Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA.
Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
Ecol Lett. 2022 Aug;25(8):1813-1826. doi: 10.1111/ele.14060. Epub 2022 Jun 28.
Global change is altering patterns of community assembly, with net outcomes dependent on species' responses to the abiotic environment, both directly and mediated through biotic interactions. Here, we assess alpine plant community responses in a 15-year factorial nitrogen addition, warming and snow manipulation experiment. We used a dynamic competition model to estimate the density-dependent and -independent processes underlying changes in species-group abundances over time. Density-dependent shifts in competitive interactions drove long-term changes in abundance of species-groups under global change while counteracting environmental drivers limited the growth response of the dominant species through density-independent mechanisms. Furthermore, competitive interactions shifted with the environment, primarily with nitrogen and drove non-linear abundance responses across environmental gradients. Our results highlight that global change can either reshuffle species hierarchies or further favour already-dominant species; predicting which outcome will occur requires incorporating both density-dependent and -independent mechanisms and how they interact across multiple global change factors.
全球变化正在改变群落组装模式，净结果取决于物种对非生物环境的直接和通过生物相互作用介导的反应。在这里，我们评估了 15 年的氮添加、增温和融雪处理实验中高山植物群落的反应。我们使用动态竞争模型来估计物种组随时间变化的密度依赖性和非密度依赖性过程。在全球变化下，竞争相互作用的密度依赖性变化驱动了物种组丰度的长期变化，而通过非密度依赖性机制，环境驱动因素限制了优势物种的生长反应。此外，竞争相互作用随环境而变化，主要与氮有关，并在环境梯度上驱动非线性的丰度响应。我们的结果强调，全球变化可能会重新排列物种层次结构，或者进一步有利于已经占主导地位的物种；预测哪种结果会发生需要结合密度依赖性和非密度依赖性机制，以及它们如何在多个全球变化因素中相互作用。
