- Trees clean the air, consuming carbon dioxide and producing the oxygen we need to breathe. Foliage filters dust and helps remove toxic pollutants from the atmosphere as well. Tree leaves capture and remove a wide range of smog-producing compounds such as ozone, carbon monoxide, nitrogen oxides, airborne ammonia, and some sulfur dioxidecons.
- Trees reduce runoff that is formed from rain and melted snow, flooding driveways, yards, and streets. This runoff is untreated and carries all sorts of pollutants such as soil, leaves, grass, oil, salt, fertilizer, pet waste, pesticides, and delivers it to our rivers and lakes. Trees retain runoff before it can leave your yard. They absorb harmful pollutants that can be absorbed by the soil. This reduces flooding, replenishes groundwater, and maintains the quality of rivers and lakes.
- They alter the environment in which we live by moderating the climate. Water from the roots is drawn up to the leaves where it evaporates. The conversion from water to gas absorbs huge amounts of heat, cooling hot city air. Urban neighborhoods with mature trees can be up to 11 degrees cooler in summer heat than neighborhoods without trees. The pictures below show how tree cover in a city can affect the city’s temperature. These pictures are from a case study of the city of Atlanta. Because of the decrease in tree cover, Atlanta’s average temperature has increased (see diagrams below)
1972 1993Graphics from The Forest Where We Live, a documentary produced by Louisiana Public Broadcasting. These Landsat photos show the decline in vegetation and tree cover (shown in green) as built-up urban areas (shown in black) grow. Red and yellow areas are a mixture of the two. Downtown Atlanta is in the center of each photo, and Hartsfield International Airport is at bottom center.
- Trees hold topsoil in place to prevent flooding and loss of essential farmland and roadways.
- Trees protect vital water supplies and shelter crops from wind.
- Urban forests serve as wildlife habitats, supplying food, water, and cover for a variety of animals, which enhance recreation and educational opportunities of a community