Liu Lingli, Wang Xin, Lajeunesse Marc J, Miao Guofang, Piao Shilong, Wan Shiqiang, Wu Yuxin, Wang Zhenhua, Yang Sen, Li Ping, Deng Meifeng
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, 100093, China.
University of Chinese Academy of Sciences, Yuquanlu, Beijing, 100049, China.
Glob Chang Biol. 2016 Apr;22(4):1394-405. doi: 10.1111/gcb.13156. Epub 2016 Feb 9.
Soil respiration (Rs) is the second-largest terrestrial carbon (C) flux. Although Rs has been extensively studied across a broad range of biomes, there is surprisingly little consensus on how the spatiotemporal patterns of Rs will be altered in a warming climate with changing precipitation regimes. Here, we present a global synthesis Rs data from studies that have manipulated precipitation in the field by collating studies from 113 increased precipitation treatments, 91 decreased precipitation treatments, and 14 prolonged drought treatments. Our meta-analysis indicated that when the increased precipitation treatments were normalized to 28% above the ambient level, the soil moisture, Rs, and the temperature sensitivity (Q10) values increased by an average of 17%, 16%, and 6%, respectively, and the soil temperature decreased by -1.3%. The greatest increases in Rs and Q10 were observed in arid areas, and the stimulation rates decreased with increases in climate humidity. When the decreased precipitation treatments were normalized to 28% below the ambient level, the soil moisture and Rs values decreased by an average of -14% and -17%, respectively, and the soil temperature and Q10 values were not altered. The reductions in soil moisture tended to be greater in more humid areas. Prolonged drought without alterations in the amount of precipitation reduced the soil moisture and Rs by -12% and -6%, respectively, but did not alter Q10. Overall, our synthesis suggests that soil moisture and Rs tend to be more sensitive to increased precipitation in more arid areas and more responsive to decreased precipitation in more humid areas. The responses of Rs and Q10 were predominantly driven by precipitation-induced changes in the soil moisture, whereas changes in the soil temperature had limited impacts. Finally, our synthesis of prolonged drought experiments also emphasizes the importance of the timing and frequency of precipitation events on ecosystem C cycles. Given these findings, we urge future studies to focus on manipulating the frequency, intensity, and seasonality of precipitation with an aim to improving our ability to predict and model feedback between Rs and climate change.
土壤呼吸（Rs）是陆地第二大碳通量。尽管Rs已在广泛的生物群落中得到广泛研究，但令人惊讶的是，对于在降水格局变化的变暖气候中Rs的时空模式将如何改变，人们的共识很少。在这里，我们通过整理来自113个增加降水处理、91个减少降水处理和14个长期干旱处理的田间研究数据，对全球范围内通过操纵降水来研究Rs的数据进行了综合分析。我们的荟萃分析表明，当增加降水处理被标准化为比环境水平高28%时，土壤湿度、Rs和温度敏感性（Q10）值分别平均增加17%、16%和6%，而土壤温度下降了-1.3%。在干旱地区观察到Rs和Q10的增加最大，且刺激率随气候湿度增加而降低。当减少降水处理被标准化为比环境水平低28%时，土壤湿度和Rs值分别平均下降-14%和-17%，而土壤温度和Q10值没有改变。在湿度较高的地区，土壤湿度的降低往往更大。没有降水总量变化的长期干旱分别使土壤湿度和Rs降低了-12%和-6%，但没有改变Q10。总体而言，我们的综合分析表明，在更干旱的地区，土壤湿度和Rs对增加降水往往更敏感，而在更湿润的地区，对减少降水更敏感。Rs和Q10的响应主要由降水引起的土壤湿度变化驱动，而土壤温度变化的影响有限。最后，我们对长期干旱实验的综合分析也强调了降水事件的时间和频率对生态系统碳循环的重要性。鉴于这些发现，我们敦促未来的研究专注于操纵降水的频率、强度和季节性，以提高我们预测和模拟Rs与气候变化之间反馈的能力。
