http://hdl.handle.net/1957/7866 Search the Channel search http://ir.library.oregonstate.edu/dspace/simple-search http://hdl.handle.net/1957/9139 Title: Effect of site and silvicultural treatment on insect pests and diseases of young ponderosa pine <br/> <br/>Abstract: Ponderosa pine is an important species both commercially and ecologically in western North America. This study considers the incidence of insect and disease pests on a series of replicated ponderosa pine research plantations in northern California. The studies, on an environmental gradient, contain a series of silvicultural treatments including vegetation control, fertilization application and insecticide application/ thinning. The mean annual temperature and total precipitation were used as climatic variables and the site index was considered as an environmental site variable. Needle retention was negatively correlated to the site productivity, with no treatment affects. Estimates of mean needle retention were in-line with those found in the literature. Total foliar herbivory was the lowest at the highest productivity site, again there were no treatment effects. The gouty pitch midge had the highest level of infestation on the branches of the trees at the site with the lowest productivity. The environmental variables support this with drier, warmer and higher sites being more susceptible. Sequoia pitch moth attacks were highest at the more drier and warmer sites while treatments with vegetation control appear to experience higher levels of attack. Total foliar pathogen infection was the lowest at the highest site index. There was no statistically significant difference between the other five sites and no treatment effect was established. Western gall rust was the highest that the most productive sites and treatments that were fertilized had higher levels of infection. The year of gall infection was associated with the occurrence of El Niño events in the study time period. <br/> <br/>Description: Graduation date: 2009 http://hdl.handle.net/1957/9103 Title: Effects of beaver on streams, streamside habitat, and coho salmon fry populations in two coastal Oregon streams <br/> <br/>Abstract: The effects of beaver (Castor canadensis) on stream morphology, riparian zones, and coho salmon (Oncorhynchus kisutch) fry in Cape and Cummins Creeks, Oregon, were examined using stream surveys, vegetation transects, and coho salmon fry counts in 1987. The basin around Cape Creek has been extensively logged since the late 1940's. Cummins Creek is surrounded by primarily old-growth forest. Cape Creek had higher densities of coho fry (P < 0.0004) than Cummins Creek. Coho fry were two to ten times more numerous in pools (P < 0.001) than in glides or riffles, respectively. The density of beaver dams in the autumn on the two streams was 1.2 and 1.1 dams/km on Cummins and Cape Creeks, respectively. By building dams, beaver added 7% and 14% more pool habitat in Cummins and Cape Creeks, respectively. This extra pool habitat was used by coho fry. Beaver ponds were larger than non-beaver ponds and thus contained more coho fry per pond. Densities of coho fry were, however, the same between beaver and non-beaver ponds. Beaver preferred to cut salmonberry (Rubus spectabilis), alder (Alnus rubra), and vine maple (Acer circinatum) stems 2-9 cm in diameter for food and dam construction. Mean distance from the stream for foraging was 17.5 m (SDS=10.1). Beaver foraged up to 90 in from the stream bank along tributaries. The percentage of available stems (for salmonberry, alder, and vine maple) cut for the small size class (0.5-3 cm) decreased after 5 in from the stream, after 20 in for the medium size class (3-9 cm) and remained stable out to 30 m for the large size class ( > 9 cm). Most cutting tended to be upstream of the dam site. The mean area affected by cutting around the dam site was 1944 sq. in (SD=921 sq. m). Proximity to a logjam, tributary, or debris slide; midstory conifer cover; overstory conifer cover; and vine maple cover were factors that separated used beaver sites from unused random sites using stepwise discriminant analysis. Proximity to a logjam, tributary, or debris slide was positively associated with the discriminant function and accounted for 50% of the variability in the discriminant function. Vine maple cover was also positively associated with dam location in the discriminant function, while midstory and overstory conifer covers were negatively associated with the dam location. Based on the results of this study, I believe beaver provide extra coho salmon rearing habitat, especially in late summer during reduced water flows. In heavily managed streams, beaver may be able to provide structure and stability in the stream at a much lower cost than stream rehabilitation projects. <br/> <br/>Description: Graduation date: 1990; Presentation date: 1989-12-06 http://hdl.handle.net/1957/9025 Title: Patterns of crown damage within a large wildfire in the Klamath-Siskiyou bioregion <br/> <br/>Abstract: The 2002 Biscuit Fire burned through more than 200,000 ha of mixed conifer/ evergreen hardwood forests in southwestern Oregon and northwestern California. The remarkable size of the fire and the diversity of conditions through which it burned provided an opportunity to analyze the correlates of burn severity across vegetation types and disturbance histories and to describe the weather, topographical, and fuel conditions that gave rise to the mosaic of crown damage. In chapter two, I focused on a region that had burned previously by the 1987 Silver Fire then was subject, in part, to salvage-logging and conifer planting before being reburned by the Biscuit Fire. I used the Landsat-based differenced normalized burn ratio (dNBR) to quantify severity in both fires and took a hypothesis-testing approach to answering two questions: First, was severity in the Biscuit Fire associated with severity in the Silver Fire in unmanaged areas? And second, did areas that were salvaged-logged and planted with conifers after the Silver Fire burn more or less severely in the Biscuit Fire than comparable unmanaged areas? I found that areas that burned severely in 1987 tended to re-burn at high severity in 2002, after controlling for the influence of several topographical