These surfaces allow rainwater to flow across them, picking up pollutants that are on the surface in the process. Leaves and bark from trees catch the rain and reduce its impact on the ground. In addition, the roots slow the movement of water through the soil, thus reducing soil erosion so that less pollution is flushed into rivers, streams, and wetland areas. Trees Mask Noise . Leaves, twigs, and branches on trees and shrubs will mask sound and absorb sound energy.
Plants seem to absorb the higher sound frequencies at a greater rate.
Human hearing is more sensitive to high frequencies, so plants filter out the most bothersome frequencies. Barriers of trees also deflect sound away from an area. Sometimes just screening the source of unwanted noise from view will alter a person's perception of the quietness of a site. Trees Reduce Glare . The light-colored, smooth surfaces of buildings and roadways result in glare and reflection problems in urban areas.