The cost of urban expansion: modeling past and future impacts on ecosystem carbon storage in the Chang-Zhu-Tan urban agglomeration

Urban expansion’s direct and historical ecological consequences are well recognized, but its indirect and future implications remains unclear. This study employs an integrated modeling approach, combining the InVEST, FLUS and linear regression models, to explore how urban expansion in the Chang-Zhu-Tan Urban Agglomeration (CZTUA) has driven and will continue to drive land use changes, resulting in the loss of ecosystem carbon storage both in the past and under future development pathways. From 1990 to 2020, the construction land increased significantly by 85,482.09 hm 2 , with newly expanded construction land mainly distributed around the periphery of existing built-up areas. Concurrently, the ecosystem carbon storage decreased significantly by 8.9 × 10 8 kg, and the expansion direction of low-carbon storage areas aligns with that of newly expanded construction land. Under the ecological protection scenario, construction land shows a contraction trend by 2030 and 2060, with a slow decrease in ecosystem carbon storage. Contrastly, under the natural and urban development scenarios, construction land demonstrates an expansion trend, accompanied by an accelerated reduction in ecosystem carbon storage. Construction land expansion primarily exerts significantly negative impacts on aboveground and belowground carbon storage, while its adverse effect on soil carbon storage remains relatively limited.