State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
School of Atmospheric Sciences, Center for Monsoon and Environment Research, Sun Yat-sen University, Zhuhai, Guangdong 519082, China.
Sci Total Environ. 2021 Feb 25;757:143768. doi: 10.1016/j.scitotenv.2020.143768. Epub 2020 Nov 14.
Steppe soils are important biological sinks for atmospheric methane (CH), but the strength of CH uptake remains uncertain due to large spatiotemporal variation and the lack of in situ measurements at regional scale. Here, we report the seasonal and spatial patterns of CH uptake across a 1200 km transect in arid and semi-arid steppe ecosystems in Inner Mongolia, ranging from meadow steppe in the east plain to typical and desert steppes on the west plateau. In general, seasonal patterns of CH uptake were site specific, with unimodal seasonal curves in meadow and typical steppes and a decreasing seasonal trend in desert steppe. Soil moisture was the dominant factor explaining the seasonal patterns of CH uptake, and CH uptake rate decreased with an increase in soil moisture. Across the transect, CH uptake showed a skewed unimodal spatial pattern, with the peak rate observed in the typical steppe sites and with generally higher uptake rates in the west plateau than in the east plain. Soil moisture, together with soil temperature, soil total carbon, and aboveground plant biomass, were the main drivers of the regional patterns of CH uptake rate. These findings are important for model development to more precisely estimate the soil CH sink capacity in arid and semi-arid regions.
草原土壤是大气甲烷（CH）的重要生物汇，但由于时空变化大且缺乏区域尺度的原位测量，CH 吸收的强度仍然不确定。在这里，我们报告了在内蒙古干旱和半干旱草原生态系统中跨越 1200 公里的地带的 CH 吸收的季节性和空间格局，范围从东部平原的草甸草原到西部高原的典型和沙漠草原。总的来说，CH 吸收的季节性模式是特定于地点的，在草甸和典型草原中呈单峰季节性曲线，而在沙漠草原中呈下降的季节性趋势。土壤湿度是解释 CH 吸收季节性模式的主要因素，CH 吸收速率随土壤湿度的增加而降低。在整个地带，CH 吸收呈现出偏态单峰空间格局，在典型草原站点观察到峰值速率，并且通常在西部高原的吸收速率高于东部平原。土壤湿度、土壤温度、土壤总碳和地上植物生物量是 CH 吸收速率区域格局的主要驱动因素。这些发现对于模型开发很重要，可以更精确地估计干旱和半干旱地区的土壤 CH 汇容量。
