Urban trees reduce the demand on sewer systems during periods of storm water run-off. Tree’s canopies absorb rain water lessening the amount of water to enter the sewer system. When a raindrop is intercepted by a tree’s canopy, it does not impact the soil, thus limiting erosion. These valuable soils are retained and the sewer system does not have to process the particulate matter. Also, trees increase the soils capacity to store rainfall though transpiration and increasing soil organic matter.
Environmental Energy Savings
Trees can also aid an urban environment by conserving energy. This is done by shading buildings from the summer’s sun and blocking them from the winter’s wind. Radiant energy from the sun is absorbed by deciduous trees in the summer and is only filtered by branches in winter. We are cooler when we stand in the shade of trees and are not exposed to direct sunlight. In winter, we value the sun’s radiant energy and, because of this, we should plant only small or deciduous trees on the south side of homes.
Trees improve air quality by absorbing gaseous pollutants such as sulfur dioxide, nitrogen dioxide, ozone and smog. Trees also intercept particulates in the air associated with soil tillage, construction and erosion. These airborne contaminates have been associated with asthma, heart and lung disease, and cancer. Trees also sequester carbon, initially though photosynthesis, converting carbon into sugars. Over time these sugars are made into woody material, storing the carbon from the atmosphere