be to manage the area for livestock grazing or improve- 

 ment of wildlife habitat. Decisions can then be made to 

 manipulate the existing plant community through knowl- 

 edge of its natural potential by changing management 

 objectives or land treatments to address the management 

 goals. 



Both existing vegetation and potential natural vege- 

 tation information are important and widely used. In 

 combination, they are valuable for understanding and 

 managing the vegetation resource and the area on which 

 it is produced. 



Water (Aquatic) Element 



A water classification system should provide a frame- 

 work to group open bodies of water according to their 

 ability to support life on and in them. A system devel- 

 oped on this basis would reflect the inherent potential of 

 water to serve as a habitat or as a resource. A fully devel- 

 oped hierarchical system that addresses local, State, 

 regional, and national levels, however, is unavailable. 



There are classification systems for river and river 

 zones based on dominant fish species, longitudinal distri- 

 bution of benthic fauna, degree of productivity, nature 

 of source, stream order, and selected chemical and phys- 

 ical characteristics (Hawkes 1975, Hynes 1970, Pennak 

 1971). Worldwide classification systems, such as those of 

 lilies and Botosaneau (1963) and Pennak (1971), are based 

 on multiple characteristics that utilize more universal cri- 

 teria than do local and regional systems. Classifications 

 for lakes are generally based on geographical, hydrolog- 

 ical, water-mixing, and trophic characteristics (Cole 

 1978, Hutchinson 1957, Wentz 1980, Wetzel 1975, Winter 

 1977). Estuaries have been classified according to topog- 

 raphy (Pritchard 1952), salinity structure (Cameron and 

 Pritchard 1963, Pritchard 1955), and stratification (Dyer 

 1973). Other classification systems incorporate water- 

 related parameters and water bodies in a general context 

 or through regionalized mapping (Anderson and others 

 1976, Bailey and others 1978, Platts 1980, Rowe 1979, 

 West and Shute 1978). None of these classification sys- 

 tems deal fully with wetlands — land areas permanently 

 wet or intermittently covered with water. 



In wetlands, vegetation and soils influence the fluc- 

 tuations in water regime and the chemical and physical 

 characteristics of water. The extent and duration of water 

 influences the development of vegetation and soils in the 

 transition areas between permanently waterlogged and 

 nonwaterlogged conditions. A new classification system 

 of wetlands and deepwater habitats (Cowardin and others 

 1979) provides a basic framework for an aquatic classifi- 



cation system and provides a direct intergrade into the 

 soils and vegetation elements (fig. 2). 



Cowardin and others (1979) described wetlands as 

 . . . lands transitional between terrestrial and aquatic 

 systems, where the water table is usually at or near 

 the surface or the land is covered by shallow water. 

 For purposes of this classification, wetlands must 

 have at least one or more of the following three attri- 

 butes: (1) at least periodically, the land supports 

 predominantly hydrophytes; (2) the substrate is pre- 

 dominantly undrained hydric soil; and (3) the sub- 

 strate is nonsoil and is saturated with water or cov- 

 ered by shallow water at some time during the grow- 

 ing season of each year. 

 In this context, wetlands include a variety of situations, 

 including marshes, swamps, and bogs; areas of hydric 

 soil devoid of vegetation because of high salt concentra- 

 tion or abrasive actions of water; areas without soil or 

 vegetation such as gravel and sand bars and beaches; and 

 areas near and around shorelines with nonhydric soils 

 supporting hydrophytic vegetation. 



I 



o 



CO 



> 



o 



*%>. 



•*« 



e r 



'i \ 



\ 



tf 



X 



% 



Dry 



Vegetation 



Wet 



Figure 2 — The relative position of vegetation and soil from dry to wet 

 environments in relation to water conditions and the classification sys- 

 tem of Cowardin and others (1979). The areas under the curves are not 

 meant to depict areal extent of the categories. The vegetation element 

 reported herein extends from dry (xeromorphic) communities to wet 

 (hydromorphic) communities. The soil element extends from dry (aridic) 

 to wet (hydric) situations. 



11 



