Differences in population size structures characterize grass response to long‐term livestock removal

Questions How does desert grassland vegetation respond to long-term grazing removal? Is grass response the result of differences in number or size plants? Does differ over time and relation precipitation patterns? Location Santa Rita Experimental Range, southwestern United States. Methods Four times between 2011 2020, we measured cover woody plants native non-native perennial grasses, density, size, biomass individual grasses on 40 permanent transects inside outside 10 (88–104 years old) livestock exclosures (0.1–4.0 ha) occurring same ecological site. We used linear mixed models compare variables grazed vs ungrazed through calculated cumulative frequency distributions plant diameters. Results The did not by treatment. Instead, had a greater cover, most abundant Arizona cottontop (Digitaria californica). Moreover, populations natives showed structure skewed larger sizes. Non-native no treatments. Patterns inter-annual influenced abundance, but their removal. Conclusions Long-term removal grasslands affected that plants. Response was characterized more rather than plants, and, importantly, population smaller areas suggests limits vigor longevity. Absence likely reflects lower palatability resistance non-natives. is due low permeability seed dispersal.