable length of time to achieve i n the highly heterozygous pine tree.  First, i t homozygosity  Secondly, outcrossing the  inbred l i n e s , which w i l l be greatly reduced i n vigour, i s l i k e l y to restore the vigour of the parental types only; heterosis cannot be expected.  Very few of the thousands of inbred l i n e s  of a g r i c u l t u r a l crops, when outcrossed, show heterosis i n a measure that makes them valuable commercially ( A l l a r d , 1960). T h i r d l y , i n theory any v a r i a t i o n that i s obtained by inbreeding  and outcrossing can be obtained by crossing alone. It i s concluded that the inbreeding of Lodgepole pine can have no d i r e c t a p p l i c a t i o n i n the production of seed, or in the genetic improvement of the species.  S e l f i n g , however,  can be a u s e f u l technique for evaluating the inherent q u a l i t i e s of the species (Orr Ewing, 1954).  I t w i l l also be necessary to  e s t a b l i s h the degree and effects of s e l f - c o m p a t i b i l i t y i n Lodgepole pine, and therefore a small experiment must be set up for t h i s purpose. Controlled P o l l i n a t i o n Techniques The method of c o n t r o l l e d p o l l i n a t i o n i n Pinus was f i r s t developed at the I n s t i t u t e of Forest Genetics i n P l a c e r v i l l e , C a l i f o r n i a , and gradually improved over a period of forty years. for  This method, which has proved i t s e l f s a t i s f a c t o r y  controlled p o l l i n a t i o n of Lodgepole pine, was studied by  the w r i t e r during the summer of 1961. I t i s proposed that t h i s method, modified to include some recent technical developments, be used i n the breeding program. The I s o l a t i o n of Female Flowers It i s necessary to i s o l a t e ovulate flowers before pollen flow.  This i s accomplished by covering them during the "buds  small" stage with sausage casing, which i s impervious to moisture. A s t r i p of cotton i s f i r s t wrapped around the branch at the  72 point of attachment of the bag. material may  Strong twine or other suitable  be used to t i e the bag to the branch.  The number of buds enclosed i n each bag i s recorded  so  that t t i s possible to ascertain whether a reasonable surplus of buds over the desired number has been bagged. The C o l l e c t i n g of Pollen As soon as the tree begins to shed i t s p o l l e n , unopened male flowers are picked and brought indoors.  I f aceto-carmine  smears show that pollen grains have completed second d i v i s i o n in the development of the gametophyte, the male flowers  will  ripen a f t e r picking, whereas flowers c o l l e c t e d p r i o r that stage may not ripen. A simple and e f f e c t i v e way  of extracting large amounts of  pollen i s to place the flowers i n f l a t trays i n a greenhouse. This i s the method used at the North Idaho Forest Research Center.  Genetics  However, some contamination i s l i a b l e to occur  using t h i s method, and the use of a pollen extractor i s advisable. This consists of a pollen-proof bag f i t t i n g t i g h t l y over a funnel that empties through a rubber tube into a glass receptacle. The extractor i s hung i n a warm room and shaken vigorously before drawing o f f the p o l l e n .  The pollen should be processed  before use i n the manner devised by Worsley (1958).  73 Controlled P o l l i n a t i o n A hypodermic syringe i s used for placing the p o l l e n inside the bag which covers the female flowers. i s then covered with gummed paper.  The hole thus made  When the ovulate flowers  reach stage seven (conelets enlarged), the p o l l i n a t i o n bags are removed. Hand-pollinated pine conelets of the previous season are protected from attack by insects by enclosing the cones i n cloth bags.  NATURAL AND  INDUCED MUTATIONS AND  THE BREEDING OF PINE In 1936 Nilsson-Ehle discovered a t r i p l o i d aspen i n Sweden which grew more r a p i d l y than the d i p l o i d aspens.  This finding  generated great interest i n the potentials of breeding polyploid trees.  E f f o r t s to induce polyploidy by physical means such as  x-ray, heat, or u l t r a - s o n i c treatment are only moderately promising i n trees, and require expensive equipment.  However,  i t has been found that colchicine e f f e c t i v e l y doubles the chromosomes and i s not c o s t l y .  This accounts f o r the widespread  acceptance of colchicine by forest tree breeders.  Mergen (1959)  and Hyun (1954) have both induced polyploids i n the genus Pinus by means of c o l c h i c i n e .  Mergen concluded from h i s study that  the best results w i l l be obtained i f the germinating seed or seedling can be kept under conditions of optimum growth during the treatment.  With pines at l e a s t , colchicine should be pre-  vented from touching the r a d i c l e or root during the treatment period.  