Planting and Vegetation Recovery on Exposed Mud Flats Following Two Dam Removals in Wisconsin

Abstract

Previous studies of vegetation establishment in dam removal sites have shown that natural vegetation community establishment is highly variable and frequently includes species often considered undesirable in restorations. In this article, we examined two case studies where dam removal sites were planted with native species following dam removal in an effort to promote native species establishment and exclude invasive species. Some planted species established soon after the dam removals, but surveys four years later showed a decline in planted species and an increase in non-native species. In both cases, reed canarygrass (Phalaris arundinacea) became well established in the interval between surveys. A seedbank analysis of sediments from four intact reservoirs with similar physical characteristics to the removal sites showed that reed canarygrass is not active in the seedbank. This suggests that there may be an opportunity to exclude it from dam removal sites if management actions are taken after removal. However, in these two cases, planting following removal did not exclude reed canarygrass and few of the planted species persisted four years after planting.