Individual-plant selectivity by sheep in drylands scales-up at plant population level and controls the forage supply and its accessibility

Diet selectivity by domestic herbivores controls plant community structure and dynamics and may induce rangeland degradation, particularly in drylands. However, management decisions frequently ignore herbivore selectivity. Here, we studied how grass morphology controls sheep selectivity for individual plants, and how this selectivity interacts with grazing intensity to determine population plant-size distributions and the forage supply. In Patagonian steppes, we manipulated the plant morphology (size and standing-dead proportion) of three dominant grass species differentially preferred by sheep for four years. Then, we evaluated how these morphological alterations affected intra- and inter-specific preference patterns. We also evaluated how grazing intensity (ungrazed, moderate grazing, and intensive grazing) affected the plant-size distribution of the three species, the forage supply, and its accessibility. For the highly preferred species, herbivores selected plants that were either n..., ,