Han Hongyan, Du Yue, Hui Dafeng, Jiang Lin, Zhong Mingxing, Wan Shiqiang
International Joint Research Laboratory for Global Change Ecology School of Life Sciences Henan University Kaifeng Henan China.
College of Life Sciences University of Chinese Academy of Sciences Beijing China.
Ecol Evol. 2017 Nov 9;7(24):10804-10814. doi: 10.1002/ece3.3536. eCollection 2017 Dec.
Changes in water and nitrogen (N) availability due to climate change and atmospheric N deposition could have significant effects on soil respiration, a major pathway of carbon (C) loss from terrestrial ecosystems. A manipulative experiment simulating increased precipitation and atmospheric N deposition has been conducted for 9 years (2005-2013) in a semiarid grassland in Mongolian Plateau, China. Increased precipitation and N addition interactively affect soil respiration through the 9 years. The interactions demonstrated that N addition weakened the precipitation-induced stimulation of soil respiration, whereas increased precipitation exacerbated the negative impacts of N addition. The main effects of increased precipitation and N addition treatment on soil respiration were 15.8% stimulated and 14.2% suppressed, respectively. Moreover, a declining pattern and 2-year oscillation were observed for soil respiration response to N addition under increased precipitation. The dependence of soil respiration upon gross primary productivity and soil moisture, but not soil temperature, suggests that resources C substrate supply and water availability are more important than temperature in regulating interannual variations of soil C release in semiarid grassland ecosystems. The findings indicate that atmospheric N deposition may have the potential to mitigate soil C loss induced by increased precipitation, and highlight that long-term and multi-factor global change studies are critical for predicting the general patterns of terrestrial C cycling in response to global change in the future.
气候变化和大气氮沉降导致的水和氮有效性变化，可能会对土壤呼吸产生重大影响，土壤呼吸是陆地生态系统碳损失的主要途径。在中国蒙古高原的半干旱草原上，已经进行了一项模拟降水增加和大气氮沉降增加的控制实验，为期9年（2005 - 2013年）。在这9年中，降水增加和施氮相互作用影响土壤呼吸。这些相互作用表明，施氮减弱了降水对土壤呼吸的刺激作用，而降水增加则加剧了施氮的负面影响。降水增加和施氮处理对土壤呼吸的主要影响分别是刺激了15.8%和抑制了14.2%。此外，在降水增加的情况下，观察到土壤呼吸对施氮的响应呈下降趋势和两年振荡。土壤呼吸对总初级生产力和土壤湿度的依赖性，而非对土壤温度的依赖性，表明在调节半干旱草原生态系统土壤碳释放的年际变化中，资源碳底物供应和水分有效性比温度更为重要。研究结果表明，大气氮沉降可能有减轻降水增加引起的土壤碳损失的潜力，并强调长期和多因素的全球变化研究对于预测未来陆地碳循环对全球变化的总体模式至关重要。
