Issue
Although trees offer more than aesthetics in a landscape, the true value of their contribution is usually unknown. A street tree inventory conducted on the University of Arizona campus assisted a larger effort undertaken by the City of Tucson’s Department of Urban Planning and Design to assess the species distribution, annual costs/benefits and maintenance priorities for municipal trees.
What has been done?
The UA Campus Arboretum conducted a study from November 2007-November 2008 documenting the distribution, yearly costs and benefits of more than 2,000 individual trees flanking campus roads. Information for each tree, including species, size, condition and location, was logged into a PDA and loaded into a software program called STRATUM, part of the i-Tree Suite of software developed by the Center for Urban Forest Research at UC Davis. The model in the software was adapted for Phoenix and desert Southwest tree species.
Impact
According to the inventory, the 2,000 street trees in the study annually sequester 246,620 tons of carbon dioxide (CO2); reduce the energy costs for UA facilities by $18,230; reduce emission, pollutants and particulates by 9,994 pounds; and intercept more than a million gallons of rainfall or stormwater (reducing flooding). If all 7,000 trees on campus were inventoried, the combined benefit of the UA’s urban forest could be three to four times higher. Within species, each Chinese pistache on campus contributes about $74 every year, including energy and water saved, carbon dioxide sequestered, and aesthetic value. Mesquites contribute $112; Aleppo pine, $156; California palm, $33 and blue paloverde, $93. With some campus trees living 40, 60 or even 100 years, their contributions can be considerable over their life spans. The trees contribute to quality of life and reduce the university’s “carbon footprint.”
Web
- UA Campus Arboretum: http://arboretum.arizona.edu
Contact
Elizabeth Davison(520) 621-1582
email: edavison@ag.arizona.edu