Spatiotemporal Evaluation and Driving Factor Screening for Regulating and Supporting Ecosystem Service Values in Suzhou–Wuxi–Changzhou Metropolitan Area’s Green Space

Abstract

The green space system in metropolitan areas is crucial for maintaining environmental health and stability by regulating and supporting ecosystem service values (ESVs). The Suzhou–Wuxi–Changzhou metropolitan area is located in the core of the Yangtze River Delta, and its green space exemplifies this importance, despite facing challenges from rapid urbanization in past decades. Studying the categories of ESVs and their driving factors can facilitate the comprehension of ESVs’ dynamics, thereby promoting regional sustainable development. In this article, we used the inVEST module to calculate six ESV indicators (soil retention, annual water yield, habitat quality, carbon storage, nitrogen, and phosphorus absorption) of the Suzhou–Wuxi–Changzhou metropolitan area’s green space system from 2015 to 2020 and combined it with the entropy weight method (EWM) to allocate weights for these indicators and evaluate the total value of the ESVs. To address the weakness of the inVEST model in calculating the total value of multiple ESVs, the Xgboost algorithm was combined with PCA methods to screen its main driving factors from numerous measures. Finally, the GWR method was used to reveal the spatial and temporal change in the main driving factors’ impacts on ESVs in the study area over five years. The result shows (1) the spatial distribution of the total value of regulating and supporting ESVs in the Suzhou–Wuxi–Changzhou metropolitan area has become more uneven in 2020 compared with 2015; (2) the most important driving factors include landscape diversity, topographic gradient, economic activity intensity, humidity, and surface temperature; and (3) based on the analysis of GWR results, the study area has an overall increase in regional soil erosion due to the expansion of impervious areas. And some mountainous areas have habitat fragmentation because of incorrect economic activity. This study provides a new perspective for evaluating the sum of multiple types of ESVs and exploring their driving factors, as well as revealing the ecosystem problems of the Suzhou–Wuxi–Changzhou metropolitan area in recent years. It also provides a reference for policymakers to maintain local ecological stability and security.

Keywords

• metropolitan area green space system
• ecosystem service value
• inVEST module
• Xgboost
• PCA-GWR