Giant Trees Exhibited Great Cooling Effect in Residential Area Southwest of China

Abstract

In recent years, extreme weather has become more and more frequent. The extreme heat in summer is a serious threat to human health. Chongqing is one of the hottest cities in China, and the high temperature in summer can cause skin cancer and heat stroke. Green plants in residential areas play a great role in cooling down air temperature. However, there are no accurate numerical references for which plants have a better cooling effect. Therefore, seven species of trees with the highest planting rate were selected in seven residential areas as research objects in this study. By measuring the temperature under the trees and related control factors, this study was conducted to clarify the following: (1) Which species of tree has the best cooling effect? (2) Whether tree species and size matter with the cooling effect. (3) What are the controlling factors and principles that affect the tree cooling effect? The results showed that: (1) Giant trees have the best cooling effect. (2) The cooling effects of Ficus virens, Camphor tree, and Ficus macrocarpa were significantly better than the other four species of trees. (3) The high rate of water replenishment in plants gives giant trees a greater cooling effect. This study is of great practical significance to the selection of plants in the green belt of residential communities, and has great theoretical significance to understand the principle of the plant cooling effect.