Chen Jie, Biswas Asim, Su Haohai, Cao Jianjun, Hong Shuyan, Wang Hairu, Dong Xiaogang
College of Geography and Environmental Science, Northwest Normal University, Lanzhou, China.
School of Environmental Sciences, University of Guelph, Guelph, ON, Canada.
Front Plant Sci. 2023 May 8;14:1076902. doi: 10.3389/fpls.2023.1076902. eCollection 2023.
China has the second-largest grassland area in the world. Soil organic carbon storage (SOCS) in grasslands plays a critical role in maintaining carbon balance and mitigating climate change, both nationally and globally. Soil organic carbon density (SOCD) is an important indicator of SOCS. Exploring the spatiotemporal dynamics of SOCD enables policymakers to develop strategies to reduce carbon emissions, thus meeting the goals of "emission peak" in 2030 and "carbon neutrality" in 2060 proposed by the Chinese government. The objective of this study was to quantify the dynamics of SOCD (0-100 cm) in Chinese grasslands from 1982 to 2020 and identify the dominant drivers of SOCD change using a random forest model. The results showed that the mean SOCD in Chinese grasslands was 7.791 kg C m in 1982 and 8.525 kg C m in 2020, with a net increase of 0.734 kg C m across China. The areas with increased SOCD were mainly distributed in the southern (0.411 kg C m), northwestern (1.439 kg C m), and Qinghai-Tibetan (0.915 kg C m) regions, while those with decreased SOCD were mainly found in the northern (0.172 kg C m) region. Temperature, normalized difference vegetation index, elevation, and wind speed were the dominant factors driving grassland SOCD change, explaining 73.23% of total variation in SOCD. During the study period, grassland SOCS increased in the northwestern region but decreased in the other three regions. Overall, SOCS of Chinese grasslands in 2020 was 22.623 Pg, with a net decrease of 1.158 Pg since 1982. Over the past few decades, the reduction in SOCS caused by grassland degradation may have contributed to soil organic carbon loss and created a negative impact on climate. The results highlight the urgency of strengthening soil carbon management in these grasslands and improving SOCS towards a positive climate impact.
中国拥有世界第二大草地面积。草地土壤有机碳储量（SOCS）在维持国家和全球碳平衡及缓解气候变化方面发挥着关键作用。土壤有机碳密度（SOCD）是SOCS的一个重要指标。探索SOCD的时空动态能使政策制定者制定减少碳排放的策略，从而实现中国政府提出的2030年“碳排放达峰”和2060年“碳中和”目标。本研究的目的是量化1982年至2020年中国草地SOCD（0 - 100厘米）的动态变化，并使用随机森林模型确定SOCD变化的主要驱动因素。结果表明，1982年中国草地平均SOCD为7.791千克碳/平方米，2020年为8.525千克碳/平方米，全国净增加0.734千克碳/平方米。SOCD增加的区域主要分布在南部（0.411千克碳/平方米）、西北部（1.439千克碳/平方米）和青藏高原（0.915千克碳/平方米）地区，而SOCD减少的区域主要在北部（0.172千克碳/平方米）地区。温度、归一化植被指数、海拔和风速是驱动草地SOCD变化的主要因素，解释了SOCD总变化的73.23%。在研究期间，西北地区草地SOCS增加，而其他三个地区减少。总体而言，2020年中国草地SOCS为22.623Pg，自1982年以来净减少1.158Pg。在过去几十年中，草地退化导致的SOCS减少可能造成了土壤有机碳流失，并对气候产生了负面影响。研究结果凸显了加强这些草地土壤碳管理以及改善SOCS以实现积极气候影响的紧迫性。
