ever, many of the species of animals for which the aquatic portion of a wetland is critical are equally dependent on the surrounding terrestrial habitat. The importance of terrestrial habitat beyond the margin of standard wetland delineation has been unequivocally demonstrated for salamanders and freshwater turtles (Burke and Gibbons 1995; Semlitsch 1998) and is implicit on the basis of the ecology and behavior of other terrestrially dispersing species, including frogs, snakes, and mole crickets (Dole 1965; Semlitsch 1986; Seigel et al. 1995). The issue of including terrestrial habitat in the characterization of wetlands and in evaluating the appropriateness of restored and created wetlands extends to the aspect of terrestrial connectivity between small wetlands in a regional landscape and is an essential feature for assuring the persistence of some wetland species (Semlitsch and Bodie 1998). The biological portion of a functional wetland habitat forms a trophic structure that includes consumers as well as producers; hence, consideration must be given to environmental features of wetlands that are requisite for completion of the life cycle of wetland faunal inhabitants.
On the basis of these facts and principles, the incorporation of animal populations requiring terrestrial movement into the design of compensatory wetlands requires that interwetland distances be taken into account (Semlitsch and Bodie 1998). Local populations can be extirpated and regional species forced to extinction if there are no opportunities for recolonization of wetlands during periods of environmental stress (e.g., extended drought). Also, an undisturbed upland buffer that goes beyond the jurisdictional wetland boundary under the Clean Water Act is essential for some species (Semlitsch and McMillan 1980; Burke and Gibbons 1995; Semlitsch 1998). Therefore, both terrestrial connectivity between wetlands in the landscape and the terrestrial habitat surrounding the prescribed wetland must be considered in designing mitigation wetlands. The ecological requirements for key faunal components of many wetland systems should become a consideration in compensatory mitigation if wetland integrity is to be maintained.
A guiding principle in wetland mitigation is that where impacts are permanent, mitigation should be too. However, wetland compensation sites are new features in the landscape, so there must be confidence that the mitigation will protect and preserve desired wetland functions in perpetuity. Permanence means locating, designing, and managing the site for its long-term sustainability in a changing landscape. Permanence also means establishing the institutional means for assuring protection and management of the site over time.