CRS-36 



While all wetlands have these two characteristics, they differ from site 

 to site. Three additional characteristics, size, location and condition, fur- 

 ther distinguish each wetland. 



Wetlands vary greatly in size, from broad expanses along the Southeast 

 and Gulf Coasts to small pockets in the arid West and the formerly-glaciated 

 Northeast. Some large wetland areas have been the sites of large manmade alter- 

 ations. One might rationalize that any recognized functions that are reduced 

 by alteration of small portions of larger wetland areas are insignificant, 

 since only a small part of the total area is altered. 1/ This reasoning is 

 often inaccurate, however. Wetlands are water systems and any alteration 

 affecting the movement or quality of water is transmitted to other areas where 

 water movement patterns or quality are also changed. 



Size does not necessarily correlate with the ability to perform the var- 

 ious functions associated with each type of wetland. While some of the smallest 

 wetlands contain less complex ecosystems and may, therefore, have less overall 

 natural value, the opposite also may be true. 



The location of any wetland area in relation to adjacent ecosystems and 

 human activities has a major influence on the functions it performs. Human 

 activities that alter land adjacent to wetlands, such as clearing surrounding 

 vegetated areas for agriculture or developing land as building sites, affect 

 wetland functions. These changes alter key natural inputs that sustain wet- 

 lands, including the rate and pattern of water flow and the rate, pattern, 

 and makeup of sediments. Wetlands most distant from developments will usually 

 be altered least. A second aspect of location is relationships among wetland 



1/ The terms "function" and "value" are used throughout the report. 

 "Function" means the service provided by wetlands such as habitat or flood 

 control. "Value" is a measure, usually economic, of wetlands performing one 

 or more functions. 



