Date of Award
Master of Science
Wildlife and Fisheries Science
Matthew J. Gray
David A. Buehler, James A. Fordyce
Hardwood bottomland ecosystems provide critical habitat for various wildlife among numerous ecosystem services. Since the 1800s, these forested wetlands have been logged and drained for agriculture. The federal government passed a series of legislative acts that protected wetlands and provided monetary support for restoration. The Wetlands Reserve Program (WRP) was established in 1990 with the goal of restoring ecological function in wetlands. Although several studies have measured plant and wildlife responses to WRP restorations, no standard protocol has been developed to monitor the state of ecological restoration at sites. Index of biotic integrity (IBI) models are commonly used to evaluate ecological function by assigning scores derived from biological characteristics measured at disturbed sites and comparing them with reference sites. Therefore, the objectives of my study were to: (1) characterize vegetation, amphibian and bird communities among 17 WRP restoration and 4 reference bottomland sites, and (2) develop IBI models for these communities to use in monitoring ecological restoration. My study was conducted across 10 counties in western Tennessee from March – August 2008, and communities were measured using standard sampling techniques. I detected 15 amphibian and 95 bird species at bottomland WRP sites, which ranged 2 – 21 years old. Anurans were common among sites, but salamanders were only detected at reference sites containing mature forests. The bird community changed predictably in response to succession, with grassland birds dominating young restoration sites and scrub-shrub and forest birds dominating older restoration and reference sites. Vegetation structure was related to site age, and a good predictor of bird community composition. Variables retained in the vegetation IBI model included density of snags, logs and overstory trees, basal area, and percent vertical cover measured using a profile board. The bird IBI model contained relative abundance of bark feeding, branch nesting, and twig nesting guilds. Presence of salamanders was the only variable in the amphibian IBI model. My results indicate that the WRP is contributing to the regional biodiversity of western Tennessee. The IBI models that I developed can be used for monitoring ecological restoration in Tennessee hardwood bottomlands; however, their applicability outside this region should be validated.
Summers, Elizabeth Anne, "Evaluating Ecological Restoration in Tennessee Hardwood Bottomland Forests. " Master's Thesis, University of Tennessee, 2010.