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3 Methods

The status of and trends in southern forested wetlands were derived primarily from National Wetland Inventory (NWI) reports (Dahl 1990 Hefner and Brown 1985; Hefner and others 1994, Dahl 2000). Information from these reports was used to develop a composite picture of the acreage and loss of forested wetlands in the South from the 1780s to the present. Acreages were taken directly from the U.S. Fish and Wildlife Service Wetland Status and Trend reports. For the 10 Southeastern States of Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, and Arkansas. Data for the 1986-1997 time period, generated for this report by the Fish and Wildlife Service, were also used directly. The NWI Status and Trends reports represent the most comprehensive and consistent source of information on forested wetland conversions and losses over the last 200 years.

Information from the National Resources Inventory (NRI) prepared by the Natural Resources Conservation Service (NRCS) and the Forest Inventory and Analysis (FIA) units of the USDA Forest Service were used to fill gaps in information about impact and restoration acreages, and changes in forest type and ownership. National Wetland Inventory and NRI data have similar geographic coverage but are not directly comparable because NRI does not classify wetlands in the same manner as NWI and does not include Federal land or coastal areas in its estimates. The FIA forested wetland data cover only five States -- Virginia, North Carolina, South Carolina, Georgia, and Florida. To date FIA has collected wetland data at only one point in time for each state. Thus, data does not represent changes in forested wetland acres over time. Since NRI and FIA data are limited geographically and temporally, NWI data are the primary basis for the status and trend numbers reported herein.

Literature, including hydrogeomorphic approach models for low-gradient riverine wetlands, pine flatwood wetlands, hardwood flat wetlands, and forested depressions were reviewed to develop hypotheses about the effects of alteration on the structure and function of forested wetlands. Hypothesized impacts were then checked against scientific studies done in similar wetlands where available. Predominant forested wetland types in the South (Messina and Conner 1998) were placed in HGM classes. Functional assessment models for those classes and/or subclasses were then reviewed to hypothesize, based upon structural alterations to the wetland, the impacts of alterations by silviculture, agriculture, or development. Due to the large geographic area encompassed by the Southern Forest Assessment (13 States) and the large variability in on-site wetland and surrounding landscape conditions, the estimated impacts are generic. The specific projects must be individually assessed. The generic assessments of impacts described here do provide useful insights into the ecological ramifications of these activities, the fate of wetlands which have been modified, and potential hypotheses for additional research. Wetland restoration literature was reviewed, as were ongoing studies on the extent and success of wetland restoration. NRI and data from the Wetland Reserve Program (WRP) administered by NRCS was also used to estimate the number of acres where wetland restoration have been attempted. The assumption with WRP data is that acres enrolled in this program result in a gain in forested wetland.