Date of Award
Open Access Thesis
Master of Science (MS)
David R. Brown
Stephen C. Richter
Brad R. Ruhfel
Wetland ecosystems have experienced severe declines across the United States, prompting efforts to assess the status of remaining wetlands and regulate their development. The Clean Water Act and the policy of “No Net Loss” have resulted in a system of permitting and mitigation for impacts to wetlands. Professional judgments of wetland quality are inherent in regulatory decisions related to preservation and mitigation, but many states, and until recently including Kentucky, have no standard, quantifiable means of assessing wetlands to guide the decision process. A rapid assessment method has recently been developed for Kentucky, but there is no intensive assessment method for wetlands. Indices of biotic integrity (IBIs) are multimetric assessment methods that use characteristics of biological communities in wetlands as indicators of ecological integrity, or the degree to which a habit resembles a pristine reference condition. IBIs are increasingly being developed for specific regions and nationally as tools to aid in regulatory decisions and for ambient monitoring purposes.
The goal of this study was to develop a vegetation-based IBI (VIBI) to assess the condition of wetlands in Kentucky and test it against the recently developed Kentucky Rapid Assessment Method (KY-WRAM). Using survey data from 110 primarily riverine wetlands across five river basins in Kentucky from 2011 to 2015, I calculated 125 candidate vegetation metrics and tested their correlation to a disturbance index, which was comprised of aggregated measures of anthropogenic landscape, physical, and hydrological alterations. Forested, emergent, and shrub wetlands were included in the survey sample. Ultimately, one VIBI was developed for all wetland vegetation classes and consisted of two metrics, MeanC, the average of all species CC values at a site, and Absolute Cover of Nonnatives. These metrics are broad enough to apply to a wide range of wetland vegetation classes and HGM types and reflect wetland condition via floristic quality and the degree of invasion by nonnatives. The final VIBI distinguished KY-WRAM category one wetlands from category three wetlands for both development (F2,79 = 16.54, p<0.001) and validation (F2,13 = 15.59, p<0.001) datasets.
Further work should test the applicability of this VIBI on wetlands in the two additional basins of Kentucky and on other wetland types, in addition to accumulating a greater sample size for some types tested in this study. Because emergent wetlands tended to score lower overall than forested wetlands, separate interpretation of emergent and forested wetland scores should be considered, but I recommend doing so only after more sites are added to the dataset.
Copyright 2016 Noelle Newman Smith
Smith, Noelle Newman, "A Vegetation-Based Index of Biotic Integrity for Wetlands of Kentucky" (2016). Online Theses and Dissertations. 427.