Changes to the landscape pattern of coastal North Carolina wetlands under the Clean Water Act, 1984-1992

Wetland management in the United States is organized through a permit process that requires a permit be filed with the U.S. Army Corps of Engineers prior to wetland alteration. A collection of these permits from 1984 through 1992 was analyzed in conjunction with classified Landsat Thematic Mapper data from 1984 and 1992 in order to quantify changes to wetland habitat in the study area in coastal North Carolina. The wetland management process in the U.S. focuses on a site-by-site review, possibly overlooking important changes to wetlands at the landscape-scale. These the two datasets were used to determine if wetland habitat loss was occurring at permit sites, but also to determine if landscape-scale wetland fragmentation and reorganization were occurring in the area surrounding each permit site under the wetland management process. The use of these two datasets attempted to span two scales: the site-specific scale often used in the management of wetlands, and the landscape-scale where effects of such management are evident. Important conclusions from the research include the following. First, while several sources imply that coastal wetlands are disproportionately protected as a result of the widespread recognition of their habitat value, estuarine wetlands were altered much more frequently in the study area than their inland counterparts. Second, despite federal level efforts that require compensatory mitigation when wetland habitat is lost, such mitigation was required in only three percent of permits, ensuring wetland loss. Third, correlation between estimates of wetland loss from the Permit Record and from the remotely sensed record was minimal, highlighting the problems inherent to wetland delineation and implying alterations to habitat not evidenced in the permit record. Finally, landscape-scale changes of loss, fragmentation and habitat reorganization have occurred in estuarine emergent wetland habitat in areas adjacent to several permit sites, implying unanticipated additional impacts to permitted actions. Wetland loss at the permit site occurred with additional fragmentation in 80 percent of the sites examined. The results highlight the lack of agreement between management and landscape-scale wetland structure, function and change, and imply the importance of examining the spatial context of permit sites in the permit review and evaluation procedure.