Climate and Grazing Affect Prairie Grass Reproduction
Most stems of North American Great Plains grasses come from below-ground vegetative buds rather than from seeds, therefore, grassland biomass production depends on bud outgrowth into stems. Climate change and grazing can alter the amount of bud outgrowth of both invasive and native grasses. Invasive species could expand under climate change, especially if their bud outgrowth is superior to bud outgrowth of native species under a range of environmental conditions.
Forest Service research examined the bud outgrowth of the native western wheatgrass (Pascopyrum smithii) and the invasive smooth brome (Bromus inermis) under a range of environmental conditions including multiple temperatures, drought, and clipping.
Smooth brome had more buds per stem than western wheatgrass. A greater proportion of smooth brome buds became stems under all temperature and moisture conditions. Western wheatgrass bud outgrowth was reduced at temperatures above 72 degrees Fahreinheit (22.22 degrees Celsius). Short-term drought did not significantly impact bud outgrowth of either species.
Clipping increased western wheatgrass bud mortality and temporarily reduced its bud outgrowth.The robust bud outgrowth of smooth brome under a range of environmental conditions is a key mechanism enabling its expansion into northern mixed-grass prairie in North America.
Forest Service Partners