Rhabdogloeum pseudotsugae Sydow has been suspected of being the imperfect stage of Rhabdocline pseudotsugae Sydow since their original description by Sydow in 1922. Because Rhabdogloeum has been reported so seldom in North America, and never in Europe, this possibility has been considered slight by most investigators. Investigation of the problem of Rhabdocline pseudotsugae in British Columbia revealed several new aspects of the association between the two leaf-cast diseases. Inspection of Rhabdocline and Rhabdogloeum collections from the interior of British Columbia indicated that the association of Rhabdogloeum pseudotsugae and Rhabdocline pseudotsugae is more prevalent than was formerly believed. Collections from the coast, and on Vancouver Island in particular, indicated that the association is probably less prevalent there than in the interior. In relation to the frequent and widespread occurrence of Rhabdocline throughout the Douglas fir range however, Rhabdogloeum is seldom found. If Rhabdogloeum pseudotsugae is the imperfect stage of Rhabdocline pseudotsugae, then it appears that frequently the Rhabdogloeum stage and occasionally the Rhabdocline stage is completely suppressed, as both stages have been found dissociated from each other. Frequent observation of a group of tagged Rhabdocline-infected trees on Vancouver Island over a period of two years did not reveal the presence of a Rhabdogloeum stage. Tissue cultures of lesions from these tagged trees, however, resulted in the growth of a fungus quite similar in appearance to that produced in tissue cultures by lesions typical of those produced by Rhabdogloeum pseudotsugae. This supports the view that Rhabdogloeum pseudotsugae is the imperfect stage of Rhabdocline pseudotsugae. Observation of these trees indicated that Rhabdocline pseudotsugae is capable of vegetating two years before producing apothecia. Apparently it is also capable of vegetating more than two years or of infecting leaves other than those of the current year. / Science, Faculty of / Botany, Department of / Graduate

The effect of two commercial fertilizers on some wood properties of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) has been determined at macro- and micro- levels. Three trees, approximately 30 years of age, representing two treatments, (NH₄)₂SO₄ and NPK (N-NO₃), and an untreated control, were available. Selected trees had been fertilized first in the year 1957 at 21 to 23 years of age, and subsequently in the year 1959, with 400 lb of fertilizer per acre each time. Sections from five vertical levels of each tree were examined. The wood investigated represented each growth increment formed after 1956 and some selected ones before 1956. Response to treatment was found in the year following fertilization, with an accelerated growth rate, and a general decrease in specific gravity, per cent latewood and mean tracheid length. Maximum growth response occurred the year of re-fertilization or the year following. The greatest reduction of per cent latewood and specific gravity accompanied re-fertilization. For both fertilizers, a 4.4 per cent reduction in specific gravity followed the two separate applications, but differences in specific gravity before and after treatment were not statistically significant. Tracheid length reduction subsequent to NPK treatment was 14.5 per cent compared to less than one per cent with (NH₄)₂SO₄, but again the differences before and after treatment were not statistically significant. The tree with initially longer tracheids responded more adversely than that with shorter tracheids. Relationships between several wood characteristics indicated that macro-specific gravity was highly influenced by per cent latewood, diameter at breast height and increment width. These three variables together accounted for 57.6 per cent of the total variability in specific gravity. Macro-specific gravity was highest at the base and lowest at the top of the tree, and at any one height it was lower near the pith and higher towards the bark. Six consecutive growth increments, representing three age segments (before treatment, including and after first and second treatments, respectively), were studied at micro-level from breast height sections of each tree. Six positions within each increment were examined. Results indicated a 20 per cent reduction in tensile strength due to NPK treatment that was highly significant statistically. No apparent influence was found for (NH₄)₂SO₄; tensile strength values were, however, lower following re-fertilization as compared to untreated control. Micro-specific gravity and tracheid length followed trends similar to those of tensile strength. Strong correlation (r=0.92) was observed between micro-specific gravity and micro-tensile strength. It is proposed that N in the form of (NH₄)₂SO₄, when compared to NPK, was a better fertilizer for the two treated trees examined. It was concluded that weak residual effects of fertilization on these Douglas fir trees persisted four to five years after re-fertilization. For both treatments, increased specific gravity and growth rate resulted whereas cell length failed to demonstrate normal increase with age. / Forestry, Faculty of / Graduate

