BROADLEAF FORESTS

Broadleaf forests grow in regions that have a fairly long growing season and plentiful rainfall. Every continent except Antarctica has broadleaf forests, which are also called hardwood forests. In areas with cold, snowy winters, almost all the trees in broadleaf forests lose their leaves each autumn. In tropical areas, most broadleaf trees are evergreen.

Before the 1800's, broadleaf forests covered much of the Eastern United States. They included such trees as ashes, birches, maples, and oaks. During the 1800's, most of the trees in these forests were cut down to provide lumber and fuel and to make room for farms and cities. Today, only a few parts of the Eastern United States have large broadleaf forests. Western Europe also had great forests of broadleaf trees, including ashes, beeches, and oaks. But most of these forests have been cut down.

Broadleaf forests that consist largely of quaking aspens and balsam poplars cover parts of southern Canada and large areas of southern Siberia. Forests of birches and oaks grow in eastern Europe and along the Yellow Sea coast of China and Korea. Southeastern Australia has valuable forests of eucalyptus trees. These broadleaf trees grow nearly as tall as California's needleleaf giants, the redwoods. Some eucalyptus trees stand more than 300 feet (91 meters) tall. About 600 kinds of eucalyptus trees grow in Australia. Almost all of these trees are evergreen.

In many areas, mixed forests of broadleaf and needleleaf trees grow alongside broadleaf or needleleaf forests. Central Canada, the Eastern United States, central and southern Europe, and eastern Asia all have large mixed forests.

Remarkable broadleaf forests grow in tropical regions where the weather is always hot and rain falls regularly every month of the year. In these tropical rain forests, many of the trees look alike. They are tall, and many tower more than 150 feet (46 meters). The trees have leathery, dark-green leaves. Because the trees receive plenty of moisture throughout the year, most of them are evergreen. The trees may thus look alike, but they belong to many species. Many palms grow among the broadleaf trees in the tropical rain forests. The largest rain forests are in South and Central America, central Africa, and Southeast Asia.

NEEDLELEAF FORESTS

Needleleaf forests grow mainly in regions that have long, cold winters. These forests, which are also called softwood forests, stretch across Canada, northern Europe, and Siberia. Many firs, larches, and spruces grow in these northern forests, along with a few broadleaf trees, such as birches and willows. Some willows grow even farther north than needleleaf trees do. But they seldom reach more than shrub size. Needleleaf forests also blanket slopes in such mountain ranges as the Alps and the Rocky Mountains.


The Canadian needleleaf forests extend southward into the Western United States, where they include many of the world's largest trees. Many California redwoods tower over 300 feet (91 meters). Tall Douglas-firs also grow in the Western United States.

A few needleleaf forests grow in warmer regions. For example, the Southeastern United States has large forests of pines, such as loblolly pines and longleaf pines. These forests provide great quantities of wood for lumber and wood pulp.

NEEDLELEAF TRESS ARE ABOUT 500 SPECIES

Needleleaf trees include such familiar trees as firs, hemlocks, pines, redwoods, and spruces. There are about 500 species of needleleaf trees. Most of these trees have narrow, pointed, needlelike leaves. But a few types, such as cedars and junipers, have narrow, scalelike leaves.

Most needleleaf trees are evergreen, though they produce new needles each year. The oldest needles turn yellow or brown and drop, but the youngest needles remain green and do not fall. A few species of needleleaf trees are deciduous. One kind is the larch, which grows in northern forests throughout the world. Another deciduous needleleaf tree is the baldcypress that grows in swamps of the Southeastern United States.

Foresters call needleleaf trees softwoods because most of them have softer wood than broadleaf trees have. But the wood of Douglas-firs, yews, and some other needleleaf trees is hard.

Needleleaf trees belong to a group of plants called gymnosperms. Gymnosperms do not have flowers and their seeds are not enclosed to form fruits. Most gymnosperm trees bear their seeds in cones composed of hard scales. The seeds lie open on the surface of the scales. Botanists call such trees conifers.

Most conifers grow north of the equator. The conifers belong to four families-the pine, yew, cypress, and taxodium families. The pine family is by far the largest. It includes not only pines, but also such trees as firs, hemlocks, larches, and spruces. Pine trees make up a large genus (group of species) within the pine family. Loblolly pines, ponderosa pines, and white pines are a few North American members of this genus. The yew family includes such well-known ornamental trees as English yews and Japanese yews. Although yews are classified as conifers, they do not produce cones but cup-shaped "berries." Many members of the cypress family, such as arborvitae and junipers, have scalelike leaves and give off a spicy fragrance. The taxodium family includes baldcypresses and the largest of all living trees-the redwoods and giant sequoias.

Two conifer families-the podocarpus family and the araucaria family--grow mainly south of the equator. Podocarpus trees are tall evergreens with broader leaves than those of most needleleaf trees. The araucaria family includes the Chile pine. This strange-looking tree has snakelike branches covered with sharp, scaly leaves. It is sometimes called the monkey puzzle tree because its sharp leaves make it difficult to climb.