Widths of 22,734 bands of earlywood and latewood were measured systematically along the average radii at the centers of the annual height increments of 18 Douglas fir trees. Shapes of the annual growth layers of earlywood and of latewood, respectively, formed during an accrued growth period of 589 years were investigated: (i) using relative measures embodied in diagramatic computer outputs; (ii) using absolute measures by statistical and graphical techniques; (iii) by computing Hohenadl's form factor (lambda 0.9) for each year's growth of; a) imaginary "earlywood stems" consisting of layers of earlywood; b) imaginary "latewood stems" consisting of layers of latewood; c) actual stems consisting of total annual layers. The form of earlywood layers differed markedly and consistently from that of latewood layers. The maximum width of earlywood layers in individual trees occurred within a zone located in the upper portion of the live crown; in the stand it was within a zone parallel with the surface of crown canopy. Width of earlywood was at its minimum at some distance above the stem base. This distance increased with tree age. Latewood layers were usually widest along the basal portion of the stem. As a result, the form factors of "earlywood stems" were considerably higher than those of "latewood stems". The shapes of the growth layers, and hence the form of stems consisting of these layers, could not be reconciled satisfactorily with the tenets of Schwendener - Metzger's mechanistic, or Hartigfs nutritional, or Jaccard's water conductive, or hormonal theories of stem formation. Therefore, a new scheme was proposed using the following concepts: (1) Heating of stems by solar energy constitutes a purely physical process; the rate of energy transfer between a tree and its environment determines the temperature of its cambial tissues. (2.) Because trees are not homoiothermous organisms, at a given time various parts of the cambial cylinder may possess different temperatures even in an isothermal environment. (3) A pronounced stratification of the environment due to gradients in air temperature or in length of time of positive net flux of energy has been observed in forests throughout the world. (4) Radial growth may proceed at varying rates for unequal periods of time within the different parts of the cambial cylinder, depending largely on the levels of subcortical temperatures. (5) Consequently, the shapes of the annual layers of earlywood and latewood may reflect the respective spring and summer environmental energy gradients. (6) Then the average form of trees from forests of the temperate latitudes, which is that of a quadratic paraboloid, may reflect the average microclimatic structure prevailing in these forests during the growing season. Form of open-grown trees, eccentricity of stems, roots and branches, and other so far unexplained anomalies in radial growth may be clarified similarly. Indirect and some preliminary direct evidence supporting the proposed conceptual scheme of stem formation was presented. In addition, influence of some selected factors of macroclimate on the amount of radial growth expressed in terms of the average widths of growth layers was analysed. Individual trees have been used as sampling units. The trends in the growth series were removed by analysis of covariance: average layer width indices were derived by calculating deviations from the straight lines fitted by least squares to the adjusted mean layer widths. The degree of autocorrelation of both growth and weather series was largely nonsignificant. Correlations between the growth indices of earlywood and latewood were nonsignificant or low. In the individual trees, six weather variables accounted for from 10 to 48 per cent of the total variability observed in the radial growth of latewood. Temperatures of the previous summer could not be related to the amount of radial growth of earlywood of the current year. Since the approximate minimum true correlation in the universe was zero the general influence of macroclimate was nonsignificant. It appears that other studies have neglected the influence on growth of microenvironmental factors and that there is need for research on the means by which distribution and amount of radial growth are controlled by the net flow of energy. / Forestry, Faculty of / Graduate

