Fifty years of forest hydrology in the Southeast
The forests of the southeastern United States are incredibly valuable and diverse, both for timber production and for the aquatic habitat they provide. These overlapping values and diverse conditions have spawned numerous studies to assess how forest management affects hydrology and water quality. In the mountains, key watershed studies include those conducted at USDA Forest Service research facilities at Coweeta Hydrologic Laboratory in North Carolina and Fernow Experimental Forest in West Virginia. Research on hilly topographies includes work from the Oxford Hydrologic Laboratory in Mississippi and Grant Forest in Georgia. The South also has vast tracts of forested flatwoods and wetlands that represent poorly drained sites, which are not commonly studied in other regions. Hydrologic research is made difficult in these sites because of conditions such as shallow relief, poorly defined drainages, and periodic inundation. Some key research on these types of sites include the IMPAC study in central Florida, the Santee Watershed Study in South Carolina, the Belle Baruch Hydrologic Institute in South Carolina, the North Carolina State Wetland Research Program, and the Mobile-Tensaw River Delta Study in Alabama. The lessons of watershed research in the South are that site-specific conditions that influence hydrologic and water quality response must be properly identified to apply appropriate management practices and interpret water quality impacts from forest operations. Although roads represent a major source of srdiment in upland sites, they sometimes have proven to be minor sources in poorly drained locations. Management practices that disturbed wetland forest soils and would be expected to dramatically accelerate sediment loss from comparable upland sites instead have been found to increase sediment trapping efficiency. Water quality assessed as impaired for one site may be typical of natural conditions for another. Rapid recovery from disturbance is often seen, as these productive forest sites revegetate in response to disturbance. Connecting all these varied responses to forest management and our desire to interpret them is a basic requirement to understand the hydrologic cycle, determine how water pathways lead to runoff, and measure how water interacts with watershed physical and biological processes, including evapotranspiration. Extensive literature citations guide further investigation of these issues.