基于碳汇潜力的碳排放空间关联网络结构特征及影响因素——以长江中游城市群为例

Structural characteristics and influencing factors of carbon emission spatial associa-tion networks based on carbon sink potential:a case study of urban agglomerations in the middle reaches of the Yangtze River

考虑碳汇潜力的碳排放空间关联是促进城市群协同减排的重要基础,更是实现碳中和的有力抓手。以长江中游城市群为研究区,对传统引力模型进行修正,构建兼具碳汇潜力的碳排放空间关联网络,采用社会网络分析(SNA)和二次指派程序方法(QAP)探究长江中游城市群碳排放空间关联网络的时空特征与影响因素。结果表明:①研究期间长江中游城市群碳排放网络关联关系数、网络密度和网络关联度呈增长趋势,网络效率和网络等级度不断下降,且网络等级度在2010年后始终为0,表明碳排放空间关联网络日益稠密、网络通达性较强,存在多重叠加的溢出渠道,但等级结构并不森严。基于碳汇潜力的长江中游城市群碳排放空间关联网络从“双核化”向“多极化、多线程”网络形态发展,核心城市的扩散作用不断增强。此外,以抚州、宜昌、鹰潭、上饶和吉安等为代表的高碳生态承载力地区,在碳排放空间关联网络中的受益关联性大于溢出关联性。②2020年,长江中游城市群碳排放空间关联网络形成四大板块,相较于板块内部成员间的碳排放空间关联效应,板块间的碳排放空间关联效应更为明显,即板块间的“碳排放转移”效应较为普遍。净溢出板块主要分布在武汉都市圈、宜荆荆都市圈和长株潭城市群外围城市,处于网络核心圈层位置;净受益板块主要分布在环鄱阳湖城市群东部,“碳排放避难所”效应显著。经纪人板块集中在环鄱阳湖城市群西部,板块间表现出“净溢出板块→经纪人板块→净受益板块”的碳排放传递路径,呈现出明显的“梯度转移”特征。双向溢出板块主要位于长江中游城市群西部,对净溢出和净受益板块都存在碳排放的空间溢出。研究期内,净溢出板块的成员虽然有所变化但总数保持不变,经纪人板块的成员有所增加,而净受益和双向溢出板块的成员均减少,环鄱阳湖城市群的“碳排放避难所”效应有所弱化。③地理邻近关系能够促进城市间碳排放关联关系的建立,而城市间的经济集聚程度、土地利用强度和经济发展水平上的互补性,促使碳排放空间关联网络随着城市间分工与协作的加强而呈现出千里“碳缘”一线牵的特点。

Acknowledging the carbon sink potential in carbon emission spatial associations is crucial to fostering collaborative emis-sion reduction within urban agglomerations,thereby furthering the achievement of carbon neutrality.This study focused on the urban ag-glomerations in the middle reaches of the Yangtze River and enhanced the traditional gravity model by including the carbon sink poten-tial to create a carbon emission spatial association network.Both social network analysis(SNA)and the quadratic assignment procedure(QAP)were employed to investigate the spatio-temporal properties and influencing elements of the network.The findings revealed that:①The network measures of carbon emission relations,network density,and network connectivity for the urban agglomeration in the middle reaches of the Yangtze River increased over time.However,network efficiency and network level degree declined continuously,with the latter dropping to zero after 2010,suggesting an increase in density and accessibility of the network and the existence of multi-ple overlapping spillage channels without a strict hierarchical structure.Over time,based on the carbon sink potential,the network transformed from a dual-core to a multipolar and multithreaded structure,with the diffusion effect of core cities strengthening continu-ously.Furthermore,regions with high ecological support for carbon,such as Fuzhou,Yichang,Yingtan,Shangrao,and Ji'an,displayed stronger benefit associations than spillage associations in the network.②In 2020,the network constituted four major blocks.The inter�block carbon emission spatial associations were more pronounced than the intra-block associations,signifying a strong carbon emission transfer effect between blocks.The net spillage blocks were primarily located in the periphery of the Wuhan metropolitan area,the Yichang–Jingzhou–Jingmen metropolitan area,and the Changsha–Zhuzhou–Xiangtan city group,central to the network.The net benefit blocks were mostly found in the eastern part of the urban agglomeration around Poyang Lake,displaying a significant carbon emission shelter effect.Broker blocks were predominantly situated in the western part of the urban agglomeration around Poyang Lake,and a distinct carbon emission transfer path of‘net spillage block→broker block→net benefit block’was observed,presenting a clear‘gradient transfer’pattern.Bidirectional spillage blocks were primarily in the western part of the urban agglomerations,contributing to carbon emission spatial spillage in both net spillage and net benefit blocks.Over time,while the number of members in the net spillage blocks remained constant,the members in the broker blocks increased,and members in the net benefit and bidirectional spillage blocks decreased,indicating a weakening of the‘carbon emission shelter’effect around Poyang Lake.③The study also revealed that geo-graphical proximity,complementarity of economic agglomeration,land use intensity,and economic development level among cities could promote the establishment of carbon emission associations,demonstrating a distant‘carbon affinity’relationship as urban divi-sion of labor and cooperation intensified.