Floristic Inventory and Vegetation Analysis of Lands Adjacent to the Missouri River on the Lower Brule Sioux Reservation

A floristic survey was conducted on lands adjacent to the Missouri River on the Lower Brule Sioux Reservation in central South Dakota. Selected natural areas, including grasslands, badlands, wetlands, and woodlands, were explored and inventoried multiple times during the growing seasons of 2011-2012. The annotated checklist of the vascular plants includes 442 species in 258 genera and 78 families, including 182 species previously unrecorded in Lyman County. The woodlands of the Medicine Creek floodplain and Ft. Hale ravines were surveyed between 2011-2013; trees and understory vegetation were sampled in 2013 using 12, 50-m belt transects, including 4 in the Medicine Creek floodplain and 8 from individual Ft. Hale drainages. The Medicine Creek floodplain (S = 88, Native S = 63, C̅ = 2.64, FQI = 21.95) supported woodland dominated by green ash; the herbaceous layer included flood tolerant mesophytes and ruderals interspersed in a matrix of Virginia wildrye. The Ft. Hale ravines (S = 101, Native S = 81, C̅ = 3.56, FQI = 31.71) supported nearly pure stands of bur oak and subcanopies of eastern red cedar saplings. The shaded understories were sparsely vegetated and were characterized by a combination of ecologically conservative mesophytes, ruderals, and vegetative specimens of species more common in adjacent open habitats. Understory cover data from the Ft. Hale ravines and Medicine Creek floodplain were compared with similar data collected in Missouri River floodplain forests in central North Dakota in the early 1970s. Nonmetric Multidimensional Scaling produced a 2- dimensional solution clearly distinguishing Missouri River floodplain forests from the Reservation woodlands (stress = 19.380, cumulative R2 = 0.610). A comparison of species inventories taken from the Ft. Hale ravines, Medicine Creek floodplain, and North Dakota floodplain forests indicate the Reservation woodlands are both less diverse and less ecologically conservative than either the cottonwood (S = 158, Native S = 127, C̅ = 4.29, FQI = 48.29) or the later succession ash-elm-box elder forests (S = 157, Native S = 127, C̅ = 4.59, FQI = 51.07) of the North Dakota floodplain.