With colchicine i t i s very easy to obtain polyploidy  i n d i v i d i n g c e l l s , but the problem i s to devise a s a t i s f a c t o r y method of i s o l a t i n g and perpetuating the polyploid t i s s u e . The doubling of the chromosomes, either during meiosis or during mitotic d i v i s i o n of the gametophyte, has some p o t e n t i a l . This method w i l l shorten the waiting period needed to obtain  75 reproductive structures with doubled chromosome numbers, and allow the production of both t r i p l o i d and t e t r a p l o i d plants with stable chromosome complements (Mergen, 1959). Hyun induced polyploidy i n several pine species (P. ponderosa, P^ j e f f r e y i , X P^ attenuradiata) with 0.2 per cent and  0.4  per cent c o l c h i c i n e , and produced tetraploids and mixoploids with 2n, 3n, and 4n tissues i n various combinations. individuals showed very poor growth.  However, these  At six years they were only  two feet high, and s i c k l y i n appearance, whereas the controls of the same age were nearly twenty feet t a l l . Mehra (1960) pointed out that natural polyploids are exceedingly rare i n conifers.  The only cases so f a r known are  the C a l i f o r n i a Coast redwood (Sequoia sempervirens), which i s a hexaploid; Juniperus chinesis, a t e t r a p l o i d ; and Juniperus synamata, also a t e t r a p l o i d .  He also pointed out that the  occurrence of polyploid races within a species i s unknown, but that there are records of stray polyploid individuals i n some species.  For example, a single tree of European larch (Larix  decidua) of t e t r a p l o i d constitution, has been found i n Denmark; a t e t r a p l o i d Norway spruce (Picea abies) i n Sweden, and a t r i p l o i d Juniperus v i r g i n i a n a i n the U. S. A. Richens (1945) and Gustafsson (1960) gave f a i r l y complete accounts of most of the mutants, induced and natural, i n the p r i n c i p a l forest trees. A survey of the work dealing with a r t i f i c i a l l y induced  76 mutations i n Pinus shows that the mutations are always deleterious.  I t i s suggested, therefore, that at the present stage i n  the development of forest genetics i t would appear to be much more p r o f i t a b l e to concentrate on selection and breeding of desirable commercial types of Lodgepole pine from the abundant v a r i a t i o n found i n natural forests and i n plantations, rather than from random mutants, a r t i f i c i a l l y induced.  Mutation  breeding must remain a minor adjunct to the above method, and w i l l continue i n t h i s position u n t i l two important questions are answered: 1.  Do a r t i f i c i a l l y induced mutations d i f f e r i n any way  from natural mutations, or do mutagenic agents merely reproduce the same spectrum of v a r i a b i l i t y that occurs naturally? 2.  Do mutations with phenotypically constructive expres-  sions occur often enough to make the search f o r them p r o f i t a b l e , and t h e i r incorporation into commercially acceptable v a r i e t i e s competitive with other methods of breeding ( A l l a r d , I960)?  CYTOGENETICS AND Buchholz  THE BREEDING OF PINE  (1945) investigated the embryological aspects of  hybrid vigor i n the embryos of the hybrid Pinus murraybanksiana. He stated that about two weeks longer was required for the embryos of the wind-pollinated control to reach the same midstages of development than f o r the embryos of the hybrid.  He  concluded that the set of observations indicated d e f i n i t e l y that the embryos of the hybrids actually grow much more rapidly (though they do not reach.a greater size than the control), and that the embryo enjoys a higher growth rate before the seed i s mature as well as after planting. The seed of the pine i s f u l l grown and has reached i t s ultimate size at the time of f e r t i l i z a t i o n .  This applies  without known exception to the pine family, and to nearly a l l conifers.  The seed coat becomes stony near the time of f e r t i l i -  zation, and there can be no enlarging effect on the seed size due to the a c t i v i t i e s of the contained embryo, whether i t be hybrid or otherwise.  If fertilization fails,  the seed coat  remains f u l l y as large as when f e r t i l i z a t i o n has taken place. An abortive seed may be f u l l grown, an empty s h e l l complete with wing, but with the contents shriveled.  Therefore i t i s  not possible to d i s t i n g u i s h hybrid seed by a morphological study, for the p r i n c i p a l differences are physiological and biochemical  78 (Buchholz, 1945). The pines are included i n the family Pinaceae.  A l l genera  within t h i s family, with two exceptions, show the haploid chromosome number of n - 12.  The exceptions are Pseudolarix. which  has n = 22, and Pseudotsuga., which has n = 13 (Mehra, 1960). There are a number of major c l a s s i f i c a t i o n s of the pines; the best known being Shaw (1914) and P i l g e r (1926).  However,  from the point of view of tree breeding the most important i s that proposed by D u f f i e l d (1952).  The former c l a s s i f i c a t i o n s  are based primarily on morphological, anatomical and biochemical differences, the l a t t e r gives equal value to the c r o s s a b i l i t y of the species.  