农田生态系统碳汇研究进展

A review of research advances on carbon sinks in farmland ecosystems

农田生态系统碳汇包括农作物生物量碳汇和农田土壤碳汇两个方面,中国农田生态系统面积大,碳储量高,是全球生态系统碳循环的重要组成部分。厘清中国农作物生物量和土壤有机碳含量、变化率和影响因素对于解析全球碳循环和维系粮食安全具有重要意义。梳理农田生态系统碳汇相关概念的基础上,比较农田生态系统碳汇研究方法的适用性及存在问题,通过以往研究和SoilGrids250数据研究中国农田生态系统碳库时空分布,并分析农田生态系统碳汇的影响因素及固碳方法。结果表明,中国近30年来农作物生物量呈现增加趋势,农田土壤有机碳含量普遍较低且空间分布不均,0—5cm土壤有机碳含量平均值在16.7 g/kg到86.5 g/kg之间,增加农田土壤有机碳含量是未来中国农田生态系统碳汇的重要方向。肥料和有机残留管理、保护性耕作、种植模式、灌溉等管理措施是增加土壤有机碳汇的主要措施,但农田生态系统碳汇潜力估算仍存在不确定性。最后,从农田生态系统碳汇潜力估算、影响因素厘定和增汇技术研发3个方面提出未来研究方向。研究结果有助于推动农田生态系统碳汇科学研究和技术推广,为实现农田生态系统助力“碳中和”寻求重要路径。

Farmland ecosystem carbon sequestration includes two parts:crop biomass and farmland soil carbon sequestration.China′s farmland ecosystem has a large area and high carbon storage,and is an important part of the global ecosystem carbon cycle.It is of great significance to clarify the content,change rate and the influencing factors of crop biomass and soil organic carbon in China for deepening the scientific understanding of global ecosystem carbon sink and maintaining food security.In this review,the related concepts of farmland ecosystems carbon were analyzed firstly,and the associated methods on carbon sinks were compared.Based on previous studies and SoilGrids250 data,the spatiotemporal distribution of carbon pools in farmland ecosystems in China was analyzed,and the influencing factors and carbon sequestration methods of farmland ecosystems were also analyzed.The results showed that the crop biomass in China has been increasing in the past 30 years,and farmland soil organic carbon content was low and its spatial distribution was uneven.Fertilizer and organic residue management,conservation tillage,planting patterns,irrigation and other management measures were the main measures to increase soil organic carbon sinks,but there were still uncertainties in the estimation of the carbon sink potential of farmland ecosystems.Finally,future research directions were put forward from three aspects:improving estimation accuracy of farmland ecosystem carbon sequestration,studying the influencing mechanism of both climate change and human activities,and developing agricultural technology to promote carbon sequestration.This review results help to promote scientific research and technology promotion of carbon sequestration in farmland ecosystems,and seek pathway for realizing“carbon neutrality”of farmland ecosystems.