Assessing the impact of urban land expansion on ecosystem carbon storage: A case study of the Changzhutan metropolitan area, China

Abstract

The extension of urban development can encroach onto ecologically important land, such as forests and farmland, and have a significant impact on regional ecosystem carbon storage. Although there has been extensive research on the carbon storage response to land use changes, limited exploration has been conducted on the changes in ecosystem carbon storage resulting from the expansion of construction land.. In the current research, we analyzed the characteristics involved in the growth related to built-up space in the Changzhutan metropolitan area from 1990 to 2020. Using the InVEST model, we evaluated the resulting effects on ecological carbon sequestration, and using the PLUS model, we simulated the effects of building land expansion under four scenarios: natural development, farmland protection, ecological protection, and comprehensive development. Additionally, our aim was to quantify the possible implications of the development of built-up areas on regional carbon storage. (1) The Changzhutan metropolitan area expanded its construction land by 721.58 km2 from 1990 to 2020, with the expansion mainly concentrated in the urban fringe areas, and the land type mainly changed from forests and farmland to construction land. (2) The ecosystem carbon sequestration in the Changsha-Zhuzhou-Xiangtan metropolitan area decreased by 22.66 × 106 t from 1990 to 2020, with the most significant decrease occurring from 2005 to 2010 when the expansion of construction land was 284.43 km2. (3)By 2030, the Changzhutan metropolitan area is projected to expand its construction land by 312.05 km2, 175.65 km2, 68.21 km2, and 68.90 km2 under the scenarios of natural development, farmland protection, ecological protection, and comprehensive development, respectively. Land use change in each scenario is expected to cause carbon storage losses of 10.01 × 106 t, 11.01 × 106 t, 2.07 × 106 t, and 1.95 × 106t, compared to 2020. (4) Over the investigation time span, expansion of construction ground in metropolitan Changzhutan had a negative impact on regional carbon storage, reaching a stable state from 2005 to 2020, and the effect pertaining to growth from the area of development upon the carbon accumulation of regional ecosystems under the comprehensive protection scenario in 2030 was −0.46. Considering the spatial heterogeneity analysis of regional carbon storage, this scenario would substantially upgrade the functional area surrounding the region and increase the biological system stabilization, which is conducive to achieving carbon neutrality goals.