Abstract: A typical steppe was selected in the Inner Mongolia as the research object. Using a laboratory incubation method, 50 g dried soil sample was put in 300 mL flask, adjusting content to 25% (W/W) with water. The flasks were sealed after injecting pure CH₄ (CH₄ initial concentration in the bottle are respectively 2.24, 340 and 7000 μL·L^-1) and cultured at (25±1)℃. The changes of CH₄ uptake in different fencing years (0, 8, 11, 14, 21 and 25 years) were studied. Results showed that appropriate fencing duration increased the capacity of CH₄ uptake compared with free grazed grassland. Fenced years significantly influence the CH₄ absorption of soil (F=11.1134, P<0.01). The capacity of CH₄ absorption reached the maximum after fenced for 8 years and reached the minimum after fenced for 14 years. Cumulative CH₄ uptake increased with soil organic carbon decreasing and initial CH₄ concentration increasing. Cumulative CH₄ uptake and soil organic carbon content was negatively correlated at the initial CH₄ concentration of 2.24 and 340 μL·L^-1 (R=0.9292, P<0.01; R=0.7502, P<0.05). It indicated that the main influencing factors of CH₄ uptake were soil organic carbon and CH₄ concentration.

Key words: Typical steppe, Fencing duration, CH₄ uptake

摘要： 选取内蒙古典型草原不同围封年限(0,8,11,14,21,25年)土壤为研究对象,采用室内培养的方法,调节含水量至25%(W/W),并注入纯CH₄(使瓶内初始CH₄浓度分别为2.24,340,7000 μL·L^-1)后密封,在(25±1)℃条件下恒温培养,研究不同围封年限土壤对CH₄吸收能力的影响。结果表明:与自由放牧草地相比,重度退化草地采取生长季围封恢复措施后,围封年限对CH₄吸收有显著影响(F=11.1134,P<0.01),草地围封8年时土壤吸收CH₄的能力达到最大,而在14年时吸收能力最小。针对不同初始外源CH₄浓度而言,CH₄的累积吸收量随CH₄初始浓度的升高而升高,在低、中初始CH₄浓度下CH₄的累积吸收量与土壤有机碳含量成负相关(R=0.9292,P<0.01;R=0.7502,P<0.05),表明土壤有机碳和外源CH₄浓度是影响土壤CH₄吸收的重要因子。

关键词: 典型草原, 围封年限, CH₄吸收