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 prevents the blowing of the soil and formation of sand dunes, or which retards the erosion and washing of the soil and regulates the waterflow, or which acts as a barrier to cold or hot winds, and exercises other beneficial influences on climate and surroundings–protection forests.
- 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 money from the growing of wood crops, just as agriculture and horticulture are finally concerned in producing values from food crops. In the economy of agriculture, wood-crops may be grown on land which 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 regulation, 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 only attained 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. Since his crop takes many years to mature, some times 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 regulation.
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.