A Watershed Prioritization Model for Community-Centered Riparian Forest Restoration in Tennessee

Riparian forests are unique ecosystems that act as transitional areas between land and water that are a vital part of a healthy and functional stream ecosystem. Due to the rapidly changing landscape, riparian forests are increasingly threatened by urban development, agriculture, and invasive species, which contributes to a trend of degrading water quality in Tennessee. To address declining riparian forest quality in the face of land-use changes, the purpose of this study was to develop a simple watershed prioritization model that identifies areas that are highly susceptible to poor water quality, and where riparian plantings would be most beneficial. This study consisted of a spatial analysis assessing connections between 3 land-cover types (Forest Cover, Impervious Cover, and Open Area) within HUC-12 watersheds and associated Tennessee Macroinvertebrate Index (TMI) scores, and a field analysis connecting land and riparian cover variables to resulting stream temperatures. The spatial analysis indicated that all three land-cover types were found to have a significant predictive relationship with TMI score outcomes, with greater predictive ability achieved when combining land-cover types into a single “score”. Assessment of stream temperatures in connection with adjacent riparian vegetation and upstream land-cover factors support the importance of forests in maintaining lower temperatures, as well as the contribution of urban development to higher temperatures with broader ranges. The results of the analysis and further review of literature informed the development of a watershed priority model that emphasizes the importance of targeting HUC-12 watersheds with higher levels of impervious surface and low forest cover for riparian restoration efforts. This model could be a helpful tool for the communication of water quality and urban forestry initiatives to public audiences.