Jia Xiaohong, Zhou Xuhui, Luo Yiqi, Xue Kai, Xue Xian, Xu Xia, Yang Yuanhe, Wu Liyou, Zhou Jizhong
Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China; Shapotou Desert Research and Experimental Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, United States of America.
Coastal Ecosystems Research Station of Yangtze River Estuary, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, The Institute of Biodiversity Science, Fudan University, Shanghai 200433, China.
PLoS One. 2014 Dec 9;9(12):e114203. doi: 10.1371/journal.pone.0114203. eCollection 2014.
Regulatory mechanisms of soil respiratory carbon (C) release induced by substrates (i.e., plant derived substrates) are critical for predicting ecosystem responses to climate change, but the mechanisms are not well understood. In this study, we sampled soils from a long-term field manipulative experiment and conducted a laboratory incubation to explore the role of substrate supply in regulating the differences in soil C release among the experimental treatments, including control, warming, clipping, and warming plus clipping. Three types of substrates (glucose, C3 and C4 plant materials) were added with an amount equal to 1% of soil dry weight under the four treatments. We found that the addition of all three substrates significantly stimulated soil respiratory C release in all four warming and clipping treatments. In soils without substrate addition, warming significantly stimulated soil C release but clipping decreased it. However, additions of glucose and C3 plant materials (C3 addition) offset the warming effects, whereas C4 addition still showed the warming-induced stimulation of soil C release. Our results suggest that long-term warming may inhibit microbial capacity for decomposition of C3 litter but may enhance it for decomposition of C4 litter. Such warming-induced adaptation of microbial communities may weaken the positive C-cycle feedback to warming due to increased proportion of C4 species in plant community and decreased litter quality. In contrast, clipping may weaken microbial capacity for warming-induced decomposition of C4 litter but may enhance it for C3 litter. Warming- and clipping-induced shifts in microbial metabolic capacity may be strongly associated with changes in plant species composition and could substantially influence soil C dynamics in response to global change.
由底物（即植物源底物）诱导的土壤呼吸碳（C）释放的调节机制对于预测生态系统对气候变化的响应至关重要，但这些机制尚未得到很好的理解。在本研究中，我们从一个长期的田间操纵实验中采集土壤，并进行了实验室培养，以探讨底物供应在调节实验处理（包括对照、升温、剪枝以及升温和剪枝）之间土壤碳释放差异中的作用。在这四种处理下，添加了三种类型的底物（葡萄糖、C3和C4植物材料），添加量相当于土壤干重的1%。我们发现，在所有四种升温和剪枝处理中，添加所有三种底物均显著刺激了土壤呼吸碳释放。在未添加底物的土壤中，升温显著刺激了土壤碳释放，但剪枝则使其降低。然而，添加葡萄糖和C3植物材料（C3添加）抵消了升温效应，而添加C4植物材料仍显示出升温诱导的土壤碳释放刺激作用。我们的结果表明，长期升温可能会抑制微生物对C3凋落物的分解能力，但可能会增强其对C4凋落物的分解能力。这种升温诱导的微生物群落适应性可能会由于植物群落中C4物种比例增加和凋落物质量下降而削弱碳循环对升温的正反馈。相反，剪枝可能会削弱微生物对升温诱导的C4凋落物分解能力，但可能会增强其对C3凋落物的分解能力。升温和剪枝诱导的微生物代谢能力变化可能与植物物种组成的变化密切相关，并可能在很大程度上影响土壤碳动态以响应全球变化。