and biophysical covariates. Areas unaffected by the initial fire tended to burn at the lowest severities in 2002. In addition, areas that were salvage-logged and planted after the initial fire burned more severely than comparable unmanaged areas, suggesting that post-fire logging and planting did not reduce future fire severity as had been suggested by some. In chapter three, I again focused on the twice-burned landscape, but this time I used a temporal sequence of digital aerial photography plots (6.25 ha) to measure changes in shrub-stratum, hardwood, and conifer cover. I estimated the strength and nature of relationships between crown damage and several fuel, topographical, weather, and management variables. Median crown damage, including damage to the shrub-stratum, on unmanaged plots was 63% after the Biscuit Fire and was most strongly related to damage in the Silver Fire. Plots that burned severely in the Silver Fire and had succeeded to a mix of shrubs and tree regeneration experienced high levels of Biscuit Fire damage. Plots dominated by large conifer cover after the Silver Fire had the lowest levels of Biscuit Fire canopy damage. Median crown damage was 39% for conifer cover and 85% for hardwood cover, and was most strongly related to daily average temperature and "burn period," an index of fire weather and fire suppression effort. Damage in the tree-stratum was largely independent of Silver Fire severity. Plots that had experienced stand replacing fire in 1987 and then were logged and planted with conifers had median crown damage of 100%. Plots that experienced a stand replacing fire but were unmanaged had median crown damage of 95%. The managed areas were at higher topographical positions and had greater total pre-fire cover, which may explain the small difference. These results suggest that in productive, fire-prone landscapes, the patch mosaic of young regenerating forest created by mixed-severity fire can structure the severity pattern of future wildfires occurring at short intervals and support the previous studies findings that post-fire logging and planting did not reduce fire severity. In Chapter four, I expanded my focus to include the entire region burned by the Biscuit Fire and again used digital aerial photos taken before and after the fire to interpret patterns of crown damage and relate them to several fuel, topographical, weather, and management variables. Ninety-eight percent of plots experienced some level of crown damage, but only 10% experienced complete crown damage. The median level of crown damage on unmanaged plots was 74%. Median conifer damage was 52%. The most important predictors of total crown damage were the percentage of pre-fire shrub-stratum vegetation cover and average daily temperature. The most important predictors of conifer damage were average daily temperature and burn period. Increasing levels of shrub-stratum cover were associated with increasing levels of conifer damage and hardwood damage. Large conifers had 32% median crown damage while small conifers had 62% median crown damage. Owing largely to widespread shrub-stratum cover, low-productivity ultramafic soils had 92% median crown damage compared to 59% on non-ultramafic sites. Patterns of damage were similar within the area that burned previously in the 1987 Silver Fire and edaphically comparable areas without a recently history of fire. Median crown damage in conifer plantations was 89% and plantation age was, by far, the most important predictor of the level of damage. Plantations under 20 years old experienced the highest rates of damage. I conclude that weather and vegetation conditions--not topography--were the primary determinants of Biscuit Fire crown damage. These findings suggest that in productive fire-prone ecosystems, fuel treatments that open tree canopies and stimulate shrub-stratum development may be counterproductive. <br/> <br/>Description: Graduation date: 2009 http://hdl.handle.net/1957/8987 Title: Sitka spruce and western hemlock regeneration after selective harvesting, Tongass National Forest, southeast Alaska <br/> <br/>Abstract: The objectives of this study were to determine the species composition and density of natural conifer regeneration following selective logging in southeast Alaska. Therefore, we quantified the density and size of new cohort spruce and hemlock and current seedling bank in 17 selectively logged stands. All stands were in mixed hemlock-spruce forests that were logged between 1900 and 1984, located at or near sea level, and not managed after this first logging. New cohorts included trees that germinated after logging plus advanced regeneration that was shorter than 1.4 in (standard height for diameter measurement - diameter at breast height, d.b.h.) at time of logging. With the exception of one tree, we found new cohort spruce only in plots that had been logged. New cohort hemlock were common in both logged and unlogged plots. New cohort spruce basal area ranged from 2 to 19 m2 / ha. Individuals were as large as 104 cm d.b.h. but generally ranged between 19 and 55 cm d.b.h. New cohort hemlock basal area ranged from less than 1 to 32 m2 / ha. The largest tree was 102 cm d.b.h. but most ranged from 11 to 51 cm d.b.h. The absence of new spruce in unlogged plots strongly suggests that disturbance favors spruce recruitment. The seedling bank included trees 0 to 3 m tall and less than 2.5 cm d.b.h. These seedlings became established after logging. The seedling bank density of both species was high; spruce ranged from 3,000 to 114,000 and hemlock ranged from 47,000 to 723,000 seedlings / ha. Rooting substrate (logs or undisturbed forest floor) was significant for both species (spruce p = 0.05, hemlock p = 0.0001). There were always more seedlings on logs than on undisturbed forest floor. By leaving spruce seed trees, judicious soil disturbance, planned entries to regulate overstory density and possibly planting spruce seedlings where the seed source is poor, we believe spruce can be regenerated in these systems. Pre-commercial thinning may be necessary to keep vigorously growing cohorts of spruce and hemlock in these stands, just as it is necessary in young stands regenerated after clearcutting. <br/> <br/>Description: Graduation date: 1998