Estimating Carbon Stock Change Caused by Multi-Scenario Land-Use Structure in Urban Agglomeration

Land-use changes remain a major source of terrestrial ecosystem carbon stock (TECS) change. However, existing studies estimating TECS change caused by land-use changes, considering the mixed land-use structure and its continuous structural changes in the land-use change model, are still absent. Our study first analyzed land-use changes during the years 2000-2020 in the Changsha-Zhuzhou-Xiangtan (CZX) urban agglomeration, and then simulated the multi-scenario mixed land-use structure pattern in 2030, and finally estimated its effects on TECS change. Results show that: (1) The TECS change in CZX urban agglomeration during the years 2000-2020 are trending downward, decreasing 5.62 Tg. (2) Over the past 20 years, land-use changes in CZX urban agglomeration were dominated by the increase of artificial surfaces, and the decrease of forest, farmland, and grassland, which are major sources of TECS reduction. (3) The total TECS in inertial development, cultivated land protection, and ecological priority scenarios, are 95.82 Tg, 95.97 Tg, and 97.31 Tg, respectively. Compared to TECS in 2020, the decrease is 2.61 Tg, 2.46 Tg, and 1.12 Tg, respectively. While the spatial pattern of losses in TECS is trending toward sustained expansion in the inertial development and cultivated land protection scenario, the ecological priority scenario is more concentrated. The results can provide decision support for regional carbon accounting, for the assessment of terrestrial carbon stock, and for the planning of the "dual-carbon" (refer to peak carbon and carbon neutrality in dioxide emissions) goal.