Xue Kai, Yuan Mengting M, Xie Jianping, Li Dejun, Qin Yujia, Hale Lauren E, Wu Liyou, Deng Ye, He Zhili, Van Nostrand Joy D, Luo Yiqi, Tiedje James M, Zhou Jizhong
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
mBio. 2016 Sep 27;7(5):e00976-16. doi: 10.1128/mBio.00976-16.
Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened.
Global change involves simultaneous alterations, including those caused by climate warming and land management practices (e.g., clipping). Data on the interactive effects of warming and clipping on ecosystems remain elusive, particularly in microbial ecology. This study found that clipping alters microbial responses to warming and demonstrated the effects of antagonistic interactions between clipping and warming on microbial functional genes. Clipping alone or combined with warming enriched genes degrading relatively recalcitrant carbon, likely reflecting the decreased quantity of soil carbon input from litter, which could weaken long-term soil C stability and trigger positive warming feedback. These results have important implications in assessing and predicting the consequences of global climate change and indicate that the removal of aboveground biomass for biofuel production may need to be reconsidered.
刈割（即收获地上植物生物量）在农业和生物能源生产中很常见。然而，在气候变暖背景下微生物对刈割的反应却知之甚少。我们研究了草地变暖和刈割对土壤性质、植物和微生物群落，特别是对微生物功能基因的交互作用。单独刈割不会改变植物生物量生产，但变暖和刈割相结合使地上生物量峰值增加了47%，地下净初级生产力增加了110%。单独刈割以及与变暖相结合分别使凋落物输入土壤的碳减少了81%和75%。由于碳输入减少，无论是单独刈割还是联合处理，参与降解相对难分解碳的基因丰度都增加了38%至137%，这可能会削弱土壤碳的长期稳定性，并引发与变暖相关的正反馈。单独刈割还使固氮、矿化和反硝化基因的丰度增加了32%至39%。这种潜在的固氮刺激有助于弥补单独刈割导致的土壤铵水平20%的下降，并有助于维持植物生物量水平不变。此外，刈割往往与变暖产生拮抗作用，特别是在对氮循环基因的影响方面，这表明单因素研究无法预测多因素变化。这些结果表明，单独刈割或与变暖相结合会改变土壤和植物性质以及土壤微生物功能基因的丰度和结构。由于长期土壤碳稳定性可能会被削弱，因此需要重新考虑为生产生物燃料而去除地上生物量的做法。
全球变化涉及多种同时发生的改变，包括气候变暖和土地管理实践（如刈割）所导致的改变。关于变暖和刈割对生态系统交互作用的数据仍然难以捉摸，特别是在微生物生态学方面。本研究发现，刈割会改变微生物对变暖的反应，并证明了刈割和变暖之间的拮抗作用对微生物功能基因的影响。单独刈割或与变暖相结合会使降解相对难分解碳的基因富集，这可能反映了凋落物输入土壤的碳量减少，这可能会削弱土壤碳的长期稳定性并引发变暖正反馈。这些结果对于评估和预测全球气候变化的后果具有重要意义，并表明可能需要重新考虑为生产生物燃料而去除地上生物量的做法。
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