Waste is avoided in all possible ways, stumps are cut low and tops high on the trunk, first class trees are not used for skids, bridges, roads, etc., care is taken in "falling" trees and in dragging out logs, that they will not injure other trees. Just as economical disposal of the log has already been carried to a high degree of perfection in the saw-mill, (see Handwork in Wood, Chapter II,) so one object of forestry is to carry this economy back into the woods.
One of the underlying ideas in conservative lumbering is that the "yield," i.e., the amount of wood taken out of a healthy forest in a given time, shall be equal to the amount grown during the same period. If less is taken out than grows, some trees will overmature and decay; if more is taken out than grows, the forest will ultimately be exhausted.
This principle may be carried out in a number of ways; but in any case it is necessary to know how fast the forest is reproducing itself, and this is one of the functions of the forester. The United States Forest Service makes a definite offer of cooperation with farmers and lumbermen and owners of forests to provide them with skilled foresters for direction in this matter.
In the United States, the most practicable way of determining the yield is by area, i.e., a certain fraction of a forest is to be cut over once in a given length of time, a year or longer. The time between two successive cuttings on the same area must be long enough to allow the young trees left standing to ripen.
In a word, conservative lumbering involves (1) the treatment of the forest as a source of crops, (2) systematic gathering, and (3) young growth so left as to replace the outgo.
The important place that forests fill in the national economy may be realized partly by the citation of a few facts as to the forest products. The lumber industry is the fourth in value of products among the great manufacturing industries of the United States, being exceeded only by the iron and steel, the textile, and the meat industries. It turns out a finished product worth $567,000,000.00. And yet lumber constitutes only about one-half of the value of the total output of forest products. Its annual value is three-fourths of a billion dollars, ($666,641,367 in 1907,) while the annual value of wood fuel, is $350,000,000. More than two-thirds of the people burn wood for fuel. The next largest single item in the list is shingles and laths, $32,000,000. (See Forestry Bulletin No. 74, p. 7.)
Outside of food products, no material is so universally used and so indispensable in human economy as wood. (Fernow, Econ., p. 21.)
The importance of forest products may also be learned from a mere list of the varied uses to which they are put. Such a list would include: fuel, wood and charcoal; houses (over half the population of the United States live in wooden houses); the wooden parts of masonry and steel buildings; scaffolding; barns, sheds and outhouses; ships, with all their parts, and the masts and trim of steel ships, boats and canoes; oars and paddles; railway ties (annual expenditure $50,000,000), railway cars, a million in number; trestles and bridges (more than 2,000 miles in length); posts and fencing; cooperage stock (low estimate, $25,000,000 annually); packing crates, including coffins; baskets; electric wire poles (annual cost about $10,000,000); piles and submerged structures, like canal locks and water-wheels; windmills; mining timbers (yearly cost, $7,500,000), indispensable in all mining operations (for every 100 tons of coal mined, 2 tons of mining timber are needed); street paving; veneers ($5,000,000.00 worth made annually); vehicles, including carriages, wagons, automobiles and sleighs; furniture; machines and their parts; patterns for metal molding; tools and tool handles; musical instruments; cigar boxes; matches; toothpicks; pencils; (315 million a year in the U. S., requiring over 7 million cubic feet of wood); engraving blocks; shoe lasts, shoe trees and parts of shoes; hat blocks; agricultural implements; hop and bean poles; playthings and toys, for both children and adults; Christmas trees and decorations; pipes; walking sticks; umbrella handles; crutches and artificial limbs; household utensils; excelsior.
Products other than wood: Turpentine and resin (worth $20,000,000 a year); tar; oils; tan-bark, 1½ million cords (worth $13,000,000 a year); wood alcohol; wood pulp (worth $15,000,000 a year); nuts; cellulose for collars, combs and car wheels; balsam, medicines; lampblack; dyes; paper fiber (xylolin) for textiles; shellac and varnish ($8,500,000 worth imported in 1907); vinegar and acetic acid; confections (including maple sugar and syrup at $2,500,000 a year).
(3) The Esthetic and sentimental uses of the forest, tho not to be estimated in dollars and cents, are nevertheless of incalculable benefit to the community. They would include the use of the forest as pleasure grounds, for hunting, fishing, camping, photography, and general sightseeing. Notable instances of the growing appreciation of these uses of the forest are the reservation of the Yellowstone and Yosemite Parks as pleasure grounds.