Plant CSR strategies and community assembly differ across water- and energy-limited alpine ecosystems

Understanding plant strategies is critical for predicting biodiversity responses to global change. Here we show Grime’s Competitor, Stress-tolerator, and Ruderal (CSR) strategies and assemblages at 543 plots in 246 sites across alpine ecosystems on the Qinghai-Xizang Plateau, by integrating plant traits with data on geography, climate, soil, disturbance, and productivity. The S-strategy predominates, showing context-dependent variations and environmental determinants. Climate outweighs soil in water-limited meadow and shrubland with higher C-/R-strategies, but the opposite in energy-limited steppe (on R-strategy) and desert with a prevalent S-strategy, reflecting a core trade-off between resource acquisition and stress tolerance. Disturbance conversely impacts meadow and steppe with opposite effects on S- vs. C-/R-strategies. Habitat filtering converges CSR strategies, shifting to neutrality or limiting similarity along gradients, with contrasting trends for C-/S- vs. R-strategies. These results provide a trait-based framework for understanding vegetation change and community reassembly across alpine ecosystems under climate change and grazing pressure. Competitor, stress-tolerator, and ruderal (CSR) strategies of alpine ecosystems suggest context-dependent roles of geography, climate, soil, disturbance, and productivity, with community assembly shifts from habitat filtering to limiting similarity.