Response of Mountain Grassland Vegetation to Clipping in Southwestern Montana

Abstract

Native vegetation composed of a mixture of grasses and forbs was clipped at different times during the growing season to determine when major species were most damaged by herbage removal. Production of herbage and flower stalks was compared on treated and contiguous control plots the years following 1, 2, and 3 successive years of clipping. Clipping harmed the forbs much more than the grasses and caused a conspicuous shift toward grasses in total herbage composition. Production of Aster integrifolius and Potentilla gracilis was affected adversely by a single clipping in July just before and during flowering; by the end of 3 years of clipping, herbage production of these species was reduced approximately 50%, and the number of flower stalks was reduced approximately 80%. Festuca idahoensis, Bromus marginatus, and Agropyron trachycaulum generally were most harmed by clipping in late July and August, from flowering to seed ripening. Removal of herbage either during early growth or after the foliage began to dry did not damage either the forbs or grasses appreciably. Both Bromus and Agropyron benefited temporarily from reduced forb competition. Total vegetative production did not decrease significantly until the third year of clipping.