Assessment

* Natural Diversity Database

* Terrestrial Vertebrates Restricted to the Sierra Nevada

Management Strategy

* SNEP Significant Areas Inventory

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Plant Diversity Of Californias 7,000 vascular plant species, about 50% occur in the Sierra Nevada. Of these, more than 400 species are found only in the Sierra Nevada, and 200 are rare.

Threats to Plant Diversity Three plant species marginally within the Sierra Nevada (Monardella leucocephala, Mimulus whipplei, and Erigeron mariposanus) appear to have become extinct in the last hundred years.

Vertebrate Diversity About 300 terrestrial vertebrate species (including mammals, birds, reptiles, and amphibians) use the Sierra Nevada as a significant part of their range, although more than 100 others include the Sierra Nevada as a minor part of more extensive ranges elsewhere.

Extinction Three modern vertebrate species once well distributed in the range are now extinct from the Sierra Nevada: Bells vireo, California condor, and grizzly bear.

Vertebrate Species at Risk Sixty-nine species of terrestrial vertebrates (17% of the Sierra fauna) are considered at risk by state or federal agencies, which list them as endangered, threatened, of special concern, or sensitive.

Loss of Foothill Habitat Eighty-five terrestrial vertebrate species require west-slope foothill savanna, woodland, chaparral, or riparian habitats to retain population viability; 14% of these are considered at risk.

Loss of Riparian and Old-Growth Habitat The most important identified cause of the decline of Sierran vertebrates has been loss of habitat, especially foothill and riparian habitats and late successional forests.

Genetic Diversity Activities occurring in the Sierra Nevada that pose the greatest indirect and direct threats to genetic diversity are those that break the chain of natural selection and adaptation.

Genetic Management Genetic guidelines that alert managers to activities likely to have genetic consequences and inform managers about preferred management of seeds, plants, mushrooms, animals, insects, and other germ plasm have been mostly lacking, inadequate, or poorly implemented in land management of the Sierra.

Community Distribution Excluding marginal plant communities mainly distributed in the Mojave Desert and Great Basin, the Sierra Nevada encompasses eighty-eight plant community types as defined by Californias Natural Heritage Division.

Private Ownership of Plant Communities Many of the foothill community types fall largely within private lands, notably grassland (88% of the mapped distribution on private lands), valley oak woodland (98%), blue oak woodland (89%), interior live oak woodland (71%), and foothill pineoak woodland (82%).

Grazing Livestock grazing has been implicated in plant compositional and structural changes in foothill community types, meadows, and riparian systems, and grazing is the primary negative factor affecting the viability of native Sierran land bird populations.

Timber Harvest Six forest types are mostly found on lands available for firewood cutting or timber harvest, including interior live oak (81%), black oak (56%), east-side ponderosa pine (72%), Sierran mixed conifer (67%), Sierran white fir (62%), and lower cismontane mixed coniferoak (70%).

Type Conversions Nearly 800,000 acres of oak woodlands in the Sierra Nevada have been converted to other land uses and vegetation types over the last forty years, a decline of almost 16%.