Influence of Urban Tree Traits on Their Ecosystem Services: A Literature Review

Trees in cities are vital to the health of the urban ecosystem and residents' wellbeing. Besides providing habitats, trees provide food via fruits and young leaves, reduce temperature, and enrich landscape aesthetics with spring flowers and autumn foliage. The generation and supply of these ecosystem services are closely related to their traits, such as the size of the canopy and the sparseness of the leaves, which directly affect their ability to shade and cool. Studies focusing on ecosystem services often consider green space as a whole, and some distinguish the difference between trees and grass. Relatively fewer studies examined the influence of tree traits on the supply of ecosystem services. Understanding the association among species, traits, and ecosystem services would be helpful in generating actionable knowledge for urban tree planting. However, these studies are often scattered under different research topics. To this end, we reviewed and summarized studies on the relationship between urban tree species/traits and ecosystem services according to provision, regulation, and cultural service types. Based on 45 publications, we found that leaf area, crown size, diameter at breast height, tree height, and leaf shape may influence various ecosystem services. We presented a preliminary framework of "trait- service" and argued that with the help of such a framework, future research should generate actionable knowledge for practitioners to identify potential tree species for selection according to desired services.