The methods of cutting adapted to secure natural regeneration by seed in the forest naturally separate themselves into three systems, each of which may be best adapted to some special condi tions. They are known as (1) the selection method ; (2) the strip method ; (3) the sprout method ; and (4) the group method.
Selection method.—The selection method refers to the cutting of mature trees and the removal of inferior trees to make room for the better kinds. In this system much care should be exer cised to prevent the growth of grass, which generally comes in when the cutting is done more rapidly than the seeding trees can seed the bare land and furnish it with a good covering that will keep out the grass and other weeds. On the other hand, it is just as important to exercise great care in providing sufficient light for the young seed lings which have started, as that they can make a good growth and not be shaded out by the older trees. The removal of a single tree, even though it be a large one, often lets in so little light that seedlings cannot get a good start. For this reason the group method (referred to later) is probably best adapted for general use, since it opens up a sufficient space to warrant considerable attention being paid to securing good conditions for the young seedlings.
Strip method.—The strip method may be used to advantage where the soil and tree growth is very uniform over large areas. The strip method is a form of clear cutting and is chiefly applicable to large tracts of even-aged pure stands of conifers or any light-seeded species and when there is a ready market for timber of all sizes. The location of the strips and their alternate cutting involves the laying out of plan of management for many years ahead. The woodlot owner, therefore, will seldom find it necessary to resort to this method of forest treatment.
Under this system the trees are removed in nar row strips, as a rule not wider at any time than twice the height of the trees, no that the remain ing older trees can easily re-seed the denuded land ; but the best width of the strips will depend on the species and the local conditions. For example, in the case of oak, perhaps, the strips should not be wider than the height of the trees, while in the case of birch, elm, maple and pines, the strips might exceed in width six or eight times the height of the trees, and still they would be re-seeded suc cessfully. Such strips should generally be started
on the side opposite the prevailing winds at seeding time, so that the seeds may be blown on to the denuded land. Of course, in the case of oak, beech and similar trees, where the wind has compara tively little effect on the carrying of the seed, this point is not to be so much insisted on.
Group method (Fig. 463).—The group method is a system of cutting irregular strips successively on the inside of certain groups. This may be termed a natural method, and for general use, especially in mixed woods, and where the land and tree condi tions are rather variable, it is much the best. If this system is followed, one can adapt the method of cutting to the different species and to the differ ent conditions which may be found in the forest. For example, a tamarack swamp, a dry knoll cov ered with oak, a steep hillside, and level rich rocky land covered with elm, and very often various other conditions, would very likely all be included in almost any forest track of considerable size in the northern states, and each part, for best results, should receive special treatment. Under this plan we can begin with one group or several, and we can start our regeneration in each group perhaps where there is already a good growth of desirable young trees. In fact, this system gives us a chance to begin regeneration where the greatest necessity or the best opportunity for it already exists. The size of the openings will depend, as in the strip method, on the species grown and on the natural conditions of the land. As a rule, the first open ings should be one-fourth to one-half acre or more, and the strips taken around these openings should not exceed in width the height of the trees in the strips next to be cut ; but, as previously stated, this matter should be determined largely by the kinds of trees. Successive strips should be cut only when the previous strips have become well stocked with trees, that is, when regeneration is accomplished. Of course, the regeneration in each of these strips should be given the same care that would be given to any well-managed forest in order to bring about a predominance of the most valuable kinds under the best light and soil conditions.