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Provision of forage for wild and domestic ungulates, and the associated impacts of their herbivory, are contentious issues for wildland management in western North America. We quantified the composition, above-ground net production (ANP), and utilization of herbaceous and shrub vegetation in five non-forest and seven forest cover types across the core spring-summer-fall range of the Yakima elk herd in the eastern Washington Cascade Range. We randomly sampled each cover type along three elevational transects during a two-year period. Riparian/meadow was the most productive cover type (2,752 kg ha-1 ANP). High-productivity forest at low to high elevations produced 900-1200 kg ha-1 ANP. High-elevation forest and grassland, shrubland, and shrub-steppe produced 600–700 kg ha-1 ANP. The low-productivity forest cover types and parkland produced 100–400 kg ha-1 ANP. Utilization of forbs, grasses, and shrubs combined averaged 47% of ANP across all cover types, ranging from 26% in high-elevation forest to 63% in shrub-steppe. Grasses and forbs were equally utilized at about 57% of ANP, whereas shrubs were utilized at only 4% of ANP. Twenty-two of 55 shrub species accounted for the majority of shrub productivity and showed little to no long-term browsing; but, several shrub species were moderately to severely hedged. Moderate to high levels of ungulate utilization indicate potentially strong impacts of ungulate herbivory on pattern and process in eastern Cascades forests. Dry forest restoration management to reduce fuel loads and restore resiliency to disturbance likely will increase forage for ungulates, especially in closed-canopy true fir and Douglas-fir stands.
In the past several years, a fungal epidemic has devastated hibernating bat populations in eastern North America, with an estimated loss of 5.7 to 6.7 million bats as of January 2012. The potential for the disease to spread to bat populations in the western states and Canadian provinces remains unknown, but is cause for significant concern. This wildlife health crisis has been dubbed white-nose syndrome (WNS), for the distinctive white fungal growth that appears on the muzzles, ears, and wing membranes of affected bats. This fungus, the recently named species Geomyces destructans, has been determined to be the causal agent of WNS. However, relatively little is currently known about the ecology of this organism, its potential for invasiveness in the Northwest, and about how disease spreads within and between bat populations. Our purpose here is to summarize current epidemiological knowledge about WNS, in an ecological context relevant to efforts to understand the epidemic and predict its potential to spread to western bat populations. Because of strong similarities between WNS and some invasive fungal diseases of crops and forests, our approach is to incorporate epidemiological perspectives borrowed from the field of plant pathology as well as from wildlife pathology. We highlight research needs that will help to understand, predict, and manage this devastating wildlife disease.
Accurate quantitative descriptions of bull trout (Salvelinus confluentus) growth are important for understanding life history and developing reliable stock assessments. In the absence of age validation, important steps are to review the precision of age estimation methods and evaluate whether age estimates yield growth rates consistent with known fish growth based on tag recoveries. We assessed the precision of age estimates using pelvic fin rays and scales for migratory bull trout (297–605 mm total length) from the North Fork Clearwater River, and then compared growth estimates derived from both structures with growth based on tag recoveries. Fin rays produced a lower coefficient of variation (CV = 5.84) than scales (CV = 12.56). Ages estimated from scales were higher for fish aged < 5 with fin rays and lower for fish aged ≥ 5. Comparisons of growth estimates derived from 70 tagged bull trout at large from 0.35 to 3.02 years with age-length equations based on fin ray and scale annuli indicated that ages estimated from fin rays (N = 189, predicted length of an age 3 fish = 310mm) were closely related to the apparent ages estimated from the mark-recapture model (apparent age of a 310mm fish = 2.9) whereas scales (N = 65, predicted length of an age 3 fish = 408mm) were not. This is the first study to assess the precision of structures for modeling growth of larger migratory bull trout. However validation of annuli formation from the recapture of known-age fish is recommended.
English sole is used as a sentinel species for contaminant studies in Puget Sound because it is abundant, easily sampled, and broadly distributed in the northwestern United States. Moreover, this species exhibits a number of well-documented effects of polycyclic aromatic hydrocarbon (PAH) exposure. To assess the potential for contaminant exposure during spawning migrations and to track the localized movements of adult English sole in the vicinity of Eagle Harbor, we used acoustic telemetry. In August 2007, we collected 19 English sole from Eagle Harbor, a small embayment of Puget Sound with a long history of PAH contamination and subsequent remediation actions. Fish were surgically implanted with uniquely-coded acoustic transmitters and their movements were tracked via an array of eight submersible receivers inside Eagle Harbor and near its entrance. In addition, we obtained detection data from over 70 other receivers throughout Puget Sound that were maintained by a consortium of regional researchers. All tagged fish were detected immediately after release, and 18 were detected outside of Eagle Harbor at a variety of locations in Puget Sound. Some of these fish made rapid movements across the sound and traveled minimum distances of 32 to 106 km. Half of the fish detected outside Eagle Harbor returned to their capture site in spring 2008, approximately eight months after tagging. This fidelity to summer feeding habitats has important implications for both contaminant studies and flatfish management. In addition, our results illustrate the power of data sharing and the value of pooling resources to maintain large arrays of acoustic receivers.
There is a limited understanding of the distribution and transport of solutes in the coastal forest-peatland systems of northern British Columbia, Canada. The purpose of this research was to evaluate the sources, concentration and flux of major ions and dissolved organic carbon (DOC) in the soil-groundwater system of a forest-peatland complex in the coastal western hemlock (CWH) forest zone. DOC dominated the groundwater flux, with most of it exported during high flow conditions. Inorganic ion concentration increased and DOC decreased with ground surface slope and community type from open peatland to bog woodland, bog forest, swamp forest and upland forest. Base cations, HC03- and DOC in the peatland forest communities differed significantly (P < 0.05) from concentrations in the upland forest. The greatest concentrations of ions derived from mineral weathering were found in the upland forest where the absence of peat, deep mineral soil (85-465 cm) and steep surface slope (26%) combined to increase dissolution by recharging groundwater. N03-, S042- and P043- were at or below detection limits. Concentrations of DOC, metals and HC03- decreased from summer to spring with dilution by rainfall and decreasing decomposition. In addition to providing novel data in a data-sparse region, this study provides an analysis of the processes controlling runoff production and the transport and transformation of biogeochemical elements impacting stream water quality.
We investigated the diet of the western terrestrial garter snake (Thamnophiselegans) along the Grande Ronde River in southeastern Washington. Snakes were collected with mass, snout-vent length and sex recorded. Of the 38 snakes collected 27 contained 31 prey items. The most abundant prey item was sculpin fish (Cottusspp.) (81.5%). There was no statistically significant relationship between size or sex of snake and prey presence, absence or size. Our data demonstrate that there is no change in prey base in relation to snake size or age. This is also the first population of Thamnophiselegans shown to specialize on Cottid fish in October, pre-overwintering hibernation.
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