Therefore much wasted e f f o r t , i n attempting to  cross uncrossible species, w i l l be saved by following Duffield's c l a s s i f i c a t i o n rather than the older and better known systems of P i l g e r and Shaw.  SOURCES OF HEREDITARY VARIATION Selection of Naturally Occurring Trees with Desirable  Character-  istics Characteristics of a raw material which are desirable for one p a r t i c u l a r use may i n another.  considered  not be considered  desirable  Branchiness, with i t s accompanying knots, i s an  undesirable c h a r a c t e r i s t i c i n veneer manufacture, but, nevertheless, i s of l i t t l e importance to the pulp and paper manufacturer, who  i s more interested i n f i b e r length and wood density.  The complete r a t i o n a l i z a t i o n of s i l v i c u l t u r e would e n t a i l the production of diverse types of forest trees each i n i t s way suited to a p a r t i c u l a r industry. s i t i o n at the present  best  This i s not a p r a c t i c a l propo-  time, nor i s i t r e a l l y desirable, for the  processing industries can be r e l i e d upon to develop techniques of u t i l i z i n g the raw material that i s a v a i l a b l e .  For example,  the pulp and paper industry of the Eastern United States i s now u t i l i z i n g the large hardwood forests of that area.  It is  usually much easier to develop techniques for the manufacture of a raw material than to attempt to change the nature of the raw material i n order to accommodate a p a r t i c u l a r manufacturing process. For the reasons stated above, and because of the d i f f i c u l t i e s involved i n selecting for a large number of c h a r a c t e r i s t i c s , i t  80 i s proposed that a r t i f i c i a l selection i n Lodgepole pine be confined to six basic c h a r a c t e r i s t i c s which are always desirable i r r e s p e c t i v e of the f i n a l use to which the wood i s put.  These  six c h a r a c t e r i s t i c s are as follows: 1.  Resistance  to disease  2.  Good seed production  3.  Rapid growth rate  4.  Wood of high s p e c i f i c gravity  5.  Straightness of stem  6.  Light branching habit  It i s obvious that c h a r a c t e r i s t i c s one and two are not only desirable, but e s s e n t i a l . There i s l i t t l e value i n selecting  for three, four, f i v e and six i f the species cannot be  propagated cheaply, and i n abundance. H e r i t a b i l i t y i n the narrow sense for a l l these characteri s t i c s except number six i s good (Zobel, 1960).  There are few  r e l i a b l e studies with respect to branching habit, though F i e l d i n g (1953) reported that clones i n general resemble t h e i r parent trees i n important c h a r a c t e r i s t i c s such as the number of whorls of branches produced annually, branching defects, the angle of branching and the r e l a t i v e s i z e of the branches. One of the most common diseases a f f e c t i n g the Shore form of Lodgepole pine i s Western G a l l Rust (Cronartium harknessii). The most noticeable r e s u l t of rust i n f e c t i o n i s the stimulation of the host to abnormal tissue development r e s u l t i n g i n malformed  81 organs, or parts of the host, such as g a l l s , swollen stems, stunting and l e a f casting.  I t i s found i n stands lacking  vigor due to poor growth on low q u a l i t y s i t e s .  For example,  in the stands growing on muskeg on Lulu Island almost every tree i s severely infected.  Where growth i s more vigorous, as i n  Ladner and the east coast of Vancouver Island, the disease i s much less prevalent.  Nordin (1954) suggested that healthy  trees  of the Inland form are l i k e l y to be less prone to t h i s disease. There i s l i t t l e doubt that selected, vigorous  stock, growing on  good s i t e s , w i l l be l i t t l e affected by t h i s disease.  The Euro-  pean plantations of Lodgepole pine appear to be completely free of Western G a l l Rust. Lodgepole pine i s an extremely early seed producer. I t i s not uncommon to f i n d ten to twenty cones on a tree f i v e years old,  and though there i s considerable v a r i a t i o n i n cone bearing  a b i l i t y , i n general the species i s a consistent, as w e l l as a precocious, seed producer (Tackle, 1959).  A study of flowering  i n the Lodgepole pine provenance t r i a l stands at P l a c e r v i l l e suggests that p a r t i a l dioeciousness  exists i n some trees.  Therefore, before s e l e c t i n g trees f o r further propagation, both flowering habit as w e l l as f e r t i l i t y must f i r s t be determined. Height growth and straightness of bole are strongly heritable i n the narrow sense i n forest trees (Zobel, 1960).  1 Personal  communication.  Both of these  82 c h a r a c t e r i s t i c s are r e l a t i v e l y easy to recognise, and trees of superior growth and form can be rapidly selected, both on the Coast and i n the I n t e r i o r .  I t has been shown that Shore pine i s  not a scrub tree, nor does i t normally possess a contorted bole. Nevertheless, trees of i n f e r i o r quality, genetically  determined,  do e x i s t .  