The characteristics of plant clusters influence on the cooling effect: A case study in a subtropical Island Park, China

Abstract

Plant clusters planted in urban green spaces have a significant potential to improve the microclimate. To put this potential to the test, eleven plant clusters (20 m × 20 m) in size were selected as sample plots in Haitan Island, China. We measured the microclimate including air temperature, relative humidity, solar radiation, and wind speed on sunny days from 8:00–17:00. The data were collected from July to September 2020. The purpose of this study was to determine the relationship between plant cluster characteristics and microclimate to enhance tourists comfort. The findings indicated that eleven sample plots had eighteen tree species with four distinct plant functional types. The air temperature difference between the interior and exterior of the plant clusters was substantial and the cooling effect dTair ranged from 2.65% to 5.19%, while the reduction of solar radiation dSR was between 58.08% and 98.33%. Crown area, wind speed, relative humidity, and solar radiation all affected air temperature, as determined by Piecewise SEM analysis. The cooling effect was mostly affected by crown area, canopy density, wind speed, and solar radiation showing that canopy structure affected air temperature by altering solar radiation penetration. Meanwhile, leaf transpiration generated water vapor, which increased relative humidity and cooled the air. Quantitative data on the crown area and canopy density were provided so that forestry management practices can improve people’s comfort while in the area.