增温和刈割对高寒草甸土壤呼吸及其组分的影响

评估土壤呼吸及其组分对增温等全球变化的响应对于预测陆地生态系统碳循环至关重要。本研究利用红外线辐射加热器(Infrared heater)装置在青藏高原高寒草甸生态系统设置增温和刈割野外控制实验。通过测定2018年生长季(5—9月)土壤呼吸和异养呼吸，探究增温和刈割对土壤呼吸及其组分的影响。研究结果表明：(1) 单独增温使土壤呼吸显著增加31.65% (P<0.05)，异养呼吸显著增加27.12% (P<0.05)，土壤自养呼吸没有显著改变(P>0.05)；单独刈割对土壤呼吸和自养呼吸没有显著影响(P>0.05)，单独刈割刺激异养呼吸增加32.54% (P<0.05)；(2) 增温和刈割之间的交互作用对土壤呼吸和异养呼吸没有显著影响(P>0.05)，但是对自养呼吸的影响是显著的(P<0.05)，土壤呼吸和异养呼吸的季节效应显著(P<0.05)；(3)土壤呼吸及其组分与土壤温度均成显著指数关系，与土壤湿度呈显著的正相关关系(P<0.05)，处理影响它们的响应敏感性。本研究表明青藏高原东缘高寒草甸土壤碳排放与气候变暖存在正反馈。

Effects of warming and clipping on soil respiration and its components in an alpine meadow

Evaluating the responses of soil respiration and its components to warming and land use are crucial for predicting terrestrial ecosystem carbon cycling in the context of global change. Thus, a manipulative field experiment with warming and clipping was conducted in an alpine meadow, Qinghai-Tibetan Plateau to examine how soil respiration and its components in responses to warming and clipping in the growing season (May to September), and their relationships with soil temperature and soil moisture. Results showed that: (1) warming significantly increased soil respiration (31.65%) and heterotrophic respiration (27.12%) while did not affect soil autotrophic respiration. The clipping had no effect on soil respiration and soil autotrophic respiration, but significantly increased heterotrophic respiration by 32.54%; (2) the interaction effects of warming and clipping were insignificant for soil respiration and heterotrophic respiration while were significant for soil autotrophic respiration, and the seasonal dynamics of soil respiration and heterotrophic respiration were significant; (3) soil respiration and its components showed a significant exponential relationship with soil temperature and a positive linear relationship with soil moisture under warming and clipping treatments. Our study suggests positive feedback between soil carbon emissions and global changes such as warming and clipping in an alpine meadow on the eastern Qinghai-Tibetan Plateau.