Such trees are multinodal, and have heavy, f a s t i g i a t e  branches.  They are often very good seed producers.  Such trees,  which at present provide the bulk of the Lodgepole pine seed being sent to Europe, should be avoided i n the selection program. Shore pine stands of excellent form are common on the East coast of Vancouver Island, the coast of Oregon and i n many areas i n Washington, including the Kitsap Peninsula and i n the v i c i n i t y of Olympia.  The most desirable stands of the Northern coastline  are near Terrace i n the Skeena Valley (Wood, 1957). The SBbre variety of Lodgepole pine tends to have more branches and denser foliage than the Inland form (Report on Forest Research, B. F. C , 1955).  Nevertheless, there i s s u f f i -  cient v a r i a t i o n within the Coast form to be able to select for uninodal, l i g h t branching types. Selection for the improvement of the extensive plantations of Lodgepole pine i n England and Ireland should be carried out within those plantations f o r two p r i n c i p a l reasons:  f i r s t , out-  standing trees are immediately^observable, and selection can be rapid, for phenotypes which are w e l l above the average condition of the stand i n growth q u a l i t i e s or other desirable c h a r a c t e r i s t i c s  83 can be considered of superior genotype u n t i l progeny t r i a l s prove otherwise.  Secondly, as the phenotype i s the r e s u l t of the  interaction of environment and genotype, i t i s more desirable to carry out a r t i f i c i a l selection of an introduced species i n i t s new habitat rather than i n the country of i t s o r i g i n .  The  genotypes most adaptable to the new environment w i l l have shown i n the phenotype which can then be selected for further propagation.  Selection i s purely v i s u a l , whether i n natural stand or  plantation, but i f carried out i n even-aged and w e l l stocked stands, the selected trees w i l l normally be those that have survived competition and are best f i t t e d f o r that p a r t i c u l a r s i t e (Mergen, 1959). This type of selection w i l l assure Lodgepole pine seed of known o r i g i n from good phenotypes at a cost competitive with that from commercial sources.  Above a l l i t w i l l tend to counter-  balance the dysgenic practices now common of c o l l e c t i n g cones from i s o l a t e d , deformed trees; for the c h a r a c t e r i s t i c s that make a tree a t t r a c t i v e to the commercial c o l l e c t o r (extreme limbiness and a large crown combined with low, stunted growth) are those excluded by the tree improver.  The method of i n d i v i d u a l "Plus"  tree selection, with i t s accompanying high selection d i f f e r e n t i a l , i s not advocated for Lodgepole pine.  I t i s not necessi-  tated by the proposed breeding program which i s designed to produce a variety incorporating a r e l a t i v e l y small, number of desireable c h a r a c t e r i s t i c s , of which the most important i s rapid  84 growth rate, while at the same time producing seed free of grossly undesireable c h a r a c t e r i s t i c s .  The selection c r i t e r i a ,  therefore, w i l l be applied to stands rather than to i n d i v i d u a l trees. Recombination  of Naturally Occurring Variation by Means of  Hybridization I n t e r - s p e c i f i c hybridization Jack pine (Pinus banksiana Lamb.) i s a North American species occupying an enormous range from Nova Scotia and Maine westward to B r i t i s h Columbia, and i n Alberta crosses n a t u r a l l y with Lodgepole pine (Moss, 1949).  This hybrid, known as  Pinus murraybanksiana. has been produced a r t i f i c i a l l y at the I n s t i t u t e of Forest Genetics, P l a c e r v i l l e , C a l i f o r n i a .  It is  f e r t i l e , and i s d i s t i n c t l y superior i n vegetative vigor to the Lodgepole pine while possessing the l i g h t branch quality of the Jack pine parent.  The hybrid has attracted the attention of  commercial lumber companies of the P a c i f i c Northwest, and D u f f i e l d and Righter (1953) suggested that i t should be tested i n England and Ireland and those parts of A u s t r a l i a and  New  Zealand where Lodgepole pine has been successful. I n t e r s p e c i f i c hybrids are now occupying an important posit i o n i n the planting programs of many countries. The hybrid Pinus attenuata X Pinus gadiata U. S. Forest Service, and New  i s now being planted by the  Zealand, A u s t r a l i a and Spain  85 have imported quantities of seed and scions from C a l i f o r n i a . This remarkable tree can show a height increment of nine feet per annum.  The hybrid Pinus r i g i d a X Pinus taeda i s supplanting  the pitchpine (P^. r i g i d a ) as the p r i n c i p a l forest tree i n South Korea (S. K. Hyun, 1956).  I t surpasses the pitchpine i n volume  growth by about 500 per cent besides having better form.  