The benefits of parks enhance the local eco-system in many noticeable ways. Not only do trees and plants create necessary oxygen; they play a crucial role in retaining ground and rain water, and removing toxins from the environment. American Forests is an organization that studies municipal forests and the drawbacks of declining natural areas in cities. They educate by providing fascinating information like the fact that two trees can produce enough oxygen for one person and can absorb twenty pounds of carbon pollution every year. Parks also give shade, cooling down a large area and reducing heat retention. Air-conditioning requirements are reduced in a community with more canopy coverage. A car that is parked in the shade stays fifty degrees cooler than one parked under the sun. In urban locales, natural spaces must be developed and maintained through human intervention and assistance, notes Marcus Hiles.