The formation of plantations by the sowing of seed has been more generally prac ticed on the continent than in Britain. In this way the vacancies in the natural forests of France and Germany are filled up. In this way also great sandy tracts have been covered with wood on the coasts of Pomerania and of France This has particularly been accomplished on a scale of extraordinary magnitude in the downs of drifting sand, between the rivers Adour and Gironde. The operations there were begun by M. "Ire montier in 1789, and deserve to be mentioned as perhaps the most important operations in A. that have ever been performed in the world. Vast forests of pinaster now occupy what was originally loose sand destitute of vegetation.
Too little attention has hitherto been generally paid to the adaptation of the kinds of trees that are planted to the soil and climate; and to this cause many failures in A. are to be ascribed. Some trees grow well even in exposed situations, and are fit to be employed in these, either to form entire plantations, or to occupy the outer part, and so to shelter other trees, which in general are not planted until the outer zone or belt of the most hardy kinds is somewhat advanced; some succeed only in rich soils; some are incapable of enduring the sea-breeze; others, as the sycamore, the elder, and the pin aster, are comparatively unaffected by it. Some trees suffer from an amount of moisture from which alders or willows mould rather derive advantage; but, in general, the thorough drainage of the land intended for a plantation is one of the circumstances most important to its success.
To the necessity of this thorough drainage we must look as compensating, or more than compensating, the influence which woods exercise in condensing the moisture of the atmosphere, and in rendering a climate cold and damp; marshy soils being in this respect still worse. The shelter afforded by plantationsjudiciously disposed, whether in belts or otherwise, is also of great importance in rendering them suitable for that improved agriculture in which thorough drainage is of the first necessity, and which is always productive of amelioration of climate. The influence of plantations is, there fore, whole, beneficial, although vast masses of forests are Injurious to climate; and it must be admitted that in some localities the planting of trees has been carried to excess, so that fields often suffer, particularly in autumn, from want of free circulation of air, and the landscape is often restricted to very narrow limits. The remedy in such cases is obvious; and it not unfrequently happens that within a short distance new plan tations might be formed with every prospect of benefit.
Much has been written about the pruning of forest trees, with a view especially to the production of taller and straighter stems; and considerable difference of opinion exists as to the extent to which pruning should be practiced. It is, however, very gen erally delayed till the branches to be removed have attained too great a size, and is then very rudely performed, to the spoiling of the timber rather than to the improvement of it. The practice of leaving snags, instead of cutting branches clean off,. has particularly bad effects. Pines and firs, from their manner of growth, need pruning less than trees
of other kinds. When trees have been planted, not merely for profit but for ornament, this ought to be remembered in pruning, which, however, is too often intrusted to per sons utterly devoid of taste; and trees which, as they naturally grew, were very beauti ful, are so treated with axe and saw that they become deformities instead of adorning the scene.
In forming plantations, different kinds of trees are very generally mixed, although i masses of one particular kind are also frequently planted. It is usual, however, to plant along with those which are destined most permane'ntly to occupy the ground, trees of other kinds as nurses, to be gradually removed as the plantation advances in growth. For this purpose, spruce and larch are more generally employed than any other tree; although Scotch fir and birch are also deemed suitable for certain situations. The removal of some of these nurses affords the first returns of profit from the plantation, which is afterwards thinned from time to time. Plantations far more frequently suffer from being thinned too little, than from being thinned much. To the want of proper thinning is to be in part ascribed the failure of many of those narrow belts of planting which are too common in Scotland, and which, having been intended for shel ter, very imperfectly serve their purpose, and seem to have suffered from the hardest usage themselves. The thinning of a plantation which has been allowed to grow too thick, must, however, be very gradually performed, that it may be beneficial, and not injurious. After a sudden thinning, a plantation sometimes ceases to thrive, and many trees are often laid prostrate by the next storm; for trees accommodate themselves both in their roots and branches to the situations in which they grow.
A. considerable number of years must elapse before any pecuniary return is' derived from a plantation, yet this mode of employing soils is often found to be the most remun erative of which they are capable, even without reference to the improvement of adja cent lands to which shelter is afforded; and the increased demand for timber in Britain. for sleepers of railways and other purposes, tends to the still further encourage ment of A.
The resinous products of pine-woods are not considered as a source of profit in Britain; but the tar, turpentine, and resin obtained from them in some parts of Europe, form articles of commerce. The great pinaster plantations already mentioned, on the sands between the Adour and Gironde, now yield products of this kind in large quan tity. The employment of trees for ornamental purposes belongs not so much to A. as to landscape gardening (q.v.). The transplanting (q.v.) of large trees is only practiced for ornamental purposes. Hedgerow trees are planted chiefly for ornament, although sometimes they may afford useful shelter; but where this is not the case, they can sel dom be reckoned profitable, as they are injurious to crops. Copse or coppice-wood differs so much, both in its uses and in the mode of its management, from other planta tions, that it must be briefly noticed in a separate article.