Strategies for Enhancing Carbon Sink Capacity and Optimizing Blue-Green Infrastructure in Guilin City Based on ArcGIS and the InVEST Model

Enhancing carbon sink capacity and optimizing urban blue-green infrastructure (UBGI) are crucial for urban planning and sustainable development. Based on the ArcGIS 10.8 platform and the InVEST model, this study comprehensively evaluates the spatiotemporal evolution characteristics of three ecosystem services (carbon storage, habitat quality, and water retention) in Guilin. By applying the coupling coordination degree model, bivariate spatial autocorrelation, and K-means clustering methods, it systematically reveals the synergistic and trade-off relationships among multiple ecosystem services in karst cities, identifies the spatial differentiation pattern of ecological spaces, and proposes UBGI optimization strategies. The results show that the three types of ecosystem services in Guilin exhibited a spatiotemporal differentiation pattern of stable high values in mountainous areas and continuous expansion of low values around urban areas from 1993 to 2023, with their changes mainly driven by the significant negative impact of human activity intensity (nighttime light, population density). Guilin’s ecological space can be divided into four functional zones: Ecological Core Cluster (77.50%), Degraded Carbon-Poor Cluster (1.47%), Habitat Protection Cluster (0.46%), and Buffer Balance Cluster (20.58%). Carbon storage, habitat quality, and water retention showed significant spatial gradient differences (Kruskal–Wallis nonparametric test, p < 0.001) and local decoupling characteristics. Furthermore, the study proposed key ecological management thresholds, such as impervious surface ratio < 15% and forestland ratio > 30%, and constructed a differentiated “zoning-classification-grading” UBGI optimization strategy system based on the four functional zones, including ecological corridor construction, promotion of vertical greening and sponge facilities, supplementary planting of native vegetation, and integration of ecological agriculture. These strategies aim to enhance the synergistic efficiency of ecosystem services, improve regional carbon sink capacity, and provide a scientific basis for Guilin’s ecological planning, the implementation of “dual carbon” goals, and the construction of the National Innovation Demonstration Zone for Sustainable Development Agenda.