Grazing and Burning Japanese Brome (Bromus Japonicus) on Mixed Grass Rangelands

Abstract

Japanese brome (Bromus japonicus Thunb. ex Murr.) is an introduced, annual cool-season grass adapted to the central and northern Great Plains. Japanese brome has negatively impacted perennial grasses and decreased seasonal animal gains. Prescribed spring burning and defoliation have been effective in reducing brome density or cover, but little information directly compares the two common strategies. The objectives of this study were to 1) compare annual spring burning and grazing to reduce Japanese brome populations; and 2) evaluate trends of vegetative composition and biomass in burned, grazed, and unburned rangelands infested with Japanese brome. Paddocks with Japanese brome were assigned to one of four treatments: 1) annual prescribed spring burning, 2) spring grazing, 3) a combination of annual spring burning and grazing, and 4) an idle control. Treatments were applied annually from 2000 to 2004. Japanese brome density was greatest in the idle control in all years, even when low winter and spring precipitation limited Japanese brome recruitment. Late spring Japanese brome density was similar in all treatments with grazing or burning in four of the five seasons. Spring burning resulted in less than 65% litter cover the last 3 years, whereas the idle control and spring grazing had over 80% litter cover the last 4 years. Western wheatgrass (Pascopyrum smithii [Rydb.] A. Lö ve) decreased with spring grazing in burned and unburned paddocks. Buffalograss (Bouteloua dactyloides [Nutt] J. T. Columbus) composition decreased in the idle control treatment. Blue grama (Bouteloua gracilis [Willd. ex Kunth] Lag. ex Griffiths) and sideoats grama (Bouteloua curtipendula [Michx.] Torr.) composition varied by year. Even though annual burning and spring grazing were equally effective in limiting Japanese brome density and biomass compared to the idle control, Japanese brome was still present after 5 years, which indicates the difficulty of eradicating Japanese brome from ecosystems where it has become naturalized. Resumen El ''Bromo japone´s'' (Bromus japonicus Thunb.) es un pasto introducido de estación fría adaptado a las Grandes Planicies Centrales y del Norte. El ''Bromo japone´s'' ha impactado negativamente a los pastos perennes y disminuido la ganancia animal estacional. El fuego prescrito en primavera y la defoliación han sido efectivos para reducir la densidad y cobertura del ''Bromo japone´s,'' pero poca información compara directamente estas dos estrategias comunes. Los objetivos de este estudio fueron: 1) comparar la quema anual en primavera y el apacentamiento para reducir las poblaciones de ''Bromo japonés,'' y 2) evaluar las tendencias de la composición vegetal y biomasa en pastizales infestados con ''Bromo japone´s'' quemados, apacentados y sin quemar. Los potreros con ''Bromo japone´s'' fueron asignados a uno de los siguientes tratamientos: 1) quema anual prescrita en primavera, 2) apacentamiento en primavera, 3) una combinación de quema anual en primavera y apacentamiento, y 4) un control sin uso; los tratamien...

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