THE FOREST AS A UNIT In a literal and an emphatic sense the wooden walls of a nation are its forests. The trees on mountain slopes restrain the waterflow in the valleys, preventing flood and drought, and thereby hoarding for cities their supply of water. Trees temper climate, drain swamps, add a stimulating tonic to the air, and take from it the poisonous carbonic-acid gas. The pine forests are sought by invalids for the healing of lung troubles in every country. Our Adirondacks and the Colorado mountains have their proto types in the pine-clad health resorts of southwestern France and the region around Baden in Germany, whose famous Black Forest has a balsamic breath.
European nations that have cut down their forests and failed to store them have proved their national weakness and their dependence upon wiser neighbours. The Mediterranean countries are among the foolish—buying lumber continually from Norway, Sweden and Germany, and suffering in climate, water supply and in the poverty of the peasant class, the results of having no home forests.
Tree roots are rock breakers, able to make their way even through granite boulders. The root hairs excrete an acid that eats away limestone and disintegrates rock particles, while the mighty pressure of growth is crowding the sides of cracks apart. In time, with water and frost and other forces co-operating, the forbidding rock ledges have a crumbling layer kept from blowing away by the falling leaves and sheltering undergrowth. The leaf carpet rots, earthworms mingle its substance with this "rock meal," and the name of the mixture is soil—broken-down vegetable and mineral substance yielding plant food to the hungry roots of trees.
Thus a forest makes soil, deepening and enriching it the more the roots take from it. "Virgin soil" is that which has been covered with trees for hundreds of years. Waste land moist enough to grow trees may be reclaimed by this agency in a few years. Even semi-arid regions will grow trees if only the proper ones are chosen. This is the lesson Kansas and Nebraska are learning after long experiment and repeated failure.
The meaning of trees in a landscape—the beauty value of them—is oftenest overlooked by those who have always seen them. When crossing such a monotonous stretch of treeless country as the plains of Arizona that wait for irrigation, the Easterner for the first time has a full appreciation of the beauty of his familiar wooded hillsides, and tree-lined streets. Out of homesickness for forest scenery, as well as the necessity for pro tection and wood supply, came the great tree-planting crusade that swept over the Middle West and will yet dot every state with homes surrounded by groves.
It is proper to recognise here the influence that men have unconsciously drunk in from trees. Myth and song have remem bered and repeated the feelings of primitive races to whom trees gave shelter and raiment and food. The old Druids worshipping the oak expressed a veneration which we all inherit, whatever our race and line. Contact with trees is a purifying, uplifting experience. Work in the woods develops a hardy, clean and intelligent race. When we lose our wonted strength of mind and body go to to the woods to find it.