Response and multi-scenario prediction of carbon storage to land use/cover change in the main urban area of Chongqing, China

Carbon storage services play an important role in maintaining ecosystem stability. Land use/cover change (LUCC) is the dominant factor generating changes in the ecosystem carbon storage. Demonstrating the impact of LUCC on regional carbon storage changes and predicting future carbon storage under different land use scenarios is of great significance for promoting regional carbon peak and carbon neutrality goals. Taking the main urban area of Chongqing as an example, this study analyzes carbon storage changes from 2000 to 2020 and the response to LUCC. The Markov-FLUS model is employed to predict the land use pattern of the main urban area in 2035 under four scenarios, and the InVEST model is used to assess carbon storage in 2035 under different scenarios. The results can be summarized as follows: 1) In the past 20 years, the area of cultivated land in the main urban areas of Chongqing decreased by 743.29 km2, and the area of construction land increased by 773.48 km2. About 18.8 % of the main urban area of Chongqing was transferred, the conversion of cultivated land to construction land being the most important type of transfer. 2) In 2000, 2005, 2010, 2015, and 2020, the carbon storage in the main urban area was 59.85, 59.29, 57.90, 56.95, and 54.07 Tg, respectively, showing an annually decreasing trend with a cumulative decrease of 5.78 Tg. The cultivated land occupation by construction land is the leading factor for the rapid decrease of carbon storage. The spatial distribution of carbon storage in the main urban area differs significantly, exhibiting a low in the middle and high in the surrounding areas. 3) In 2035, the carbon storage in the main urban area shows different degrees of decline in the Natural Trend Scenario (NTS), the Food Security Scenario (FSS) and the High Urbanization Scenario (HUS), decreasing by 3.37, 0.59, and 5.25 Tg, respectively. The only increase by 1.51 Tg is found in the Ecological Security Scenario (ESS). Therefore, under the background of the “Dual Carbon” targets and the important positioning of Chongqing as an important ecological barrier in the Yangtze River Basin, the ESS can be considered in the future development planning of the main urban area of Chongqing, which can both increase carbon sink and ensure ecological security.