Treesearch

Sierra Nevada Ecosystems. The Sierra Nevada evokes images particular to each individual's experience of the range. These images take on the quality of immutability, and we expect to find the range basically unchanged from one year to the next. The Sierra Nevada, however, including its rocky foundations and the plants and animals that inhabit it, changes continually through time. Ecosystems respond to cumulative effects from the past; the old-growth forests in the Sierra today evolved under different conditions from those of the present. To understand how the landscapes of the Sierra Nevada...

The Tertiary period, from 2.5 to 65 million years ago, was the time oforigin of the modern Sierra Nevada landscape. Climates, geology,and vegetation changed drastically in the Sierra Nevada during thistime, and analyses of this period provide both context for and insightinto vegetation dynamics of the current and future Sierra. During theearly Tertiary, warm-humid, subtropical to tropical conditions prevailedon the low, rolling plains of the area now the Sierra Nevada. Fossiltaxa with tropical adaptations and affiliations were widespreadthroughout the region. In the Sierra Nevada, ginkgo...

Abstract: The combined effects of wind velocity and percent slope on flame length and angle were measured in an open-topped, tilting wind tunnel by burning fuel beds composed of vertical birch sticks and aspen excelsior. Mean flame length ranged from 0.08 to 1.69 m; 0.25 m was the maximum observed flame length for most backing fires. Flame angle ranged from -46o to 50o. Observed flame angle and length data were compared with predictions from several models applicable to fires on a horizontal surface. Two equations based on the Froude number underestimated flame angle for most wind and...

The Sierra Nevada Ecosystem Project (SNEP) case-study assessmentof the Mammoth-June Ecosystem Management Project(MJEMP) was undertaken to review and analyze the efficacy of alocal landscape analysis in achieving ecosystem-management objectivesin the Sierra Nevada. Of primary interest to SNEP was applicationof the new U.S. Forest Service (USFS) regional process forlandscape analysis, especially use of historic and natural range ofvariability. An underlying assumption in current USFS approaches isthat managing lands within historical and natural ranges of variabilitywill promote ecological...

Symptoms of ozone injury on western pines, ranging from effects on needles to effects on portions of ecosystems, can be differentiated from symptoms induced by other natural biotic and abiotic stressors occurring in the same area. Once identified in laboratory and field studies, quantification and monitoring of these symptoms can be used to provide reliable information on the effects of air pollution on forest trees and ecosystems. Monitoring symptoms of ozone injury can be used to determine status, changes, and trends in effects ranging from needle injury to tree growth. This chapter...

Official conservation efforts for the northern spotted owl began in the United States in 1975 when it was declared “threatened” in the state of Oregon; efforts continued in a sporadic and unsystematic way through the 1980s. In 1989 the Interagency Scientific Committee (ISC) was established by Congress and charged with the development of a scientifically defensible conservation strategy covering the entire range of the northern spotted owl, which includes parts of the states of Oregon, Washington, and California. The ISC collated all spotted owl research and approached questions concerning...

The Sierra Nevada Ecosystem Project mapped 945 areas in the Sierra Nevada of ecological, cultural, and geological significance. Theseareas contain outstanding features of unusual rarity, diversity, andrepresentativeness on national forest and national park lands. Morethan 70% of the areas were newly recognized during the SNEP project. Local agency specialists familiar with local areas mapped553 ecological areas (average size 1,359 ha [3,349 acres]), 198 culturalareas (average size 2,371 ha [5,804 acres]), and 194 geologicalareas (average size 3,822 ha [9,443 acres]) during workshopsheld...

Recent petitions to list the fisher (Martes pennanti) under the Endangered Species Act have brought attention to fisher conservation. Although commercial trapping of fishers in California ended in 1946, summarizing the commercial harvest data can provide a historical perspective to fisher conservation and may indicate the prevalence of incidental fisher captures in traps set for other species. We investigated the relationships between historical fisher harvests and the price paid for fisher pelts, number of trapping licenses sold, cost of a trapping license, total number of 5 sympatric...