长江流域固碳服务流动路径量化及驱动因子分析

Quantification and Driving Factors of Carbon Sequestration Service Flow Paths

摘要: 量化生态系统固碳服务的供给、需求及固碳服务流动路径，探索服务流驱动因子，以期为区域碳的空间格局管理提供依据。以长江流域为研究区，采用多源数据融合、InVEST模型、流动比率的方法、引入主风向的概念，研究长江流域固碳服务供给量与需求量的平衡关系，分析固碳服务空间流动的人为和自然驱动因子。结果表明：长江流域2015年、2020年碳固定量分别为248.7 t/hm²、249.1 t/hm²，主要的碳需求区为林地生态系统；碳排放量分别为21.7 t/hm²、22.6 t/hm²，建设用地是主要的碳供给区域。区域总体上碳需求值大于碳供给值。2) 2015、2020年长江流域上、中、下游固碳服务供需比分别为0.09、0.089、0.136和0.09、0.09、0.138，各省市固碳服务碳需求碳供给比率均小于1。3) 2015年，福建省碳服务流流量最大，为2370 t/km²；青海省碳服务流流量最小，为1523 t/km²；2020年，广西壮族自治区碳服务流流量最大，为2710 t/km²；青海省碳服务流流量最小，为1628 t/km²。4) 人口与土地利用因子是碳排放最主要的正向驱动因子，维持碳的供给。气候和降水对研究区的碳排放起负作用。长江流域2015年、2020年区域总体上碳汇值大于碳源值，依次由长江流域的上游、中游到下游区域，碳需求区域逐渐变大。未来长江流域低碳发展的实现需要加强上游碳需求区域保护，平衡中、下游固碳服务供需平衡。

Abstract: To quantify the supply and demand of ecosystem carbon sequestration services and the flow paths of carbon sequestration services, and to explore the service flow drivers, with a view to providing a basis for the management of regional carbon spatial pattern. Taking the Yangtze River basin as the study area, we adopt the methods of multi-source data fusion, the InVEST model, flow ratio, and introduce the concept of main wind direction to study the equilibrium relationship between the supply and demand of carbon sequestration services in the Yangtze River basin, and analyze the anthropogenic and natural drivers of the spatial flow of carbon sequestration services. The results showed that: 1) The carbon fixtion of the Yangtze River Basin in 2015 and 2020 was 248.7 t/hm² and 249.1 t/hm², respectively, and the main carbon demand region was woodland ecosystem. Carbon emissions were 21.7 t/hm² and 22.6 t/hm², respectively. Construction land was the main carbon source region. On the whole, the carbon demand value is greater than the carbon supply value. 2) In 2015 and 2020, the supply-demand ratio of carbon sequestration services in the upper, middle and lower reaches of the Yangtze River Basin was 0.09, 0.089, 0.136, and 0.09, 0.09, 0.138, respectively. The ratio of carbon sequestration services to carbon sources in each province was less than 1. 3) In 2015, Fujian province had the largest carbon service flow, which was 2370 t/km²; Qinghai province has the lowest carbon service flow, which is 1523 t/km². In 2020, Guangxi Zhuang Autonomous Region has the largest carbon service flow, which is 2710 t/km². Qinghai province has the lowest carbon service flow, which is 1628 t/km². 4) Population and land use factors are the most important positive drivers of carbon emissions, maintaining carbon supply. Climate and precipitation have negative effects on carbon emission in the study area. The carbon sink value of the Yangtze River Basin in 2015 and 2020 was larger than the carbon source value, and the carbon demand area gradually increased from the upper, middle and lower reaches of the Yangtze River Basin. In order to achieve low-carbon development in the Yangtze River basin in the future, it is necessary to strengthen the protection of the upstream carbon demand area and balance the supply and demand of carbon sequestration services in the middle and downstream.