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Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy
"obligates" (species confined to wetlands) not just "facultative" species (those that occur in both wetland and upland habitats). Obviously, if less of the wetland is under regulatory domain, development can continue without a net loss (in the legal sense).
Although the delineation of wetlands is outside the scope of this chapter, one question is central to the committee's charge: Can damaged wetlands be restored? If so, then restoring one wetland might compensate for damaging another. The answer often depends on how good the wetland science is. Determining whether a damaged wetland has been restored requires good information on wildlife, vegetation, soil, and hydrology.
This chapter discusses the functional values of wetlands and describes historic losses and damages. Current wetland restoration technology is summarized, along with constraints on achieving restoration goals, problems encountered during restoration, opportunities for major restoration projects, programs for wetland restoration, and reasons for varying opinions on the success of wetland restoration. Conclusions, recommendations, and research needs complete the chapter; however, recommendations on wetlands policy and institutional changes pertaining to wetlands are included in Chapter 8.
Definition of Wetlands
In the scientific view, wetlands are transitional areas between terrestrial and open-water systems. In the legal view, wetlands are discrete units subject to regulatory jurisdiction. The diversity of wetland types makes it difficult to have a single definition for a wetland.
According to the U.S. Fish and Wildlife Service (FWS), "wetlands are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water" (Cowardin et al., 1979). The FWS lists three attributes that help identify wetlands: the presence of hydrophytes, hydric soils, and saturated or inundated substrate. The temporal nature of some wetlands is acknowledged—hydrophytes and hydrologic indicators need only be present periodically. This definition is more inclusive than that used by the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (COE) (Clean Water Act, Section 404 (b)(1) guidelines) for regulatory purposes. The major federal agencies involved in wetland regulation have adopted a uniform manual for delineating wetland boundaries (Federal Inter-agency Committee for Wetland Delineation, 1989).
The diversity of wetland habitat types and the diversity of species they support are impressive. The classification system of Cowardin