You probably know that the trees in your yard provide shade, privacy, carbon absorption, wildlife habitat, and air quality benefits. Trees are like the lungs of the planet, they breathe in carbon dioxide and breathe out oxygen.
Did you know that trees are also valued for the amount of polluted stormwater they soak up, helping keep basements dry, streets less prone to floods, and yards less soggy?
Polluted stormwater from urban/suburban areas washes oil, gasoline, salts, and other debris from the roadways and parking lots into streams, wetlands, rivers, and oceans. The harder the surface, such as concrete, asphalt, and rooftops, the more quickly the polluted stormwater is washed into our waterways. This taints our drinking water and degrades our ecosystem.
Human activities disrupt the natural water cycle. While the amount of rainfall may remain the same, changes in the land use from agriculture, lawns, and paved surfaces result in more stormwater runoff.
As trees reduce the amount of stormwater runoff, they also cut erosion and pollution carried into our waterways by heavy rains.
Red maple, white oak, and shagbark hickory trees are noted for their absorption in this area. A 25-inch diameter red maple soaks up about 8,500 gallons of stormwater each year. Rain is intercepted by the tree canopy and is held on bark, leaves and branches. This means there is less water reaching the ground below.
Trees cut runoff by breaking up the rainfall, and the water cascades down the tree trunk and sinks into the soil below. The drip from a tree’s branches and leaves has less force than rainfall, so the impact and resulting soil erosion is lessened.
When mulched, trees act like a sponge that filters the water naturally and recharges the underground aquifer. In dry periods, trees redistribute water by drawing up water in the soil to the shallower roots. And, in wet periods, trees move excess water from the surface to deeper soils. When a yard is saturated, the trees convey the water deeper to deep dry soils where it can be used by the tree in the future.