Spatio-temporal pattern of urban vegetation carbon sink and driving mechanisms of human activities in Huaibei, China

Carbon neutrality is a strategic choice for the sustainable development of global cities. Quantitatively assessing the spatio-temporal patterns of urban vegetation carbon sink and the impact of human activities has become an essential basis for adjusting urban carbon balance. We used Huaibei, a typical city with vigorous human coal resource mining activities, as the case study area. We regarded the net ecosystem productivity (NEP) as an indicator parameter of vegetation carbon sink and calculated it based on the improved Carnegie-Ames-Stanford approach (CASA). We then revealed the spatial–temporal evolution of vegetation carbon sink through trend analysis, coefficient of variation, and standard direction. Finally, we used geographic detectors to evaluate the impact of human activities on NEP. We found that net primary productivity (NPP) accuracy was good, and the R2 value was 0.755 compared with MODIS NPP products. NEP was characterized by the first decrease and then increase, showing a slow increase overall, with an average trend coefficient of 0.15 gC·m−2·a−1. The average value in 2010 was the lowest at 18.30 gC·m−2·a−1. In terms of spatial characteristics, NEP showed a gradual decrease from north to south. High and severe fluctuations were distributed along the southeast, mainly concentrated in Duji District, Xiangshan District, and Lieshan District. The driving factors with reliable explanatory power for NEP were population density, GDP, and road density, while land use type, soil erosion intensity, and mining and collapse area had weak explanatory power. Meanwhile, factors of cooperative interaction enhanced the explanatory power of the results.