Many terrestrial plant communities, especially forests, have been shown to lag in response to rapid climate change. Grassland communities may respond more quickly to novel climates, as they consist mostly of short-lived species, which are directly exposed to macroclimate change. Here we report the rapid response of grassland communities to climate change in the California Floristic Province. We estimated 349 vascular plant species’ climatic niches from 829,337 occurrence records, compiled 15 long-term community composition datasets from 12 observational studies and 3 global change experiments, and analysed community compositional shifts in the climate niche space. We show that communities experienced significant shifts towards species associated with warmer and drier locations at rates of 0.0216 ± 0.00592 °C yr⁻¹ (mean ± s.e.) and −3.04 ± 0.742 mm yr⁻¹, and these changes occurred at a pace similar to that of climate warming and drying. These directional shifts were consistent across observations and experiments. Our findings contrast with the lagged responses observed in communities dominated by long-lived plants and suggest greater biodiversity changes than expected in the near future.

许多陆生植物群落，尤其是森林，已被证明在应对快速气候变化方面滞后。草原群落可能对新气候反应更快，因为它们主要由短命物种组成，这些物种直接受到宏观气候变化的影响。在这里，我们报告了加利福尼亚植物区系省草原群落对气候变化的快速反应。我们从 829,337 条出现记录中估计了 349 种维管植物物种的气候生态位，从 12 项观察研究和 3 项全球变化实验中汇编了 15 个长期群落组成数据集，并分析了气候生态位空间的群落组成变化。我们表明，群落以 0.0216 ± 0.00592 °C ^yr-1（平均值 ± s.e.）和 -3.04 ± 0.742 mm ^yr-1 的速率向与温暖和干燥地区相关的物种发生了显着转变，并且这些变化以类似于气候变暖和干燥的速度发生。这些方向偏移在观察和实验中是一致的。我们的研究结果与在以长寿植物为主的群落中观察到的滞后反应形成鲜明对比，并表明在不久的将来生物多样性的变化比预期的要大。