The objective of this study was to examine the relationships between Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) foliar nutrient status and forest floor chemical properties. Foliar nutrient analysis data were collected on 27, 50- to 140-year-old Douglas-fir stands, for which the forest floor chemical properties had previously been analysed. The 27 sites encompassed a broad geographical area within the Coastal Western Hemlock Biogeoclimatic Zone. Foliar samples were individually analysed for total S, N, P, K, Ca, Mg, B, Cu, Zn, Fe, Al, Mn and for AFe (active iron). Four foliar nutrient ratios (N/S, N/P, K/Ca, Ca/Mg) were additionally calculated. As the foliar sampling intensity was often below that recommended in the provincial sampling guidelines, the precision of the within-site foliar nutrient variable mean values was examined for the lowest sampling intensity used in this study (n=8). Foliar nutrient and ratio variances from 6 of the 27 sites, for which 15 trees per site had been sampled, were used as population variance estimates. A sampling intensity of n=8 was found to be sufficiently large to provide foliar nutrient variable mean estimates with an allowable error of 20% (∝ =0.5) for all but the following foliar nutrients and ratios: B, Cu, Ca/Mg and K/Ca. Two combinations of forest floor horizons were examined for possible relationships with foliar nutrient variables: L plus F and L plus F plus H. These two combinations of forest floor horizons were referred to as the LF and the LFH layers. The two criteria used to select forest floor chemical properties are as follows: (1) the precision of the forest floor chemical property site estimate was less than or equal to 20% (∝=0.5) for the field sampling intensity used, or (2) the forest floor chemical property was an established measure of nutrient availabilty. The 12 LF and 16 LFH chemical properties selected included: LF and LFH: pH (CaCl₂), total-S, -N, -P, -Cu, -Zn, -Mg, -K, -C, Min-N (anaerobic mineralizable N), KC1-N (KC1 extractable N, A (lipids), and LFH (only): exK, exCa, exMg (1M NH₄OAC exchangeable bases) and extP (Bray P₁ extractable P). Simple linear relationships between foliar nutrient variables and LF and LFH chemical properties were initially examined. Strong negative associations were found between foliar S and certain forest floor chemical properties, namely LF: pH, LMg and LFH: pH, LMg, LexMg, LexCa, LexK (here and following, L signifies the natural logarithm). It was hypothesized that these relationships reflected the effect of the different sources of plant available sulphur predominant on the higher (17 sites) and lower (10 sites) forest floor pH sites. Organic sulphur mineralization and mineral weathering were suggested as the major sources of plant available sulphur for the higher forest floor pH sites; anthropogenic atmospheric sulphur was suggested as the major source of plant available sulphur for the lower forest floor pH sites. The efficacy of forest floor (LF and LFH) chemical properties for predicting and classifying foliar nutrient status was examined through the use of multiple regression and discriminant analysis, respectively. These analyses were performed for the four foliar nutrient variables for which a range in sufficiency and possible deficiency (actual or inducible) was indicated for the stands sampled: foliar N, S, AFe and N/S. One regression model of potential predictive value was found for foliar LS. Together, LFH pH and LFH LCu statistically accounted for 79% of the observed variation in foliar LS. Several LF and LFH chemical properties were able to reliably classify stands into the following total foliar S groupings: sufficient and deficient (actual or inducible). LF LMg and LF A provided the best classification of stands into the groupings: S sufficiency and N-inducible S deficiency, as defined by foliar N/S. Three LFH chemical properties: P, S, and LexK provided the best classification of stands in terms of adequate and slight to severely deficient foliar N status. LF and LFH chemical properties were only poorly able to classify foliar AFe status. It was concluded that the relationships found in this study could not be extrapolated beyond the present study, due to the unforeseen, yet probable, influence of slightly acidic precipitation on both nutrient cycling and foliar nutrient status for 10 of the 27 stands examined. / Land and Food Systems, Faculty of / Graduate

This thesis is in the form of four self contained papers that report aspects of a study of the energy balance of a young Douglas-fir forest growing at the University of British Columbia Research Forest at Haney, B.C. The chapters discuss the experimental methods used and special instrumentation developed, the data analysis, and some attempts to understand the relationships observed by employing simple forest models and ideas on boundary layer equilibration processes. Chapter 1. The psychrometric apparatus design for Bowen ratio determination reported by Sargeant and Tanner was modified and a new apparatus built. Modification of the intake design improved the symmetry and rigidity of the sensor mounting. Wet and dry bulb differences were measured with an error less than 0.01°C over a vertical distance of 1 meter. Continuous measurements of the Bowen ratio over a 7.8-meter Douglas-fir forest were made for 6 weeks. An example of the energy balance for the forest for 1 day using this equipment is reported. Chapter 2. Daily evapotranspiration from a Douglas-fir forest was calculated using Webb's average Bowen ratio method. Webb's method is generalized to include the effects of the diabatic wind profile. Over a 17-day period characterized by light winds, the modified Webb method agreed with the daily totals of half-hour energy balance calculations to within 1 1/2% on the average, while Webb's method overestimated by 26% on the average. Chapter 3. Energy balance measurements of evapotranspiration from a young Douglas-fir forest are reported for a period of 18 days in July 1970 when soil water was not limiting. Peak daily evapotranspiration rates characteristically occurred two to three hours after solar noon and evaoptranspiration showed a short-term independence from net radiation. This behaviour is interpreted as being a consequence of the large forest roughness. Daily evapotranspiration and net radiation were, however, well correlated. Values of surface diffusion resistance calculated from Monteith's combination formula are presented. Daytime values showed significant day-to-day differences and an attempt to define a potential evapotranspiration rate assuming a constant daytime surface resistance was not successful. Comparison of evapotranspiration measurements with a potential evaporation formula for wet surfaces developed by Priestley and Taylor suggests that evaporation of intercepted water proceeds 20% more rapidly than evapotranspiration from the non-wetted canopy. Chapter 4. The process of modification of the Bowen ratio, with distance downwind of a change in surface wetness, is considered with the view to establishing the final equilibrium ratio of the fluxes of sensible and latent heat after advective effects become negligible. A method of generating, from the coupled equations for heat and vapour diffusion, two new diffusion equations in composite variables, which may be solved independently, is developed. The method leads to the conclusions that there is a basic difference between equilibration over land and over water. Also the rate of equilibration depends strongly on atmospheric mixing and hence surface roughness and atmospheric stability. It is concluded that, for terrestial surfaces, the equilibrium evaporation rate is approximated by LE = (S/[s+y])(Rn - G) for 24 hour periods. This result is in accord with some recent experimental findings. / Land and Food Systems, Faculty of / Graduate

