Response of vegetation carbon sequestration potential to the effectiveness of vegetation restoration in karst ecologically fragile areas in Guizhou, southwest China

In the southwest karst areas of China, changes in overlying vegetation due to ecological restoration cause considerable carbon sequestration (CS). Assessing the CS potential of vegetation restoration in this areas is crucial for promoting the optimization and regulation of regional vegetation restoration(VR) policies. This study is based on net primary productivity, maximum vegetation coverage and average vegetation coverage. Using the VR effectiveness index (Ej) to quantitatively evaluate the spatiotemporal characteristics of VR effectiveness, quantifying the spatiotemporal pattern of vegetation restoration CS using the vegetation photosynthetic CS model, and clarifying the main driving mechanisms of vegetation restoration CS. This results showed that more than 54.25 % of the studied area in the ecologically fragile areas has achieved significant VR (Ej >= 20) from 2000 to 2020. The spatial distribution of vegetation CS intensity and potential was higher in the southwest than in the northeast. Moreover, there was a strong spatial correlation between the areas with greater vegetation CS densities and the areas with poor natural background conditions, showing that the effectiveness of ecological restoration and economic growth complement each other. The correlation between the potential for vegetation CS and the current value of vegetation cover was r = 0.06 (p < 0.05) and the correlation with the magnitude of change in vegetation cover was r = 0.38 (p < 0.05), which indicates that vegetation CS has a greater potential where the magnitude of vegetation greening is greater. The greening range of vegetation was constrained by the natural background environment in ecologically fragile areas, and the continuous enhancement of positive feedback intervention and weakening of negative feedback tended to promote the greening range of vegetation on the ground surface and increased the CS potential. This results provide a reference for the long-term goal of "carbon neutrality" in response to VR and CS in ecologically fragile areas to offset atmospheric CO2 emissions.