Source: http://www.cfr.washington.edu/research.envmind/Roadside/Rsd-Prefs-FS9.pdf Virginia Cooperative Extension; op. cit.

Source: Time Magazine: Why Are Cities Cutting Down Trees; http://www.landscapeonline.com/research/article/9263 Virginia Cooperative Extension: The Value of Landscaping; op. cit. 6 Turfgrass Resource Center: Our Precious Plane; http://www.turfgrasssod.org/trc/environment.html http://urbangardenguide.com/homepage/trees/