Urban park green spaces and their potential in regulating urban heat Island (UHI) effects in urban-rural gradient in Shanghai, China

Urban parks are crucial for mitigating UHI, and maximizing their cooling benefits within limited space is vital for sustainable urban development. To analyze key factors influencing cooling benefits of parks in urban-rural gradient and quantify the degree of their impact from the perspectives of landscape patterns and land cover, we selected 189 established parks within Shanghai's urban-rural gradient, based on park directory by Shanghai Greening Bureau and data availability. We primarily employed an enhanced regression tree model to investigate the relationships between landscape patterns and land cover of parks and Land Surface Temperature (LST). Subsequently, guidelines for park planning and design were proposed. Results indicate that key factors for inner ring parks are AREA, Edge Density (ED), Building, and Water, with optimal cooling efficiency achieved under the following conditions: 20 ha area, 0.11 <= ED <= 0.12, building ratio <= 0.25, and water ratio of 0.1. For middle ring parks, key factors are Fractional Vegetation Cover (FVC), Path Cohesion Index (COHESION), Building, and Water, with optimal efficiency achieved when building ratio <= 0.1 and water ratio of 0.1. For outer ring parks, key factors are ED, FVC, and Water, with optimal efficiency requiring a ED <= 0.01or 0.05 <= ED, and a water ratio of 0.12. These thresholds are crucial for urban park construction and renovation.