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

No description available.

Thesis (M.S.)--Humboldt State University, 2008. / Includes bibliographical references (leaves 19-28, 49-57). Also available via Humboldt Digital Scholar.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 58-62). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographic references (leaves [53]-56).

Thesis (M.S.)--Oregon State University, 2003. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2004. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2004. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.