Increasing Warm-Season Native Grass Biomass Using Fire, Herbicide, and Nitrogen Applications

The North American Great Plains tallgrass prairie was once a system of native cool and warm season grasses, which have been degraded by non-native invasive plants. Native grass restoration is highly desirable to improve ecosystem functions and productivity. In this two-year study, the impact of fire, herbicide, and nitrogen on productivity and the presence of invasive species [primarily the cool season grass, smooth brome (Bromus inermis Leyss.)] and native warm season native grass species [big bluestem (Andropogon gerardii Vitman), sideoats and blue grama (Bouteloua curtipendula (Michx.) Torr.), and B. gracilis (Willd. Ex Kunth) Lag. ex Griffiths] were investigated. Spring fire or a glyphosate application increased warm season grass biomass and decreased cool season grass biomass at peak warm season growth (August) during the treatment year. A second consecutive year of fire or herbicide further increased warm season grass biomass. If left untreated in the second year, cool season grasses tended to increase when sampled in August. Longterm management implementation is needed to suppress the tenacious cool season species and encourage the reestablishment of warm season grass populations