The cellulose fraction in 100-micron thick microtome sections from three growth increments of a Douglas fir tree was sytematically degraded through random scission of chains by means of 0.1, 1.0, 10.0, and 15.0 megarad doses of gamma irradiation. Degree of cellulose polymerization (DP) was estimated from results of intrinsic viscosity measurements on dilute solutions of cellulose nitrate in acetcne. Control and irradiated samples were tested in tension parallel to grain by employing a micro-scale test method. Tests were done at 25, 50, and 70°C temperatures in combination with moisture-free, air-dry, and water-saturated conditions of test specimens. Ultimate tensile strength, an elastic constant, ultimate tensile strain, and work to maximum tensile load have been calculated from experimental data. Results were statistically analyzed in relation to cellulose chain length, temperature and moisture content. Regression equations based on experimental results have been constructed. These explained a large part of the variations in tensile strength properties and are reported as three-dimensional diagrams. It is shown that tensile strength behavior of Douglas fir earlywood and latewood are distinctly different. Strength properties of latewood are not only higher by a factor of approximately 2 to 8 than those of early-wood, but also the response of the two growth zones to changes in cellulose chain length, temperature, and moisture content at test is different. The above characteristics are due to different deformation mechanisms in tension parallel to grain of the two growth zones. It is suggested that deformation in earlywood is intra-cellular, whereas in latewood it is primarily an inter-tracheid, phenomenon. Decrease in cellulose DP reduced strength, ultimate strain, and work to maximum load more in the low than in the high DP regions. This is explained by the increasing importance of inter-chain and/or inter-fibrillar slippage with decreasing chain length. Elastic properties are but little affected by changes in cellulose DP if the crystalline-amorphous ratio of cellulose in wood is not altered significantly by the treatment applied, such as accompanies gamma irradiation. A change in wood moisture content at time of test from the moisture-free to the water-saturated condition reduced strength properties of Douglas fir by approximately 20 to 50 per cent. The reductions in late-wood strength were significantly higher than in earlywood. A convex upward curve configuration relating strength and elasticity to moisture content is suggested from the experimental data. Effect of temperature on strength properties of Douglas fir within the range of 25 to 70°C is minor in comparison with that of moisture content. The relationship is probably linear. Tensile strength characteristics of Douglas fir wood with degraded cellulose are more sensitive to changes in moisture content than are those of wood having cellulose of long-chain structure. This behavior of wood in tension is also explained by the slippage mechanism of deformation. / Forestry, Faculty of / Graduate

An analysis was made of the distribution of and interactions between three major species of insects in cones of Douglas fir. This was based on over 3,500 cones from 93 trees in 1961 and 4,000 cones from 97 trees in 1962. High variation in damage was found among trees for each of the three insect species studied (Contarinia oregonensis Foote, Megastigmus spermotrophus Wachtl., and Dioryctria abietella D.&S.) In C. oregonensis this variation was significantly related to the height of the trees and dates when cones became pendent. The percentage of filled seeds and average cone size of the trees were important in M. spermotrophus. The average cone size of the trees and duration of vegetative bud flushing were significantly associated with D. abietella. The within tree-variation of damage by C. oregonensis was highly significant and consistant from tree to tree and year to year. Damage increased significantly from the bottom to the top of live crown. Suggestions are made to help increase the seed yield by chemical control of insects by selection of uninfested or slightly infested trees by sequential sampling, and by selection of cone and seed insect resistant trees for seed orchards. Although no tree was wholly resistant to all three insects the best, with only 4.8 per cent of its seeds damaged, was so much better than average that it may be of considerable economic importance. The great range in apparent resistance of trees to attack by cone and seed insects should be recognized in further studies and attempts be made to determine biologically sound reasons for the observed differences. / Forestry, Faculty of / Graduate

