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49 leaves ; 29 cm Typescript Thesis (M.S.)--University of Oregon, 1974 Includes bibliographical references (leaves 45-49) Unif. Title University of Oregon theses, Dept. of Biology, M.S., 1974

The impacts of clearcut harvesting and four intensities of mechanical site preparation were evaluated in the Virginia Piedmont using gauged watersheds. The four treatments were: 1) control, 2) chop and burn, 3) shear-disc, and 4) shear, rake-pile, disc. A combination of soil solution, streamwater and soil sampling and a series of soil incubations, both laboratory and <i>in situ</i> monitored changes in the treatment areas following site preparation. Available nitrogen reserves decreased substantially in the shear, pile, disc treatment area but increased in the chop and burn and shear-disc treatment areas following site preparation. Increased soil moisture and temperature following disturbance stimulated nutrient mobilization. Soil solution KCI extractable and <i>in situ</i> soil incubations all indicated that nitrogen mineralization was greater in the site prepared watersheds. Among the site prepared areas, treatment response followed a site preparation intensity dependent gradient. Fifteen, 26, 20 and 45% respectively of the available nitrogen reserves were mineralized within one year following site preparation in the control, chop and burn, shear-disc and shear, pile, disc watersheds. Streamwater nutrient export also increased following disturbance. Soil erosion increased in a 1:6:60 proportion in the chop and burn, shear-disc and shear, pile, disc treatment areas. Higher soil erosion led to increased sediment export in the site prepared areas. / M. S.

I studied breeding birds and vegetation in 6 largely pristine old-growth ponderosa pine (Pinus ponderosa) stands and in 3 logged stands that just met the USDA Forest Service's minimum habitat quality standards for old-growth ponderosa pine. Bird populations were similar in all stands. However, brown creepers (Certhia americana) and hermit thrushes (Cattarus guttatus) were low in abundance or absent in 2 of the minimum stands, yet were common in all other stands. Both species preferred cool, moist microenvironments for nesting and/or foraging; conditions that appeared lacking in the more xeric minimum stands. Both species are characteristic of boreal forests, which are cooler and wetter than ponderosa pine forests. I suggest that unlogged old-growth ponderosa pine forests create microhabitats that approximate conditions in more boreal forests. The minimum standards on drier sites appear inadequate in maintaining creeper and thrush habitat. Suggested modifications of the standards include, among others, canopy cover ≥ 50%.

The objective was to analyze the effects of logging and prescribed burning on carabid beetles (Coleoptera: Carabidae) at a jack pine stand and white spruce plantations in order to assess short-term impacts of these forestry practices on the diversity of this beetle group. In addition, soil scarification was also included at the jack pine stand. Based on previous reports on forest disturbance influences on carabids, it is hypothesized that short-term effects of studied forestry practices do not reduce carabids' diversity. Four carabid assemblage characteristics were compared: (a) number of catches; (b) dry mass; (c) species richness; and, (d) diversity index. Species responses and dry mass distributions were also investigated. Treatments either increased or maintained studied variables compared with control sites. Diversity indices were highest in burnt-over areas. Similar response patterns of species or groups of species were observed in both forest types. The presence of regenerating sites among the natural landscape increased carabid diversity.

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Effects of log storage on water quality, zooplankton and juvenile salmonids were investigated at Babine Lake, British Columbia in a series of enclosure, field and laboratory experiments. Enclosures were stocked with lake zooplankton and treated with lodgepole pine (Pinus Contorta) and white spruce (Picea glauca) logs for two 25 day periods. Oxygen depletion, to levels as low as 2.5 mg/l, and increased lignin and tannin (L-T) concentration (a measure of wood leachate) occurred in log treated enclosures. Zooplankton density significantly decreased with increased log number, but changes in community diversity were not consistent. In field studies at Morrison Arm, Babine Lake, extreme oxygen depletion (<1 mg/l) was observed in localized surface waters within a log storage area. Dye tracer studies within the log bundles implied reduced water movement, which may be involved in oxygen depletion. Local zooplankton abundance was usually lower at log storage sites than nearby undisturbed littoral sites and sockeye fry held in situ for 24 h periods acquired fewer and/or a lower diversity of prey items in log storage areas. Laboratory toxicity studies indicated that spruce bark leachates were more toxic than pine, but lethally toxic bark leachates had higher L-T values than those measured in the Morrison Arm log storage area. In chronic Daphnia bioassays, mortality rates significantly increased and fecundity rates significantly decreased during long term exposure to low concentrations of bark leachates. Results of enclosure experiments, field studies and laboratory bioassays provide evidence that zooplankton are reduced in abundance by conditions which accompany log storage, possibly through chronic toxicity or reduce fecundity. Because fry diet was sensitive to small changes in food abundance, there is potential for reduced survival of sockeye fry exposed to low oxygen concentrations and reduced food levels. / Science, Faculty of / Zoology, Department of / Graduate

