PATTERNS AND PROCESS OF SANDBAR REVEGETATION ON THE MISSOURI NATIONAL RECREATIONAL RIVE

Decades of flow regulation have reduced sandbar area and recruitment of cottonwood and willow along the Missouri River. Conflicts exist between managing sandbars for habitat (removing vegetation) for threatened sandbar-nesting birds (i.e., Piping Plover) and allowing natural recruitment of early successional riparian woodland (set-aside bars) that may support other species and ecological values. Recent changes in topography, geomorphology, and vegetation were examined on sandbars that have been “set aside” from management within seven reaches of the Missouri National Recreational River (MNRR) in southeastern South Dakota, USA. An existing time series of maps of sandbar landcover, derived from satellite imagery, was analyzed using ArcGIS to track vegetation and geomorphic changes from 2008-2016. Digital Elevation Models (DEMs) were used to detect elevational changes from 2012-2014/2016, the years following the 2011 flood. Sandbar area was highest on most reaches in 2012 and declined thereafter, and most areas did not show significant elevation changes from 2012-2014/2016. Cottonwood was the most frequent tree species, followed by Russian olive, while sandbar willow was the most abundant shrub species. Redcedar and sweet clover were the most frequent woody and herbaceous invasive plant species, respectively. My findings will inform managers from the National Park Service and US Army Corps of Engineers about how the sandbars in the MNRR have evolved since the 2011 flood. This information is critical for managing the bars in a way that will balance the needs of sandbar-nesting birds and the multiple species of birds and other wildlife that use early successional riparian vegetation