What Are Trees Worth to Cities?

David Nowak whittles down 30 years of studying the economic value of forests to this advice: If you can only plant one tree, plant it in a city.

After all, in an era of overwhelming need for urban infrastructure improvements, trees offer cities some of the best bang for their buck. Trees remove carbon dioxide, filter air pollution, and produce oxygen. They absorb rainwater, UV radiation, and noise. They slow down traffic, improve property values, and reduce human stress and mental fatigue. And they provide shade, which means we have to use less energy to cool down.