Abstract
The construction and restoration of wetlands have become, in a relatively short time, among the most discussed and practiced applications of ecological engineering. This interest in wetland building has been stimulated by our new-found appreciation of the functions and values of wetland systems, especially their abilities to cleanse polluted waters and provide habitat for a diversity of waterfowl and wildlife (Mitsch and Gosselink, 1993). Wetlands, as endangered ecosystems in many parts of the world (see e.g., Williams, 1990; Dugan, 1993; Mitsch, 1994), are often the last refuge for plants and animals which are, themselves, threatened or endangered. As a result of the concern for losing these wetland functions, policies have been adopted in many parts of the world, especially in the USA, that have encouraged or even required the restoration or creation of wetlands. This special issue of Ecological Engineering consists of 6 papers submitted to the journal independently on subjects related to wetland construction and restoration. By no means is this compilation the only word on this subject. Our inaugural issue of Ecological Engineering in 1992 was on the subject of constructed wetlands for the control of nonpoint source pollution (Olson, 1992) while a recent special issue provided detailed hydrologic, biogeochemical, and ecological results from one set of constructed wetlands in Midwestern USA (Sanville and Mitsch, 1994). Several other publications and symposia (e.g., Hammer, 1992; Moshiri, 1993; Mitsch, 1994) have also addressed the issue of wetland creation and restoration in detail.