|Standard Cyclopedia of Horticulture|
Forestry is the rational treatment of forests; this treatment may vary with the object in view. Forests may subserve various objects, giving rise to three classes of forests: they furnish wood materials for the arts—supply forests; they furnish a soil cover, which may prevent the blowing of the soil and formation of sand-dunes, or may retard the erosion and washing of the soil and may regulate the waterflow, or act as a barrier to cold or hot winds, and exercise other beneficial influences on climate and surroundings—protection forests; or, finally, they furnish enjoyment to the esthetic and sporting elements in man, as game-preserves and parks—luxury forests. Any two or all three objects may be attained simultaneously in the same forest. In the end, and in a more limited sense, forestry is the art and business of making revenue from the growing of wood crops, just as all agriculture is finally concerned in producing values from food crops and other crops. In the economy of agriculture, wood crops may be grown on land that is too poor for field crops.
This art is divided into two distinct and more or less independent branches, namely silviculture, the technical branch and forest management, the business branch. Silviculture is a branch of the larger subject arboriculture, and comprises all the knowledge and skill applied in producing the wood crop, relying mainly on natural sciences. While horticulture and silviculture have both to deal with trees, their object and with it their treatment of trees are totally different: the orchardist works for the fruit of the tree, the landscape gardener for the pleasing form; in both cases the object is attained by the existence of the tree and its single individual development; the forester is after the substance of the tree, the wood; his object is finally attained only by the removal of the tree itself. He deals with masses of trees rather than individuals: it is logs in quantity and of desirable quality, clear of knots, not trees, that he is working for; hence, his treatment differs from that of the horticulturist.
The clear long boles free of knots are secured by a dense stand, when by the shade of neighbors the lower branches are made to die and break on. When in this way clear boles to a certain height are secured, the stand is opened up by thinnings in order to secure expansion of crown and thereby more rapid increase in diameter of bole. There are several ways of reproducing the crop, namely artificially by sowing or planting, the latter being done with one- to four-year-old plants, at the rate of 1,500 to 4,000 to the acre; or by natural regeneration, either by sprouts from the stump, the so-called coppice, which is applicable to hardwoods and for the production of fuel wood and small-dimension material, or else by seed from mother or nurse trees. There are various procedures of securing a crop by seed, a so-called timber forest, which differ by the rapidity of the removal of the old crop or nurse trees, and by the size and progress of the opening—strip system, group system, selection system, and, the most refined, shelterwood system.
Since the crop takes many years to mature—sometimes a century and more—in order to carry on a continuous forestry business, from which to secure annual returns, special arrangements peculiar to this business must be made: these arrangements, naturally influenced by the economic conditions of the country, form the subject of forest organization or management.
The ideal of the forester to which he attempts a gradual approach with his actual unregulated forest is known as the "normal forest." It supposes that a rotation has been chosen, i.e. a year or period when the timber will be ripe (determined in various ways); that as many stands are at hand as there are years in the rotation, differing by one year from each other, so that each year a mature area can be harvested—a normal age-class gradation; that the increment on the whole area is the best attainable for species and site —a normal increment; that the amount of wood standing, the stock on which the increment is deposited, is the proper one for each age-class—a normal stocks This is the standard with which the actual forest is compared to judge its abnormalities, which by the management are to be, as far as practicable, removed.
Since the forest crop takes from thirty to one hundred years and more to mature, i.e., to produce desirable size, highest value, or best interest rate on the investment, it is a business which does not appeal to private enterprise: the long-time element, as well as the influence of forests on water-flow and other cultural conditions make forestry particularly a business to be conducted by the state or other long-lived corporation.
The horticulturist, as such, is mainly interested in the rational treatment of such forests as have a protective value, influencing climatic, soil and water conditions in general and locally.
The raising of trees for shade, for ornament, and for avenues is not forestry, but a branch of arboriculture (which see); the ornamental utilization of forests, as a part of grounds, is discussed under Woods.