UMR 1347 Agroecology, INRA, Dijon, France.
Environ Microbiol Rep. 2014 Apr;6(2):173-83. doi: 10.1111/1758-2229.12126. Epub 2013 Dec 2.
Despite the central role of microbes in soil processes, empirical evidence concerning the effect of their diversity on soil stability remains controversial. Here, we addressed the ecological insurance hypothesis by examining the stability of microbial communities along a gradient of soil microbial diversity in response to mercury pollution and heat stress. Diversity was manipulated by dilution extinction approach. Structural and functional stabilities of microbial communities were assessed from patterns of genetic structure and soil respiration after the stress. Dilution led to the establishment of a consistent diversity gradient, as revealed by 454 sequencing of ribosomal genes. Diversity stability was enhanced in species-rich communities whatever the stress whereas functional stability was improved with increasing diversity after heat stress, but not after mercury pollution. This discrepancy implies that the relevance of ecological insurance for soil microbial communities might depend on the type of stress. Our results also suggest that the significance of microbial diversity for soil functional stability might increase with available soil resources. This could have strong repercussions in the current 'global changes' context because it suggests that the combined increased frequencies of extreme climatic events, nutrient loading and biotic exploitation may amplify the functional consequences of diversity decrease.
尽管微生物在土壤过程中起着核心作用，但关于其多样性对土壤稳定性影响的经验证据仍然存在争议。在这里，我们通过研究土壤微生物多样性梯度上微生物群落对汞污染和热胁迫的稳定性来检验生态保险假说。多样性是通过稀释灭绝方法来操纵的。从胁迫后遗传结构和土壤呼吸的模式来评估微生物群落的结构和功能稳定性。454 核糖体基因测序揭示了稀释导致了一致的多样性梯度的建立。无论受到何种压力，丰富物种的群落都能增强多样性稳定性，而在热胁迫后，随着多样性的增加，功能稳定性得到提高，但在汞污染后则不然。这种差异表明，生态保险对土壤微生物群落的相关性可能取决于压力的类型。我们的研究结果还表明，微生物多样性对土壤功能稳定性的重要性可能随着土壤资源的增加而增加。在当前的“全球变化”背景下，这可能会产生强烈的影响，因为这表明极端气候事件、养分加载和生物利用的频率增加可能会放大多样性减少的功能后果。
