酸雨
Air pollution is caused by anthropogenic factors, such as power plants, factories, and automobiles. It is related to acid rain and water pollution. Vegetation in high elevation is easy to collect pollutants. Acid rain damages the plants and makes streams more acidic. Acidic water affects aquatic species, such as fish, salamanders, and also vegetation. Air pollution affects ground ozone, which experience a biochemical change with sun light. The ground ozone damages plants. In the National Park Service, 30 plants species were damaged by the ground ozone and plants in higher elevation are prone damage.