关键词: 生态系统服务, 嘉陵江流域, InVEST模型, 权衡协同, 地理探测器

Abstract:

Ecosystem services, which play a pivotal role in directly and indirectly satisfying human requirements, are provided by natural ecosystems through their structure, function, and processes. These services are extremely diverse and exhibit uneven spatial distributions. Intricate interaction mechanisms and dynamic relationships prevail among different services, which manifest mainly as trade-offs and synergies. Thus, analyzing the dynamic changes, driving mechanisms, and interactions of ecosystem services within a watershed holds great significance for ecological protection and coordinated regional development. The Jialing River Basin, serving as a pivotal ecological barrier in the upper reaches of the Yangtze River, is endowed with a rich and diverse ecosystem and assumes crucial functions, such as water conservation and ecological regulation. Nevertheless, irrational development and utilization within the basin have engendered a series of issues. These include inefficient utilization of water resources, wetland degradation, soil erosion, and secondary environmental risks stemming from upstream mining and industrial development. These problems present dual challenges in terms of both economic development and environmental protection. Currently, research on ecosystem services in river basins is predominantly centered on spatiotemporal dynamics and interactions. However, there is a lack of in-depth exploration of internal disparities and complex mechanisms within the basin. This is particularly evident in the comprehensive analyses of trade-offs and synergies at both basin-wide and regional scales. Although certain studies have explored individual ecosystem services within the Jialing River Basin, there remains a dearth of research on the comprehensive analysis of multiple ecosystem services and their intricate interactions. Therefore, this study was conducted as follows. Initially, the InVEST model was utilized to analyze and quantify the spatiotemporal dynamics of four key ecosystem services, namely, soil retention, habitat quality, carbon storage, and water yield, in the Jialing River Basin for the years 2000, 2010, and 2020. Second, by leveraging the GeoDetector method, single-factor and interactive-factor detections were utilized to quantitatively analyze the driving mechanisms of individual and interactive factors for each service. Subsequently, Pearson correlation analysis and spatial autocorrelation methods were employed to evaluate the trade-offs and synergies among different ecosystem services as well as the spatial distribution characteristics of these relationships. Finally, the basin was partitioned into regions based on the topographic position index. Subsequently, the interactions among different ecosystem services within each topographic gradient zone were analyzed. Key findings are as follows: 1) The ecosystem services within the Jialing River Basin, on the whole, exhibit a tendency of “overall growth with local stability”. Soil conservation and water yield services have experienced a remarkable increase; however, conspicuous disparities exist in their spatial distributions. High-value regions for soil retention are concentrated in the precipitous and densely vegetated southeastern and northwestern areas. Conversely, water yield services manifest a “southern-high, northern-low”. High-value regions are located in the southern part where precipitation is abundant. Habitat quality has experienced a slight decline, predominantly attributed to human activities, and carbon storage has remained relatively stable with a spatial distribution analogous to that of habitat quality. Specifically, high-value zones are located in the well-vegetated northwestern and southeastern regions, while low-value zones are found in highly urbanized areas, such as the Chengdu-Chongqing Economic Circle. 2) Additionally, changes in ecosystem services within the Jialing River Basin are jointly driven by natural factors and human activities. Single-factor analysis demonstrated that habitat quality was predominantly influenced by land use and vegetation cover. Soil conservation is closely associated with slope gradient and precipitation. Water yield is principally affected by precipitation and elevation. Carbon storage was strongly correlated with vegetation and precipitation. The analysis of interaction factors revealed that soil conservation was augmented under the synergistic action of slope gradient and vegetation. The water yield service demonstrated greater stability in the context of the interaction between the slope gradient and precipitation. Carbon storage and habitat quality were markedly affected by the synergistic effects of vegetation, precipitation, and land use. 3) The trade-offs and synergies of ecosystem services in the Jialing River Basin showed significant differences over time, across space, and among the different topographic gradient zones. From 2000 to 2020, across the entire region, there was a stable trade-off relationship between water yield service and carbon storage. There were stable synergistic relationships between carbon storage and habitat quality as well as between soil conservation and habitat quality, and the synergistic effects gradually increased. Spatially, the characteristics of trade-off and synergy showed a gradient change from northwest to southeast. Areas with a high degree of trade-off were concentrated in the northwest, whereas those with a strong synergistic effect were distributed in the north and east. The analysis of the classification based on the topographic position index showed that there are significant differences in the relationships between ecological services within different gradient zones. The interaction in zone 1 was relatively weak. The synergistic effect is enhanced in Zones 3 and 4, while in Zone 5, it mainly manifested as a trade-off relationship. Based on these findings, the optimization of ecosystem services in the Jialing River Basin requires a comprehensive consideration of its spatiotemporal heterogeneity, as well as the trade-off and synergistic relationships from the perspectives of both the entire region and its sub-regions. Scientific management measures should be implemented according to the local conditions. Future research should further enhance model optimization, conduct multiscale analyses, and explore driving mechanisms to more comprehensively and accurately uncover the trade-offs and synergies of ecosystem services, leading to a deeper understanding of their interactions. This study reveals the spatiotemporal dynamic characteristics of ecosystem services in the Jialing River Basin as well as their trade-off and synergistic relationships, providing a scientific basis for optimizing the ecological function layout and improving the level of ecological services in the basin. The findings provide a theoretical basis and practical reference for achieving mutually beneficial outcomes in both ecological protection and coordinated development in the Jialing River Basin.

Key words: ecosystem services, Jialing River Basin, InVEST model, trade-offs and synergies, GeoDetector