ARBORICULTURE (from Lat. arbor, a tree), a term literally signifying the cultivation of trees, but in use generally- restricted to the planting and management of timber-trees, or employed as exclusive at least of the cultivation of fruit-trees, which is a branch of horticulture or gardening.
The ancients practiced A. to some extent, but chiefly with the view of beautifying their villas, or of forming public walks in the vicinity of cities. It is only for similar purposes, and on a very limited scale, that A. is yet anywhere practiced in America. The planting of timber trees for economical purposes, or with a view to profit, is unnecessary whilst natural forests are abundant, and can scarcely be referred even in Britain to an earlier period than the beginning of the 16th c., nor did it become at all general till a much later date. The early forest laws of England, as of other feudal countries, had reference chiefly to game, for the sake of which it was, and in order to the enjoyment of the chase, that large tracts were depopulated and converted into forests by the first Norman kings. Plantations for timber and fuel were, however, certainly made in England in the 16th c.; and the importance of the subject was urged on public attention by authors of that period. In the 17th c., the greatly increased demand for oak, for the building both of ships and of houses, gave a new impulse to A., which attracted more than ever before the attention both of the government and of the great landowners; the publication of Evelyn's Silica also (lid more than any previous work to promote a taste for it. It was in this century that nurseries for forest trees were first established. It was not until the beginning of the 18th e. that the first extensive planta tions were made in Scotland, nor until towards the end of that century that A. became general in that country or in Ireland. How much the very landscape has been changed by it—how great a difference has been made by the conversion of bleak hills and barren wastes into woods—how much the scene has been changed by the new forms of foreign trees, some of which are now in many districts more abundant than those which are indigenous, it is not easy to imagine; and bow much these changes have promoted and arc indicative of improvements in agriculture and increased productiveness of fields, is equally difficult to estimate.
The A. of France, Germany, and other parts of Europe, to this day, consists in a great measure of the management of natural forests: and in the more eastern parts of the continent this is almost exclusively the case. 'Without a careful management of the natural forests, many districts of France and Germany would soon be destitute of fuel; by means of it an increased supply of valuable timber is also obtained; and extensive domains belonging to the state., or to private proprietors, are rendered much more pro
ductive. It is in Germany that the management of the forests has received the greatest attention, and has been most systematically and scientifically conducted.
The forest trees of Britain, and of temperate climates generally, are conveniently divided into two classes—the one consisting of coniferous trees or pines and firs (nadel holz, i.e., the " needlewood" of the Germans), the other including all other kinds holz, i.e., the " leaf-wood " of the Germans); the latter being sometimes subdivided into trees, of which the most important in Britain are oak, ash, elm, beech, birch, hornbeam, sycamore, walnut, and chestnut; and trees, as willow, poplar, lime, alder, and horse-chestnut. Of these and other trees, of their particular uses, and of the soils and situations to which they are adapted, notice is taken in separate articles.
Plantations are generally formed in Britain by means of trees raised from seed in a nursery; but sometnnes also by sowing the seed on the ground intended for the planta tion; in which case, if circumstances permit, a crop of grain is often sown along with the seeds of the trees, as these do not in general vegetate very soon; and the young plants derive advantage from the absence of choking weeds when the grain-crop is reaped, and from the protection afforded by the stubble. It has been supposed by some, but there is no sufficient evidence in support of the opinion, that more healthy and vigorous trees are obtained by sowing on the spot than by planting those which have been raised in a nursery. However, only very young trees can be planted with advan• tage, those which have attained a greater size requiring a degree of attention far beyond what is possible in plantations even of very moderate extent. The time of planting is from November to February. The most approved mode of planting is in small pits, in which the roots are disposed in a natural manner, and which are then carefully filled up with earth; but it is often thought sufficient when the tree to be planted is very young, to make a slit for it with the spade, or two slits, one at right angles to the other in the form of the letter T. Other methods are also adopted, particularly for rocky situations, in which the spade cannot be used. Economy is often a consideration of great importance in determining the mode of planting.