Street Trees in a Chinese Forest City: Structure, Benefits and Costs

Street trees provide critical ecosystem services and economic benefits that are often disregarded, due to their unknown monetary value. This study analyzed the structural characteristics of Dalian's street trees and estimated the monetary value of structural and functional benefits by i-Tree Streets. Dalian's street trees encompassed 28 species and were dominated by Ginkgo biloba, Platanus acerifolia and Sophora japonica, comprising 64.1% of a total of 57,699 trees. The age structure of street trees was distributed somewhat unevenly, with 18% young trees, 56% maturing trees, 25% mature trees and 1% old trees. These trees provide annual functional benefits valued at US$4.9 million and delivered a benefit-cost ratio of 3.2:1. The largest values associated with energy savings and property value were $1.7 million ($29/tree) and $1.5 million ($25/tree), respectively. The net carbon reduction benefits were valued at $935,205 ($16/tree). Smaller benefits resulted from air quality improvement ($381,088 or $7/tree) and stormwater runoff ($459,457 or $8/tree). The structural benefits were valued at $130 million, with the value of $4.5 million for carbon storage. These findings suggested that the benefits produced by street trees were worth the management costs. Our results provide a thorough understanding of the benefits produced by street trees to policy-makers and managers, and help them make informed policies to maximize and sustain the flow of benefits.