Coppice, Fig. 123. In the simpler form of this system, the forest is divided into a certain number of parts, say thirty, and one part is cut down each year. New sprouts at once start up, which will mature a year later than those in the part cut the previous year. Where the trees of each part are thirty years old at cutting, thirty years is called the "rotation period." The coppice is said to be managed on a thirty-year rotation. The system is widely used in eastern United States, for fuel, posts, charcoal, railway ties, and other small stuff, as well as for tan-bark. This system is modified by maintaining an overwood composed of seedling trees or selected sprouts above a stand of sprouts. This is called the Reserve Sprout method and is used with admirable results by the French.
Seed Forests. In contrast with coppice forests, those raised from seeds produce the best class of timber, such as is used for saw logs.
Fig. 124. Seeding from the Side. White Pine. New Hampshire. U. S. Forest Service.
Seeding from the side, Fig. 124. Many forests naturally spread at their borders from the scattering of their seeds. "Old field pine" is so called from its tendency to spread in this way on old fields. This natural "Seeding from the Side" has given rise to the "Group System," in which an area of ripe trees is cut off and the trees alongside are depended upon to reproduce new ones on the cut-over area. The openings are gradually enlarged until all the old timber is cut out, and the young growth has taken its place. In its best form there is a definite "rotation period," say eighty years. This system is simple, safe, and very useful, especially for small openings in woodlots. A modification of this is the "Strip System," in which long narrow openings, say seventy-five yards wide, are cut out and gradually widened. The strips are cut in the proper direction so that the prevailing winds will cross them, both for the sake of avoiding windfalls and to help scatter the seed. Where the soil is very dry, the strips may run east and west to protect the seedlings from the sun.
Fig. 125. Virgin Forest, Trees of All Ages. Jackson Co., North Carolina. U.S. Forest Service.
Selection Forests. The typical virgin forest, Fig. 125, is one in which trees of all ages are closely intermingled, and it may be either "mixed" or "pure." If a farmer had a woodlot of this character and every year went over it with the ax, cutting out such trees as he needed for his purpose, and also trees whose removal would improve the woods, but taking care not to cut out each year more than the amount of the average growth, he would be using the "Selection System." This system is the best way of keeping a forest dense and of preserving one which is difficult to start afresh, as on a mountain slope; it is practicable where the woods are small or under a high state of care, as in Europe, where this system has been in use for seven centuries. But the cost of road maintenance and of logging is high and it is therefore impracticable in most lumber regions in the United States, except for woods of especial value, like black walnut.
Localized Selection. If instead of the whole forest being treated in this way every year, it were divided up into perhaps twenty parts, and from each part there were taken out each year as much lumber as would equal the annual growth of the whole forest, such a system would be called "Localized Selection." The cost of logging would be greatly reduced and if care were taken to leave standing some seed trees and to cut no trees below a determined size, as twelve inches, the forest would maintain itself in good condition. This system has been applied with great success in certain private forests in the Adirondacks.