Woody plant removal impacts on sediment yield from north-central Oklahoma grasslands

Abstract

Encroachment of Juniperus virginiana L. (eastern redcedar) into grassland ecosystems has been reported to increase water loss via evapotranspiration, potentially reducing water resources available to municipal and aquatic ecosystems. This concern, when coupled with increasing water demands of Oklahoma, has inspired research aimed at documenting the hydrologic implications of harvesting woody biomass from encroached rangelands. In order to quantify the water quality and quantity influences of woody plant removal from encroached watersheds, sediment yield and runoff of varied vegetation catchments were collected and compared across seven experimental watersheds near Stillwater, OK. The objective of this study was to determine the effects of encroached eastern redcedar removal and subsequent land use, i.e. restored prairie and pancium virgatum (switchgrass) cultivation, on annual sediment and water yield. Results showed grassland watersheds generated higher runoff compared to eastern redcedar woodland, while redcedar woodlands produced higher flow-weighted average sediment concentrations compared to grasslands. However, no significant difference between tallgrass and redcedar sediment means were found. Additionally, redcedar removal and one-year switchgrass cultivation or two-year grassland recolonization increased annual sediment yields. These results imply woody plant removal may increase watershed water yield and sediment, but longer time periods and quality indices are needed to assess the full hydrological implications of woody biomass removal.