The Green in Trees: The Return on Investment of New Haven Street Trees, A Study on Species Differentiation

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Mark Ashton
Essay Abstract: 
Street trees benefit society by providing much-needed ecosystem services such as stormwater reduction, energy savings, carbon sequestration, air quality improvements, and aesthetic benefits. The magnitude of these benefits varies with species. To maximize the ecosystem services obtained and increase the return on investment of planting trees in New Haven, CT, Urban Resources Initiative (URI), the city's main tree-planting body, should begin to take ecosystem service potential into consideration during the species selection process. This paper sought to determine the most valuable tree species in terms of each ecosystem service respectively. i-Tree Streets, a benefits assessment tool, was used to determine the annual return on investment of ten tree species planted in New Haven. Results showed that generally large-stature shade trees performed better than small ornamental trees. All else equal, Gleditsia triacanthos was the top performer overall and Syringa reticulata was the worst. Further research is warranted on these species’ biological processes to determine what factors other than size impact the magnitude of benefits provided. GIS was also employed to identify areas of New Haven in critical need of specific ecosystem services to further aid in decision-making and management of New Haven’s urban forest.