Treesearch

High foliar nitrogen concentration ([N]) is associated with high rates of photosynthesis and thus high tree productivity; however, at excessive [N], tree productivity is reduced. Reports of excessive [N] in the Douglas-fir forests of the Oregon Coast Range prompted this investigation of growth and needle physiological responses to increasing foliar N concentrations in 1-year-old Douglas-fir seedlings. After 1 year of N fertilization, total seedling biomass increased with each successive increase in N fertilizer concentration, except in the highest N fertilization treatment. Of the many...

We have collected sporocarps and tuberculate ectomycorrhizae of both Rhizopogon vinicolor and Rhizopogon vesiculosus from three 50 x 100 m plots located at Mary's Peak in the Oregon Coast Range (USA); linear map distances between plots ranged from c. 1 km to c. 5.5 km. Six and seven previously developed microsatellite markers were used to map the approximate size and distribution of R. vinicolor and R. vesiculosus genets, respectively. Genetic structure within plots was analyzed using spatial autocorrelation analyses. No significant clustering of similar genotypes was detected in either...

Plethodon stormi and Plethodon elongatus are two closely related species of plethodontid salamanders that are restricted to the Klamath Province of northwestern California and southwestern Oregon. Discovery of three localities south of the Klamath River, in the Scott River drainage, not assignable to either P. elongatus or P. stormi, motivated closer examination of this complex. We describe molecular (mitochondrial DNA) and morphological variation among specimens collected from the three newly discovered populations and compare these to populations of P. elongatus and P. stormi from...

Rangelands are plant communities dominated by grasses, forbs, and shrubs. Their primary use by humans worldwide is for livestock grazing, but these communities also are habitat for wildlife. Traditionally, wildlife-related concerns of range managers focused on predators of livestock and on wildlife species that are hunted. Today, managers are interested in biodiversity and a wide range of species. Management of public rangelands in the United States is constrained by federal and state laws, which require managers to address the impact of management activities on all wildlife.

We used logistic regression to derive scaled resource selection functions (RSFs) for female black bears at two study areas in the North Cascades Mountains. We tested the hypothesis that the influence of roads would result in potential habitat effectiveness (RSFs without the influence of roads) being greater than realized habitat effectiveness (RSFs with roads). Roads consistently had a negative influence on black bear RSFs across seasons and study areas. Roads reduced habitat effectiveness during all seasons at both study areas and changes in the potential habitat values ranged from 1.7%...

We studied the effects of post-harvest treatments on regeneration and forest composition 13-27 years following harvest in high-elevation forests of the North Cascade Range, Washington. Eighteen sites encompassing three common post-harvest treatments were examined at elevations ranging from 830 m to 1460 m. Treatments included: (1) sites broadcast burned and planted with Abies amabilis or Abies procera; (2) unburned sites seeded with A. amabilis or A. procera; and (3) unburned sites mostly planted with A. amabilis. Overstory and understory species composition was determined and compared to...

We examined the seed ecology of Iliamna longisepala as an aid to developing a conservation strategy for this rare endemic forb of northcentral Washington. We conducted field, greenhouse, and laboratory studies to quantify: (1) densities of buried viable seed among sites with different histories of burning, (2) post-fire spatial distributions of germinants relative to reproductive plants and bum severity, (3) seed production and its annual variation, and (4) germination requirements. Density of seed in the soil was not significantly related to history of burning, but sites that experienced...

We examined movements of North American elk (Cervus elaphus) in northeastern Oregon, USA. Movement vectors at 449 locations over a 7762 ha area were calculated based on 16,724 sequential observations of 94 female elk-year combinations during spring (15 April-14 May) 1993, 1995, 1996. We calculated movement vectors at the start of morning and evening feeding bouts (0500, 1900 h) and during periods of least activity (0100, 1500 h). Here, we measured characteristics of habitat patches (habitat type, mean patch size, coefficient of variation in patch size, edge density, mean shape index, and...

Western hemlock (Tsuga heterophylla (Raf.) Sarg.) families were grown under different levels of shade for 2 or 3 years at two nursery sites to determine whether families performed differently relative to one another in the different shade environments. Differences were found both for levels of shade and families, but no family x shade interaction was found. Results suggest that families selected in full-sun environments (clearcuts or farm fields) may be well suited for use in silvicultural systems where seedlings are planted in understory conditions.

As highlighted in previous chapters, the primary biological objectives of CFIRP were to assess impacts of diverse silvicultural treatments on vegetation structure and growth and on the abundance and diversity of wildlife. Stand conditions resulting from implementation of the CFIRP research design, however, provided for the overlay of additional research projects that utilized subsets of CFIRP units. Described below are studies focused on genetic ramifications of the CFIRP silvicultural treatments, and chemical and biological interactions between ambrosia beetles (family Scolytidae) and...