Ecological network analysis of the carbon metabolism system in mountainous cities based on the land-carbon nexus: a case study of the main urban area of Chongqing, China

The analysis of urban carbon metabolism will help to mitigate global warming and achieve China's "Dual Carbon " targets. Taking the main urban area of Chongqing (MUAC) as an example, this study accounted for the carbon release and carbon absorption in MUAC, constructed an urban carbon flow model based on the land-carbon nexus, and evaluated the urban carbon metabolic system from 2000 to 2020 by using the ecological network analysis method. The results show that MUAC is dominated by a "carbon source " effect, and the net carbon flow is always negative. The negative carbon flow mainly comes from the conversion of cultivated land to construction land, and the positive carbon flow mainly comes from the conversion of construction land to cultivated land and woodland. The ecological relationship of carbon metabolism in MUAC is dominated by exploitation and control relationships, which mainly exist in the ecological relationship between construction land and cultivated land, and the spatial distribution is concentrated in the central and western areas of MUAC. Our research results can provide a reference for Chongqing's green and low-carbon sustainable development as a means toward the realization of the "Dual Carbon " targets and provide a reference for other similar mountainous cities in western China.