Chapter XIV Thinning Plantations
In the successful rearing of timber trees for profit there is, perhaps, no other branch of more importance than a good knowledge of the art of thinning, and, at the same time, one on which so great a diversity of opinion exists.
Thinning plantations, be they old or young, must always be subject to great modification, according to the nature of the trees and soil, or ultimate design of the plantation being operated upon, and is a matter requiring great tact, forethought, and discrimination, and this can only be acquired by long experience and by those having a good insight into the peculiarities and properties of our forest trees.
The same rule as regards thinning will not apply to, say, fir, hardwood, and mixed plantations; and far less will it hold good in the case of an ornamental and a profitable wood. No universal rule can, however, be laid down for thinning, but general principles can be given that will be sufficient for the guidance of those who have to undertake such work.
In thinning any plantation two important points are to be borne in mind—first, cut away all diseased, dead and dying trees; second, study the relationship of trees and soil, and act accordingly. To be more explicit, we might say that in the first case, the removal of all dead and dying trees is a necessity, and that being done, one can proceed with the disposal of the standards to be left. In the second case, by suiting the trees to the soil, at least as far as possible, great benefit results, and an instance of this that came under our own observation lately will be given as an example. A plantation 130 acres in extent was composed of oak, larch and Spanish chestnut, placed at regular distances apart throughout the whole extent of the wood. Now, the soil was gravelly for a considerable distance down, and, consequently, fairly well suited for the chestnut, but just the reverse for the larch, which, on such a soil, generally becomes “pumped,” or rotten at the core. In thinning this particular plantation, it would have been very unwise to cut away the chestnut and the oak and leave the larch, and this had happened to some extent before the proper system of management and adaptability of soil to tree was thought of. Larch may look healthy enough, and show but small indications of disease, even when growing on gravel up to twenty or thirty years of age, so that it is with difficulty that the inexperienced become aware of the pending doom that usually awaits this tree when planted on such a soil. This example is merely given to point out how carefully thinning should be gone about, and that in all cases it is a wise policy to study soil in relation to the future crop of timber before an axe is laid to the tree.
At the outset of these remarks on thinning plantations it should be distinctly borne in mind that there are two chief objects for which trees may be grown, each requiring a special mode of management, in order that the best results may be obtained.
The first is their management in a purely economical sense or with a view to profit; the second, their management with a view to ornament. There is also a third object that is well worthy of consideration, and that is the growing of timber in one and the same wood, both for ornament and utility combined, and this is very frequently the case with home woodlands that are visible from roads and drives, with strips bounding parks or pleasure-grounds, and on small properties.
To produce ornamental trees of natural appearance is by no means difficult, as by allowing the individual specimens ample room for branch development, the desired effect is gradually brought about. Far greater difficulty, however, attends the production of the greatest quantity of the most valuable trees on a given space of ground. Here many questions of the greatest moment, on which difference of opinion exists, crop up: such as at what age thinning should be commenced, to what extent should it be engaged in, what time should elapse between each thinning, and which trees should be removed.