Publications

The introduction of nonnative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grassland on the Colorado Plateau (U

Genetic and morphological diversity of Phyllodoce empetriformis (Sw.) D. Don and Phyllodoce glanduliflora (hook.) Cov. were surveyed in Mount Rainier National Park in the Cascade Mountains of Washington State. Paired populations at high and low elevations were sampled at three study areas between 1720- and 2451-m elevation. Allozyme analysis of four polymorphic loci indicates high levels of geneti

We explored spatial patterns of low-frequency variability in radial tree growth among western North American conifer species and identified predictors of the variability in these patterns. Using 185 sites from the International Tree-Ring Data Bank, each of which contained 10a??60 raw ring-width series, we rebuilt two chronologies for each site, using two conservative methods designed to retain any

We examined epiphytic macrolichen communities in Pseudotsuga menziesii (Douglas-fir) forests across the western Oregon landscape for relationships to environmental gradients, stand age and structure, and commercial thinning. We used a retrospective, blocked design through the Coast and the western Cascade ranges of Oregon. Each of our 17 blocks consisted of a young, unthinned stand (age 50-110 yr)

No abstract available.

Marbled Murrelets (Brachyramphus marmoratus) are threatened seabirds that nest in coastal old-growth coniferous forests throughout much of their breeding range. Currently, observer-based audio-visual surveys are conducted at inland forest sites during the breeding season primarily to determine nesting distribution and breeding status and are being used to estimate temporal or spatial trends in mur

We sought a simple and effective transplant method that could be used to measure biomass accumulation rates of epiphytic bryophytes. Trials were carried out in the Pseudotsuga menziesii-dominated forests of western Oregon. We tested multiple transplant methods over a 13-month period while comparing accumulation rates of Antitrichia curtipendula (Hedw.) Brid. and Isothecium myosuroides Brid. among

Electrocution on power lines is one of many human-caused mortality factors that affect raptors. Cost-effective and relatively simple raptor-safe standards for power line modification and construction have been available for over 25 years. During the 1970s and early 1980s, electric industry efforts to reduce raptor electrocutions were very coordinated and proactive, but predictions about resolving

Satellite telemetry was used to determine fall migratory movements of Ospreys (Pandion haliaetus) breeding in the United States. Study areas were established along the lower Columbia River between Oregon and Washington; in north-central Minnesota; on Shelter Island, New York; and in southern New Jersey. Seventy-four adults (25 males, 49 females) were tracked from 1995 through 1999. Migration route

Mixed conifer and hardwood stands in southwestern Oregon were studied to explore the hypothesis that competition effects on individual-tree growth and survival will differ according to the species comprising the competition measure. Likewise, it was hypothesized that competition measures should extrapolate best if crown-based surrogates are given preference over diameter-based (basal area based) s

Killdeers (Charadrius vociferus) are considered a common species that inhabits a wide range of wetland and upland habitats throughout much of North America, yet recent information suggests that they may be declining regionally, if not throughout much of their range. To address this issue, we examined population trends of this species at multiple spatial and temporal scales using data from two majo

Many plants exploit patchy resources through clonal foraging. Plants established in field plots were used to determine if Elymus lanceolatus ssp. lanceolatus (Scribner et J.G. Smith) Gould (thickspike wheatgrass) showed a clonal foraging response to neighbour densities, as it had previously shown to patchy soil nutrients. Neighbours consisted of the rhizomatous E. lanceolatus ssp. lanceolatus and