Aphids are a widespread family of plant pests, whose abilities to suppress shoot and root growth are well documented for many terrestrial plants. Only a few studies have been conducted on conifer aphids of the genus Cinara. Cinara pseudotsugae are known to attack Douglas-fir seedlings, an important crop in the Pacific Northwest. Douglas-fir are most susceptible to aphid damage as seedlings, especially in nurseries where conditions favor aphid outbreaks. A parasitoid wasp (Pauesia sp.) attacks C. pseudotsugae, and may be useful as a biological control agent. Studies of its natural history and host interactions are needed to assess its potential as a bio-control agent. This study examined the effects of an experimental range of aphid densities on the growth of total shoot and root volume and biomass and shoot morphology of Douglas-fir seedlings. Eighteen-week tests explored short term effects of different aphid feeding intensities in both the greenhouse and field. Long term effects were tested by exposing greenhouse seedlings to 16 months of aphid feeding. The ability of the plants to recover was tested by allowing one set of seedlings to grow aphid free for one year, after being exposed to aphid feeding for 18 weeks. The success rate of parasitoids over an 18 week period was compared to aphid density in both greenhouse and field tests. Increasing aphid destiny was significantly related to decreasing root and shoot dry weights in greenhouse tests. Growth suppression increased slightly during the second year of testing, regardless of whether or not aphid feeding continued. The results for root and shoot volumes were highly variable. However, root tissue density was significantly reduced after the second year of testing. Few shoot characteristics showed consistently significant aphid effects among the trials. Stem diameter and height decreased and needle density of new buds increased significantly with aphid feeding in most tests. Root and shoot growth of field plants did not show any significant aphid effects. Percentage of parasitoid success was independent of aphid density except at the lowest aphid densities. There was a block effect on parasitoid success in the field test, that may have been a result of varying environmental conditions. These results indicate that even short term aphid feeding can have long lasting effects on plant growth and structure. The effect on shoot and root growth was small, but there were no signs of recovery. The long term effects of the reduced root tissue density on Douglas-fir is unknown. / Graduation date: 1998

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 153-169). Also available on the World Wide Web.

Thesis (Ph.D.)--University of Washington, 1998. / Vita. Includes bibliographic references (p. [128]-144).

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 146-151). Also available on the World Wide Web.

Two study plots containing Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) newly infested by Douglas-fir beetle (Dendroctonus pseudotsugae Hopk.) were established and photographed with large-scale (1:1000), colour infrared film on July 29. 1979 - approximately three months after possible insect attack. Ground checking confirmed attacked trees and also showed that at the time of photography all trees had visually green, healthy-appearing foliage. All trees, both attacked and non-attacked in each plot were matched to their photographic images, and visual photo interpretation for damage types and densitometric analysis of the original transparencies were done. For each tree-crown image included, the yellow, magenta and cyan dye layer density measurements were taken and these values plus three ratios derived from them were tested statistically using analysis of variance and stepwise discriminant analysis. Significant differences were found between the optical density values of the images of healthy and attacked trees. The ratio values had much smaller variances than did the individual dye layer densities and all three ratios showed significant differences between healthy and attacked trees. Stepwise discriminant analysis produced significant separation of damage classes. Two-thirds of the successfully attacked trees were correctly classified and were confirmed by a second ground check in January, 1980. It is concluded that successfully beetle-attacked trees have a unique spectral signature than can be detected on colour infrared air photos approximately three months after initial attack when the trees still support visually green, healthy-appearing foliage. / Forestry, Faculty of / Graduate

Thesis (M.S.)--Oregon State University, 1963. / Typescript. Includes bibliographical references (leaves 89-93). Also available on the World Wide Web.