In  Europe the majority of poplar clones being propagated are  culti-  vars of natural hybrids, e.g., Populus X berolinensis (Denmark, Germany, Norway, Sweden); Populus X euramericana (Holland, France, Belgium, Germany, United Kingdom); Populus tremuloides X P. tremula, and Populus deltoides X P_^ trichocarpa (Sweden, Denmark and Finland).  In B r i t a i n selection and breeding of the larches  (Larix decidua and Larix l e p t o l e p i s ) was  begun i n 1950,  and seed  of the f i r s t generation hybrid l a r c h (Larix X eurolepis Henry) i s now  being produced on a large scale i n seed orchards, while  Picea X l u t z i i (P. sitchensis X P^ glauca) from the Ksnai Peninsula i n Alaska, i s an important tree i n the r e a f f o r e s t a t i o n of Iceland. There i s l i t t l e doubt, therefore, that a breeding program of any tree species i s incomplete i f i t does not include the i n t e r s p e c i f i c hybridization of the species to be genetically improved. attempted.  Crosses between r e l a t e d species should always be For example, i f Pinus s i l v e s t r i s and Pinus contorta  could be crossed the hybrid would obviously be of greater in B r i t a i n and Ireland than the Pj_ contorta X  value  Banksiana hybrid.  86 I n t r a s p e c i f i c hybridization The value of i n t r a s p e c i f i c hybridization as the p r i n c i p a l means of improving the vegetative vigor of Lodgepole pine i s e f f e c t i v e l y demonstrated by the r e s u l t s of experiments carried out at the I n s t i t u t e of Forest Genetics, P l a c e r v i l l e .  Crosses  between geographic ecotypes of the species have been made, and the progeny of each cross then subjected to the Institute's standard progeny t e s t .  In each case the i n t r a s p e c i f i c hybrid  has shown i t s e l f superior to the control i n height and diameter increment.  This r e s u l t i s not surprising f o r such hybrid  v a r i e t i e s of a g r i c u l t u r a l crops make better use of heterosis than any other breeding procedure yet developed ( A l l a r d , 1960). Matthews and McLean (1957) stated that i n t r a s p e c i f i c hybridization w i l l be used to obtain genetic improvement °f Pinus s i l v e s t r i s i n B r i t a i n , and Bannister (1959) advocated the technique f o r the improvement of Pinus radiata i n New Zealand. M. V. Edward (1957) recommended selecting suitable provenances of Lodgepole pine to combine the vigor of the coastal, and the s t r a i g h t , narrow-crowned properties of the Inland form. There i s l i t t l e doubt that i t i s possible to combine these desirable c h a r a c t e r i s t i c s i n one s t r a i n , and such a combination i s worth seeking.  Nevertheless, i t i s certain that trees of  suitable form can be found on the coast, and by f a r the greatest benefit to be obtained from such a cross i s the increased growth  87 rate of the progeny over the parental types. Heterosis i s seldom discussed i n r e l a t i o n to "plus" tree s e l e c t i o n , for the method of plus tree s e l e c t i o n i s not  designed  to achieve a heterotic e f f e c t i n the progeny of the selected trees.  On the contrary, i f the selected trees are  concentrated  in a small area i n a continuous population there i s l i k e l y to be a d e t e r i o r a t i o n i n vigor at worst, and at best the maintenance of parental v i g o r . In the proposed program for the genetic improvement of Lodgepole pine heterosis i s d i r e c t l y sought.  Therefore, i n t r a -  s p e c i f i c hybridization w i l l form the basis of the breeding program. The areas s t i p u l a t e d for s e l e c t i o n must be s u f f i c i e n t l y f a r apart to obtain genetic d i v e r s i t y .  Nevertheless, i t i s necessary  to avoid introducing a s t r a i n much more adapted to a continental climate than maritime.  For these two reasons s e l e c t i o n should  be i n the following areas: A.  North Coastal - The Skeena v a l l e y region  B.  North Interior - Prince George region  C.  South Coastal - Coast of Washington and Oregon  D.  South Interior - Upper Fraser River and Shuswap Lake region  Denoting each region by i t s respective c a p i t a l l e t t e r  one  can see that i n the f i r s t generation s i x d i f f e r e n t combinations are possible:  88 N. Coastal S. I n t e r i o r  N. I n t e r i o r  AD  N. Coastal  S. Coastal  BD  CD  AB  AC  N. I n t e r i o r  BC  In the second generation i t would be possible to produce thirteen d i f f e r e n t hybrid populations, twelve incorporating three regions and one incorporating a l l four:  AD  BD  CD  AB  AC  BC  ABDD  ACDD  AABD  AACD  ABCD  BCDD  ADBB  ABCD  BBCD  ABCD  ADCC  BDCC  AABC  ACBB  BD CD AB AC  ABCC  This hybrid progeny, besides possessing greater vigor than the parental types, should also exhibit the desirable s i l v i c u l t u r a l c h a r a c t e r i s t i c s p e c u l i a r to the d i f f e r e n t regional types. For example, i t might be possible to select from the hybrid progeny a genotype possessing the rapid growth q u a l i t i e s of the South Coastal type, and the hardiness of the North I n t e r i o r strain, Trees w i l l be selected i n each of the four regions, and must incorporate at least the s i x c h a r a c t e r i s t i c s already discussed. Scions should be taken from these trees and grafted on vigorous stock i n an area s u f f i c i e n t l y i s o l a t e d from stands of Lodgepole pine to avoid contamination.  