Treesearch

Rainfall simulation is a commonly used approach for studying runoff and erosion from forest roads, and a method is needed to estimate infiltration parameters from these experiments. We used two algorithms, the Simplex and Shuffled Complex Evolution, to estimate parameters for a physically based infiltration and overland flow model. Each algorithm was tested by estimating parameters for 92 field-measured hydrographs from forest roads. Nine of the field-measured hydrographs allowed us to further test whether estimated parameters could be extended to other antecedent conditions and plot...

The single-species approach to conserving threatened and endangered species in the United States is insufficient, given the number of species (more than 700) officially considered at risk of extinction (i.e., formally listed under the Endangered Species Act of 1973), the rate at which new species are being listed (more than 50 species a year), and the number of species awaiting listing (more than 3,500 candidate species). Regions supporting many endangered species were located in the humid Southeast and the arid Southwest, and tended to be unique with respect to taxonomic composition,...

This report provides analysis of long-range trends in paper recylcling and impacts on the timber outlook for the 1993 RPA Assessment Update. Paper recycling is projected to increase substaintially in the next decade. Increased recylcing will extend timber resources and fiber supply.

Biological diversity in the United States is summarized in three categories: genetic diversity, species diversity, and community/ecosystem diversity. Major changes have occurred in the distribution and abundance of native diversity in the United States over the past 300 years. Native plant and animal diversity has declined over teh past three decades, and is likely to continue to decline because of human population growth and associated development.

Although the quality of water draining forested watersheds is typically the best in the Nation, some forest management practices can seriously impair streamwater quality. Sediment is the main concern. High suspended sediment levels, and adverse changes in stream channels, are potential problems in several regions, especially after road construction, and some harvesting and grazing practices. Impacts are most serious where fish reproduction is affected. Nitrate and water temperature are less serious problems. Harvesting can increase nitrate levels markedly, in some locations and removal of...

Current management guidelines for the Northern Goshawk (Accipiter gentilis) in the Southwest call for a mosaic habitat consisting of approximately 10 percent of the forest area in grass-forb/ shrubs, 10 percent in 2.5-12.7 cm trees, 20 percent in 12.7-30.5 cm trees, 20 percent in 30.5-45.7 cm trees, 20 percent in 45.7-61.0 cm trees, and 20 percent in 61.0 cm and greater trees. This habitat mosaic was conceived as convenient categories to describe a generally balanced, ecologically sustainable, forest ecosystem. In reality, however, the vegetative structural percentages vary. We describe...

The flammulated owl (Otus jlammealus) is an insectivorous species (Marshall 1957, Ross 1969) that breeds in dry, montane conifer forests of western North America. In Colorado , this owl fed primarily on small lepidopterans, although its diet included a variety of arthropods (e.g., Orthoptera, Diptera, and Arachnida) as summer progressed (Reynolds and Linkhart 1987). Some authors (Bent 1938, Bailey and Niedrach 1965) have reported that flammulated owls occasionally prey on small mammal s and birds. However, none of these authors provided direct evidence of flammulated owls feeding on...

Recent wetland area trends were estimated from the National Resources Inventory (NRI) for nonfederal rural lands for the period 1982-1987. NRI-based estimates of wetland area for states comprising the conterminous United States were highly correlated with estimates made by the US Fish and Wildlife Service and with estimates of coastal salt marsh wetlands made by the National Oceanic and Atmospheric Administration. Net wetland area declined by 1.1% (~363,200 ha) during the five-year study period. Conversion to open water, primarily caused by natural flooding in western inland basins, was...

The cedar (Thuja plicata) -hemlock (Tsuga heterophylla) -white pine (Pinus monticola) forests are some of the most productive in North America. Silvicultural practices used in these forests originated in Europe and usually concentrated on producing high-value commercial products.Beginning in the 1960s society's interest in the management of natural resources, especially forests, increased, and a component of society no longer desired forests managed exclusively for timber production. But a significant portion of the public still expect a high level of wood products. As society changed in...

Fluctuations in atmospheric carbon dioxide is influenced by carbon storage and cycling in terrestrial forest ecosystems. Currently, only gross estimates are available for carbon content of these ecosystems and reliable estimates are lacking for Rocky Mountain forests. To improve carbon storage estimates more information is needed on the relationship between carbon and organic matter, carbon concentrations of forest components, and how carbon storage varies among vegetation types. Therefore, this study used four different vegetation types (habitat types) to supply a portion of this informati...