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

作者：Gastón R. Oñatibia, Martı́n R. Aguiar, Martı́n Oesterheld · 发表于：Journal of Applied Ecology · 年份：2023 · DOI：10.1111/1365-2664.14427 · 被引用次数：9 · 研究领域：Ecology and Vegetation Dynamics Studies、Rangeland Management and Livestock Ecology、Wildlife Ecology and Conservation

Abstract 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 4 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 naturally or experimentally short, with low proportion of standing‐dead biomass. In contrast, morphological changes did not alter the within‐species selectivity of the least preferred species. Grazing intensity strongly changed the population plant‐size distribution of preferred species in ways that resembled the experimental manipulations of morphology. Moderate grazing showed the greatest morphological heterogeneity among individuals. When integrating the green biomass of forage species' ...