Treesearch

The spatial and temporal scales of hyporheic exchange within the stream corridor are controlled by stream discharge and groundwater inflow interacting with streambed morphology. While decades of study have resulted in a clear understanding of how morphologic form controls hyporheic exchange at the feature scale, we lack comparable predictive power related to stream discharge and the spatial structure of groundwater inflows at the reach scale, where spatial heterogeneity in both geomorphic setting and hydrologic forcing are present. In this study, we simulated vertical hyporheic exchange...

This report highlights key findings from a comprehensive vegetation survey of all forested land across the state of Oregon. A total of 5,180 forested field plots in Oregon were visited by Forest Inventory and Analysis (FIA) crews over a 10-year period from 2001 to 2010. Oregon has 30 million acres of forest, covering nearly half the state. The structure and composition of Oregon’s forests differ considerably across the state, particularly east versus west of the Cascade Range. Western Oregon forests are dominated by higher productivity classes (85 to 224 cubic feet per acre annual growth)...

Weasels Mustelaspp. are specialized, small predators which demonstrate pronounced differences in size and social status according to sex and age, and these differences may manifest in spatial patterns including home range size and habitat selection. In forested North America, favored prey (voles; Microtusspp. and Myodesspp.) of short-tailed weasels Mustela ermineaoften reach high abundances in early stage forest, but availability of that cover type is limited where intensive plantation forestry occurs. We estimated home range size, including home range core area and arrangement, habitat...

Predators may limit populations of small carnivores indirectly through exploitative competition for resources, and directly through interference competition, including predation. We evaluated direct effects of predation by large predators on small, specialist carnivores by estimating annual survival and cause-specific mortality. We used known fate models to estimate annual survival of 23 radio-collared short-tailed weasels (Mustela erminea) in western Oregon in 2012–2013. Further, we reviewed published and unpublished studies of radio-tracked weasels (Mustela spp.) in North America, to...

There is worldwide interest in managing forests to improve biodiversity, enhance ecosystem services and assure long-term sustainability of forest resources. An increasingly important goal of forest management is to increase stand diversity and improve wildlife and aquatic habitat. Well-planned silvicultural systems containing a mixture of broadleaf-conifer species have potential to enhance stand diversity and provide other ecosystem services earlier than typical even-aged conifer plantations. Here, we use the example of mixed Sitka spruce/western hemlock and red alder in young, managed...

In their analysis of resampled and remeasured plot data from the USDA Forest Service Forest Inventory and Analysis (FIA) program, Barrett and Pattison (2017, Can. J. For. Res. 47(1): 97–105, doi:10.1139/cjfr-2016-0335) suggest that there is neither evidence of a recent regional decrease in yellow-cedar (Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little) live tree basal area nor a decrease in the species’ extent in southeastern Alaska. Here, we identify substantial, broad-scale agreement between their estimated extent of concentrated yellow-cedar mortality and that resulting from a...

Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2)...

With the passage of the Multiple Use Sustained Yield Act of 1960, the U.S. Forest Service has managed its 193 million acres of forest and grassland for multiple uses, including timber, watersheds, and wildlife. Using today’s terminology, some of these purposes are considered ecosystem services, which encompass a breadth of benefits provided by forests, including their ability to absorb and store atmospheric carbon, a greenhouse gas linked to climate change. National forests are now working to mitigate climate change, but the tradeoffs involved in managing for multiple ecosystem services...

In frequent-fire forests of the interior Western United States, historical (prefire suppression) conditions are often used as a reference to set management objectives, guide prescriptions, and monitor treatment effectiveness. We quantified the historical size, density, composition, and spatial patterns of dry mixed-conifer forests in the Blue Mountains of Oregon to establish reference conditions that could be used for ongoing forest-restoration efforts. In total, 14 reconstruction plots ranging from 2.3 to 5.0 ha were established, with plots located on ponderosa pine (Pinus ponderosa...

Understanding sex-specific differences in behavior and survival is essential for informative population modeling and evolutionary biology in animal populations. Uneven sex ratios are common in many migrant passerine species; however, the underlying mechanisms remain unclear. We used molecular sex determination, nest monitoring, and radio telemetry of fledgling Ovenbirds (Seiurus aurocapilla), to determine if sex-specific patterns of production, survival or behavior were present prior to the first migration. We tested whether: 1) sex ratios were skewed towards males at fledging; 2) postfledg...