Society's concern for wetlands requires the silviculturist to manage these sites cautiously. With proper management, their functions are preserved; water remains free of sediment, wildlife habitat is enhanced, fisheries are improved, floods are controlled, biogeocycling takes place, landscapes are protected, and eutrophication avoided. Prevention of eutrophication allows for denitrification of organic matter, microbial immobilization, and retention of soluble phosphate in the silt and clay components of these soils. In addition to providing sites for growing trees for mankind's needs, wetlands enhance flyways and breeding grounds for migratory birds, provide habitat for rare and endangered plants, supply sinks for pollutants, and nourish food chains for living organisms (micro-and macrofauna). In the southern pine coastal plains, wetlands have minimal value for flood control or groundwater recharge.
Government agencies, environmentalists, and foresters define wetlands variously. For the present purpose they are sites in which hydrophytes grow in hydric soils. Thus, plants that grow and reproduce in anaerobic soils, those soils saturated long enough during the growing season to develop anaerobic conditions in the surface horizon, indicate bonafide wetlands. Such sites generally include forested swamps and bogs, pocosins, mangrove swamps, shrub swamps, freshwater basins, riparian zones along streams, and flood plains. Some classifiers include pine flats and certain pine plantations on land formerly farmed. Streamside riparian zones need not be wetlands.
Forested wetlands support trees or tall shrubs; they may be drained or undrained. Vegetation includes hardwoods, as in the swamps of the coastal plains; bald- and pondcypress, as in swamps and domes; pond pine, as in the pocosins; and Atlantic white-cedar, as in peaty sites along the Atlantic coast. All of these forest types may be surrounded by southern pines or, at the fringes, intermixed with pines. During dry periods, buttressed trunks and silt marks on boles indicate wetlands.
As wetlands are lost to agriculture and economic development, new wetlands are created. This occurs in the reclamation of surface-mined sites on previously forested uplands. Natural drainages develop on the restored land, ponds fill, hydrophytes seed-in, and forest trees follow.
Of the South's 57 million acres of wetlands, 30 million are forested. Some 7% of the total is in the loblolly-shortleaf pine type; 15% in oak-pine; slash pine, 3%; and an unreported percentage in pine flatwoods of the Southeast and Gulf Coast.16
Wetland silviculture should follow Best Management Practices, sometimes controlled by federal and state regulations, the latter involving the Environmental Protection Agency and the Corps of Engineers. The procedures include delaying logging until surface soils dry sufficiently following rain to avoid puddling of the soil, using rubber-tired skidders cautiously to avoid soil compaction, limiting the number of skid trails, and "putting roads to bed" following harvest. Practices should be designed to (1) enhance plant and animal habitat (including establishing game food plots, (2) encourage valuable species that are tolerant of flooding, and (3) avoid sedimentation by proper treatment of forests at higher elevations. Feral hogs should be controlled by harvest; their consumption of mast of desirable species prevents tree reproduction and seedling establishment. Conversion of true wetlands to pine plantations, as in the past, will not likely be condoned. On the whole, timber harvests have minor and transient effects, scarcely impacting the forest.
Under some circumstances, silviculture may include the regulation of water levels by drainage, ditching, and controlling water flow from wetlands to lower bodies of water with outlet gates. These gates also protect forested sites from intrusion of saline tidal water.
Riparian zones that serve as buffers between agricultural or urban development and wetlands filter sediment and microbes. Periodic harvests in these zones may enhance nutrient retention, enabling young growth that is more vigorous than the older harvested stems to promptly utilize available nutrients before they are leached into water bodies at lower elevations.
Some 15 wetlands across the South are included in the Ramsas Treaty as "wetlands of international importance." Wetlands are also designated in categories for regulation under the Fish and Wildlife Coordination Act, which grants review authority to the Fish and Wildlife Service of the U.S. Department of Interior over dredge-and-fill activities permitted by the U.S. Corps of Engineers and the U.S. Environmental Protection Agency.15
With an understanding of the vegetation-related geography of the South, the reader now considers ecological associations—how the climate, soils, physiography, and living organisms interact to produce the forests of the region.
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