## 4 Discussion  
### Response of CS to Land Use Change  
Land use is essential in determining the carbon dynamics within terrestrial ecosystems [29], thereby influencing the CS mechanism and causing fluctuations in [30]. The specific shift involves the rise in high-density LUCC types and the fall in low-density LUCC types, thereby improving regional CS [31; 32]. The study reveals that CS in the region has exhibited a fluctuating pattern since 2000 (Figure 5, Table 5). This variation is strongly linked to the enactment of China's farmland-to-forest policy in 2002, which aimed to secure ecological land, restore degraded farmland, prevent soil erosion, and substantially expand woodland areas. However, rapid economic growth, coupled with the expansion of urban areas and the decline in forested regions, has led to widespread vegetation destruction and ecosystem degradation [33]. Consequently, the average yearly growth in carbon sequestration has slowed, and certain forested areas have been converted into agricultural and urban land. The main cause of carbon loss in the region originates from the growth of urban areas, and the decline in woodland also contributes significantly to CS loss. This is consistent with the findings of [PERSON] et al. (2020), who also observed that urbanization and the expansion of urbanized land have a major effect on reducing CS [34]. LU patterns are closely linked to biomass, vegetation coverage, and the CS capacity of various land types, which directly influence regional CS changes [35]. Table 6 emphasizes the effect of various LU types on CS, revealing trends in soil CS, vegetation CS, and total CS. The results show that forests, grasslands, and arable land contribute more than 95% to the CS of terrestrial ecosystems. Nevertheless, future development trends may pose significant challenges to ecosystems and food security, especially as policy directions and development pathways may lead to marked changes in LU patterns and spatial distribution [36]. In response to the strategy of \"carbon neutrality, carbon peak\", the best model of regional low-carbon development is proposed. According to the results, CS is expected to rise in 2050 under the ecological protection scenario. However, in the ND scenario, the growth of land for economic activities negatively impacts the ecological environment, although this model provides high LU flexibility and allows for the natural process of urbanization and industrialization, it fails to effectively guarantee the systematic protection of ecology and agriculture. This approach will lead to a disorderly reduction in arable and ecological land, and ultimately increase carbon loss. In scenarios focused on arable land protection, while there may be a short-term increase in CS, the long-term effect is uncertain, and CS may eventually decline. A continued emphasis on farmland protection policies may not foster stable CS growth in the future [26]. Forests are under increasing pressure from both natural and human-induced degradation [37]. In contrast, the EP scenario effectively avoids ecosystem degradation, promotes the steady growth of forest CS by rationally adjusting the conversion of agricultural land and other land types to forests, and is relatively cheap in economic cost. Therefore, future planning and management should reduce human intervention, and focus on strengthening the protection of forest land and grassland to improve carbon sequestration capacity. The conclusion that rational socio-economic development and land adjustment can effectively mitigate carbon loss is consistent with existing research [38; 39; 40; 41], and supports ecological conservation measures that can effectively address regional ecosystem imbalances and ensure the long-term stability of CS.