When Dave Nowak of the U.S. Forest Service and Scott Maco of Davey Tree Expert Company began collaborating on the creation of a suite of urban forest analysis tools called i-Tree, they imagined that users would be mostly city foresters from the United States.
Six years later, the U.S. Forest Service is releasing i-Tree version 5.0 with changes inspired by users from 105 countries. Version 5.0 is upgraded to rapidly assess urban trees and forests throughout Canada and Australia, two of the countries leading i-Tree’s international expansion.
“It’s neat to see how this program has grown,” Nowak said. “We didn’t expect this kind of response, but the i-Tree partnership has done an outstanding job in reaching potential users.”
City foresters certainly number among i-Tree users, but teachers, researchers, 
non-government organizations, consultants and homeowners are also finding that the ability to calculate benefits such as energy savings and storm water interception is essential to urban natural resources management and stewardship.
One of the major updates to version 5.0 is the addition of a new web form that allows the use of smartphones and tablets. An entirely new function within i-Tree Design forecasts the growth and benefits of trees through time, based on species and location-specific growth models.
i-Tree version 5.0 includes many new options and enhancements to the existing applications, including the ability to survey historical Google images in i-Tree Canopy and the ability to use i-Tree Eco to assess the human health impacts of air pollution removal by trees.
More than 10,000 copies of i-Tree have been downloaded across the world since the free software suite was launched in 2006, and today international users make up the fastest growing segment of i-Tree users. Canada, Australia, India, the United Kingdom and Italy are leading that expansion, but i-Tree is being used everywhere from Ethiopia to Pakistan and Papua New Guinea to Norway.
i-Tree was developed, supported and distributed through a group of partners including the U.S. Forest Service, Davey Tree Expert Company, National Arbor Day Foundation, Society of Municipal Arborists, International Society of Arboriculture, and Casey Trees. All programs are available free of charge at www.itreetools.org
