Atree is a woody plant with a single, strong trunk and many branches that lives year after year. A large group of trees covering not less than 25 percent of the area where the tops of the trees, called crowns, interlock to form an enclosure, or canopy, at maturity make up what is called a forest. This chapter is about rain forests. Sometimes the term rain forest is used to refer to any forest in tropical or semitropical regions. (Tropical regions are those around the equator.) In this chapter, however, rain forest refers only to evergreen tropical forests that do not undergo seasonal changes. Rain forests also occur in a few regions with temperate (moderate...