Development Vs. Urban Tree Canopy

The Philadelphia region has lost 46 million trees in 15 years - including a 24 percent decline in fast-growing Chester County - reducing its ability to prevent floods and purify the air... Based on satellite images from 1985 and 2000 and field inspections by urban foresters, a new study by a Washington-based nonprofit group pegs the value of the lost trees at more than $100 million."