Our I.iviui^ Rcsntirct's — Tcrn'strial Ecosvstcm.s 



221 



This kind of coiiinuinity occurs on saturated 

 saline mud Hats associated with rare inland salt 

 springs in Illinois, Michigan, and New York 

 (Ambrose et al. 1994; Anderson et al. 1994). 

 The environmental characteristics that support 

 this biological association have similarly 

 restricted the use of this habitat for agricultural 

 production and most other types of land conver- 

 sion, although some communities have been 

 degraded by salt-extraction operations. Though 

 this community is unlikely to disappear because 

 of human-induced disturbance, individual com- 

 munities should be protected from degradation 

 due to incompatible land use. 



In contrast, the mesic tall-grass prairie asso- 

 ciation (Andropogon geraidii-Sorghastruin 

 nutans-Spowholus heterolepis [Liatnis spp. - 

 Silphium kiciniatum] herbaceous vegetation) in 

 the Midwest was common a century ago but is 

 very rare today. The existing occurrences of this 

 association type represent remnants of a com- 

 munity whose acreage has rapidly declined 

 because of the value of its habitat for agricul- 

 tural production (Ambrose et al. 1994). It has 

 also suffered from the large-scale alteration of 

 historical fire regimes. Rare communities such 

 as this are quite threatened and require immedi- 

 ate protection and management. 



Future 



The list of nationally rare communities will 

 help ensure their recognition and set priorities 

 for their protection, an important step for con- 

 servation. Even if the list of rare communities 

 were complete, however, it would still be insuf- 

 ficient to conserve and manage biological diver- 

 sity. A comprehensive national conservation 

 strategy for all communities, including common 

 ones, is necessary to protect and manage the full 

 spectrum of biological diversity and ecological 

 systems. 



The development of a standard community 

 classification system has dramatically increased 

 our capability to make better informed conser- 

 vation and ecosystem management decisions at 

 multiple geographic scales. The synthesis of 

 existing community data on nationally rare 

 types has identified the strengths and weakness- 

 es of the existing information base, infomiation 

 that will help us decide how to accumulate and 

 analyze data to fill critical gaps in our knowledge. 



The acquisition and management of the eco- 

 logical and biological data needed to complete 



Table 3. Knowledgf gaps lelaled lo .slate communlly classification, lanlving. and niventory. 



State classification not 

 completed 



No state ranks 



Coarse state classification 



Limited inventory 



(Maryland 

 Rtiode Island 

 South Dakota 

 West Virginia 



Alabama 



Georgia 



North Dakota 



South Dakota 



the national classification represent a major 

 challenge. The success of many ecosystem 

 management initiatives will depend upon this 

 information. A concerted cooperative effort is 

 necessary to conserve and manage our biologi- 

 cal and ecological resources. 



References 



Anihrose. D,. J. Dratce. and D. Fuber-Langendoen. 1904. 

 Rare plant communities of tlie United States: midwest- 

 em region. In D.H. Grossman. K.L. Goodin, and C.L. 

 Reuss, eds. Rare plant communities of the contenninous 

 United States: an initial survey. The Nature 

 Conservancy. Arlington, VA. In press. 



Anderson. M.G.. L.A. Sneddon, and K.J. Melzler. 1994. 

 Rare plant communities of the United States: eastern 

 region. In D.H. Grossman. K.L. Goodin. and C.L. 

 Reuss, eds. Rare plant communities of the contenninous 

 United States: an initial survey. The Nature 

 Conservancy. Arlington, VA. In press. 



Driscoll. R.S., D.L. Merkel, R.L. Radloft, D.E. Snyder, 

 and J.S. Hagihara. 1984. An ecological land classifica- 

 tion framework for the Llnited States. LI.S. Forest 

 Service Miscellaneous Publ. 14,19. 



Grossman. D.H.. K.L. Goodin, and C.L. Reuss. eds. 1994. 

 Rare plant communities of the conterminous United 

 States: an initial survey. The Nature Conservancy, 

 Arlington. VA. In press. 



Master. L. 1991. Assessing threats and setting priorities for 

 con.servation. Conservation Biology 5(4):,S,S9-563. 



Patterson, K.D, D.J. Allard. and S.^Landaal. 1994. Rare 

 plant communities of the United Slates: southeastern 

 region. In D.H. Grossman. K.L. Goodin. and C.L. 

 Reuss, eds. Rare plant communities of the contenninous 

 United States: an initial survey. The Nature 

 Conservancy, Arlington, VA. In press. 



Reid. M., L. Engelking. and R Bourgeron. 1994. Rare 

 plant communities of the United States: western region. 

 In D.H. Grossman. K.L. Goodin, and C.L. Reuss, eds. 

 Rare plant communities of the conterminous United 

 States: an initial survey. The Nature Con.servancy, 

 Arlington, VA. In press. 



United Nations Educational, Scientific and Cultural 

 Organization (UNESCO). 1973. International cla.ssifi- 

 cation and mapping of vegetation. Series 6, Ecology and 

 conservation. United Nations Educational, Scientific 

 and Cultural Organization, Paris. 93 pp. 



Westhoff. V, and E. van der Maarel. 1973. The Braun- 

 Blanquet approach. Pages 626-828 in R.H. Whitlaker, 

 ed. Handbook of vegetation science. Part V. Ordination 

 and classification of communities. Junk, The Hague. 



For further information: 



Dennis H. Grossman 



The Namre Conservancy 



1815 N. Lynn St. 



Arlinaton.VA 22209 



