64. Forest

The tropical hardwood forests, including rain forests, occur throughout the lowland areas of the tropics—especially along the routes of rivers in Central and South America and in central and W Africa—and in the East Indies, the Malay Peninsula, and parts of India, Indochina, and Australia. They are characterized by an annual rainfall of 160–400 in. (406–1,000 cm) annually, with an average temperature of at least 80°F; (27&degC ;), and support a great diversity of plant life. The foliage is a luxuriant and interlaced community from ground level to the tree canopies, and the trees support the omnipresent woody vines or liane. Although some tropical forests are deciduous, most tropical trees are considered evergreen because their leaves are not shed simultaneously at a certain season; however, they are believed to drop and renew their leaves sporadically each year. Even though they cover only 7% of the earth's landmass, about one half of the planet's species live there.

The temperate hardwood forests of North America, Europe, and Asia are marked by seasonal rainfall distribution. The trees, typically species of beech, maple, ash, oak, elm, and basswood, are deciduous but are often mixed with conifers conifer (kŏn`ĭfûr) [Lat., =cone-bearing], tree or shrub of the order Coniferales, e.g. especially in areas of poorer soil. The temperate hardwood forests overlap the boreal, or northern, conifer forest belts, which encircle the earth in the sub arctic and cool, temperate regions south of the treeless tundra (tŭn`drə), treeless plains of N North America and N Eurasia, lying principally along the Arctic Circle. The vegetation is typically fir and spruce in northern regions and at higher altitudes, and pine, larch, and hemlock in southern regions and at lower altitudes. In transitional areas, especially where there is a pronounced season without rain (e.g., the chaparral (chăpərăl`), type of plant community in which shrubs are dominant.

In the United States east of the prairies are the northern (boreal) forest belt, in which sugar maple, beech, and birch mix with the conifers; the hardwood forest belt, a typical temperate forest; and the warmer southern forest belt, encompassing many stands of smaller pines and cypress thickets. In the chiefly coniferous Rocky Mt. forest belt, the Ponderosa pine is most common. The Pacific forest belt has the heaviest stands of trees in America and probably in the world. The characteristic redwood and giant sequoia mingle with Douglas fir and other species. For proper administration and management, the state has 16 Forest Circles, 62 Territorial Divisions, 129 Territorial Subdivisions, 362 Territorial Forest Ranges, 1,354 Sub ranges and 7,056 Beats. T o render specialized services 16 Production Divisions, 11 Research, Extension& Lok Vaniki Divisions, 1 Wildlife Division, 3 Working Plan Circles and 9 National Parks have been instituted.

In early times the only no forested areas of the earth were those where the land was either excessively dry (e.g., the plains and deserts) or excessively wet (e.g., the swamps). Where the environment was favorable, forests extended from the equator to the timber line, i.e., as far as those regions in the extreme north or at high altitudes where generally there is perpetual snow. Climatic conditions favor the continued expansion of the forests as the ice cap continues to recede and the timber line to withdraw, since the forests, with their mammal and bird inhabitants, move into formerly glaciated regions. However, the favorable natural conditions are more than countered by forest clearing by humans and through fire. About 30% of the world is forested today, but the ratio between forest and population varies immensely. More than one half of the world's softwood timber (the major forest product) comes from North America and Europe—an area with only a fourth of the world's population. Yet the Mediterranean countries have been cleared of most of their forests for centuries, and the forested area of the United States has shrunk in 300 years from about one half to one third of the total land acreage. The United States and Canada share 16% of the world's forests; the former Soviet Union contains 21%, Africa has 20%, and Latin American has 24%.