In natural forests at least 75 percent of all rainfall is captured by tree cover and released back into the atmosphere or absorbed into the ground. By contrast, in a typical urban community, less than 40 percent of all rainfall is environmentally conserved.

Why?
Because leaf systems naturally intercept rainfall and tree base and root networks tackle the challenge of stemming and filtering stormwater runoff. Where communities promote urbanization, but neglect community forestry, costly retention may be needed to address the gap in surface water management.

Rainfall collects on impermeable surfaces – such as concrete, asphalt, buildings, parking lots and paved streets. This runoff increases in volume and velocity with the strength and duration of storms and collects pollutants, (including nitrates, phosphorus, potassium, waste and oil residue) before it empties into our natural streams, rivers, lakes and coastal waters. The result is degraded water quality and increased flooding and erosion. Coastal communities must also monitor the diversion of polluted stormwater into Gulf waters, where it compromises the health of fish and wildlife and encourages algae blooms.

Our fortune is that urban forests are able to serve many functions and provide a variety of goods and services. As prolific watersheds, trees are effective first-responders to the potential crisis of stormwater runoff.

• A mature bald cypress can absorb up to 700 gallons of water per day.
• Certain pollutants contained in surface - elements that threaten our health and the integrity of our inland and coastal waters - are actually extracted from runoff by trees and processed as glucose.
• Moreover, tree root systems are capable of combating up to 95 percent of ground erosion that occurs in developing and developed landscapes.