The paper reviews the literature on polyploidy in respect to its possible application in forest tree breeding. The occurrence of spontaneous polyploidy in various species is enumerated and its qualities outlined. An account is presented of the success and failure thus far attained in the search for improved varieties of forest tree species through polyploidy. Finally, the potentialities of polyploidy in forestry are summarized and some recommendations concerning future lines of research are outlined. The experimental work in connection with this thesis was the preliminary investigation of Douglas fir (Pseudotsuga menziesii (Mirob) Franco) aberrants found each year among the seedlings at the B.C. Forest Service nursery in Duncan. These abberrants have been thought to be spontaneous autopolyploids because they resemble such polyploids found among nursery stock of other coniferous species elsewhere. This study, however, indicated beyond any doubt that these abberrants are not polyploids. Other possibilities which might have caused the aberrant form are discussed. / Forestry, Faculty of / Graduate

The object of this work was to study the soil and nutrient requirements of Douglas fir seedlings in relation to their physiological development. For this purpose, fertilizer, irrigation, growth and nutrient uptake experiments were conducted at the Green Timbers Forest Nursery and the University of British Columbia. The experimental sites were characterized by chemical and physical soil analysis. The N, P, K, Ca and Mg content of 0-0 and 1-0 seedlings was determined. Statistical methods of analysis were used to determine the significance of experimental results. Douglas fir seedlings during the first year in the nursery (0-0) produced little dry matter and removed small amounts of nutrients from the soil. The application of 20 to 30 lbs. per acre of nitrogen increased the growth of 0-0 seedlings in 1957 and 1958. Fertilization with potassium decreased, and with phosphorus increased, the growth of 0-0 seedlings in 1957 but had no effect in 1958. Application of compost, mushroom manure and cow manure increased the growth of 0-0 Douglas fir seedlings. The fertilization of 0-0 seedlings with mineral fertilizers had no effect on their development in the subsequent year. In the second year of growth (1-0), the dry matter production and the removal of nutrients from the soil by Douglas fir seedlings exceeded that of many agricultural crops. During the summer, 1-0 Douglas fir seedlings passed through at least one period of temporary dormancy, but their growth was continuous throughout the summer. Nitrogen fertilization increased the length and dry weight of 1-0 seedlings. Application of 320 lb. N per acre decreased growth and resulted in damage to seedling tissues. High phosphorus application decreased the unfavourable effect of excessive nitrogen fertilization. The 1-0 seedlings did not respond to potassium fertilization. Phosphorus, however, increased the dry weight of the 1-0 seedlings when applied at a rate of 320 lb. P205 per acre. Late summer nitrogen applications resulted in very rapid seedling growth during autumn, however, dormancy was delayed and the seedlings were heavily damaged by frost. Nitrogen fertilization in September increased the frost resistance of dormant 1-0 seedlings. Irrigation increased the height and weight of 1-0 Douglas fir seedlings. Heavy irrigation decreased the winter hardiness of the seedlings. The duration and time of the dormant period was found to be influenced by fertilization and soil moisture conditions. Each seedling, however, had individual dormancy characteristics. / Land and Food Systems, Faculty of / Graduate

Seven seed lots of Douglas fir seed which became heavily contaminated with mold during germination tests also had low germination values. A number of fungi were isolated from the seed coat and from within surface-sterilized seed sampled from these seed lots. Several of the fungi were found to be capable of attacking the radicles of germinating seeds under the conditions of the pathogenicity tests. Some of the fungi, both pathogenic and non-pathogenic, inhibited the germination of seed treated with the spores or mycelium of the fungi during a period of stratification. The results obtained indicate that the lower germination values of the heavily contaminated seed lots were due, in part at least, to the activity of the fungi capable of attacking the germinating seed and to fungi which inhibited the sprouting of the seed by other means. Other factors relating to the treatment of the seed prior to the germination tests which would adversely affect the germination are discussed in relation to this study. / Forestry, Faculty of / Graduate

