Contiguity and edge characteristics of wetlands in five coastal counties of north Carolina, USA

Abstract

Wetland contiguity and edge were determined with a geographic information system (GIS) for five coastal counties in North Carolina. USA. The digital database was created from wetlands digitized from U.S. Fish and Wildlife Service National Wetlands Inventory maps. The GIS analysis was based on three classes of information: 1) all wetlands as one class; 2) wetlands separated by dominant vegetative community type (e.g., forest, shrub, or marsh); and 3) forest and shrub wetlands further separated by dominant vegetation (e.g., evergreen, deciduous, or mixed). The contiguity analysis supports the perception that the lower coastal plain counties are dominated by large contiguous wetlands When wetlands were clumped into one class, the number of wetlands >1,000 ha ranged from 2 to 7 and the area accounted for 77 to 96% of the total wetland area. Several of those sites were > 100,000 ha in size. When wetlands were separated into more specific classes, the number of sites < 10 ha ranged from 416 to 3,370, but the wetland area in this size class was < 5% of the total wetland area. The average size of evergreen forest and shrub wetlands was typically much greater than deciduous forest and shrub wetlands a reflection of the configuration of large, block pocosin wetlands. Percent edge was also typically lower for the evergreen forest and shrub wetlands than for deciduous forest and shrub wetlands. The counties with the highest, number of wetland sites in transition to other uses have the most land owned by private timber companies. Contiguity analysis of wetlands with GIS provides landscape-scale information for natural resource management issues such as preserve design, habitat fragmentation, rare species management, and species migration opportunities.