Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, Sichuan, China.
PLoS One. 2013;8(3):e59054. doi: 10.1371/journal.pone.0059054. Epub 2013 Mar 11.
Soil carbon dioxide (CO2) emission is one of the largest fluxes in the global carbon cycle. Therefore small changes in the size of this flux can have a large effect on atmospheric CO2 concentrations and potentially constitute a powerful positive feedback to the climate system. Soil CO2 fluxes in the alpine steppe ecosystem of Northern Tibet and their responses to short-term experimental warming were investigated during the growing season in 2011. The results showed that the total soil CO2 emission fluxes during the entire growing season were 55.82 and 104.31 g C m(-2) for the control and warming plots, respectively. Thus, the soil CO2 emission fluxes increased 86.86% with the air temperature increasing 3.74°C. Moreover, the temperature sensitivity coefficient (Q 10) of the control and warming plots were 2.10 and 1.41, respectively. The soil temperature and soil moisture could partially explain the temporal variations of soil CO2 fluxes. The relationship between the temporal variation of soil CO2 fluxes and the soil temperature can be described by exponential equation. These results suggest that warming significantly promoted soil CO2 emission in the alpine steppe ecosystem of Northern Tibet and indicate that this alpine ecosystem is very vulnerable to climate change. In addition, soil temperature and soil moisture are the key factors that controls soil organic matter decomposition and soil CO2 emission, but temperature sensitivity significantly decreases due to the rise in temperature.
土壤二氧化碳（CO2）排放是全球碳循环中最大的通量之一。因此，这个通量的微小变化可能对大气 CO2 浓度产生重大影响，并可能构成气候系统的一个强有力的正反馈。2011 年生长季期间，研究了藏北高寒草原生态系统的土壤 CO2 通量及其对短期实验增温的响应。结果表明，整个生长季对照和增温样地的总土壤 CO2 排放通量分别为 55.82 和 104.31 g C m(-2)。因此，土壤 CO2 排放通量随空气温度升高 3.74°C 增加了 86.86%。此外，对照和增温样地的温度敏感性系数（Q 10）分别为 2.10 和 1.41。土壤温度和土壤湿度可以部分解释土壤 CO2 通量的时间变化。土壤 CO2 通量的时间变化与土壤温度之间的关系可以用指数方程来描述。这些结果表明，增温显著促进了藏北高寒草原生态系统的土壤 CO2 排放，表明这个高寒生态系统对气候变化非常敏感。此外，土壤温度和土壤湿度是控制土壤有机质分解和土壤 CO2 排放的关键因素，但由于温度升高，温度敏感性显著降低。