The environmental impacts of log storage on water quality and microbiology in Babine Lake, B.C. were studied in experimental enclosures. The enclosure work was a two phase study, with data collected during the summers of 1984 and 1985. The experiments performed in the field season of 1984 involved the addition of mixed lodgepole pine (Pinus contorta) and white spruce (Picea glauca) bark debris, in different amounts, to the enclosures to examine effects on water quality (dissolved oxygen, lignins-tannins, total organic carbon, total inorganic carbon, pH, and alkalinity), bacterial activity (heterotrophy), and phytoplanktonic primary production. The 1985 study attempted to simulate a shallow water log storage facility by adding logs to the enclosures. A comparison was made of differences in water quality (including the above measurements plus chemical oxygen demand, nutrients, volatile fatty acids, and carbohydrates), and sestonic bacterial and phytoplanktonic algal populations (enumeration and biomass calculations) between (i) lodgepole pine and white spruce, and (ii) the number of logs per enclosure. The bark enclosure study resulted in organic enrichment of the enclosure ecosystem. More than 50% of the total organic carbon (TOC) was attributed to leached lignins and tannins. The leachate was capable of modifying microorganism production. Phytoplanktonic algal biomass, measured by chlorophyll ɑ, was completely eliminated at high concentrations of bark. Short term laboratory studies with bark leachate inhibited microbial activity of natural aquatic bacteria, however, from the enclosure experiments, it was apparent that with time a population of microbes would develop to utilize the chemically complex leachate. The presence of utilizable organic material (i.e. wood sugars) and an active microbial community resulted in a significant decrease in the dissolved oxygen levels. The results of the log study found significant decreases in the amount of organic extractives leached from logs compared to the TOC concentration in the bark experiment. For example, the TOC concentrations in the 5 log enclosures were approximately 20 mg/l by the end of the 25 day test period (≤ 10% was lignin and tannin carbon) ; this value was significantly smaller compared to the bark experiments, where the TOC levels in the heavy bark treatment (20 kg) reached ≃ 400 mg/l after 25 days. A comparison between the bark and log experiments (on an equivalent bark dry weight basis) found water quality degradation by bark leachates more severe than log leachates. The log leachate stimulated bacterial production and did not adversely affect phytoplankton biomass. The increase in bacterial production, a direct result of (i) an available carbon source, determined by TOC measurements and the very low concentrations of volatile fatty acids and reduced carbohydrates (rapidly utilized), and (ii) an increase in water temperature caused a decrease in dissolved oxygen levels. The spruce log enclosures for both June and July had higher heterotrophic uptake rates than the pine log enclosures. This indicated a difference in the chemical composition of the spruce and pine log leachates. This chemical difference was detected in the TOC and COD measurements and the microbial uptake kinetics experiment. These measurements found that the pine log leachate was more readily degraded (high affinity, Vmax/Kt) by a heterotrophic population than the spruce leachate, and that this difference could account for the higher dissolved oxygen demand of the pine log enclosures compared to the spruce logs. Detailed chemical analyses of the leachates in the presence of microbial inhibitors may help to delineate this discrepancy between the spruce heterotrophic uptake rates and the chemical and bacterial measurements of the pine log leachates. The enclosure studies indicated that log storage in a shallow, poorly flushed, littoral area of a lake would possibly result in an accumulation of organic components leached from the log and bark debris. The organic enrichment of the aquatic ecosystem would contribute to a potential decrease in dissolved oxygen, thus, negatively affecting fish habitat, but could increase microbial production. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

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