Land-use Impacts

Prior to settlement, Southwest Georgia was dominated by an open savannah of longleaf pine and wiregrass. Imbedded within the pine savannah were depressional wetlands, and along stream corridors, prolific hardwood forests. Logging was extensive throughout the region with much of the old-growth forests cut by the 1940's. At present, agriculture is the major land use within the region and most agricultural land is devoted to row crops (cotton, peanuts, soybeans, and corn). The acreage of row crops has increased substantially since 1960, with increases associated with the implementation of center pivot irrigation in the 1970's.

Human land use has reduced aquatic habitat. Wetlands represent about 10% of the land area, with riverine wetlands representing 71% and depressional wetlands representing 29% of total wetland area. About 23% of Georgia's wetlands have been lost since 1800 mainly as a result of conversion to agriculture and urban stormwater drainage with most losses occurring since the mid-1970's. Depressional wetlands, in particular, are threatened by agricultural land use.

Changes in land use as a result of increasing human populations have also altered our streams and rivers. Less than 45% of Georgia's streams meet designated uses (Georgia DNR 1992) with the major source of stream degradation being non-point source pollution. Agricultural and urban runoff are the primary causes of degraded water quality. In a survey of shallow groundwater wells in agricultural areas, approximately 30% had elevated nitrate concentrations and two of the wells exceeded drinking water standards. Nitrate concentrations in regional aquifers have been increasing since 1970.

Although a rural area, impact of humans is increasing and will continue to alter aquatic ecosystems of the Dougherty Plain. Human populations can affect aquatic ecosystems through the elimination of aquatic habitat, alteration of regional hydrology, and reduction in water quality. Increases in surface- water and groundwater withdrawals will result in greater intermittency of streams and rivers, particularly during drier than average years. Reductions in the availability of both surface-water and groundwater stress aquatic life. Loss or development of streamside forests reduces natural water purification processes and accelerate water quality degradation. Many of our studies address these issues by: 1) examining current conditions and long term trends within the region; and 2) by experimentation with land management options designed to reduce the impact of humans on water quality and aquatic ecosystems.