The aim of this study was to determine how several growth factors influence cellulose content in Douglas fir wood. Standard samples from eight Douglas fir trees originating from the U.B.C. Research Forest at Haney, B.C. were submitted to a slightly modified Cross and Bevan extraction procedure. In addition, the newly-developed method of Yundt and Bradway was used to give an independent estimate of cellulose from the trees which yielded extreme values for Cross and Bevan cellulose. The main factors considered as influencing cellulose yields were crown class, site and radial position within the same tree. In addition, the largest tree among the eight tested was studied to further define the extent of cellulose variation with increasing age from the pith. By analysis of a single tree lower cellulose yields were obtained for juvenile wood as compared with the mature wood in the same tree. Most of the variation in cellulose due to age was found in rings for 1-15 years. Despite the fact that two growth factors (crown class and site) were shown to have a statistically significant influence on cellulose yield, it was shown that their influence was independent of rate of growth. The four largest trees had higher cellulose yields than the four smallest trees on each plot. On the average, cellulose yields were higher for the poor site than the good site, yet the variations could not be related to size, growth rate, or per cent summerwood. There was a definite variation in cellulose content among the trees. The highest cellulose percentage was found in an individual dominant tree on the poor site and the lowest in an intermediate tree on the good site. Actual causes and controls of cellulose content among individual trees remain to be established. However, it can be stated that there is an important variation in the cellulose yields from tree to tree, and that in this sample of eight trees, yields of Cross and Bevan cellulose ranged from 54 to 66 per cent. The desirability of propagating trees with high cellulose content is discussed briefly. / Forestry, Faculty of / Graduate

The paper describes a Douglas-fir classification for the interior of British Columbia which was developed for the purpose of identifying trees susceptible to the attacks of the Douglas-fir beetle, Dendroctonus pseudotsugae Hopk. The significance of the depredations of the beetle to the objectives of sustained-yield forestry is discussed and the need for control and continuous protection stressed. A method of direct control of bark beetles is exemplified and receives criticism for its laborious-ness, high cost, and temporary protection. It is noted that foresters and entomologists are increasingly cognizant that forest management should strive for insect control through the development and maintenance of forest conditions unfavourable to insects. These conditions become manifest in vigorous forests which possess an inherent resistance to insect attack. By harvesting on a selective and critical basis the forest may be made relatively resistant and insects can be controlled by indirect means. Detailed reference is made to a system of indirect control developed for ponderosa pine forests against the attacks of the western pine beetle, Dendroctonus brevicomis Lec. The theory, development, and application of the system is considered and later referred to in the light of the results of the present study. The possibility of developing similar systems for other insects and hosts is demonstrated from the literature. Similarly, the ability of other workers, to classify Douglas fir into vigour and age groups is shown. In view of the apparent feasibility of judging the susceptibility of classes of Douglas fir to attack by beetles an attempt was made to develop a classification which might have value in this regard. A classification was developed and tabulated from data collected at Westwold, B. C. in the interior Dry Belt at an elevation of 3,000 feet. The method is described in detail and the limits of the four vigour classes and of the four age groups are statistically justified. The classification was tested for its accuracy in judging actual and relative age and vigour at Westwold and also at Lumby in the interior Wet Belt. The results of the tests are tabulated and the reason for the high degree of accuracy in judging actual vigour in terms of diametral growth attributed to the measurements of phloem streaks. Infested trees were objectively classified on an area of eight square miles at Westwold to determine which classes of vigour and age were susceptible to attack. The results reveal that the older, slower growing trees are most susceptible. Specifically, trees of over 150 years of age with a ten-year diametral growth of less than 11 millimetres are most likely to be infested. The type of host selection made by the Douglas-fir beetle is compared to a combined thinning from below and a selection cutting of the older age classes. It is suggested that, in forests subjected to endemic populations of beetles, trees of classes 2D, 3C, 3D, 4C, and 4D be harvested to increase the vigour and resistance of the residual stand and to implement indirect control. / Forestry, Faculty of / Graduate

