III.

Practice

Forestry comprises such specialties as dendrology, silviculture, forest protection, mensuration, engineering, utilization, and management. Dendrology concerns tree identification, distribution, age determination, and species characteristics. Silviculture studies the relationship of a forest to its environment and involves the development, care, and reproduction of stands of timber. Forest protection examines sources of injury, including disease, erosion, insect and animal destruction, and fire. The science of measuring forest stands, including rate of growth and potential yield of standing timber, is called mensuration. Forest engineering concerns the mechanics of cutting and transportation involved in modern timber growing and harvesting. Forest utilization considers the properties of wood and its conversion into lumber and wood products. Forest management applies business methods and the principles of technical forestry to the overall operation of forestlands.

The practice of technical forestry includes many operations, from tree planting to harvesting. Central to the operation is the cycle of cutting and replenishment. Four major methods have been developed for this purpose: clear-cutting, selection, seed tree, and shelterwood. In clear-cutting all trees in a given area are cut, and reproduction is obtained by artificial planting or by natural seeding from trees bordering the cleared areas. This method, adapted to light-demanding species, produces even-aged stands, allows control of stand composition, and is conducive to mechanized harvesting and disposal of slash, or logging debris. Selection cutting maintains a forest of mixed ages from which the largest and most mature trees are harvested periodically. Although this method is expensive and may cause injury to younger trees during logging, it provides continuous cover and an attractive forest and involves sounder ecological practices. In the seed tree method, about 10 percent of the trees in the cutting area are left in an evenly spaced pattern as a natural seed source. The shelterwood method, which involves the removal of the mature trees in cuttings over a 10- to 15-year period, promotes natural reproduction and produces relatively even-aged stands.

Other practices contribute to the development of commercial forestry. These include artificial planting by direct seeding or transplants, especially in conjunction with clear-cutting; treatment with fertilizers to increase production; and the selection and breeding of timber trees, producing strains that excel in growth, disease resistance, or other desirable characteristics. These measures fit into the pattern of an intensive forestry in which greater production is obtained through technical knowledge and increased mechanization.