In a climate and land use change context, the sequestration of atmospheric carbon in urban agglomeration is key to achieving carbon emission and neutrality targets. It is thus critical to understand how various climate and land use changes impact overall carbon sequestration in large-scale city circle areas. As the largest urban agglomeration in central China, carbon dynamics in the Wuhan City Circle area have been deeply affected by rapid urbanization and climate change in the past two decades. Here, we applied monthly climate data, spatially explicit land use maps, NDVI (Normalized Difference Vegetation Index) images and the CASA (Carnegie-Ames-Stanford Approach) model to estimate the spatial and temporal changes of carbon dynamics in the Wuhan City Circle area from 2000 to 2015. We designed six different scenarios to analyze the effects of climate change and land use change on carbon dynamics. Our simulation of NPP (Net Primary Productivity) increased from 522.63 gC × m-2 to 615.82 gC × m-2 in the Wuhan City Circle area during 2000-2015. Climate change and land use change contributed to total carbon sequestration by -73.3 × 1010 gC and 480 × 1010 gC, respectively. Both precipitation and temperature had a negative effect on carbon sequestration, while radiation had a positive effect. In addition, the positive effect on carbon sequestration from afforestation was almost equal to the negative effect from urbanization between 2000 and 2015. Importantly, these findings highlight the possibility of carrying out both rapid urbanization and ecological restoration simultaneously.
Keywords: CASA model; NPP (Carnegie–Ames–Stanford Approach); carbon sequestration; ecological restoration; landscape planning; urbanization.