College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China; Joint Center for Global Change and China Green Development, Beijing Normal University, Beijing 100875, China.
College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China; Joint Center for Global Change and China Green Development, Beijing Normal University, Beijing 100875, China.
Sci Total Environ. 2018 Jan 15;612:799-808. doi: 10.1016/j.scitotenv.2017.08.236. Epub 2017 Sep 1.
The response of soil methane (CH) uptake to increased nitrogen (N) deposition and grazing management was studied in three types of steppe (i.e., meadow steppe, typical steppe, and desert steppe) in Inner Mongolia, China. The experiment was designed with four simulated N deposition rates such as 0, 50, 100, and 200kgNha, respectively, under grazed and fenced management treatments. Results showed that the investigated steppes were significant sinks for CH, with an uptake flux of 1.12-3.36kgha over the grass growing season and that the magnitude of CH uptake significantly (P<0.05) decreased with increasing N deposition rates. The soil CH uptake rates were highest in the desert steppe, moderate in the typical steppe, and lowest in the meadow steppe. Compared with grazed plots, fencing increased the CH uptake by 4.7-40.2% with a mean value of 20.2% across the three different steppe types. The responses of soil CH uptake to N deposition in the continental steppe varied depending on the N deposition rate, steppe type, and grazing management. A significantly positive correlation between CH uptake and soil temperature was found in this study, whereas no significant relationship between soil moisture and CH uptake occurred. Our results may contribute to the improvement of model parameterization for simulating biosphere-atmosphere CH exchange processes and for evaluating the climate change feedback on CH soil uptake.
本研究在中国内蒙古的三种草原（即草甸草原、典型草原和荒漠草原）中，研究了土壤甲烷（CH）吸收对增加的氮（N）沉积和放牧管理的响应。实验采用了四种模拟 N 沉积率（分别为 0、50、100 和 200kgNha），分别在放牧和围栏管理处理下进行。结果表明，所研究的草原是 CH 的重要汇，在草生长期内的吸收通量为 1.12-3.36kgha，并且 CH 吸收的幅度随着 N 沉积率的增加而显著（P<0.05）降低。荒漠草原的土壤 CH 吸收速率最高，典型草原中等，草甸草原最低。与放牧区相比，围栏管理使三种不同草原类型的 CH 吸收量增加了 4.7-40.2%，平均值为 20.2%。大陆性草原土壤 CH 吸收对 N 沉积的响应因 N 沉积率、草原类型和放牧管理而异。本研究发现，CH 吸收与土壤温度之间存在显著的正相关关系，而土壤湿度与 CH 吸收之间没有显著的关系。我们的研究结果可能有助于改进模拟生物圈-大气 CH 交换过程的模型参数化，并评估气候变化对 CH 土壤吸收的反馈。
