Modeling the spatial distribution of the current and future ecosystem services of urban tree planting in Chicopee and Fall River, Massachusetts

Abstract

Mature urban tree canopy cover disrupts the local effects of urban heat islands and provides important ecosystem services such as energy savings through evaporation and shading, pollution removal, storm runoff control, and carbon sequestration. Sustainable urban tree canopy relies on the planting of juvenile trees. Typically, tree planting programs are only evaluated by the number of trees planted and there is a lack of analysis of juvenile trees post-planting. This study examines the value and distribution of energy savings provided by juvenile trees and how that value changes considering predicted tree growth and mortality by 2050. Using i-Tree Eco software, this study models the current and future ecosystem services provided to residents based on a juvenile tree inventory of 2271 street and residential trees planted in Massachusetts (USA) from 2014 to 2015 by the Greening the Gateway Cities Program (GGCP) in Chicopee and Fall River, MA. Juvenile trees planted by the GGCP provided $776 and $1520 (2018) in annual savings from ecosystem service in Chicopee and Fall River while services modeled to mature tree 2050 conditions show increased total annual savings of $2911 and $5840 in Chicopee and Fall River (2050). The mean total savings per tree per household were $0.77 in 2018 and $13.60 in 2050, with the majority from cooling energy savings in the summer. Services were maximized in neighborhoods where large numbers of trees were planted or when tree planting location (distance and orientation to the house) was optimized for highest savings. Analysis of the distribution of benefits reveals different planting strategies in Chicopee and Fall River. Ecosystem services from juvenile trees are concentrated in US Census block groups with more pre-existing tree canopy cover and lower median income. A tree planting density of two to three trees per acre was able to achieve the largest energy savings. Results of this study reinforce the importance of tree survivorship on sustaining the urban tree canopy to provide ecosystem services.