中国农田土壤呼吸速率及驱动因子

Soil Respiration and Driving Factors of Farmland Ecosystems in China

土壤呼吸在全球碳收支中具有重要地位.研究中国典型农业区土壤呼吸的时空格局及影响因素,有助于构建区域尺度土壤呼吸定量评价模型,能够为评估中国乃至全球农业生态系统碳/源汇特征提供依据.本研究整合了2000-2012年中国农田生态系统土壤呼吸的主要研究成果,分析了华南、西南、华北、西北和东北5个典型农业区土壤呼吸的季节变化和区域差异,以及影响土壤呼吸的主要驱动因子.结果表明,5个典型农业区的土壤呼吸均存在明显的季节变化特征;中国农田生态系统年均土壤呼吸速率为（682.8±18.3）g C m-2.5个典型农业区年均土壤呼吸速率大小表现为华南区〉西南区〉华北区〉东北区〉西北区.全国农业土壤的年呼吸通量为（0.90±0.02）Pg C;水作和旱作两种土地利用类型间土壤呼吸速率差异显著（P〈0.05）,旱作土壤呼吸速率约为水作的1.3倍;不同作物类型间土壤呼吸速率差异显著（P〈0.05）,其排序为棉花〉玉米〉大豆〉水稻〉小麦;农田土壤呼吸与年均气温、土壤温度、土壤含水量和净初级生产力等影响因素呈显著正相关（P〈0.01）,而与年均降水量的相关性不显著.

Soil respiration plays a crucial role in global carbon （C） budget. It is important to conduct the research in the typical agricultural regions, China to understand its spatial and temporal variations and their controlling factors. This will benefit not only quantitative evaluation of soil respiration at a regional scale, but also the agricultural C budget in China and even in the world. In this study, we integrated soil respiration data in agricultural ecosystems between 2000 and 2012 in China, and analyzed the seasonal and spatial variations and the factors influencing soil respiration in five typical agricultural regions （Southeast, Southwest, North, Northwest, and Northeast China）. The results showed that obvious seasonal variation was observed in five agricultural regions. The annual mean rate of soil respiration in farmland ecosystems of China was （682.8±18.3） g C m^-2 year^-1, and total C efflux from soil respiration in agricultural region of China was about 0.90 Pg C year^-1. The order of soil respiration rate in five agricultural regions was Southeast〉Southwest〉North〉Northeast〉Northwest. The significant difference in soil respiration rates was found between water-cultivation and dry-cultivation regions （P〈0.05）. Soil respiration in dry-cultivation regions was 1.3 times higher than that in water-cultivation ones. Soil respiration rate was significantly affected by crop types （P〈0.05）, with an order of cotton〉corn〉soybean〉rice〉wheat. Significant correlations were found in soil respiration with annual mean temperature, soil temperature, soil water content, and NPP （P〈0.01）. There was no significant correlation between soil respiration and annual precipitation.