Rain Forests

Rain forests have a continual abundance of rain with year-round growth. Most rain forests are tropical, but a few, such as the forest of the U.S. Pacific northwest, are temperate. Rain forests hold some of the largest trees on earth. Temperate rain forest trees often grow well over 200 feet (61 meters) in height. These rain forests occur in temperate zones where local conditions facilitate high amounts of rainfall, usually 80–120 inches or 2,000–3,000 millimeters per year. They are often near ocean breezes that deliver large quantities of moisture. Many are located on coastal mountain ranges where moisture from the ocean keeps them cool, even in the hottest months of summers, and mild in the winter.

Temperate rain forests occur in seven regions of the globe. In North America, they occur along the Pacific Coast that stretches from northern California to Kodiak Island in Alaska. In South America, they occur in the Valdivian and Magellanic temperate rain forests. The Calchian rain forests are located in the southeastern Black Sea area on the northern coast of Turkey and in Georgia. The Tasmanian temperate rain forests are in New Zealand. There is a small area of rain forest in southwestern Japan. Logging destroyed most of the temperate rain forests in northwestern Europe. Temperate rain forests may be coniferous, broadleaf, or mixed. The temperate coniferous forests of the Pacific Coast of North America include the famous giant coastal redwood trees (sequoias), Douglas fir trees, and sitka pines.

Tropical rain forests occur in the tropical zone, which lies between 1,600 miles north or south of the equator (23.5 degrees north at the Tropic of Cancer and 23.5 degrees south at the Tropic of Capricorn). Tropical rain forests occupy vast areas of South America, Central America, central Africa, and southern Asia, including the islands of the South Pacific and Indian Oceans. Tropical rain forests have an enormous biodiversity.

The trees in tropical forests also grow to 200 feet (61 meters), or more. The crowns of the trees touch each other, forming a high forest canopy that blocks much of the sunlight hitting the forest. Lower down, a second or even third canopy of trees grows. The image of a tropical rain forest as a jungle is incorrect. The canopy blocks most of the sunlight so only a few plants grow at the base of the trees. Jungles usually occur along rivers, or in areas where sunlight has been able to penetrate to lower levels on the forest floor. Tropical forests remain green, warm, and wet all year; the rain and the shade also keep temperatures on the forest floor remain relatively constant. Most of the time the temperature does not rise much above 90 degrees F (32 degrees C) or fall much below 68 degrees F (20 degrees C). Because there are no seasons in tropical rain forests, each species of plant has its own season for flowering and fruiting.

Sunlight in equatorial regions strikes from directly above. Tropical rain forests are areas where there is a constant barrage of equatorial sunlight that allows for more abundant manufacture of chlorophyll from photosynthesis. A continuous supply of food is available in tropical rain forests, while in temperate zones seasonal changes regulate the food supply. The tropical forest canopy contains an enormous variety of fauna and flora. Many canopy plants are epiphytes (air plants that grow on the branches of the trees). Enormous vines also grow on trees, sometimes killing the tree. Scientists have estimated that from one half to two-thirds of all the plant species in the world are found in tropical rain forests. These forests provide shelter and food for a still unknown number of animals, reptiles, and birds that feed on a profusion of insects, fruits, and plants. Fig trees, of which there are over 1,000 kinds in tropical rain forests, are one of the “keystone” species. Because tropical fig trees bear fruit several times a year, they provide food for a wide variety of animals, birds, and insects. Because the animals that eat figs are of-ten the prey of other animals, the figs sustain populations that provide prey to carnivores.

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