Treesearch

Down wood provides important faunal microhabitat in forests for many invertebrate taxa, small mammals, and amphibians. Habitat suitability of down wood as refugia is an increasing concern in managed forests of the US Pacifi c Northwest, where overstory reduction may result in both reduced down wood recruitment and increased temperatures within logs, which may make them unsuitable habitat refugia. We examined temperature regimes inside logs and soils to assess buff ering capabilities against summer temperature extremes and potential habitat suitability for plethodontid salamanders. Temperatu...

Variable-density thinning has received a lot of public attention in recent years and has subsequently become standard language in most of the Willamette National Forest’s timber management projects. Many techniques have been tried, with varying on-the-ground successes. To accomplish variable-density thinning, the McKenzie River Ranger District currently uses combinations of techniques such as skips, gaps, dominant tree releases, variable thinning prescriptions, designation by description (DxD), and individually marked trees within the same harvest unit. Th e major challenge associated with...

Density management through thinning is the most important tool foresters have to aff ect stand development and stand structure of existing stands. Reducing stand density by thinning increases the growing space and resource availability (e.g., light, water, and nutrients) for the remaining trees. Th is can result in increased average tree growth. More available site resources can also encourage the development of understory vegetation and trees. Alternatively, the highest amounts of stand volume (or tree biomass) growth will generally occur when the site is fully occupied. The competition...

Since the early 1990s, several studies have been undertaken to determine the planning requirements, productivity, costs, and residual stand damage of harvest operations in thinning treatments designed to promote development of complex forest structure in order to enhance ecological functioning and biological diversity. Th ese studies include the Oregon State Universityled cooperative Coastal Oregon Productivity Enhancement (COPE) project, the Willamette (National Forest) Young Stand Project (WYS), and the Siuslaw (National Forest) Th inning and Underplanting for Diversity (STUDS) project....

Headwater streams and adjacent riparian areas provide reproductive, foraging, and dispersal habitat for many forest-dependent species, especially amphibians. Although previous studies have shown that the composition of aquatic and riparian animal communities is associated with spatial and temporal patterns of stream fl ow, the relationships among stream fl ow, climate, and thinning are not well known. We characterized stream flow conditions associated with 78 headwater reaches in 13 managed forest sites in the Coast Range and western Cascade Range, Oregon, USA, tracked periodically over a...

Th inning of 30- to 70-year-old Douglas-fir (Pseudotsuga menziesii) stands is a common silvicultural activity on federal forest lands in Washington and Oregon west of the Cascade Range crest. Decreases in forest cover lead to alterations of site energy balances resulting in changes to understory and stream channel microclimates. Uncut vegetative buffers are commonly used to mitigate upland harvest eff ects on aquatic and riparian habitats and functions. To create effective buffers, we need to better understand the relationships among thinning treatments, diff erent riparian buff er widths,...

Studies over the past 40 years have established that riparian buff er retention along streams protects against stream temperature increase. Th is protection is neither universal nor complete; some buff ered streams still warm, while other streams’ temperatures remain stable. Oregon Department of Forestry developed riparian rules in the Forest Practices Act (FPA) to protect fishbearing streams from temperature increases, but it did so with acknowledgement that its rules might be insuffi cient. It developed the Riparian and Stream Function project, otherwise known as RipStream, to validate...

Down wood plays many functional roles in aquatic and riparian ecosystems. Simplifi cation of forest structure and low abundance of down wood in stream channels and riparian areas is a common legacy of historical management in headwater forests west of the Cascade Range in the US northwest. Contemporary management practices emphasize the implementation of vegetation buffers adjacent to streams, and on federal lands thinning has become a predominant form of timber harvest. Th e combined effects of thinning and riparian buff er width on the down wood dynamics in stream channels and riparian...

Down wood is associated with the function, structure, and diversity of riparian systems. Considerable knowledge has been generated regarding down wood stocks and dynamics in temperate forests, but there are few studies on effects of silvicultural practices and riparian buffer design on down wood, particularly in headwater streams. We analyzed interactive eff ects of upland thinning and riparian buffer configuration on down wood volumes and decay classes at fi ve managed forest sites in western Oregon. We tested the eff ects of two thinning treatments—an unthinned control and a moderate-dens...

Large woody debris is recognized as an important component of stream geomorphology and stream ecosystem function, and forest-land management is recognized as an important control on the quantity (and size and species distributions) of wood available for recruitment to streams. Much of the wood present in streams comes from adjacent forests, and riparian management practices now refl ect our understanding of the role these forests play in modulating and maintaining stream environments. In steep terrain, slope failures also carry wood (and sediment) to streams from upslope source areas. In...