Treesearch

This report synthesizes the literature on the role of informal economic activity in the United States postindustrial economy. Informal economic activity is expanding in the United States and is likely to continue in the foreseeable future. The formal and informal economic sectors are inextricably intertwined, with individuals and households combining elements of both sectors to construct their livelihoods. Although the informal economy is often thought of as the domain of economically marginal individuals and households, virtually everyone participates in the informal economy to some...

High resolution, active remote sensing technologies, such as interferometric synthetic aperture radar (IFSAR) and airborne laser scanning (LIDAR) have the capability to provide forest managers with direct measurements of 3-dimensional forest canopy surface structure. Although LIDAR systems can provide highly accurate measurements of canopy and terrain surfaces, high-resolution (X-band) IFSAR systems provide slightly less accurate measurements of canopy surface elevation over very large areas with a much higher data collection rate, leading to a lower cost per unit area. In addition, canopy...

Relationships between diel changes in stem expansion and contraction and discharge and refilling of stem water storage tissues were studied in six dominant Neotropical savanna (cerrado) tree species from central Brazil. Two stem tissues were studied, the active xylem or sapwood and the living tissues located between the cambium and the cork, made up predominantly of parenchyma cells (outer parenchyma). Outer parenchyma and sapwood density ranged from 320 to 410 kg/m3 and from 420 to 620 kg/m3, respectively, depending on thc species. The denser sapwood tissues exhibited smaller relative...

We studied effects of timber harvest with green-tree retention on litter-dwelling predatory arthropods (spiders and carabid beetles). Arthropods were sampled with pitfall traps at four experimental blocks in western Oregon and Washington. Within each block, arthropods were collected 5 to 7 years after treatment in five 13-ha harvest units including a control and four that represent contrasts in retention level (15 vs. 40 percent of original basal area) and spatial pattern (dispersed vs. aggregated in 1-ha patches). More than 47,000 arthropods were collected during two 6-week periods in...

To better understand the long-term basal area and diameter growth response of young, well-stocked, even-aged, mixed-species stands of western hemlock (Tsuga heterophylla (Raf.) Sarg.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) to a range of thinning intensities (heavy, moderate, light, and unthinned), 20 years of posttreatment (i.e., thinning) data were analyzed from 128 permanent study plots at 32 installations in southeast Alaska. Thinning significantly increased the basal area growth of the thinned plots relative to that of the unthinned plots. Basal area growth of the thinned...

This publication describes the bird communities of major mainland rivers of southeast Alaska and is based on a review of all known relevant studies as well as recent fieldwork. We synthesized information on the composition, structure, and habitat relationships of bird communities at 11 major mainland rivers. Information on current management concerns and research needs are also included.

Lichens are highly valued ecological indicators known for their sensitivity to a wide variety of environmental stressors like air quality and climate change. This report summarizes baseline results from the U.S. Department of Agriculture, Forest Service, Forest Inventory and Analysis (FIA) Lichen Community Indicator covering the first full cycle of data collection (1998–2001, 2003) for Washington, Oregon, and California. During this period, FIA conducted 972 surveys of epiphytic macrolichen communities for monitoring both spatial and long-term temporal trends in forest health. Major...

The effects of mechanical disturbance from traditional ground-based logging and site preparation on volcanic ash soil and associated tree growth were investigated by using two study approaches in a retrospective study. This research was conducted on volcanic ash soils within previously harvested units in the Blue Mountains of northeast Oregon and southwest Washington. We assessed soil and tree attributes and their association with higher and lower levels of soil disturbance. The two approaches were independent efforts that yielded very different results.In the first study approach, we used...

Estimates of forest carbon stores and flux for California circa 1990 were modeled from forest inventory data in support of California’s legislatively mandated greenhouse gas inventory. Reliable estimates of live-tree carbon stores and flux on timberlands outside of national forest could be calculated from periodic inventory data collected in the 1980s and 1990s; however, estimation of circa 1990 flux on national forests and forests other than timberland was problematic owing to a combination of changing inventory protocols and definitions and the lack of remeasurement data on those land...

In recent years, interest has increased in restoring Oregon white oak (Quercus garryana Dougl. ex Hook.) and prairie landscapes in the Pacific Northwest, especially where elements of historical plant communities are intact. We evaluated the effect of alternative management scenarios on the extent and condition of Oregon white oak, the extent of prairie, and the harvest and standing volumes of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) within a 2934-ha portion of Fort Lewis, Washington (named the Tenalquot Planning Area for the purpose of the project). A landscape-level analysis of...