Crosses can be made as soon as  s u f f i c i e n t flowering has r e s u l t e d .  89 I f the four selected regions are represented  i n plantations  which are not separated by great distances, then i t may  be  p r a c t i c a l to carry out the cross i n the f i e l d and eliminate the necessity to g r a f t .  This i s the technique used by Bingham  i n breeding r u s t - r e s i s t a n t white pine (Pinus monticola). The trees selected w i l l not necessarily be "plus" trees, for the i n t r a s p e c i f i c hybridization program does not e n t a i l the s e l e c t i o n of trees i n the manner necessary for the  pedigree  breeding of Coast Douglas f i r (Pseudotsuga menziesii).  There-  fore, the pollen from grafts representing a p a r t i c u l a r region w i l l be mixed, and used to p o l l i n a t e a l l other g r a f t s .  The  cross w i l l be r e c i p r o c a l . Despite care during the selection of the trees, i t w i l l be found that some trees w i l l have fewer female flowers than others. This i s to be expected i n the l i g h t of C r i t c h f i e l d s findings 1  already r e f e r r e d to.  In order to obtain the ijequired number of  bagged female flowers for each region i t w i l l be necessary to i s o l a t e more female flowers on some trees than on others. This w i l l lead to a bias within the derived progenies i n favour of the heavily flowering trees.  To o f f s e t t h i s bias the  p o l l e n c o l l e c t e d from the trees representing each region should be weighted r e c i p r o c a l l y on a volume basis before mixing. For example, i f the proportions of female flowers on trees A, B, C, D, and E of the North I n t e r i o r region were 1, 2, 3, 4, and 5, the proportion by volume of pollen used i n the mixture  90 representing that provenance i s 5, 4, 3, 2, and 1 respectively. This p r a c t i c e , of course, assumes that the pollen from each tree has the same v i a b i l i t y (Faulkner, 1961). The layout and maintenance of the seed orchard w i l l follow the procedures recommended by Matthews f o r Scots pine (Matthews, 1955, 1957). The grafts should be topped and pruned i n order to obtain a wide crown.  I f c o r r e c t l y pruned, seed-production w i l l be  enhanced, and cone c o l l e c t i n g f a c i l i t a t e d . also be increased by s o i l f e r t i l i z a t i o n .  Seed harvests can  IDENTIFICATION OF TREES WITH DESIRED HEREDITY There i s some evidence that desirable c h a r a c t e r i s t i c s i n a mature tree are correlated with observable c h a r a c t e r i s t i c s i n seedlings.  Schmidt (1938) claimed that i t i s possible to deter-  mine whether a conifer i s straight-stemmed on the basis of i t s phototrophic  behaviour i n the early stages of i t s growth.  Schrock (1951) stated that i t i s possible to extrapolate growth curve on the basis of observations  the  of growth rate made  during the f i r s t few years, and Callaham (1961) has shown a correlation between the height of a seedling at two years and i t s height at f i f t e e n .  M i t c h e l l considered  i t possible to  make selections i n five-year-old hybrid l a r c h (Larix euro1 lepis).  However, there i s as yet no sound method of deter-  mining, by p h y s i o l o g i c a l and biochemical  investigation, the  existence i n seeds, seedlings and saplings, of c h a r a c t e r i s t i c s correlated with desirable c h a r a c t e r i s t i c s i n the mature tree. By c a r e f u l morphological study i t i s possible to correlate certain measureable c h a r a c t e r i s t i c s i n young plants with t h e i r future growth q u a l i t y .  These c h a r a c t e r i s t i c s are growth rate,  straightness of stem, and branching habit, and, to a extent, resistance to disease. 1 Personal  communication.  considerable  Therefore, attempts should  be  92 made to select for those c h a r a c t e r i s t i c s at an early stage i n the progeny of the controlled crosses. l a t i o n of flowering i s successful i t may select for precociousness and  I f the a r t i f i c i a l  stimu-  also be possible to  fertility.  The present controversies concerning what one  should  select for i n a forest tree should not be allowed to delay selection i n the progeny of the controlled crosses of Lodgepole pine.  More and more the demand from the timber-consuming  industries (such as pulp and paper, hardboard and  chipboard  industries) i s for maximum dry weight per acre per annum at minimum cost.  I t i s the business of the tree breeder to work  for t h i s objective; and i t i s suggested, therefore, that the best method of a t t a i n i n g i t with respect to Lodgepole pine i s to select for the six c h a r a c t e r i s t i c s stated. It i s assumed that s e l e c t i o n of any one of these characteri s t i c s w i l l not r e s u l t i n the exclusion of another.  