Tropical rain forests stay green all year, and receive a total of 80-160 inches of rainfall a year. There are more species of plants and animals in the tropical rain forests than all of the world's other ecosystems combined. and can grow up to 200 feet tall. The crowns, or tops, of these trees form a covering of leaves above the ground called the upper canopy. The crowns of smaller trees form the lower canopy. These canopies shade the forest floor so that it receives very little sunlight . For this reason, only a few bushes and herbs can grow on the forest floor. Areas where much sunlight reaches the ground and has dense growth are called jungles. Most jungles grow near rivers or former clearings. Thundershowers occur more than 200 days a year, and the air beneath the lower canopy is always humid. The trees in tropical rain forests give off water through the pores of their leaves. This process is called transpiration , which supplies as much as half of the rain in the Amazon rain forest.