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

Salal (Gaultheria shallon Pursh.) understory in a 800 tree/ha 31-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand was cut and removed from around one of each of four pairs of adjacent trees, the root zones of which were isolated using plastic sheeting buried to bedrock. The differences in the courses of the average root zone soil water content (Φ) during the growing season were small (maximum difference = 0.03 m³ m⁻³ ) because total evapotranspiration was only slightly higher where salal was present than where it had been removed. Porometer and lysimeter measurements on selected days indicated that salal transpiration was 0.5-1 mm d⁻¹ greater than forest floor evaporation in cut subplots and that Douglas-fir transpiration was 0.2-0.5 mm d⁻¹ higher where salal had been removed. The slight increase in Φ where salal had been removed corresponded to significantly higher soil water potential and Douglas-fir pre-dawn twig xylem water potential at low values of Φ, owing to the steepness of the water retention curve for the gravelly sandy loam soil. This resulted in significantly greater tree diameter growth where salal had been removed than where it remained. Shuttleworth's development of the Penman-Monteith equation for multilayer, partially wet forest canopies was modified for use in the hypostomatous canopies of Douglas-fir and salal. This evapotranspiration theory was combined with standard hourly micrometeorological measurements, transfer resistance functions and canopy and root zone water balance equations to provide calculations of forest evapotranspiration (E) over extended growing season periods. There was generally good agreement between calculated values of E and values determined using Bowen ratio/energy balance, water balance and porometer measurements. The slightly higher values of Φ resulting from understory removal corresponded to significantly higher tree transpiration rates calculated over early (June) and late (August) growing season periods. Most of the difference in calculated tree transpiration occurred during the final one-half of these periods when at low values of Φ slightly lower Φ corresponded to significantly lower ψs where salal remained, leading to a reduction in Douglas-fir transpiration due to stomatal closure. The increase in calculated tree transpiration as a result of understory removal was greatest where understory leaf area index was highest and trees were largest. / Land and Food Systems, Faculty of / Graduate

Seven outbreaks of Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough, have recurred in the interior of British Columbia since 1915. But little is known about their impacts on renewable resources in affected stands. A study was undertaken to examine effects of the most recent outbreak on understory vegetation and tree productivity near Kamloops, British Columbia. Dry weight forage production was sampled from 1m² circular plots under various levels of stand crown cover (0-96%) and density (0-45.9m²/ha), as modified by defoliation. Crown cover was determined using a moosehorn, and from vertical photographs obtained with a 160° lens mounted on a conventional camera. Stand density was determined using a 20 factor prism. Increment cores were obtained at breast height, and radial growth analysed under the Addo-X. Ring width behaviour was compared with occurrence of past outbreaks. The ecological literature on 0. pseudotsugata was reviewed. Negligible amounts of forage were obtained from many plots with undefoliated trees. In defoliated plots with live trees, total forage production ranged from 0.0 under 96% crown cover and 45.9 m²/ha density to 648.9 kg/ha under 50% crown cover and 16.0 m²/ha density. The average yield in small openings was 3667.4 kg/ha. High variability was evident. In one stand, two years following its defoliation and consequent death, total forage yields exceeded those from nearby small openings. Forage yield data were described better by logarithmic models than by hyperbolic ones, at 95% probability. Impacts on tree growth were not demonstrable one year following defoliation. Many trees recovered even from complete defoliation. Insect outbreaks and periods of slow tree growth coincided, but quite inconsistently. Apparently, most scattered infestation patches develop independently of each other. Grazing values should increase in seriously defoliated stands even without range seeding. On poor sites and in stands managed primarily for forage production, outbreaks of 0. pseudotsugata may be left alone without necessarily endangering remote stands. Selective control favoring better sites managed for tree production should improve efficiency of investing scarce funds in protection of the inventory. Tree growth and insect outbreaks may be under the influence of some regional climatic factor, but local factors are also important. A need remains for long term impact studies on tree growth, forage yield and nutrient status, and other resources. / Forestry, Faculty of / Graduate

