Restoration of Southern Ecosystems

Restoration of the myriad communities of bottomland hardwood and wetland forests and of the diverse communities of fire-dominated pine forests is the subject of intense interest in the Southern United States. Restoration practice is relatively advanced for bottomland hardwoods and longleaf pine (Pinus palustris Mill.), and less so for swamps and shortleaf pine (P. echinata Mill.). Most bottomland hardwood restoration is taking place on private land, while restoration of swamps and shortleaf pine occurs mostly on public land. Both public and private landowners are involved in the restoration of longleaf pine. Proper matching of species to site is critical to successful restoration of bottomland hardwoods. Techniques for longleaf pine restoration include the reintroduction of growing-season fire and the planting of longleaf pine seedlings and understory species. Safely reintroducing growing-season fire, however, may require initial manipulation of other vegetation by mechanical or chemical means to reduce built-up fuels. INTRODUCTION Forest cover has declined globally, from an estimated 6 billion ha of “original” forest extent (that prevailing during most of the past 10,000 years) to the present 3.87 billion ha (Food and Agriculture Organization of the United Nations 2001, Krishnaswamy and Hanson 1999). Global assessments have identified changing land use, increasing demand for fiber, and exogenous stresses such as global climate change and air pollution as the factors causing loss of forest cover or degradation of forest condition. Many forests in the South are being subjected to similar disturbances and stresses. Restoration of the myriad communities of bottomland hardwood and wetland forests and the diverse communities of fire-dominated pine forests is the subject of intense interest in the Southern United States, as well as in other parts of the world (Parrotta 1992, Stanturf and Madsen 2002). Our objective is to present an overview of the restoration of four ecologically varied and socially valuable U.S. forest types: bottomland hardwoods, swamps, Coastal Plain longleaf pine (Pinus palustris Mill.), and Interior Highland shortleaf pine forests (P. echinata Mill.). Restoration practice is relatively advanced for bottomland hardwoods and longleaf pine, and less so for swamps and shortleaf pine. Bottomland hardwood restoration is taking place mostly on private land. Restoration of swamps and shortleaf pine is occurring mostly on public land, while both public and private landowners are attempting to restore longleaf pine. RESTORATION PRACTICES Bottomland Hardwood Forests Restoration of bottomland hardwoods occurs mostly in the Lower Mississippi Alluvial Valley (LMAV), predominantly in three States: Louisiana, Mississippi, and Arkansas (Stanturf and others 2000). The loss of bottomland hardwood forests has been more widespread in the LMAV than elsewhere in the United States. Clearing for agriculture reduced forest cover, and flood control projects drastically changed regional and local hydrologic cycles. Deforestation and 1 Forest Soil Scientist and Project Leader, U.S. Department of Agriculture Forest Service, Southern Research Station, Athens, GA 30602; Research Forester, U.S. Department of Agriculture Forest Service, Southern Research Station, Stoneville, MS 38776; Research Ecologist, U.S. Department of Agriculture Forest Service, Southern Research Station, Athens, GA 30602; Professor, Baruch Forest Science Institute, Clemson University, Georgetown, SC 29442; and Research Forest Ecologist and Project Leader, U.S. Department of Agriculture Forest Service, Southern Research Station, Hot Springs, AR 71901, respectively. So ut he rn F or es t Sc ie nc e: Pa st , P re se nt , a nd F ut ur e Fo re st H ea lt h 124 drainage resulted in a loss of critical wildlife and fish habitat and reduced floodwater retention (MacDonald and others 1979, Sharitz 1992, U.S. Department of the Interior 1988). The dominant goal of all restoration programs in the LMAV has been to create wildlife habitat and improve or protect the quality of surface water (Haynes and others 1995, King and Keeland 1999, Newling 1990). Afforestation of small areas (usually no more than 100 ha) within a matrix of active agriculture is typical. Although we know how to afforest many sites (Stanturf and others 1998), recent experience with the Wetlands Reserve Program in Mississippi illustrates the difficulty of applying this knowledge broadly (Stanturf and others 2001). Afforestation is a process in which something can go wrong at any of several steps. Proper matching of species to site is critical to successful restoration (Baker 1977, Baker and Broadfoot 1979, Broadfoot 1976, Dicke and Toliver 1987, Groninger and others 2000, Krinard and Johnson 1985, Stine and others 1995). Availability of planting stock, however, probably has the greatest influence on the assignment of species to sites. Provenance and family within provenance may account for differences in survival and growth of common species (Dicke and Toliver 1987, Greene and others 1991, Jokela and Mohn 1976, Land 1983). Few foresters in the LMAV specify seed source constraints in purchasing agreements. This lack of quality control, or use of uncertified seed, could potentially reduce establishment success, productivity, and forest health. Bare-root seedlings were used to stock 64 percent of afforestation area to 1997, with direct seeding applied on 29 percent of the afforestation area (King and Keeland 1999). Descriptions of direct seeding techniques are readily available (Allen and others 2001). Suitable techniques for collecting and storing seed of bottomland hardwood species are well documented (Bonner and others 1994). Site preparation is used to condition the seed or seedling bed; decrease competing or undesirable vegetation, such as nonnative pests; reduce herbivore habitat; improve nutrient availability; and improve access for the planting operation (Baker and Blackmon 1978; Kennedy 1981, 1993). Site preparation can increase survival and improve early growth of hardwood planting stock (Baker and Blackmon 1978, Ezell and Catchot 1998, Russell and others 1998). Contractors use crews of both hand and machine planters, but differences between the operational rates of establishment success of the two methods are unknown (Russell and others 1998). Observations indicate that either method can be effective if properly supervised (Gardiner and others 2002, Michelak and others 2002).