Evaluation of anuran richness in restored wetlands of central Louisiana

Bottomland hardwood forests and associated fauna, including frogs, are disappearing. The 1990 Farm Bill created a wetland restoration program on private lands called the Wetland Reserve Program (WRP) that has the potential to reverse the declines in species associated with bottomland hardwood forests. As of September 2005, nearly 85,000 ha had been enrolled in Louisiana, but the structure and value of these wetlands to frogs is not known. I evaluated 22 restored and 8 reference wetlands from January through May in 2004 and 2005 to determine the effects of local and landscape scale habitat characteristics on frog species richness and occurrence. I used chorus count surveys, egg mass searches, and dipnet surveys to detect frog species each season. Vegetation characteristics at each wetland were determined seasonally. I evaluated landscape influences by using aerial photography and satellite imagery of the sites to determine the surrounding land use. I used multiple linear and logistic regression analysis and t-tests to evaluate the effects of local and landscape variables on species richness and individual species occurrence. I detected 12 of the 13 species expected to occur. Frog species richness did not differ between restored and natural wetlands, but species richness was higher in 2004 than 2005 (P \u3c 0.0001), presumably due to much greater amounts of rainfall in 2004. Species richness in 2004 was positively influenced by median water depth and canopy cover (P = 0.0011). In 2005, permanent flooding, median water depth, emergent and floating vegetation, and canopy cover positively influenced species richness (P \u3c 0.0001). Species richness also increased with forest in the surrounding landscape. Bullfrogs and bronze frogs were associated with canopy closure, herbaceous vegetation, and nearby forest. Northern cricket frogs were associated with shallow wetlands with floating vegetation, litter, and nearby forest. Gray tree frogs were found in wetlands with canopy cover, low emergent vegetation, and nearby agriculture. Restored wetlands in this study provided suitable frog habitat and supported similar frog species comparable to reference wetlands; however, additional frog and vegetation monitoring should be continued to evaluate restored sites throughout maturation