Multiple factors influence the vegetation composition of Southeast U.S. wetlands restored in the Wetlands Reserve Program

DE STEVEN, D. (USDA Forest Service, Southern Research Station, Center for Bottomland Hardwoods Research, Stoneville, MS 38776) AND J. M. GRAMLING (Department of Biology, The Citadel, Charleston, SC 29409). Multiple factors influence the vegetation composition of Southeast U.S. wetlands restored in the Wetlands Reserve Program. J. Torr. Bot. Soc. 140: 453–464. 2013.—Degradation of wetlands on agricultural lands contributes to the loss of local or regional vegetation diversity. The U.S. Department of Agriculture’s Wetlands Reserve Program (WRP) funds the restoration of degraded wetlands on private ‘working lands’, but these WRP projects have not been studied in the Southeast United States. Wetland hydrogeomorphic type influences hydrodynamics and thus the vegetation of restored sites, but species composition may also be affected by prior land-condition and restoration methods. We examined the variation in restored wetland vegetation of 61 WRP sites (representing 52 projects) across the Southeast region. Field surveys identified the common plant species at each site, and species composition was analyzed in relation to hydrogeomorphic type and specific restoration methods that were linked to pre-restoration habitat status. At least 380 plant species were recorded across all sites. Site floristic composition generally reflected variation in wetness conditions and vegetation structure. Wetlands restored by ‘non-intensive’ methods overlapped in species composition irrespective of hydrogeomorphic type, as a consequence of successional dynamics related to natural hydrologic variation. More distinctive species composition occurred in wetlands restored by ‘intensive’ methods designed to compensate for intense agricultural land-use before restoration. In the Southeast U.S., WRP wetlands are supporting a variety of plant assemblages influenced by hydrogeomorphic settings, site land-use history, and differing restoration approaches.