A huge volume of our nation's green waste is from trees, taken from populated areas, felled and shredded. Some quick searching led me to believe it could be as much as one-third. And yet, we log along stream-beds and in environmentally sensitive areas, shipping logs and lumber great distances, burning up more fuel.
Companies such as California Urban Lumber remove logs from municipalities and incorporated areas (Never a log from the Rainforest! is one of their mottoes) and mill them into lumber. The wood is used locally for furniture manufacture and for construction. The lumber is air-dried rather than kiln-dried (because it is more sustainable). To become even more "green," they might be getting solar-electric panels soon, further helping to make urban forestry a 21st century solution.
As we move into a future where energy costs more, I really admire people who are learning how to make cities more self-sustaining. Cities are already pretty efficient at distributing resources, but there is room for improvement. I hope urban planners are becoming more savvy to ways we can close resource cycles. They could look to urban forestry for an example.