干旱区生态环境知识资源中心(Arid): Ecological Investigations of the Federally Endangered Shivwits Milk-Vetch (‘Astragalus ampullarioides‘) Annual Report, 2006.

Arid

报告编号	PB2007107139
	Ecological Investigations of the Federally Endangered Shivwits Milk-Vetch (‘Astragalus ampullarioides‘) Annual Report, 2006.
	Miller, M. E; Mann, R. K; Goldstein, H; Yount, J. D.
英文摘要	Astragalus ampullarioides (Welsh) Welsh, the Shivwits milk-vetch, is an herbaceous perennial legume that was listed as federally endangered in September 2001 (U.S. Fish and Wildlife Service 2001). Known populations of this edaphic endemic species are restricted to Washington County, Utah, with the majority of occurrences found on gently sloping outcrops of the Triassic Petrified Forest Member of the Chinle Formation at the edge of the Mojave Desert. At the time of listing in 2001, surveys estimated a total of 1000 individuals for the species. In April-May 2006, surveys estimated approximately 4205 individuals distributed among 6 populations (U.S. Fish and Wildlife Service 2006). Of the total number of individuals estimated in spring 2006, over 75 percent were distributed among three subpopulations in Zion National Park and approximately 60 percent occurred at a single 0.3-ha site in the Park. In addition to small population sizes and limited geographic distributions, the species is threatened to varying degrees by urbanization, livestock grazing, off-road vehicle use, and invasive exotic plants.
英文关键词	Plants(Botany) Endangered species Ecology Legumes Surveys Habitat Populations Mortality Soils Vegetation Natural resources management Conservation Annual report Shivwits milk-vetch Astragalus ampullarioides
出版年	2007
语种	英语
国家	United States
URL	http://r.cnki.net/KCMS/detail/detail.aspx?DbCode=KJBG&dbname=KJBGW&filename=59fb2cd431c97d1d54a00277
来源机构	United States Geological Survey
资源类型	科技报告
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/273537
推荐引用方式 GB/T 7714	Miller, M. E,Mann, R. K,Goldstein, H,等. Ecological Investigations of the Federally Endangered Shivwits Milk-Vetch (‘Astragalus ampullarioides‘) Annual Report, 2006.,2007.