Chinook salmon, mountain sheep and old growth forests are disappearing in the Sierra Nevada, as people and pollution threaten the health of this California treasure.
That is the conclusion of a three-year, $6.5 million study, the Sierra Nevada Ecosystem Project (SNEP). Requested by Congress and funded primarily by the U.S. Forest Service, it is the most thorough study ever done on the 400-mile-long mountain range. The final report on the project--produced by a large team of scientists and researchers from public universities, resource agencies and independent consulting firms--assesses the ecological, economic and social conditions in the Sierra Nevada and offers management options to enhance the region. It found that, while the mountain range is in fairly good health now, rapid population growth, ongoing neglect and pollution from the Central Valley threaten the future of the region's forests, species diversity and air and water quality.
"This study raises our understanding of the Sierra Nevada to a new level," said Don Erman, the SNEP science team leader and UC Davis professor of wildlife, fish and conservation biology. "We can solve most of the problems of the Sierra but we, as a society, must act soon. The options available to us to ensure the long-term sustainability of this national treasure will begin to close down rapidly."
Project scientists devoted most of their efforts to analyzing existing information rather than conducting new studies or experiments. Key findings
include:
* Aquatic and associated riparian systems are the most altered and impaired habitats in the Sierra. Chinook salmon and steelhead, which once ran in most of the major streams, have been nearly eliminated from the range due to dams and impoundments.
* "Old growth" forests have been drastically reduced by a variety of human activities, including timber harvesting, indiscriminate burning in the 19th century and fire suppression in this century.
* Air quality in the Sierra represents both extremes. At times, the air quality in the northern Sierra Nevada is among the cleanest in the world. But farther south along the west side, ozone and small particulates from Central Valley sources creep up the mountainside, resulting in some of the worst air quality in the nation.
* Plant diversity in the Sierra is enormous--more than 3,500 species of plants (about half the state's total) are found in the area. The biggest threats to the integrity of these plant communities are human settlement, livestock grazing and fire suppression. Oak woodlands and other plant communities in the foothill region have been converted to human settlement at an "alarming rate" in the last century.
* Terrestrial vertebrates--mammals, birds, reptiles and amphibians--number about 400 species in the Sierra. Sixty-nine species of terrestrial vertebrates (17 percent of the Sierra fauna) are considered at risk. Species perilously in decline include bighorn mountain sheep, Yosemite toad, western pond turtle and California horned lizard. Three native species once common in the Sierra Nevada are no longer found there--grizzly bear, Bell's vireo and California condor.
* Human settlement in the Sierra Nevada is taking place at a rapid pace. As of 1990 an estimated 650,000 people lived in the Sierra Nevada, with 70 percent of that population located in the foothills of the west side. Projections suggest that by the year 2040, the population will swell to between 1.5 million and 2.4 million people.
The SNEP report is available at county UC Cooperative Extension offices, at University of California campuses at Davis, Berkeley, Riverside and Los Angeles and electronically via the Internet at http://ceres.ca.gov/snep
