The forest rotation.
There is a popular fancy that a natural rotation of trees exists, and where soft woods are cut hard-woods naturally follow, and the reverse. In reality, there is little to justify this notion. Under natural conditions, sometimes hard-wood will follow pine, or pine will follow the hard-woods, where the two were mixed at the time of cutting and there was on the ground a young growth which had an opportunity to grow when its competitor was removed.
When land is severely burned after being cut over, the trees that show first are the kinds that produce seed in great abundance, and whose seed will float long distances in the wind, such as poplar and birch ; or else those having fruits especially liked by birds, such as the bird cherry, which is widely distributed. The pine, and perhaps other trees. may come in later, owing to their being seeded later, or owing to the later advent of con ditions favorable to their germination and growth. It may often happen in the case of burned-over pine land, that pine seed is distributed over it the first year after it is burned, but owing to the lack of protection from the sun the young seedlings, which are very delicate and require slight shade, are destroyed.
On the other hand, the young poplars, on newly cleared land, may find just the condition for growth, and the land becomes thickly seeded ; later there comes a general weakened condition of the poplars by reason of too much crowding. Under the growth of these weakened poplars, pine seedlings may find the right conditions of shade for their most suc cessful growth, and will gradually force their way up through the poplars, and finally kill them out. On the other hand, the poplars, birches and other trees, grasses and shrubs growing on the land when the timber is cut, may make so strong a growth as to kill, for a time, the young pine seedlings that are on the land.
Forest regeneration.
The term regeneration is commonly used in for estry to signify the renewal of forest trees on the land. It is a convenient term and well worthy of general use. The different forms of regeneration may be referred to as, (1) regeneration by natural seeding ; (2) regeneration by artificial seeding ; (3) regeneration by planted seedlings ; (4) regenera tion by planted cuttings ; (5) regeneration by sprouts and suckers (i. e., coppice-growth).
The method of regeneration best adapted for one section may not be at all fitted for another section under different conditions, and often it is best to combine two or more of the different forms of regeneration. Where natural regeneration of valuable species can be easily brought about, it is generally the best practice. This is especially true in sections where timber is comparatively cheap, as is generally the case in this country where the returns from the land can hardly be expected to pay for any great amount of labor.
(1) Natural regeneration by seed may be greatly assisted by stirring the surface of the soil in good seed years, just before the seed is scattered, and by thinning enough to let in light and air to the seedlings. When it is desired to have an open field adjoining woodland thus seeded, the land may be plowed or loosened with a disk harrow or drag, and put in such condition as to make a sufficiently good seed-bed. When the soil will not permit of such exceptional treatment, it may be loosened by a drag made by tying together several oak branches or small logs, which, when dragged over the ground several times, will gradually break up the surface. This will be especially necessary where there is a thick covering of mold or "duff" on the land. This same method of stirring the soil is applicable when the land is to be seeded by hand. Good seed years do not often occur in our most desirable species, and it is very important to take advantage of these good years when they do come.
Natural re-seeding is almost the only practical means of re-stocking large areas of forest lands, as other methods are too expensive. It generally takes place readily, and the chief reason why it is not more successful is the frequent destruction of the young seedlings by fires, by cattle and improper methods of logging.