[Analysis of Land Carbon Metabolism in Ningbo Based on Ecological Network Utility]

This study aims to elucidate the influence mechanism of land use on carbon metabolism and provide a foundation for promoting sustainable land resource utilization and facilitating urban green low-carbon transformation. Taking Ningbo City as the primary research focus, a carbon metabolism analysis framework is formulated, leveraging multi-source data collection. This framework employs ecological network analysis, the standard deviation ellipse method, and push-pull models to trace carbon element flow processes, elucidating the spatiotemporal evolution patterns of carbon metabolism. Consequently, a strategy for mitigating land use-related carbon emissions is proposed. The key findings are as follows： ① Between 2000 and 2020, net carbon emissions （measured in carbon, C） in Ningbo increased from 4.061 2 million tons to 30.193 7 million tons, representing a 6.43-fold increase. ② Vertical net carbon emissions were negative, with all land types except woodland and grassland exhibiting negative carbon metabolism compartments, whereas woodland and grassland had positive carbon metabolism compartments. During the study period, horizontal net carbon emissions in Ningbo were negative, attributed to the conversion of cultivated and forest lands to other construction lands. ③ Predation restriction was the dominant ecological relationship, with an overall ecological function value of 0.86. Compared to that from 2000-2010, the centroid of the 2010-2020 Predation Restriction standard deviation ellipse shifted eastward by 1.47°, whereas the centroid of the Competitive Relationship ellipse rotated westward by 10.46°, accompanied by a decrease in the overall ellipse range. ④ Cultivated land, forest land, and other construction land were the main types of thrust, and other construction land and urban land were the main types of pull. In conclusion, multiple measures need to be taken to reduce the carbon metabolism density of land use while developing carbon sink enhancement strategies for ecological land classification, with the goal of optimizing the land use structure and reducing carbon and increasing sinks in territorial space.