Light  branching habit i n the Shore form does not appear to be associated with slow growth.  The r e l a t i o n s h i p between rate of growth and  wood density has been the subject of many studies, the most recent of which indicate that i t i s possible to develop high y i e l d i n g strains without any s i g n i f i c a n t reduction i n wood density.  Work conducted on Monterey pine (Pinus radiata) i n the  Australian C a p i t a l T e r r i t o r y by F i e l d i n g and Brown (1958,  1960)  has shown that any c o r r e l a t i o n e x i s t i n g i n t h i s species between the inherent rate of growth of the i n d i v i d u a l tree and  the  93 density of i t s wood i s so small as to be n e g l i g i b l e . Progeny t r i a l s To evaluate and select that portion of the controlled crosses showing heterosis and other desirable c h a r a c t e r i s t i c s the progeny must be planted out i n a conventional  experimental  design embodying r e p l i c a t i o n and randomization, both of which are e s s e n t i a l to the c a l c u l a t i o n of the error term.  Variables  such as growth rate, wood s p e c i f i c gravity and degree of flowering are evaluated by t or F t e s t s , including analyses of variance, and, when applicable, of covariance  (Publication No.  30, U. S. D. A., 1960). Those hybrids showing the desirable c h a r a c t e r i s t i c s w i l l be retained and the i n f e r i o r ones eliminated.  The remaining  trees w i l l then be allowed to i n t e r - p o l l i n a t e f r e e l y .  Undesir-  able parental types w i l l be eliminated from the o r i g i n a l seed orchard, which w i l l continue to be the source of F^ hybrid seed. The commercial hybrid In breeding cross-pollinated crops, the basis of improvement l i e s i n the controlled u t i l i z a t i o n  of the heterosis that  occurs i n hybrids among certain genotypes.  This controlled  u t i l i z a t i o n can be achieved by the production of a synthetic variety.  The term "synthetic v a r i e t y " i s used by plant breeders  to designate a v a r i e t y that i s maintained from open-pollinated seed following i t s synthesis by hybridization i n a l l combinations  among a number of selected genotypes ( A l l a r d , 1960).  Therefore,  the hybrid progeny obtained i n the manner described i s analogous to the parental form of the synthetic v a r i e t i e s produced by the breeders of n a t u r a l l y cross-pollinated a g r i c u l t u r a l crops, and i n theory w i l l behave s i m i l a r l y when bred i n t e r se.  SUMMARY OF BREEDING PROGRAM 1.  Trees exhibiting c e r t a i n desirable c h a r a c t e r i s t i c s are  selected i n four areas which are s u f f i c i e n t l y far apart to obtain genetic d i v e r s i t y . 2.  Scions are cut from these trees and grafted on root  stock. 3.  When s u f f i c i e n t flowering r e s u l t s , the pollen from a l l  trees representing a p a r t i c u l a r region i s mixed and used to p o l l i n a t e a l l other trees. 4.  The cross w i l l be r e c i p r o c a l .  The progeny of the i n t r a s p e c i f i c cross w i l l be sub-  jected to progeny t e s t s .  The r e s u l t i n g superior progeny w i l l  be allowed to i n t e r p o l l i n a t e f r e e l y to produce a synthetic variety. 5.  Undesirable regional forms w i l l be eliminated from the  o r i g i n a l seed orchard, which w i l l continue to be the source of F^ hybrid seed for further propagation 6.  of the synthetic v a r i e t y .  Stages 1 and 2 are eliminated I f the four desired  regional forms are represented  i n plantations or provenance  t r i a l s within a l i m i t e d area.  Stage 3 i s then c a r r i e d out i n  the f i e l d .  96  BIBLIOGRAPHY A l l a r d , R. W. 1960. P r i n c i p l e s of plant breeding. 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Publication of Faculte des  1960. Polyploidy and mutagenesis i n forest tree F i f t h World Forestry Congress, Seattle, Wash.  Haasis, F. W. and Thruff, A. C. Temperature r e l a t i o n s of Lodgepole pine seed germination. Geology. 12: 728-744. Harlow, W. M. and Harrar, E. S. 1958. Textbook of dendrology. McGraw-Hill Book Company, New York. 561 p. Hansen, H. P. 1947. P o s t g l a c i a l forest succession, climate, and chronology i n the P a c i f i c Northwest. Trans. Am. P h i l o s . Soc. 37: 1-130. Heusser, C. J . 1960. Late-pleistocane environments of North P a c i f i c North America. Special publication no. 35. American Geographical Society. 308 p. Hyun, S. K. 1954. Induction of polyploidy i n pines by means of colchicine treatment. Silvae Genetica 3: 25-33. . 1956. Forest tree breeding i n Korea. International Union of Forest Research Organization, 12th Congress. 1939. Huxley, J . S. Clines: an a u x i l i a r y method i n taxonomy. Bidr. tot de Dierhunde 27: 491-520. Jaccard, P. and Frey-Wissling. 1953. Recherches comparatives sur l a production de resine chez l e s pins scandinaves et chez l e s pines indigines. M i t t . Schwiez. Centralanst. f. d. f o r s t e . Versuelsw. 