CHAP. CX1IJ.

coni'feka:. ^bie'tin.®.

2135

Thinning and Felling. Thinning ought to be carried on in connexion withpruning; and, when large timber is to be produced, this is no less necessaryin the case of the Albietinas than in that of the broad-leaved trees; thoughthe former, from their narrow conical shapes and great height, do not requireso much room as the latter. The advantages derived from thinning will beshown in a striking manner from actual practice in Britain, when we cometo treat of the larch.

The pine and fir tribe, not being trees that stole, are never cultivated ascoppice-wood; and when a grove of pines is felled, the roots ought to betaken up, in order to clear the way for the succeeding crop. In the Germanand French works on the culture of the Jbietinse, there is much differenceof opinion as to whether a grove of pines or firs, when full grown, and fit fortimber, ought to be wholly cut down at once, “like a crop of corn” (to useMr. Main’s phrase), or cut down by degrees by thinning out. If the lattermode is considered the best, another point arises for discussion; which is,whether the smaller trees are to be taken out, so as to leave room for thelarge ones to grow larger, which is called exploitation par eclaircies; orthe larger ones removed to leave room for the small ones to increase insize, which is called exploitation en jardinant. In the Dictionnaire des Eauxet Forets , a comparative view is given of these two modes, and the preferenceis given to the first; but both, it is alleged, are inferior to the mode of cuttingdown the entire grove or forest at once; and this seems the most rational,because, when the air is once let in to a grove of full-grown pines, theyseldom increase much in size afterwards; doubtless, from the influence ofthe weather on their naked trunks, which have, till then, been shaded andprotected by the evergreen branches of the trees that have been removed.Deciduous trees, as they never receive so much protection from one another,never suffer so much from thinning, whether when young, or when matureand fit for felling as timber. The season for felling the /ibietinae is duringwinter; but in the Alps and the Pyrenees, and also in the north of Swedenand Norway, where the ground is covered with snow for six or seven monthsin the year, the trees are cut during summer. It is alleged that the woodfelled during the latter season, from the greater quantity of sap con-tained in it, must necessarily be less durable than that felled when the sapis dormant. This, however, must chiefly apply to the sap wood; becausethe heart wood, which alone is used for important purposes, is not pene-trated by the ascending or descending sap. After the trees are felled, theroots are dug up, broken into small pieces, and distilled for tar; or burnedin covered heaps for that product jointly with charcoal.

In situations naturally adapted for the progress of pines and firs, the self-sown seeds keep up a perpetual succession of the same species for an un-known period : but when the plantation is cut down before the trees haveshed abundance of seeds; or where, from being an artificial plantation oftrees all planted at the same time, the ground is so completely shaded,as to prevent the vegetation of the seeds which may have dropped on it;or where the soil is not naturally congenial to the Abietinae; in any ofthese cases, this order ought to be succeeded by another totally differentfrom it, but at the same time suitable for the soil. Many authors haveobserved that native woods, both in England and America, when cut down,are generally succeeded by a different kind of tree (see Gard. Mag., v.p. 421.); and others, that pine forests, when destroyed accidentally by fire,in America, are usually succeeded by oak. M. Le Comte of Riceborough,Georgia, has for upwards of thirty years paid great attention to the subjectof the natural succession of woods ; and the following are the results of hisobservations respecting pine forests:—■ “ The pine lands in the southernstates have generally old oak grubs, which, by reason of the periodical fires,are prevented from becoming trees, notwithstanding which they still continuealive (see p. 1891.); and when land is turned out (that is, when the culti-vation of it is relinquished), the pines, being naturally unproductive of