In light of the continuing debate regarding overcompensation we studied the responses of above-ground biomass in a high-elevation, semi-arid grassland to defoliation, defoliation history, and livestock grazing. The above-ground annual net primary productivity (ANPP) was measured over 2 years in one-hundred twenty, 1-m2 plots that were exposed to single- and multi-year defoliation and grazing treatments. Plant communities showed an average increase in ANPP of 31%?45% due to a single defoliation event. The most conservative estimate of average ANPP of defoliated subplots was 29.4 g m?2 greater than the non-defoliated controls. A history of defoliation, due to clipping or grazing, lessened the magnitude of the compensatory response, but [...]