The results of two hundred and fifty-eight static bending tests on young Douglas fir were obtained from the Vancouver Laboratory of the Forest Products Laboratories of Canada. Twenty-two trees had been sampled; seven of approximately sixty years of age from Port Moody, eight of about seventy years of age from Coombs (on Vancouver Island), and seven of approximately ninety years of age from Stave Lake. Stand site quality in each locality was similar and above average for second-growth fir from the coastal region of British Columbia. The laboratory's results were separated into two classes. Ninety-seven tests represented wood formed within the first five inches of radial growth in the tree. The remaining one hundred and sixty-one tests typified the older wood lying between the inner zone and the bark. Analyses of variance revealed highly significant differences in properties between zones. Wood from the inner zone had a faster growth rate, lower density (though wider bands of summerwood) and less strength and less stiffness in bending than wood from the outer zone. The influence of ring width, summerwood width and specific gravity on the moduli of elasticity and rupture was assessed for each zone by regression analyses. Ring width and summerwood width accounted for a significant amount of variation in modulus of elasticity and modulus of rupture in the two zones. Their influence on both moduli, however, was completely due to their association with specific gravity. Specific gravity, alone, accounted for almost twice as much of the variation in elasticity and bending strength as did ring width and summerwood width combined. The presence of compression wood in a few specimens from the outer growth zone weakened the relationship between modulus of elasticity and specific gravity in this zone but had no effect on the modulus of rupture — specific gravity relationship. In consequence, the influence of growth zone on modulus of elasticity could not be determined. The difference in average values of specific gravity between zones did not fully explain the similar difference between zones for average modulus of rupture values; an indication that radial growth zone in the tree had some influence on the bending strength independent to that exerted by density. / Forestry, Faculty of / Graduate

Longitudinal air permeability measurements of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] outer sapwood from three trees of different seed sources and growth locations were determined on microsections about 500-700 microns thick, dried by air-seasoning and solvent-seasoning. The specimens were successively reduced in length from 3.6 to 0.4 cm. Darcy's law was found to be invalid with respect to specimen length. Sapwood earlywood longitudinal air permeability was found to be a sensitive barometer of seasoning effect on pit aspiration. The objective was to determine where the variations in margo porosity were significant, and hence applicable to problem of Douglas-fir permeability. The diameters of earlywood margo openings were measured directly from electron micrographs of un-aspirated (solvent-seasoned) pits. The margo measurement was assumed to represent one plane instead of the actual three dimensional structure, and the pores observed were the ones that controlled the rate of flow. Samples from the most, intermediately and least permeable specimens were selected and prepared for the evaluation of anatomical parameters of bordered pit membranes (margo area and margo porosity) as related to permeability. The effects of pit aspiration, tracheid length, total number of pits per tracheid, number of tracheids per square millimeter, and specific gravity on permeability were also assessed. Pit partial aspiration was found as the most important variable correlated with permeability. In an order of decreasing importance, pit partial aspiration, margo porosity and specific gravity together accounted for 94 per cent of total variability in permeability of solvent-seasoned earlywood. No statistical evaluations were made to compare the three trees with respect to their permeability and the measured parameters. / Forestry, Faculty of / Graduate

Pollen morphology, pollen germination, and the effects of nutrients during pollen germination of Pseudotsuga menziesii (Mirb.) were studied. Pollen extraction was done at room temperature and the pollen morphology was studied using a staining technique. Several types of substances were introduced to the medium (double-distilled water) to culture the pollen. The substances were boric acid, calcium nitrate, potassium salt of gibberellie acid, indoleacetic acid, indolebutyric acid, naphthaleneacetic acid, thiamin, water extracts of Douglas-fir seeds, sucrose and stock solution. Incubation of pollen grains was carried out in the growth chamber where light intensity was about 3500 foot-candles during the 12-hour light period each day and the temperature was maintained at 20°G at night and 25°C during the day time. The relative humidity was kept at about 40 percent. Pollen grains were checked daily. Mature pollen grains were at the two-celled stage with two degenerated prothallial cells. When dry, the grains were cup-shaped, while turgid grains were spherical or elliptical without any furrows or sacs. The exine was thin being about 2 microns, and quite smooth. The intine was about 8 microns thick and was of uniform hyaline appearance. The pores in the exine were about 2 microns in diameter; those in the intine were enclosed with a membrane. Boron and calcium ions were very important to the pollen germination and elongation. Pollen germination was stimulated by growth-promoting substances, but was inhibited by fungicide and bactericide. Sucrose solution of 10 to 15 percent was recommended for the osmotic milieu and for nutrient purposes. Stock solution (boron 0.1 g., calcium nitrate 0.3 g., and double-distilled water 100 ml.) is the best for pollen germination and elongation. Pollen grains cultured in the medium containing stock solution B, 10 ppm IAA, and sucrose were found in four-celled stages (tube cell, two sperm cells and stalk cell) after five days. The actual germination of the Douglas-fir pollen in vitro was accomplished in this study. These may be of practical value in ensuring a uniformly high rate of seed production in Douglas-fir seed orchards, but field studies (artificial pollination) are needed to obtain further information. / Forestry, Faculty of / Graduate

