The benefits of urban wildlife enhance the surrounding eco-system in many useful ways. Trees and plants release life-giving oxygen, and play a crucial part in retaining a city’s ground and rain water. They remove toxins from the surrounding air; and Marcus Hiles notes that American Forests is a group studying municipal forests and the consequences of declining natural areas in metro areas. They educate and provide incredible factoids like this: two trees can make the oxygen for one person and can sequester up to twenty pounds of air pollution every year. Parks also produce shade canopy, cooling down significant areas and reducing heat retention. Air-conditioning requirements are much less in a community with ample shade coverage. A car that is placed under canopy stays fifty degrees cooler than one parked in the sun. In urban locations natural areas must be created and maintained through human assistance and help.