The Role of Riparian Wetland Restoration in Amphibian Conservation

Abstract

The worldwide decline in amphibian populations may be a harbinger of ecosystem degradation. Wetland and stream restoration may counter amphibian population declines by increasing habitat quality, area, and connectivity. Among the causes of amphibian declines, habitat loss and fragmentation are some of the most influential mechanisms contributing to species extinction. Connectivity between streams and riparian wetlands are not only important for stormwater and water quality management, but are also essential for the conservation and management of amphibians. Even with the dramatic expansion of stream and riparian wetland restoration projects nationwide, post-restoration monitoring of the effectiveness of restoration rarely includes assessment of wildlife populations. Assessment of population declines and restoration success requires long-term monitoring. However, long-term amphibian population studies are relatively few in North America and particularly lacking in North Carolina. The effects of integrated stream and wetland restoration on frogs and toads in the North Carolina Piedmont were analyzed, focusing on the Duke University Wetland Center Stream and Wetland Assessment Management Park (SWAMP). Anuran communities were compared in restored and reference riparian wetlands using drift fence and pitfall trap arrays along with auditory surveys. A total of 100 individual amphibians and eight species were detected in traps between summer 2010 and summer 2011. Ten species were detected with auditory monitoring, including three species heard but not seen. Mann-Whitney tests were used to assess differences among amphibian abundance at restored and reference sites. Mantel tests were used to assess dissimilarity of sites based on species composition. Neither relative abundance nor species richness estimates were significantly different among restored and reference sites, although community composition did differ by restoration status. Differences in community composition did include overlap, however, and future monitoring based on the protocol established in this study should reveal population trends over time. In addition to the SWAMP project’s specific goal of improving water quality, the restored streams and adjacent wetlands are also supporting frog and toad populations similar to those in natural riparian wetlands.