Strickland Michael S, Lauber Christian, Fierer Noah, Bradford Mark A
Odum School of Ecology, University of Georgia, Athens, Georgia 30602, USA.
Ecology. 2009 Feb;90(2):441-51. doi: 10.1890/08-0296.1.
A critical assumption underlying terrestrial ecosystem models is that soil microbial communities, when placed in a common environment, will function in an identical manner regardless of the composition of that community. Given high species diversity in microbial communities and the ability of microbes to adapt rapidly to new conditions, this assumption of functional redundancy seems plausible. We test the assumption by comparing litter decomposition rates in experimental microcosms inoculated with distinct microbial communities. We find that rates of carbon dioxide production from litter decomposition were dependent upon the microbial inoculum, with differences in the microbial community alone accounting for substantial (approximately 20%) variation in total carbon mineralized. Communities that shared a common history with a given foliar litter exhibited higher decomposition rates when compared to communities foreign to that habitat. Our results suggest that the implicit assumption in ecosystem models (i.e., microbial communities in the same environment are functionally equivalent) is incorrect. To predict accurately how biogeochemical processes will respond to global change may require consideration of the community composition and/or adaptation of microbial communities to past resource environments.
陆地生态系统模型所基于的一个关键假设是,土壤微生物群落置于共同环境中时,无论群落组成如何,都将以相同方式发挥功能。鉴于微生物群落具有高度的物种多样性以及微生物能够迅速适应新环境的能力,这种功能冗余的假设似乎是合理的。我们通过比较接种不同微生物群落的实验微宇宙中的凋落物分解速率来检验这一假设。我们发现,凋落物分解产生二氧化碳的速率取决于微生物接种物,仅微生物群落的差异就导致总碳矿化量有显著(约20%)的变化。与给定叶凋落物有共同历史的群落,与该栖息地外来的群落相比,表现出更高的分解速率。我们的结果表明,生态系统模型中的隐含假设(即同一环境中的微生物群落功能等效)是不正确的。要准确预测生物地球化学过程将如何响应全球变化,可能需要考虑微生物群落的组成和/或微生物群落对过去资源环境的适应性。