Department of Environmental Science and Policy, University of California, Davis, CA 95616.
School of Life Sciences, Arizona State University, Tempe, AZ 85287.
Proc Natl Acad Sci U S A. 2023 Sep 26;120(39):e2218501120. doi: 10.1073/pnas.2218501120. Epub 2023 Sep 18.
While an array of ecological mechanisms has been shown to stabilize natural community dynamics, how the effectiveness of these mechanisms-including both their direction (stabilizing vs. destabilizing) and strength-shifts under a changing climate remains unknown. Using a 35-y dataset (1985 to 2019) from a desert stream in central Arizona (USA), we found that as annual mean air temperature rose 1°C and annual mean precipitation reduced by 40% over the last two decades, macroinvertebrate communities experienced dramatic changes, from relatively stable states during the first 15 y of this study to wildly fluctuating states highly sensitive to climate variability in the last 10 y. Asynchronous species responses to climatic variability, the primary mechanism historically undergirding community stability, greatly weakened. The emerging climate regime-specifically, concurrent warming and prolonged multiyear drought-resulted in community-wide synchronous responses and reduced taxa richness. Diversity loss and new establishment of competitors reorganized species interactions. Unlike manipulative experiments that often suggest stabilizing roles of species interactions, we found that reorganized species interactions switched from stabilizing to destabilizing influences, further amplifying community fluctuations. Our study provides evidence of climate change-induced modifications of mechanisms underpinning long-term community stability, resulting in an overall destabilizing effect.
虽然已经有一系列生态机制被证明可以稳定自然群落动态，但这些机制的有效性——包括它们的方向（稳定或不稳定）和强度——在气候变化下如何变化仍然未知。本研究使用了美国亚利桑那州中部沙漠溪流 35 年的数据集（1985 年至 2019 年），发现过去 20 年来，随着年平均气温上升 1°C，年平均降水量减少 40%，大型无脊椎动物群落经历了剧烈变化，从本研究前 15 年相对稳定的状态转变为对气候变率高度敏感的剧烈波动状态。历史上支撑群落稳定的主要机制——物种对气候变率的异步响应——大大减弱。新兴的气候模式——特别是同时变暖和多年持续干旱——导致了群落范围的同步响应和分类群丰富度的降低。多样性丧失和竞争者的新建立重新组织了物种间的相互作用。与通常表明物种相互作用具有稳定作用的操纵性实验不同，我们发现重新组织的物种相互作用从稳定作用转变为不稳定作用，进一步放大了群落波动。我们的研究提供了证据，证明气候变化引起了支撑长期群落稳定的机制的变化，导致了整体的不稳定效应。
