Treesearch

Litter nutrient dynamics contribute significantly to biogeochemical cycling in forest ecosystems. We examined how site environment and initial substrate quality influence decomposition and nitrogen (N) dynamics of multiple litter types. A 2.5-year decomposition study was installed in the Oregon Coast Range and West Cascades using 15N-labeled litter from Acer macrophyllum, Picea sitchensis, and Pseudotsuga menziesii. Mass loss for leaf litter was similar between the two sites, while root and twig litter exhibited greater mass loss in the Coast Range. Mass loss was greatest from leaves and...

Patterns of riparian hydraulic gradients and stream-groundwater exchange in headwater catchments provide the hydrologic context for important ecological processes. Although the controls are relatively well understood, their dynamics during periods of hydrologic change is not. We investigate riparian hydraulic gradients over three different time scales in two steep, forested, headwater catchments in Oregon (WS01 and WS03) to determine the potential controls of reach-scale valley slope and cross-sectional valley geometry. Groundwater and stream stage data collected at high spatial and...

Snowshoe hares (Lepus americanus Erxleben, 1777) fluctuate in 9–10 year cycles throughout much of their North American range. Regional synchrony has been assumed to be the rule for these cycles, so that hare populations in virtually all of northwestern North America have been assumed to be in phase. We gathered qualitative and quantitative data on hare numbers and fur returns of Canada lynx (Lynx Canadensis Kerr, 1792) in the boreal forest regions of Alaska, Yukon, Northwest Territories, and northern British Columbia to describe synchrony in the time window of 1970–2012. Broad-scale...

Ongoing warming at high latitudes is expected to lead to large changes in the structure and function of boreal forests. Our objective in this research is to determine the climatic controls over the growth of white spruce (Picea glauca (Moench) Voss) at the warmest driest margins of its range in interior Alaska. We then use those relationships to determine the climate variables most likely to limit future growth. We collected tree cores from white spruce trees growing on steep, south-facing river bluffs at five sites in interior Alaska, and analyzed the relationship between ring widths and...

Microsatellite primers were developed for Nootka cypress ( Callitropsis nootkatensis ) to provide quantitative measures for gene conservation that can assist in guiding management decisions for a species experiencing climate-induced decline.

Managers charged with managing landscapes influenced by elk are challenged to establish monitoring protocols that identify when impacts are responsible for declining ecological condition. We assessed the impact of elk herbivory on plant communities on an elk winter range by comparing canopy cover of common species that represented subjectively selected heavy and light elk impacts. Winter elk use has little direct impact on existing bunchgrasses, but winter elk traffic disrupts soils and provides the potential for invasive plant establishment.

This research examines a unique case of tourism planning and explores the relationships between governance, power, and citizen participation in community decision-making. In less than two years, the community of Sitka, Alaska, undertook two separate tourism-planning processes in response to proposed tourism development. The first plan followed a participant-led governance structure; the second plan a council-led governance structure. The participant-led governance structure produced a plan through a collaborative process that empowered citizen participants and sought to limit growth, while...

Our objective was to examine effects of groups of mixed numbers and ages of male North American elk Cervus elaphus on the reproductive performance of females. We conducted research at the Starkey Experimental Forest and Range in northeastern Oregon, USA, during 1993-2000. Each spring in late March, we released 40 female elk, eight yearling (9-month old) male elk and 2-8 branch-antlered elk (i.e. =>2 years of age during rut the following autumn) into a 622-ha fenced pasture. Elk were gathered during autumn and early winter, and were brought to winter feeding grounds where blood samples were...

Model-data fusion is a process in which field observations are used to constrain model parameters. How observations are used to constrain parameters has a direct impact on the carbon cycle dynamics simulated by ecosystem models. In this study, we present an evaluation of several options for the use of observations inmodeling regional carbon dynamics and explore the implications of those options. We calibrated the Terrestrial EcosystemModel on a hierarchy of three vegetation classification levels for the Alaskan boreal forest: species level, plant-functional-type level (PFT level), and...

Climate-induced changes in the tundra fire regime are expected to alter shrub abundance and distribution across the Arctic. However, little is known about how fire may indirectly impact shrub performance by altering mycorrhizal symbionts. We used molecular tools, including ARISA and ITS sequencing, to characterize the mycorrhizal communities on resprouting Betula nana shrubs across a fire-severity gradient after the largest tundra fire recorded in the Alaskan Arctic (July-October 2007). Fire effects on the components of fungal composition were dependant on the scale of taxonomic resolution....