Cooling and Humidifying Effects of Typical Greenery Trees in Guangzhou Area

A simulation study was conducted to analyze the cooling and humidification effects of typical trees in Guangzhou area. This study used a campus residential community in Guangzhou as the model. First, the simulation platform was calibrated using the measured data to improve accuracy. The maximum root-mean-square errors for outdoor air temperature and humidity were reduced to 1.49°C and 5.63%, respectively. Second, simulation models were established for six different tree species found in urban areas, that is Mangifera indica, Syzygium jambos, Terminalia mantaly, Ficus macrocarpa, Cassia fistula, and Ficus macrocarpa, and the roles of individual plants and clusters of plants in regulating the thermal environment were investigated. The simulation software ENVI-met was used for this purpose. The results revealed that the leaf area index, crown width, and tree height had a significant impact on the surface temperature and sensible heat flux beneath the vegetation. The cooling effect of the vegetation community was more pronounced when the vegetation height exceeded 10 m. In addition, the Ficus macrocarpa tree exhibited notable cooling and humidifying effects. The Melaleuca leucadendron plant cluster was the most effective in terms of cooling and humidifying compared with other low-growing plants. At noon, the Melaleuca leucadendron cluster provided approximately 1°C lower temperatures and approximately 5% higher humidity levels than other low-growing plants. The selection of suitable trees for greening can effectively mitigate the heat island phenomenon in residential areas, enhance air humidity, and create a more comfortable outdoor environment.