Cooling Benefits of Urban Tree Canopy: A Systematic Review

As an important part of urban ecosystems, trees can effectively alleviate the urban heat island effect. Tree canopies cool and humidify through shading and evapotranspiration, regulating the urban thermal environment. So far, many studies have analyzed the heat mitigation effect of urban green spaces; however, there are relatively few studies on the cooling effect of tree canopies. Specifically, relevant research focusing on different spatial scales has not been explored. Therefore, this review systematically summarizes the research on the benefits of tree canopy cooling carried out in recent years, analyzes the research content, and evaluates the indicators and key influencing factors of the benefits of tree canopy cooling from four different spatial scales: urban, block, community, and individual. It was found that canopy factors, other vegetation factors, and environmental factors jointly affect the benefits of canopy cooling. This research focuses on the benefits of canopy cooling at different spatial scales. The smaller the research scale, the more discussion and attention will be paid to vegetation factors. This paper puts forward major directions for future research and development, providing optimization strategies for urban planning or plant design at different scales in the context of climate change.