Granular water-insoluble lignins were isolated from a series of aqueous organic solvent (organosols) cooks designed for pulping/sac-charification of Douglas-fir sawdust. Among the factors affecting yield and characteristics of the isolated organosolv lignins, only cooking time (5-20 minutes) and concentration of acid catalyst (0-0. IN HC1) were investigated as cooking variables. Cooking temperature (200°C) and solvent composition (acetone/water=60:40) were held constant. It was learned that the acidified organosolv cooking system is far more efficient in delignification and saccharification than a-queous acid hydrolysis under identical conditions. In organosolv cooking, simultaneous dissolution of lignin and sugars occurs in the cooking liquor, allowing continued and total dissolution of the wood constituents. In the present study, only the water-insoluble lignin fraction was isolated and analyzed. An almost quantitative recovery of the precipitable lignin was accomplished by evaporation of the organic solvent from the spent liquor, followed by removal of sugars dissolved in the aqueous solution and reprecipitation of the crude lignin into water. To eliminate the interference from hydrogen bonding and unconjugated carbonyl group in the isolated organosolv lignins, acetylation or reduction was carried out before the lignin samples were characterized. The resulting lignin samples were found to be completely free of cabohydrate contaminants. Both cooking time and acid concentration were found to have a profound effect on the yield of lignin fractions, and chemical and macromolecular properties of the lignin molecules due to two competing reactions, hydrolytic depolymerization and recondensation. These reactions take place simultaneously in the cooking liquor during organosolv cooking. The balance between these two reactions is believed to be responsible for not only the content of functional groups, as revealed by nuclear magnetic resonance, infrared and ultraviolet spectral analyses, but also the size of lignin molecules, as measured by gel permeation chromatographic and scanning electron microscopic analyses of the isolated organosolv lignins. The functional group contents, determined by elemental and spectral analyses, were found to be 0.86-0.97 methoxyl, 0.20-0.49 aromatic hydroxyl and 0.68-0.99 aliphatic hydroxyl groups per C₉-unit of the organosolv lignin molecules. It was also noted that 63-68% of aromatic nuclei have condensed forms with carbon-carbon linkages, having only two hydrogens on each guaiacyl nucleus. The organosolv lignins were found to have much lower molecular weights than those of protoligniri in wood. Typical values of the number average molecular weight of the isolated lignins ranged from 823 to 1,144. The low molecular weight values are due to degradation reactions during the cooking by cleavage of aryl-alkyl linkages of lignin molecules. The particle size of the spherical precipitated lignins ranged from 25 to 500 nm. / Forestry, Faculty of / Graduate

Numerical data were collected from the karyotypes of seven species in the Pseudotsuga genus, P. forrestii, P. sinensis, P. gaussenii, P. japonica, P. wilsoniana, P. macrocarpa and both varieties of P. menziesii, (Douglas-fir), menziesii and glauca. A comparative karyotype study was made utilizing chromosome number, secondary constrictions and chromosomal characteristics, to identify and separate the different species. Both varieties of Douglas-fir contained a somatic chromosome number of 2n=26 consisting of five metacentrics, six submetacentrics and two telocentric pairs. P. macrocarpa and the Asiatic species contained a somatic chromosome number of 2n=24 consisting of six metacentric and six submetacentric pairs. Douglas-fir could be identified by chromosome number. An analysis of variance and a multivariate stepwise discriminant function analysis were employed to test the validity of using karyotype data such as arm ratio, centromere index, morphological index and relative length for characterizing the cytogenetical and the geographical differences for each of the n=12 species. Good discrimination was shown among P. macrocarpa and the Asiatic species for both the analysis of variance and the multivariate analysis. The discrimination among the Asiatic species was further improved when the well separated P. macrocarpa was omitted. A high level of discrimination was observed between the two varieties of Douglas-fir by both the t-test and the multivariate analysis. The multivariate analysis was particularly helpful in selecting variables that best separated the taxa. To my knowledge, these results provide the first reported karyotype numerical analysis for the Pseudotsuga genus as well as the first reported karyotype analysis for P. gaussenii. / Forestry, Faculty of / Graduate