基于碳储量最大化的流域多目标土地利用分区优化模拟—以广西西江清水河为例

土地利用变化是影响碳固存变化的重要因素，土地利用优化对实现区域碳平衡具有重要作用。以广西西江清水河流域为研究对象，基于2000年、2010年和2020年土地利用数据，通过FLUS-InVEST耦合模型预测2060年清水河流域4种模拟情景（基线情景、耕地保护情景、水域保护情景、高碳储用地保护情景）下土地利用变化与碳储量的时空发展特征；针对高、中、低碳储能力等级区域适宜发展的方向，构建基于碳储量最大化的灰色线性规划模型，优化土地利用数量结构并运用FLUS模型模拟土地利用空间布局；利用Fragstats软件分析流域上、中、下游区域不同土地利用类型的形态格局，探讨其与碳储量的相关性并提出相应的优化策略。结果表明：1）4种模拟情景下，2060年流域碳储量仅在高碳储用地保护情景下稳定提升，其他3种情景都大幅下降；2）基于优化方案，2060年流域内林地、湿地和水域面积增加，建设用地面积稳定增长，草地、耕地面积相对减少且连片耕地保持不变，流域整体碳储量增长达1.32×10⁶ t；3）流域土地利用形态格局影响碳储量，且不同流段存在空间异质性，整体上斑块呈现复杂不规则的形态和较高的聚集度、连接度，有利于提高区域整体碳储量。优化策略能更好地满足流域不同区域的发展需求并统筹流域整体发展，增加流域碳储量的同时推动总体效益最优化。

Simulation of land use zoning optimization under multi-objective scenarios based on maximizing carbon storage: taking Qingshui River of Xijiang River in Guangxi as an example

Land use change is an important factor affecting carbon sequestration change, and land use optimization plays an important role in realizing regional carbon balance. Based on the data of land use in 2000, 2010 and 2020, the temporal and spatial development characteristics of land use change and carbon storage in Qingshui River basin in 2060 were predicted by FLUS-InVEST coupling model under different simulation scenarios (baseline scenario, cultivated land protection scenario, water area protection scenario, and high-carbon storage land protection scenario). Aiming at the suitable development direction of high, medium and low carbon storage capacity grade regions, a grey linear programming model based on the maximization of carbon storage was constructed to optimize the quantitative structure of land use and simulate the spatial layout of land use using FLUS model. Fragstats software was used to analyze the morphological pattern of different land use types in the upper, middle and lower reaches of the basin, and analyze their correlation with carbon storage, and corresponding optimization strategies. The results showed that: 1) Under the four simulation scenarios, the carbon storage in the basin would increase steadily in 2060 only under the high-carbon storage land protection scenario, and decrease significantly under the other three scenarios. 2) Based on the optimization scheme, in 2060, the area of forest land, wetland and water area in the basin would increase, the area of construction land would increase steadily, the area of grassland and cultivated land would decrease relatively and the contiguous cultivated land would remain unchanged, and the overall regional carbon storage would increase by 1.32×106 t. 3) The land use pattern of the basin affected the carbon storage, and there was spatial heterogeneity in different segments. On the whole, the patches showed complex and irregular shapes with high degree of aggregation and connectivity, which was conducive to improve the overall carbon storage in the region. Therefore, the optimization proposed in this thesis can better meet the development needs of different regions of the basin while coordinate the overall development at the same time, and eventually increase the carbon storage of the basin and promote the overall benefit optimization.