I The deciduous trees which drop their broad, flat leaves each year originally showed an unusually fine development in the deep-soiled, well-watered lowlands of the southeastern quarter of the United States. These areas, however, have been cleared for agriculture and now the best deciduous forests grow among mountains. Almost nowhere do great oaks, beeches, maples, chestnuts, tulips, ashes, and other trees make a finer growth than in North Carolina at the eastern base of the southern Appalachians. There the trunks of the trees often rise straight up fifty or seventy-five feet before branching and sometimes continue another fifty above that. In summer the climate is warmer and rainier than that of the Oregon region most favorable to the conifers, and that is the chief reason why deciduous trees rather than conifers prevail. Here, as in the other case, the presence of the mountains causing abundant rain helps in producing excellent stands of timber. 'A still better region for the broad-leaved trees is found in warm regions like the Amazon basin and the eastern base of the Andes. There the high temperature at all seasons causes most of the trees to be evergreen hardwoods like and rosewood. The relief of the Andes is important largely because their great height forces the easterly trade winds to begin to rise far out on the plain, and thus helps to produce abundant moisture ?••• here the soil is deep and the temperature high. As yet the demand for lumber is not strong enough to cause the hardwoods of the moist tropical regions to be cut extensively even in the plains, but as time goes on the lower parts of the moist, rugged tropical regions will presumably rank among the world's greatest timber regions. A given area near the eastern foot of the Andes in Brazil where the drainage is good, where showers arc frequent, and where the sun shines warmly, produces two to six times as much wood each year as the best deciduous areas in the Appalachians.
Trees as the Food Producers of Rugged Regions.—Today people usually think of trees as sources of lumber rather than of food. Yet even now great amounts of food are derived from trees, and the quan tity is steadily increasing. This increase means that .rugged lands are becoming more and more valuable for agriculture a S well as for sheep raising or lumbering. The commonest food product derived from trees is fruit, and fruit trees are well adapted to rugged regions. One reason is that they need little cultivation and therefore can grow in places where crops like potatoes are unprofitable. Another reason is that one of the great obstacles to fruit raising is late frosts in the spring, which nip the blossoms, and to a less extent early autumn frosts which injure the fruit while ripening. On the lower slopes in rugged regions frosts do not occur so late in the spring or so early in the autumn as in level regions. At night the air which is in contact with the rapidly cooling ground naturally loses its heat most quickly. The air thus cooled flows down the slopes and is replaced by warm air. Thus,
while heavy frosts may occur in the valley bottoms, the slopes remain relatively warm, as is known to almost everyone who often walks up or down hill at night. Accordingly, many farmers of the eastern states plant apple and especially peach trees on slopes so steep that ordinary cultivation is difficult. Grapes are another fine crop for such slopes.1 In the United States the steeper slopes are not being used for nuts except experimentally. In Spain, Italy, and Syria some of the finest walnut and chestnut groves cover slopes so steep that each tree has to have a little terrace around its foot to retain the soil. Again, in the Mediterranean regions, especially from south Italy eastward, the olive is one of the main sources of the fatty food which is essential to good diet. In old Greece there are four olive trees for each inhabitant and these yield 50 to 80 pounds of preserved olives per person each yea • and about three gallons of oil. The crop stands next to the small Corint grape or currant in value, and is of much greater real importance. I California, and other subtropical countries the olive is also beginnin to be important. It is one of the best crops for a rugged country witl a dry summer, for the tree needs almost no summer rain.
As population increases and as man's needs also increase new sources of food and raw materials are constantly required. A hopeful method of meeting this need, as Professor J. Russell Smith has well pointed out, is to utilize the vast areas of rugged relief. About three-fifths of Ten nessee, four-fifths of Japan, six-sevenths of Washington, and nine tenths of New England remain untilled, and this is largely because they are rough. Even in the production of lumber these large areas are used only imperfectly and unscientifically. If men were guided by science, and if they were able to see far enough into the future, many of these rugged areas might become as valuable as the chestnut orchards of France which are among the most valuable lands in that country. The future of such areas depends largely on the development of quickly growing varieties of nut and fruit trees by the same processes which have caused corn, wheat, and many vegetables to yield ten or twenty times as much as in their primitive states.
Tree crops have important advantages. A tree, when once started, can be left almost to itself. There is no need of sowing the land each spring, and then going over every foot of it to reap the crop in the fall, and while cultivation is important, it need not be so intensive as for ordinary annual crops. On the slopes of the Appalachian Mountains in Virginia and New York, for example, and of the White and Green Mountains in New England apple orchards are beginning to cover spots that formerly were given over wholly to forest. A little pruning in winter, some spraying in the spring, and the cutting of the brush and undergrowth in the summer comprise all the necessary cultivation. Roads are almost needless, for practically all the hauling is down hill.