Urban land-carbon nexus based on ecological network analysis

Land use patterns may affect carbon emissions in the urban transition process. However, land and carbon issues are often considered as isolated factors when mitigating urban carbon emissions. In this study, we proposed a spatial land-carbon nexus framework for exploring the interwoven connections of carbon emission and land-use changes. The land-related carbon transitions were accounted by the land-use conversion matrix and carbon transfer density. Then, the ecological relationships among various land-use changes were explored using ecological network analysis (ENA). A land-carbon nexus rate was proposed to depict the integrated effect of land-use changes on carbon balance. A case study was also conducted for cities in Zhejiang Province during the periods of 1995–2000, 2000–2005, 2005–2010 and 2010–2015, showing their positive and negative land-related carbon transitions, and the variations of ecological relationships as well. The results showed that: (1) The dominant negative and positive carbon transitions exhibited in land-use changes from CL (Cultivated land) to I&T (Indusial and Transportation land) and I&T to CL. (2) Spatially, natural land-use type including wetland and forest exhibited competition relationships in the urban fringe area, while others embracing I&T and UCL (Urban construction land) with mutualism relationships scattered in the central urban area. (3) The dominate driving weight contributions for 8 cities were transformed from CL to I&T from 1995 to 2015, whereas the major pulling force weight contributions were always induced by natural land-use types with carbon sequestration functions. The land-carbon nexus approach presents great potential for bridging nexus analysis with resilient spatial planning to reduce the pressure in support of low carbon transitions through urban land management.