Influences of Cattle on Postmetamorphic Amphibians on the Cumberland Plateau
Date of Award
Master of Science
Wildlife and Fisheries Science
Matthew J. Gray
Debra Miller, Lisa Muller, Ben Fitzpatrick
Global decline of amphibian populations has been linked to various anthropogenic stressors. Recent studies have quantified the influences of cropland agriculture and deforestation; however, few have examined the impacts of allowing cattle access in wetlands on resident amphibians. I compared four wetlands exposed to cattle grazing for >10 years against four wetlands that had not been grazed for >10 years, at the University of Tennessee Plateau Research and Education Center. At each wetland I measured species richness, diversity, and species-specific relative abundance of postmetamorphic amphibians captured in pitfall traps and during breeding call surveys, amphibian egg mass abundance, shoreline vegetation structure, and soil compaction from March – August 2005 and 2006. Pathogen prevalence and histopathological changes were measured from a subsample of opportunistically collected amphibians. Landscape characteristics were quantified and related to amphibian community structure. Relative abundance of green frog metamorphs was 9.8X greater in 2006 and 2.3X greater in 2005 at non-access wetlands. Relative abundance of American toads was 68X and 76X greater at cattle-access wetlands in 2005 and 2006, respectively. Breeding call abundance of American toad, Fowler’s toad, and Cope’s gray treefrog was 4 – 25X greater at cattleaccess wetlands in 2006. There were 2X more spring peepers and pickerel frogs calling at non-access wetlands in 2005 and 2006, respectively. Species richness, diversity, and egg mass abundance were not significantly different between land-use types each year. In general, body size followed a density-dependent relationship across species. Height and percent horizontal and vertical cover of shoreline vegetation were 74%, 25% and 84% greater, respectively, in non-access wetlands in 2005; trends were similar in 2006. Soil compaction was 55% greater at cattle-access wetlands. Pathogen prevalence and histopathological changes did not differ between land uses. Landscape analyses revealed species-specific associations related to wetland isolation and geometric complexity of the landscape between wetlands. My results suggest that cattle influence community composition and postmetamorphic body size of amphibians, but effects are speciesspecific. Differences in postmetamorphic abundance may be related to less vegetation structure and lower water quality at cattle-access wetlands. Fencing cattle from wetlands may be a prudent conservation strategy for some amphibian species.
Burton, Elizabeth Carrie, "Influences of Cattle on Postmetamorphic Amphibians on the Cumberland Plateau. " Master's Thesis, University of Tennessee, 2007.