An apparatus was constructed to measure the longitudinal gas-permeability of wood microsections about 150 microns thick. This apparatus was used to examine low surface tension drying methods of wood (freeze-drying and alcohol-benzene extraction) believed to maintain the bordered pit tori of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in the non-aspirated condition. Results were compared with drying methods believed to aspirate tori (air-drying, oven-drying and boiling-under-vacuum). Dry nitrogen gas-permeability measurements were made under "steady state" conditions. Similar drying techniques were used to prepare gross specimens which were subsequently subjected to “non-steady state" pressure treatment in end-penetration. Sapwood and heartwood specimens from impermeable interior-type and permeable coast-type Douglas fir were tested. With both gross sections and microsections, the two low surface tension drying methods provided more permeable wood than did air-drying. Boiling-under-vacuum was as effective as low surface tension methods in improving gas-permeability, but not creosote-permeability, whereas oven-drying was as effective as low surface tension methods in improving creosote-permeability, but not gas-permeability. The improvement was most striking in all sapwood samples, less in coast-type heartwood, and nil or not measurable in interior-type heartwood. Under the experimental conditions, latewood gas-permeability was about 2 darcies for all specimens and drying methods. Heartwood early-wood gas-permeability ranged from 0.02 to 2 darcies but was unaffected by drying methods. Sapwood earlywood gas-permeability was improved from 8 to 30 times by low surface tension drying. The greatest gas-permeability was found in the first-formed earlywood, which ranged from 2 to 100 darcies. The later-formed earlywood ranged from 0.02 to 100 darcies, depending on wood origin and drying method. Creosote-permeability of interior-type heartwood was uniformly low by all drying methods. Interior-type sapwood and coast-type sapwood and heartwood were much more permeable after low surface tension drying or oven-drying. By visual observations, after all drying methods, latewood was more permeable than earlywood. Low surface tension drying methods improve earlywood gas-permeability of sapwood, and latewood creosote-permeability of sapwood and coast-type heartwood. / Forestry, Faculty of / Graduate

Previous attempts to classify nutrient regimes of forest soil have been qualitative evaluations utilizing vegetation and/or physiographic site characteristics, morphological soil properties, and parent material. The major objective of this study was to describe and classify the soil nutrient regimes (SNR) of some Pseudotsuga menziesii ecosystems on southern Vancouver Island, British Columbia. The order of increasing variability for forest floor properties was pH(H₂0) <TC <TN <TS <TP <exMg <exCa <exK <exMn <minN. The order of increasing variability for mineral soil properties was pH(H₂0)=pH(CaC1₂) <TN <TC <exP = exMg <S0₄ <minN = exK <exCa <exMn. Consistent trends in soil property variability along gradients of soil moisture or nutrient availability or between parent material lithologies were not apparent. Multivariate analysis of understory vegetation and indicator plant analysis suggested a major trend in variation corresponding to a complex environmental gradient related to increased availability of soil moisture and nutrients. The arrangement of study plots along the gradient showed groupings which corresponded to both the calculated soil water deficit and inferred soil nutrient regime. One multivariate axis accounted for most of the variation of soil properties between study plots. The mineral soil and forest floor plus mineral soil quantities of minN, TN, exCa and exMg significantly increased along the nutrient gradient. Ordinations of mineral soil and forest floor plus mineral soil properties arranged most plots according to the moisture-nutrient gradient. Discriminant analysis of the soil properties selected linear combinations of properties which separated sites, parent material lithologies, soil moisture regime classes and SNR classes. Cluster analysis confirmed that minN and exMg of the forest floor plus mineral soil best separated SNR classes. Multivariate summaries of variation in understory vegetation and foliar nutrients were highly correlated to the soil properties which best separated SNR classes. The increasing quantities of these nutrients corresponded to increases in site index for the study sites. It was concluded that significant differences in N, Ca, and Mg availability existed between SNR classes for the study sites. These differences in nutrient availability corresponded to changes in understory vegetation, foliar nutrient status and site index for the study sites. Using forest floor plus mineral soil quantities of minN and exMg, a multivariate classification of the four SNR classes recognized in this study was proposed. / Forestry, Faculty of / Graduate