Treesearch

Fire has been described as both a major ecological force necessary for long-term functioning of Sierra Nevada ecosystems and as one of the greatest threats to human and natural resources (SNEP 1996a). Fire has shaped the terrestrial ecosystems of the Sierra Nevada for millennia. Before the mid-1800s, fires generally were frequent and mostly of low to moderate intensity, from lower-elevation blue oak woodlands through upper-montane red fir forests (Skinner and Chang 1996). Modern fire regimes are highly altered from their historical character because of the combined effects of fire exclusion...

Management practices have altered both the structure and function of forests throughout the United States. Some of the most dramatic changes have resulted from fire exclusion, especially in forests that historically experienced relatively frequent, low- to moderate-intensity fire regimes. In the Sierra Nevada, fire exclusion is believed to have resulted in widespread vegetation changes, including greater density and cover of white fir (Abies concolor) and reduction in the area occupied by hardwoods and shrubs (Parsons and DeBenedetti 1979, Vankat and Major 1978). Fire exclusion has allowed...

During the past 80 years, various disturbances (such as wildfire and wind events) and management actions (including fire exclusion, logging, and domestic livestock grazing) have significantly modified the composition and structure of forests and ranges across the western United States. The resulting fuel loadings directly influence potential smoke production from wildland and prescribed fires and affect the vulnerability of landscapes to extreme fire behavior and crown fires. Assessments of potential smoke production and tradeoffs in air quality and fire hazard relative to managed fire and...

This candidate RNA is on the Lassen National Forest in Siskiyou County. It is approximately 37 air miles (60 km) due E. of Mount Shasta and about 27 miles (43 km) N. of Fall River Mills. The cRNA lies within the Hat Creek Ranger District. Its boundaries include parts of sections 10, 11, 12, 14, and 15 of T40N, R3E MDM (41°19'N., 122°36'W.), USGS Hambone quad. Ecological subsection – Medicine Lake Lava Flows (M261Dh).

Community types and codes (Holland 1986) are in boldface; research natural area names (with ecological survey names in parentheses, if different from the research natural area names) are in plain type.

The policies and strategies that guide the use and management of lands in the Sierra Nevada ecoregion depend on objective scientific information. In recent years, the region has attracted increasing attention from visitors, developers, environmentalists, businesses, scientists, and politicians as well as local residents, resource managers, and research groups. And the effects of management decisions on the status and trends of lands and natural resources in the Sierra Nevada seem to carry more weight each year. Accordingly, a great deal of new ecological information has been collected and...

Thirty years ago, the fate of migratory deer in the Sierra Nevada was thought to be the major forest wildlife issue. Ten years later, agencies were building the California Wildlife Habitat Relationships System to allow managers to integrate all terrestrial vertebrates with timber management in comprehensive National Forest planning. Another ten years after that, Tom Knudsen wrote his Pulitzer Prize–winning series, "Sierra in Peril," describing the complexity of environmental problems. Now, managers are trying to improve the lot of all native species in the Sierra Nevada, address fire...

Nobel prizewinner Paul Crutzen argues that the Holocene period of Earth history has ended, within the past century or so, and that we are now at the beginning of the "Anthropocene," the period in which the face of the Earth and the composition of its atmosphere has been altered by our species. One indicator of this is the concentration of carbon dioxide in the Earth’s atmosphere, which started to climb in the 19th century and has now reached higher levels than for millions of years. This has implications for global climate and also for the functioning of both terrestrial and aquatic...

Mountain ecosystems of the Western United States are complex and include cold desert biomes, such as those found in Nevada; subpolar biomes found in the upper treeline zone; and tundra ecosystems, occurring above timberline. Many studies (for example, Thompson 2000) suggest that high-elevation environments, comprising glaciers, snow, permafrost, water, and the uppermost limits of vegetation and other complex life forms, are among the most sensitive to climatic changes occurring on a global scale. The stratified, elevationally controlled vegetation belts found on mountain slopes represent...

The core assumption of this symposium is that science can provide insight to management. Nowhere is this link more formally established than in regard to the science and management of forest ecosystems. The basic questions addressed are integral to our understanding of nature; the applications of this understanding are crucial to effective stewardship of natural resources (Carpenter and Turner 1998, Christensen and others 1996). For example, the challenge of managing Sierra Nevada forests motivated an unprecedented ecosystem assessment of the entire bioregion with the explicit goal of...