2. They moderate temperature and rainfall.
Trees are like natural air conditioners and water pumps. They cool the Earth by giving shade and recycling water. By cooling the air and ground around them, the shade from trees helps cool the Earth's temperature. Also, a single tree can evaporate thousands of litres of water into the atmosphere in a very short time depending upon conditions thus increasing the local precipitation (e.g. rainfall).
A 30 metre tree with 200,000 leaves can suck up 43,000 litres of water and breathe it into the air in just one growing season.
