Treesearch

Pacific trout Oncorhynchus spp. in western North America are strongly valued in ecological, socioeconomic, and cultural views, and have been the subject of substantial research and conservation efforts. Despite this, the understanding of their evolutionary histories, overall diversity, and challenges to their conservation is incomplete. We review the state of knowledge on these important issues, focusing on Pacific trout in the genus Oncorhynchus. Although most research on salmonid fishes emphasizes Pacific salmon, we focus on Pacific trout because they share a common evolutionary history,...

Variation in climate, disturbance regime, and forest management strongly influence terrestrial carbon sources and sinks. Spatially distributed, process-based, carbon cycle simulation models provide a means to integrate information on these various influences to estimate carbon pools and flux over large domains. Here we apply the Biome-BGC model over the four-state Northwest US region for the interval from 1986 to 2010. Landsat data were used to characterize disturbances, and forest inventory data were used to parameterize the model. The overall disturbance rate on forest land across the...

In rivers supporting Pacific salmon in southeast Alaska, USA, regional trends toward a warmer, wetter climate are predicted to increase mid- and late-21st-century mean annual flood size by 17% and 28%, respectively. Increased flood size could alter stream habitats used by Pacific salmon for reproduction, with negative consequences for the substantial economic, cultural, and ecosystem services these fish provide. We combined field measurements and model simulations to estimate the potential influence of future flood disturbance on geomorphic processes controlling the quality and extent of...

There is a long history of controversy surrounding Forest Service decisions; the agency is sued for NEPA violations more often than any other federal agency. Consequently, the Forest Service has spent a significant amount of time and resources addressing the requirements of the NEPA process, trying to identify and reduce risk factors associated with administrative and judicial challenges to NEPA decisions.This synthesis and annotated bibliography seeks to develop a more comprehensive understanding of the factors that influence NEPA challenge risks and successes in order to inform and guide...

We investigated carbon dynamics in the hyporheic zone of a steep, forested, headwater catchment western Oregon, USA. Water samples were collected monthly from the stream and a well network during base flow periods. We examined the potential for mixing of different source waters to explain concentrations of DOC and DIC. We did not find convincing evidence that either inputs of deep groundwater or lateral inputs of shallow soil water influenced carbon dynamics. Rather, carbon dynamics appeared to be controlled by local processes in the hyporheic zone and overlying riparian soils. DOC...

Evidence of shifting dominance among major forest disturbance agent classes regionally to globally has been emerging in the literature. For example, climate-related stress and secondary stressors on forests (e.g., insect and disease, fire) have dramatically increased since the turn of the century globally, while harvest rates in the western US and elsewhere have declined. For shifts to be quantified, accurate historical forest disturbance estimates are required as a baseline for examining current trends. We report annual disturbance rates (with uncertainties) in the aggregate and by major...

With longer and more severe fire seasons predicted, the incidence and extent of fires are expected to increase in western North America. As more area is burned, past wildfires may influence the spread and burn severity of subsequent fires, with implications for ecosystem resilience and fire management. We examined how previous burn severity, topography, vegetation, and weather influenced burn severity on four wildfires, two in Idaho, one in Washington, and one in British Columbia. These were large fire events, together burning 330 000 ha and cost $165 million USD in fire suppression...

The 2013 Rim Fire was the third largest wildfire in California history and burned 257 314 acres in the Sierra Nevada Mountains. We evaluated air-quality impacts of PM2.5from smoke from the Rim Fire on receptor areas in California and Nevada. We employed two approaches to examine the air-quality impacts: (1) an evaluation of PM2.5concentration data collected by temporary and permanent air-monitoring sites and (2) an estimation of intake fraction (iF) of PM2.5from smoke. The Rim Fire impacted locations in the central Sierra nearest to the fire and extended to the northern Sierra Nevada...

Simulating an advancing fire front may be achieved within a Lagrangian or Eulerian framework. In the former, independently moving markers are connected to form a fire front, whereas in the latter, values representing the moving front are calculated at points within a fixed grid. Despite a mathematical equivalence between the two methods, it is not clear that both will produce the same results when implemented numerically. Here, we describe simulations of fire spread created using a level set Eulerian approach (as implemented in the wildland-urban interface fire dynamics simulator, WFDS)...

Coastal carbon cycling models remain incomplete in key continental margins worldwide. Large quantities of labile terrestrial DOC are transferred to the Gulf of Alaska in a flow of freshwater discharge from thousands of watersheds that equals the discharge of the Mississippi River. The coastal margin of southeast Alaska and British Columbia is a potential hotspot of worldwide DOC metabolism and the mass and reactivity of DOC in rivers and estuaries of the region make quantifying and modeling DOC export a priority. Scaling DOC export requires a well-constrained model of streamwater DOC...