A tree is a large woody plant with one main stem, or trunk, and many branches that lives year after year. A forest is a large number of trees covering not less than 25 percent of an area where the tops of the trees, called crowns, interlock forming an enclosure or canopy at maturity. This chapter is about coniferous (koh-NIH-fuhr-uhs) forests. Almost all coniferous trees, such as pines and firs bear their seeds inside cones. Most also have stiff, flattened or needle-like leaves that usually remain green all winter. For information about other kinds of forests, see the chapters titled "Deciduous Forest" and "Rain Forest."

More than 50 percent of the world's coniferous forests are found in...