400 



Human Influemis — Our Uvini> Resources 



A summary of status ranks is presented in 

 thie Figure for the approximately 2.500 

 species of native U.S. vertebrates, for more 

 than 1,200 invertebrate species from several 

 groups for which complete data sets are avail- 

 able (butterflies, crayfish, and freshwater 

 mussels), for the approximately 16,300 

 species of native U.S. flowering plants, and 

 for the approximately 675 species of ferns 

 and conifers native to the United States. 

 These ranks are the result of collaborative 

 work with Heritage Programs, conservation 

 data centers. The Nature Conservancy's sci- 



entific staff, and many other state, federal, 

 and private cooperators. 



References 



Jenkins. R.E., Jr 1988. Information management 

 for the conservation of biodiversity. Pages 231- 

 239 in E.O. Wilson, ed. Biodiversity. National 

 Academy Press. Washington. DC. 



Master, L. 1991. Assessing threats and setting pri- 

 orities for conservation. Conservation Biology 

 5(4):559-563. 



Morse. L.E. 1993. Standard and alternative taxo- 

 nomic data in the multi-institutional Natural 

 Heritage Data Center Network. Paees 69-79 in 



F.A. Bisby. G.F. Russell, and R.J. Pankhurst, 

 eds. Designs for a global plant species infomia- 

 tion system. Oxford University Press. Oxford. 

 Stein. B.A. 1993. Towards common goals: collec- 

 tions information in conservation databases. 

 Association for Systematics Collections 

 Newsletter 21(11:1-6. 



For further information: 



Bruce A. Stein 



The Nature Conservancy 



1815 N Lynn St. 



Arlington. VA 22209 



■ All listed species 

 n Listed plant species 



■ Listed invertebrate species 



■ Listed vertebrate species 



Fig. 2. Listed species occurring by 

 jurisdiction on federal land. 

 USPS— U.S. Forest Service: 

 DoD — Depailment of Defense: 

 BLM — Bureau of Land 

 Management: NPS — National Park 

 Service: USFWS— U.S. Fish and 

 Wildlife Service. 



Fig. 3. Occurrences of all listed 

 species by land ownership catego- 

 ry. See Fig. 2 for definitions of 

 abbreviations. 



375 

 350- 



325 

 300 



275 - 

 250 



§ 225- 

 S 200- 



■S 175 



150 

 125 H 



too 



50 fl 

 25 



■ILiI IIJ 



1 



USPS DoD 



BLM 



NPS USFWS Other Not 

 federal federal 



listed as endangered or threatened under the 

 ESA. About 50% of all federally listed threat- 

 ened and endangered species occur at least once 

 on federal lands (Fig. 1 ). The other half of the 

 listed species are found on either state and local 

 public lands, tribal lands, or private lands. 

 About 25% of listed species have more than 

 half of their known occurrences on federal lands 

 and can benefit substantially from federal land- 

 managetnent protection and recovery actions. 

 About 12% of listed species are found almost 

 exclusively on federal lands, with 90%- 100% of 

 their known occurrences restricted to lands 

 under federal management. 



Number of Listed Species 



About 100 species occur on land managed 

 by most major federal agencies (Fig. 2). With 

 nearly 150 species, the U.S. Forest Service 

 (USPS) harbors the largest number of federally 

 listed species of any federal agency. This larger 

 number reflects not only the size and geograph- 

 ic extent of the landholdings, but also the inten- 

 sive biological surveys that have been conduct- 

 ed on many national forests. 



Occurrences of Listed Species 



Of the 24.573 occunences of federally listed 

 species recorded by the Natural Heritage 

 Network nationwide. 36% are found on federal 

 lands (Fig. 3). The USPS, with 16% of the total, 

 has the largest number of occurrences followed 

 by the Bureau of Land Management (8%) and 

 the Department of Defense (4% ). Both the U.S. 

 Fish and Wildlife Service and the National Park 

 Service have 3% of known occurrences on their 

 lands. 



The average number of occurrences per list- 

 ed species varies markedly among plants, verte- 

 brates, and invertebrates. There are an average 

 of 34 occurretices per listed species for all 

 species combined, 17 occurrences per plant 

 species, 1 3 occurrences per invertebrate 

 species, and 67 occunences per vertebrate 

 species. The broad distribution of some federal- 

 ly listed vertebrates heavily influences these 

 figures, however. Just 12 vertebrate species 

 (e.g.. bald eagle) account for 12,121 occur- 

 rences, representing 49% of the total for all 

 species. Excluding these 12 vertebrates, the 

 average number of occurrences for vertebrates 

 drops to 20 and the overall average to 17. 



Conclusions 



This analysis puts in perspective the rele- 

 vance of federal land inanagement for the pro- 

 tection of federally listed threatened and endan- 

 gered species. Agencies that manage federal 

 lands have substantial responsibilities and 

 opportunities for protecting listed species, par- 

 ticularly those that are found exclusively, or 

 mostly, on federal lands. An example of a plant 

 entirely restricted to federal lands is Ruth's 

 golden aster (Pityopsis riiiliii). and an animal 

 found exclusively on federal lands is the Laysan 

 duck (Anus Uiysanensis). which lives only on 

 national wildlife refuges. 



