Long-term development of tidal mitigation wetlands in Florida

Abstract

Monitoring periods for compensatory wetland mitigation projects are relatively short, typically 3 to 5 years. Although forested wetlands may require decades to develop structural characteristics similar to those of natural systems, studies that describe long-term trends in site development are rare. Eighteen mitigation sites in Florida that had originally been sampled in 1988 were re-visited in 2005. Changes in mangrove community composition and stand structure occurring over this timeframe at ten of these sites are described and compared with other mangrove wetlands in Florida. Factors limiting development of the remaining sites are discussed. The continued persistence and development of the majority of these mitigation sites indicates that the mitigation process can be successful, at least in terms of compliance with the typical permit requirements. Basal area and height had increased at most sites, and some were difficult to visually distinguish from adjacent natural stands of mangroves. However, even after 13–25 years, stand structure in mangrove mitigation wetlands in Florida still differed from that of natural sites. Although the number of mangrove species was similar, mitigation sites had lower basal area and height than natural sites, and were more dense and complex than natural sites.