Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697;
Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521.
Proc Natl Acad Sci U S A. 2018 Nov 20;115(47):11994-11999. doi: 10.1073/pnas.1811269115. Epub 2018 Nov 5.
Bacteria and fungi drive decomposition, a fundamental process in the carbon cycle, yet the importance of microbial community composition for decomposition remains elusive. Here, we used an 18-month reciprocal transplant experiment along a climate gradient in Southern California to disentangle the effects of the microbial community versus the environment on decomposition. Specifically, we tested whether the decomposition response to climate change depends on the microbial community. We inoculated microbial decomposers from each site onto a common, irradiated leaf litter within "microbial cages" that prevent microbial exchange with the environment. We characterized fungal and bacterial composition and abundance over time and investigated the functional consequences through litter mass loss and chemistry. After 12 months, microbial communities altered both decomposition rate and litter chemistry. Further, the functional measurements depended on an interaction between the community and its climate in a manner not predicted by current theory. Moreover, microbial ecologists have traditionally considered fungi to be the primary agents of decomposition and for bacteria to play a minor role. Our results indicate that not only does climate change and transplantation have differential legacy effects among bacteria and fungi, but also that bacterial communities might be less functionally redundant than fungi with regards to decomposition. Thus, it may be time to reevaluate both the role of microbial community composition in its decomposition response to climate and the relative roles of bacterial and fungal communities in decomposition.
细菌和真菌驱动着分解作用，这是碳循环中的一个基本过程，但微生物群落组成对分解作用的重要性仍然难以捉摸。在这里，我们使用了一个在加利福尼亚南部沿气候梯度进行的为期 18 个月的相互移植实验，以分解微生物群落与环境对分解作用的影响。具体来说，我们测试了微生物群落对气候变化的分解响应是否取决于微生物群落。我们将每个地点的微生物分解者接种到“微生物笼”内的一种常见的辐照叶凋落物上，这些微生物笼防止了微生物与环境的交换。我们随着时间的推移对真菌和细菌的组成和丰度进行了表征，并通过凋落物质量损失和化学特性来研究其功能后果。12 个月后，微生物群落改变了分解速率和凋落物化学性质。此外，功能测量结果取决于群落及其在气候方面的相互作用，这种作用方式与当前理论所预测的方式不同。此外，微生物生态学家传统上认为真菌是分解作用的主要作用者，而细菌则起次要作用。我们的研究结果表明，不仅细菌和真菌之间的气候变化和移植具有不同的遗留效应，而且与真菌相比，细菌群落可能在分解作用方面的功能冗余性较低。因此，可能是时候重新评估微生物群落组成在其对气候变化的分解响应中的作用，以及细菌和真菌群落在分解作用中的相对作用了。