This paper presents a study of three phases of the flight of the Douglas-fir beetle, viz: flight preparation and response, flight attitude and movements, and flight capacity. A room equipped with temperature and humidity controls was used for some of the experiments. The wing movements were studied with a stroboscope and flash photography. Flight mills were used in the studies involving flight duration and velocity. The only effect of nemic and mite associates was reduction of the duration of the initial flight caused by internal nematodes. Temperature played an important role in all phases of flight studied. Temperatures from 72° to 89° F. were optimum for spontaneous flight, while 68° F. seemed to be the lower limit of flight in the absence of additional stimuli. In sunlight, spontaneous flights occurred at 63° F. Increasing temperature caused a rapid increase in the wing-beat frequency up to the threshold for spontaneous flight, then increased only slightly to the level of heat prostration. Lower temperatures greatly reduced the duration of the initial flight and caused a broken flight pattern, but failed to influence the over-all flight duration. The effects of relative humidity followed a similar pattern to those of temperature inasmuch as evaporational cooling of the insect occurred at low relative humidities not at high relative humidities. Increased light intensity increased the speed of the flight response and caused slight increases in the wing-beat frequency; both results being attributed to increased nervous stimulation. Studies on the effect of the ehange in the beetles’ activity from dispersal to gallery construction to re-emergence, on the response to flight stimulation, showed that once gallery construction had begun the females became flight refractory, some regaining their inclination to fly after 15 days. On the other hand, the males could be expected to be either flight positive or refractory throughout the duration of gallery construction. The number of individuals responding positively to flight stimulation by tossing increased greatly following the first toss, then diminished until no further change occurred after six tosses. Wing mutilation and loading produced changes in the wing-beat frequency similar to those found by other workers, and indicated that the changes were probably due to altering the inertia of the oscillating system. Fatigue caused a gradual reduction in the wing-beat frequency over a four hour period although the final per cent decrease attributable to fatigue was much lower than that reported for other insects. The flight velocity was of the order of 90 to 115 metres per minute or 3.3 to 4.2 miles per hour, changes in the flight velocity seemingly being related directly to changes in wing-beat frequency. It is concluded from these studies that the Douglas-fir beetle is a strong uniform flier despite the complexity of components affecting several phases of flight. The various thresholds for spontaneous flight were consistently above the levels required for continuation of the activity. The flight of the Douglas-fir beetle can be expected to vary greatly from year to year and from season to season depending on the environmental factors. Of the flight movements it is the wing-beat frequency which is affected the most by environmental changes, thus varying the strength, velocity and magnitude of the flight. The Douglas-fir beetle is capable of an average flight of up to 10 miles immediately following take-off and from between 15 to 20 miles a day for several days; favourable air currents would increase these figures substantially. / Science, Faculty of / Zoology, Department of / Graduate

A study was made to determine if there is a growth response in Douglas-fir seedlings to the presence of mycorrhizal associations. Nursery, potted and pure culture experiments were carried out to induce the formation of mycorrhiza on Douglas-fir seedlings. Seedlings from natural areas were examined to give an indication of the types of mycorrhiza which occur and the age at which they are formed. Variation in the number and type of mycorrhiza as determined by site factors was studied. Well-developed mycorrhiza were found in natural seedlings as young as three months old. Most of the seedlings examined showed well-developed mycorrhiza by the end of the first growing season. Only typical ectotrophic mycorrhiza were found in Douglas-fir seedlings. They occurred in a range of sites, but the occurrence could not be correlated with variation in site factors. In the nursery and potted experiments there were no significant differences between the treatments as indicated by the height, root volume or number of mycorrhiza of the seedlings. All attempts to induce the formation of mycorrhiza on Douglas-fir seedlings in pure culture were unsuccessful. / Science, Faculty of / Botany, Department of / Graduate

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

Grand fir (Abies grandis (Dougl.) Lindl.) and amabilis fir (A. amabilis (Dougl.) Forbes) were grown in sand cultures from seed for two growing seasons in a greenhouse. The effects of deficiencies of nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur on the growth and development of the seedlings were studied. Four soil treatments were included to provide a comparison with natural media. These deficiencies caused a significant reduction of growth of both species, except in the low sulphur treatment; this was attributed to contamination. The treatments also affected the root/shoot and foliage/stem ratios, and produced a reduction in the total moisture content. The foliage was analysed for the total concentration of each of the six elements studied. In each case that of the deficient element was much reduced. The grand fir foliage concentrations were consistently higher than for amabilis fir and were influenced more greatly by the treatments. Each deficiency produced a different visual effect. These were documented photographically, chiefly in colour. The actual colours of symptoms were not specific, but the patterns generally were. Diagnostic keys to the deficiency symptoms were prepared. Magnesium and phosphorus symptoms were very distinctive, potassium and calcium were usually so, and nitrogen the least. An unreported type of calcium deficiency symptom, interpretable as a dieback phenomenon, was observed and described. Neither dry weight nor any other single criterion was able to express the net result of any treatment. A method to do this is proposed. It was found that the expression of the deficiency symptoms changed with time. In general it was observed that grand fir is more sensitive to deficiencies than amabilis fir. / Science, Faculty of / Botany, Department 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