The Moderating Mechanism of Green Space Patterns on the Urban Heat Island Effect Under the Background of Urban Intensification: A Case Study of Nanjing

Abstract

Under the background of urban intensification, the moderating role of green space patterns on Urban Heat Island (UHI) effects has become a significant topic. This study aims to systematically explore the moderating mechanisms of green space patterns on the UHI effect and their spatiotemporal evolution using Nanjing as a case study. We utilized data including the Urban Density Index (UDI), Land Surface Temperature (LST), Green Space Index (GSI), and landscape pattern indices (Patch Density (PD), Largest Patch Index (LPI), and Landscape Shape Index (LSI)) for the years 2012, 2016, and 2020. Pearson correlation analysis, Moran’s I spatial autocorrelation, and a Coupling Coordination Degree Model (CCDM) were employed to quantify these interactions. Urban intensification was associated with a more pronounced UHI effect, as indicated by positive spatial autocorrelation (Moran’s I > 0.4) and a positive correlation between UDI and LST (r = 0.19 in 2020). Conversely, contiguous green spaces demonstrated cooling potential; the correlation between LPI and LST became more negative from r = − 0.12 in 2012 to r = − 0.25 in 2020, while positive PD-LST correlations were observed in some study years. The spatial mean coupling coordination degree (D) across valid 500 m × 500 m grid cells increased from 0.50 in 2012 to 0.60 in 2020, although coordination in high-density central urban areas remained low (D < 0.3). The fragmentation of green spaces restricts their capacity to regulate urban thermal environments. To optimize green space layout and effectively mitigate the UHI effect, urban planning should prioritize improving green connectivity, expanding contiguous large green areas, and promoting green roofs.