Climatic conditions, in some parts at least, of all the continents are favorable for the development of forests. Although our knowledge concerning the exact nature and distribution of these forests is still incomplete, it is possible to estimate roughly the amount of forest land in the world as about 7,500,000,000 acres, or 22 1\2 per cent of the earth's surface. These forest lands are distributed on the various continents as follows: Asia, 28 per cent; South America, 28 per cent; North America, 19.3 per cent; Africa, 10.6 per cent; Europe, 10.3 per cent; Australia and Oceania, 3.8 per cent. In many countries forests were originally much more abundant than they are at the present time.
The softwoods or conifers occupy 35.4 per cent of the total forest area, occurring in pure stands or mixed with hardwoods. They are especially characteristic of the colder areas, about 95 per cent occurring in the north temperate zone. When they are found in warmer regions, conifers are restricted to the higher altitudes. In the case of the hardwoods, a distinction is usually made between temperate and tropical hardwoods. The former occupy 16 per cent and the latter 35.4 per cent of the total forest area. As in the case of the conifers, most of the temperate hardwoods (89 per cent) are found in the north temperate zone. It is of interest to note that three-quarters of the world's population lives in this area, and consumes nearly 90 per cent of all the wood used. The fact that both the softwoods necessary for general construction and the hardwoods have been readily available throughout this area has been of great economic importance. It has been only recently, as a result of the depletion of the native forests, that attention has been turned to the almost untouched tropical forests, save as a source of ornamental woods, dyewoods, and similar products.
Forests occupy about 26.8 per cent of the land area of North America, with conifers comprising 72.4 per cent, temperate hardwoods 20.1 per cent, and tropical hardwoods 7.5 per cent of the forests. The northern part of the continent -- Alaska, Canada, Newfoundland -- is predominantly