[Carbon Storage-based Identification and Forecasting of Regional Land Use's Carbon Source and Sink Effects Alterations: Scenario Analysis from Chang-Zhu-Tan Urban Agglomeration]

The dynamic evolution of local carbon sources and sinks is significantly impacted by alterations in land utilization. Accurately detecting and evaluating the carbon source-sink effects of these changes is critical for improving local land utilization structures and reaching the double carbon targets. The Chang-Zhu-Tan Urban Agglomeration's land utilization trends between 1990 and 2020 are investigated in this study. This study uses the InVEST model to examine carbon preservation's response to land use changes and associated source-sink dynamics. The PLUS model is also employed to evaluate the impact of land use changes on carbon storage and source-sink dynamics in five future scenarios （integrated preservation， ecological preservation， farmland preservation， urban growth， and natural growth） for 2030 and 2060. The findings show that： ① Between 1990 and 2020， a total of 2 259.04 km² of land within the Chang-Zhu-Tan Urban Agglomeration underwent transformation. The majority of this spatial change originated from farmland and woodland， while developed land emerged as the dominant type of newly developed land. ② Between 1990 and 2020， the metropolitan agglomeration of Changsha， Zhuzhou， and Xiangtan had a gradual decline in carbon storage. The geographical pattern of carbon storage exhibited spatial heterogeneity. The transformation of farmland and woodland into developed land resulted in the most significant decrease in carbon sequestration. ③ The conversion of high carbon storage land， such as forest land， to low carbon storage land types like cropland， grassland， water bodies， and construction land resulted in a decrease in carbon storage， exhibiting a carbon source effect. Conversely， the conversion of low carbon storage land types like cropland， grassland， and construction land to forest land increased carbon storage， exhibiting a carbon sink effect. ④ Projections for 2030 indicated that the total carbon storage would rank as follows： Integrated Protection （IP） > Cultivated Land Protection （CP） > Ecological Protection （EP） > Natural Development （ND） > Urban Development （UD）. By 2060， the ranking changes to IP > EP > CP > UD > ND. The Integrated Protection Scenario exhibits the highest total carbon storage in both 2030 and 2060. ⑤ In 2030 and 2060， the Protection of the Ecosystem and Integrated Preservation scenarios are more suited to showing significant carbon sink impacts and accomplishing both of the carbon goals （carbon maximum and carbon balance）. These findings establish a robust scientific framework for the development of sustainable land utilization strategies and the reduction of carbon sequestration capacity loss in ecosystems.