The impacts of warming on communities and ecosystems are predicted to be significant in mountain ecosystems because physiological processes, including rates of carbon (C) cycling, are often more temperature‐sensitive in colder environments. Plant biodiversity can also influence C exchange, yet few studies integrate how biotic and abiotic factors may directly or interactively impact ecosystem C flux. Here, we examine the link between simultaneous changes in multiple dimensions of plant diversity and peak growing season ecosystem C uptake across a climatic gradient in the Rocky Mountains, Colorado, USA. We found that taxonomic diversity (species richness), functional diversity (functional evenness), and phylogenetic diversity (mean pairwise distance) were significantly and positively related to peak growing season ecosystem C uptake (i.e., net ecosystem exchange) when considered independently. However, when abiotic and biotic factors were integrated in a structural equation model, only plant phylogenetic diversity was significantly related to C uptake. In addition, we found that actual evapotranspiration (AET—a measure that integrates precipitation and temperature) affected ecosystem C exchange indirectly via its impact on the three dimensions of plant diversity that we examined. These findings highlight complex relationships among key measures of biodiversity and ecosystem C uptake in a rapidly warming ecosystem, and the possible mechanisms that underlie relationships between biodiversity and ecosystem functioning. They also point to the need for integrating multiple dimensions of biodiversity into studies of community and ecosystem ecology.

中文翻译：

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气候和植物多样性的多个维度沿海拔梯度调节生态系统的碳交换

在山区生态系统中，变暖对社区和生态系统的影响预计会很大，因为在较冷的环境中，包括碳（C）循环速率在内的生理过程通常对温度更加敏感。植物生物多样性也可以影响碳交换，但是很少有研究整合生物和非生物因素如何直接或交互影响生态系统碳通量。在这里，我们研究了美国科罗拉多州落基山脉气候梯度上植物多样性的多个维度的同时变化与生长期峰值生态系统C吸收之间的联系。我们发现分类学多样性（物种丰富度），功能多样性（功能均匀性）和系统发育多样性（平均成对距离）与生长期高峰期生态系统碳吸收量（即，单独考虑时）。但是，当将非生物和生物因子整合到结构方程模型中时，只有植物系统发育多样性与碳吸收显着相关。此外，我们发现实际的蒸散量（一种将降水和温度结合起来的量度）通过影响到我们研究的植物多样性的三个维度而间接影响了生态系统的碳交换。这些发现强调了在迅速变暖的生态系统中生物多样性和生态系统碳吸收的关键指标之间的复杂关系，以及构成生物多样性与生态系统功能之间关系的潜在机制。他们还指出有必要将生物多样性的多个方面纳入社区和生态系统生态学研究。