19: 7-20. Jentsch, J . 1954. Pinus murrayana ( B a l f . ) . Ein anhauversuch i n mitteldeutschen Raum. Archiv. f . Forstw. 3: 288-352.  99 Jebson, W. L. 1910. The s i l v a of C a l i f o r n i a . of C a l i f o r n i a Press, Berkeley, C a l i f .  The University  Johnson, L. P. V. 1945. Reduced vigour, chlorophyll deficiency, and other effects of s e l f - f e r t i l i z a t i o n i n Pinus. Canad. Jour. Res. C.23. Joyce, A. M. 1961. General volume table for Pinus contorta i n Ireland. Government Stationery O f f i c e , Dublin. Kalela, A. 1938. A synthesis of experimental research on c l i m a t i c races of tree species. Communicationes I n s t i t u t i F o r e s t a l l s Fenniae, H e l s i n k i 26 pp. 445. Keng, H. and L i t t l e , C. R. 1961. Needle c h a r a c t e r i s t i c s of hybrid pines. Silvae Genetica, V o l . 10, No. 5, 1961. Laing, E. V. 1954. Studies of v a r i a t i o n i n c o n i f e r s . Report on forest research for the year ending March 1953, B. F. C. London. Langlet, 0. 1934. Ohr variationen hos t a l l e n (P. s y l v e s t r i s L.) och dess semband bred Klimatet. Svenska ShogsvForen. Tidshr. 32: 87-116. . 1936. Studier oner t a l l e n , f y s i o l o g i s k a v a r i a b i l i tet och dess samaband Med. Klimatet. Medol. f . Statens Shogsforsohsan, t a l t 29 Sweden. • 1938. Proveniensforsoh med o l i k a tradslag. Svenska shogsvForen. Tidshr. 36: 55-278. . pine.  1959. A c l i n e or not a c l i n e - a question of Scots Silvae Genetica 8: 13-22.  Lines, R. 1956. Provenance experiments. Report on forest research for the year ended March 1955. B. F. C. London. . 1957.  1957. Pinus contorta i n Ireland Forestry. V o l . 30. England.  Macdonald, J . A. B. 1954. British Silviculture.  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P r i n c i p l e s and procedures of s t a t i s t i c s . McGraw-Hill Book Co., New York. 479 p. Sudworth, G. B. 1908. Forest trees of the P a c i f i c slope. U. S. D. A. 1908. 441 p. Swan, 1955. Forest tree breeding. Paper Chemistry.  Publication.  Tackle, D. 1959. S i l v i c s of Lodgepole pine. U. S. D. A. 1959.  I n s t i t u t e of  Misc. pub. no. 19.  U. S. D. A. 1960. Minimum standards for progeny-testing for s e e d - c e r t i f i c a t i o n purposes. Publication no. 30. 20 p. Wood, R. F. 1955. Studies of North-west American forests i n r e l a t i o n to s i l v i c u l t u r e i n Great B r i t a i n . B u l l e t i n no. 25, B. F. C. 1955. London. 42 p. Worsley, R. G. F. 1959. The processing of p o l l e n . Genetica. 8: 143-148.  Silvae  Wright, G. W. and Baldwin, H. I . 1957. The 1938 International Union Scotch pine provenance test i n New Hampshire. Silvae Genetica. 6: 1-14.  102 Zobel, B. 1961. The inheritance of wood properties i n c o n i f e r s . Silvae Genetica. 10: 65-70.  ii  T H E SHORE FORM OF PINUS CONTORTA  3.1  THE SHORE FORM OF PINUS CONTORTA  1.  A branch with staminate flowers  2.  Diagram of involucre of the staminate flower  3.  A staminate flower  4.  An anther, side view  5.  An anther, front view  6. A branch with p i s t i l l a t e flowers 7.  A p i s t i l l a t e flower  8. A scale of a p i s t i l l a t e flower, lower side 9. A scale of a p i s t i l l a t e flower, upper side 10.  A f r u i t i n g branch  11.  A cone scale, lower side  12.  A seed enlarged  13.  V e r t i c a l section of a seed  14.  An embryo  15.  A cluster of young leaves  16.  Tip of a leaf  17.  Cross section of a l e a f  18.  A seedling plant  From Sargent (1897)  Fig-1 Regression of height on elevation for 18 different provenances of Pinus contorta growing at Placerville  '6  1000  2000  3000 ' 4000 5000 6000 Elevation in Feet  7000  8000  9000  Fig 2 Relationship of total height and elevation for 18 different provenances of Pinus contorta growing at Placerville  Placerville  Fig- 3 Regression of length on width of Pinus contorta needles from 22 different provenances growing at  Mean Ratios for Each Sample  a  Significantly different from values at foot of arrow  Not significantly different from values at foot of arrow  n  A '•  Sample Number  •021  18  •023  17  •024  20  •024  13  •027  7  028  12  028  16  •028  2  •029  15  030  19  •031  II  032  8  032  14  032  3  033  6  033  5  034  4  034  I  •039  10  •040  9  Fig- 4 Differences in ratio of needle width to length for 20 provenances of Pinus contorta sampled at Placerville  Number of Days  Fig- 5  Differences in rate of germination at 2 5 ° C between coast and interior seed of Pinus contorta-  INTERIOR FORM Pointed protuberance at funicular  COAST FORM Protuberance usually absent  end of seed Usually over 3 mm in length  Usually under 3 mm in length  Prominant ridge on upper surface  Ridge not usually prominant  Fig- 6 Method of distinguishing interior and coastal Pinus contorta seed-  10  15  20  25  30  35  40  Years after Year of Planting Out after Swan, 1955  Fig- 7  Increase in latex yields per acre by selection and breeding of superior stock  45  50  55  

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