Sierran vegetation: A gap analysis

TitleSierran vegetation: A gap analysis
Publication TypeBook Chapter
Year of Publication1996
AuthorsDavis, FW, Stoms, DM
Book TitleSierra Nevada Ecosystem Project: Final Report to Congress, vol. II, Assessments and scientific basis for management options
PublisherUniversity of California, Centers for Water and Wildlands Resources
CityDavis, California
KeywordsCalifornia, gap analysis, land management, Sierra Nevada, vegetation

Gap analysis assesses the distribution of plant community types and vertebrate species distributions among land classes defined by ownership and levels of protection of biodiversity. Gap analysis helps to identify which plant communities and species might be especially vulnerable to different human activities that can lead to habitat conversion or degradation. This chapter presents a gap analysis of plant community types the Sierra Nevada region, an area of 63,111 km2 (24,368 mi2). Ownership of the region is 37% private, 47% national forests, 10% national parks, 5% Bureau of Land Management, and less than 2% in other public lands. Land ownership and land management patterns contrast sharply between the northern Sierra Nevada versus the central and southern subregions. Parks and reserve lands contribute less than 2% of the northern region versus 27% of the central/southern. We mapped eighty-eight natural plant community types within the region. Sixty-seven types were mapped over areas greater than 25 km2 (9.65 mi2). The ownership profiles of Sierran plant communities systematically reflect the concentration of private lands at lower elevations and of national parks in the central and southern portion of the range. Less than 1% of the foothill woodland zone of the Sierra Nevada is in designated reserves or other areas managed primarily for native biodiversity, and over 95% of the distribution of most foothill community types is available for grazing. Low to middle elevation Sierran forests are not well represented in designated reserves, especially in the northern Sierra Nevada. However, large areas of most of these forest types on U.S. Forest Service lands have been administratively withdrawn from intensive timber management based on current forest plans. Many high-elevation forest and shrubland community types are well represented in parks and ungrazed wilderness areas. Our analysis identifies thirty-two widespread community types whose conservation status warrants concern and twelve types that appear well protected based on their present distributions.