Source: Ted Mellnik and Annie Gowen/The Washington Post.
The above chart from the Washington Post article "Tree canopy’s density indicates wealth of D.C. neighborhoods" attempts to illustrate a correlation between tree coverage and income in D.C. In many ways this article states the obvious--wealthier neighborhoods tend to have more trees. The authors quote environmentalists' arguments about the benefits of trees and briefly mention real estate advantages. However, I think this issue deserves deeper explanation. This is an interesting research topic. Does tree coverage matter?