Treesearch

Water uptake and transport were studied in eight liana species in a seasonally dry tropical forest on Barro Colorado Island, Panama. Stable hydrogen isotope composition (δD) of xylem and soil water, soil volumetric water content (θv), and basal sap flow were measured during the 1997 and 1998 dry seasons. Sap flow of several neighboring trees was measured to assess differences between lianas and trees in magnitudes and patterns of daily sap flow. Little seasonal change in θv, was observed at 90-120 cm depth in both years. Mean soil water δD during the dry season was -19‰ at 0-30 cm, -34‰ at...

With increases in harvest of forests in the Pacific Northwest during the late 1800s and early 1900s came a concern for future timber supplies. Unsuccessful attempts at selective logging in Douglas-fir (Pseudotsuga menziesii (Mirb.) France) and a better understanding of requirements for natural regeneration led to the adoption of moderate-sized clearcuts with adjacent uncut timber as a seed source (Curtis and Carey 1996). As a response of the need for more dependable regeneration, the 1950s saw a shift to artificial regeneration methods and the establishment of state forest practice...

This history was compiled from the memoirs, diaries, and other personal documents of the two forest entomologists in charge of the first forest insect laboratories on the west coast. It traces the lives of the two pioneers from 1902 to 1952 as they pursued their careers in the USDA Bureau of Entomology, Division of Forest Insect Investigations. Cooperative bark beetle control projects with the USDA Forest Service, Park Service, and private timber owners guided much of their early activities. Later, when the laboratories were located on university campuses, cooperative research was undertake...

The Olympic Habitat Development Study was initiated in 1994 to evaluate whether active management in 35- to 70-year-old stands could accelerate development of stand structures and plant and animal communities associated with late-successional forests. The study used a variable-density thinning prescription as the main tool to alter stand structure; the prescription entailed creating gaps and retaining uncut areas, and thinning the remaining forest matrix. We assessed tree damage (primarily windthrow) following thinning, 5-year tree growth, and 3-year vegetation development in control and...

Historically, the Alaska forest products industry has been driven by pulp production and the export of logs and cants primarily to Japan. Economic stagnation in Japan, the closure of Alaska's two pulp mills, harvest restrictions, and increased competition have severely impacted the industry. To survive, the industry must make significant investments in capital equipment, which requires adequate access to business credit. This article examines whether credit availability is a barrier to the future growth of the industry. Data were collected through a mail survey in spring 2002. Our results...

Zero-order basins, where hillslope topography converges to form drainages, are common in steep, forested landscapes but we know little about their ecological structure. We used indirect gradient analysis to characterize gradients in plant species composition and cluster analysis to characterize groups of plant species associated with specific geomorphic areas. We sampled vegetation within 63 randomly selected zero-order basins in the southern Coast Range of Oregon and collected data on herb, shrub, and overstory tree cover, as well as environmental conditions. Zero-order basin overstories...

Spruce beetle, Dendroctonus rufipennis (Kirby), populations periodically reach outbreak densities throughout the range of spruce, Picea spp., in western North America. During outbreaks it may kill thousands to millions of trees over vast areas, dramatically altering forest structure, composition, and ecological processes, thus impacting a variety of resource values (Schmid and Frye 1977, Veblen et al. 1991, Holsten et al. 1995, 1999, Ross et al. 2001). Current options for reducing negative impacts on resource values caused by the spruce beetle include harvesting high-risk trees, sanitation/...

In forested, mountain landscapes where debris flows are common, valley-spanning debris dams formed by debris-flow deposition are a common feature of headwater valleys. In this paper, we examine how wood and boulder steps, i.e., debris dams, affect longitudinal profile relief and gradient at the debris-flow-fluvial transition in three sites in the Oregon Coast Range, USA.

A density-dependent matrix model was developed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) -- western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest stands in the Pacific Northwest of the United States. The model predicted the number and volume of trees for 4 species groups and 19 diameter classes. The parameters were based on species-dependent equations linking individual tree growth, mortality, and stand recruitment to tree and stand characteristics, including stand diversity in terms of tree species and size. The equations were estimated with individual tree and stand data...

International protocols, such as those of the Montreal Process (MP), specify desired outcomes without specifying the process and components required to attain those outcomes. We suggest that the process and its components are critical to achieve desired outcomes. We discuss recent progress in northwestern North America, on three topics that will facilitate development of and reporting in sustainability protocols: (1) common terms and comparable guidelines for soil disturbance, (2) cost-effective techniques for monitoring and assessing soil disturbance, and (3) improved methods to rate...