## 4 Discussion
### Strategies for the Sustainable Management of CS  
The expansion of human activities has progressively intensified the degradation of LU carbon sequestration (CS) capacity [33; 37; 53]. Overgrazing, agricultural practices, and construction projects have led to a significant deterioration of surface vegetation, including forests and grasslands, in the BRB region [10; 54]. This, coupled with frequent occurrences of soil erosion, landslides, and debris flows, has further undermined the ecosystem's CS potential. The analysis of LU changes in soil and vegetation carbon sequestration (CS) indicated that arable land had a more pronounced influence on the decline in soil organic CS in the BRB. This LU type accounted for 35.6% of the reduction in soil CS observed in the study area. In the scenario simulation, safeguarding agricultural land boosted carbon sequestration, confirming that artificial management could adjust the change in farmland CP in the long or short terms [36]. Therefore, the government should prioritize the \"balance between arable land occupation and compensation\" in BRB to guarantee the sustainable development of regional soil organic carbon [55; 56]. In addition, woodland contributed the most to the increase in vegetation CS in BRB, and the decrease in woodland directly affected the reduction in overall CS. The decline in the woodland area reduced vegetation carbon by 147 tons, accounting for 95% of the decrease in vegetation CS within the study area. EP was the only scenario that could continuously and steadily increase CS. It demonstrates that ecological conservation measures are essential to improve the CS capacity of terrestrial ecosystems. Thus, moving forward, it is crucial to guarantee that economic growth proceeds within the boundaries of the ecological red line. This involves optimizing the regional LU structure, focusing on expanding the areas of forests and grassland, and actively promoting forestry conservation initiatives, as well as land reclamation and greening efforts [57; 58]. Moreover, steering the transformation of land into forests will contribute to maintaining the stability of the regional ecosystem and safeguarding the carbon balance. Ultimately, these actions will foster the sustainable growth of low-carbon infrastructure and achieve the transition to carbon sink.  
In addition, according to the results of the study on the correlation effect of topographic gradient and CS, the following relevant ecological protection measures and suggestions were put forward: (1) in the low-value (I-IV gradient) area (Figure 12), namely the densely populated area along and north of BRB, and the agricultural area in northern Wenxian County, we should strictly control human behavior, strengthen the intensive use of land, alleviate the contradiction between people and land, and pay attention to the construction of environmental protection projects such as urban greening and ecological livable. (2) In the topographic gradient of the high-value (IV-IX gradient) section, namely the eastern part of Diepe county, the southern part of the Dangchang, the southeastern part of the Wudu, it is necessary to establish and expand ecosystem-service-protection areas, strengthen forest management and protection, attach importance to forest and grass restoration, and enhance environmental carrying capacity and carbon sink capacity. (3) In the section of the high topographic gradient (X gradient), that is, the bare land, alpine desert and other low vegetation cover areas in counties, the protection of alpine meadows should be strengthened, rational grazing should be carried out, the interference of human activities should be reduced, the vulnerability of ecological environment should be reduced, and the ability to resist risks should be improved.