Cheng Lei, Zhang Naifang, Yuan Mengting, Xiao Jing, Qin Yujia, Deng Ye, Tu Qichao, Xue Kai, Van Nostrand Joy D, Wu Liyou, He Zhili, Zhou Xuhui, Leigh Mary Beth, Konstantinidis Konstantinos T, Schuur Edward Ag, Luo Yiqi, Tiedje James M, Zhou Jizhong
Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou, China.
Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA.
ISME J. 2017 Aug;11(8):1825-1835. doi: 10.1038/ismej.2017.48. Epub 2017 Apr 21.
Soil organic matter (SOM) stocks contain nearly three times as much carbon (C) as the atmosphere and changes in soil C stocks may have a major impact on future atmospheric carbon dioxide concentrations and climate. Over the past two decades, much research has been devoted to examining the influence of warming on SOM decomposition in topsoil. Most SOM, however, is old and stored in subsoil. The fate of subsoil SOM under future warming remains highly uncertain. Here, by combining a long-term field warming experiment and a meta-analysis study, we showed that warming significantly increased SOM decomposition in subsoil. We also showed that a decade of warming promoted decomposition of subsoil SOM with turnover times of decades to millennia in a tall grass prairie and this effect was largely associated with shifts in the functional gene structure of microbial communities. By coupling stable isotope probing with metagenomics, we found that microbial communities in warmed soils possessed a higher relative abundance of key functional genes involved in the degradation of organic materials with varying recalcitrance than those in control soils. These findings suggest warming may considerably alter the stability of the vast pool of old SOM in subsoil, contributing to the long-term positive feedback between the C cycle and climate.
土壤有机质（SOM）库所含的碳（C）几乎是大气的三倍，土壤碳储量的变化可能对未来大气二氧化碳浓度和气候产生重大影响。在过去二十年中，许多研究致力于探讨变暖对表层土壤中SOM分解的影响。然而，大多数SOM年代久远，储存在底土中。未来变暖情况下底土SOM的命运仍高度不确定。在此，通过结合长期田间变暖实验和荟萃分析研究，我们表明变暖显著增加了底土中SOM的分解。我们还表明，十年的变暖促进了高草草原中周转时间为数十年至数千年的底土SOM的分解，这种效应在很大程度上与微生物群落功能基因结构的变化有关。通过将稳定同位素探测与宏基因组学相结合，我们发现，与对照土壤相比，变暖土壤中的微生物群落拥有更高相对丰度的参与降解不同难降解有机物质的关键功能基因。这些发现表明，变暖可能会极大地改变底土中大量古老SOM的稳定性，从而导致碳循环与气候之间的长期正反馈。
