Book II. THINNING PLANTATIONS. 585 



of ourselves and of posterity ? The worst tree should never be left, but with tlie view 

 of filling up an accidental vacancy. 



3710. In thinning mixed plantations^ the removing of the nurses is the first object 

 which generally claims attention. This however should be cautiously performed ; other- 

 wise the intention of nursing might, after all, be thwarted. If the situation be much 

 exposed, it will be prudent to retain more nurses, although the plantation itself be rather 

 crowded, than where the situation is sheltered. In no cases, however, should the nurses 

 be suffered to overtop or whip the plants intended for a timber crop ; and for this reason, 

 in bleak situations, and when perhaps particular nurse plants can hardly be spared, 

 it may be sometimes necessary to prune off the branches from one side entirely. At 

 subsequent thinnings, such pruned or disfigured plants are first to be removed ; and then 

 those which, from their situation, may best be dispensed with. 



3711. At ivhat period of the age of the jylantation the nurses are to be removed, cannot 

 easily be determined; and, indeed, if the nurses chiefly consist of larches, it may with 

 propriety be said, that they should never be totally removed, while any of tlie other kinds 

 remain. For, besides that this plant is admirably calculated to compose part of a beauti- 

 ful mixture, it is excelled by few kinds, perhaps, by none as a timber tree. 



3712. But when the nurses consist of inferior kinds, such as the mountain ash or Scots 

 pine, they should generally be all moved by the time the plantation arrives at the height 

 of fifteen or twenty feet, in order that the timber trees may not, by their means, be 

 drawn up too weak and slender. Before this time it may probably be necessary to thin 

 out a part of the other kinds. The least valuable, and the least thriving plants, should 

 first be condemned, provided their removal occasion no blank or chasm; but where this 

 would happen, they should be allowed to stand till the next, or other subsequent revision. 



3713. At what distance of time this revision should take place, cannot easily be 

 determined ; as the matter must very much depend on the circumstances of soil, shelter, 

 and the state of health the plants may be in. In general the third season after will be soon 

 enough ; and if the plantation be from thirty to forty years old, and in a thriving state, 

 it will require to be revised again, in most cases within seven years. But one invariable 

 rule ought to prevail in all' cases, and in all situations, to allow^ no plant to overtop 

 or whip another. Respect should be had to the distance of the tops, not to the distance 

 of the roots of the trees ; for some kinds require more head room than others ; and all trees 

 do not rise perpendicular to their roots, even on the most level or sheltered ground. 



3714. With respect to the final distance to which trees, standing in a mixed plantation, 

 should be thinned, it is hardly possible to prescribe fixed rules ; circumstances of health, 

 vigor, the spreading nature of the tree, and the like, must determine. Whether the trees are 

 to be suffered to stand till full grown ; which of the kinds the soil seems best fitted for ; 

 whether the ground be flat or elevated ; and whether the situation be exposed or sheltered, 

 are all circumstances which must influence the determination of the ultimate distance at 

 which the trees are to stand. It may, however, be said in general, that if trees be 

 allowed a certain distance of from twenty five to thirty feet, according to their kinds and 

 manner of growth, they will have room to become larger timber. 



3715. Plantations of Scots pine, if the plants have been put in at three, or three and 

 a half feet apart, will require little care until the trees be ten or twelve feet high. It is 

 necessary to keep such plantations thick in the early part of their growth, in order that 

 the trees may tower the faster, and push fewer and weaker side branches. Indeed, a pine 

 or soft-wood plantation should be kept thicker at any period of its growth, than any of those 

 consisting of hard- wood and nurses already mentioned ; and it may sometimes be proper 

 to prune up certain plants as nurses, as hinted at above for nurses in a mixed plantation. 

 Those pruned-up trees are of course to be reckoned temporary plants, and are afterwards to 

 be the first thinned out ; next to these, all plants which have lost their leaders by accident, 

 should be condemned ; because such will never regain them so far, as after to become 

 stately timber ; provided that the removal of these mutilated trees cause no material 

 blank in the plantation. Care should be taken to prevent whipping ; nor should the 

 plantation be thinned too much at one time, lest havock be made by prevailing 

 winds ; an evil which many, through inadvertency, have thus incurred. This precaution 

 seems the more necessary, inasmuch as Scots pines, intended for useful large timber, are 

 presumed never to be planted except in exposed situations and thin soils. At forty 

 years of age, a good medium distance for the trees may be about fifteen feet 

 every way. It may be wortliy of remark, that after a certain period, perhaps by the 

 time that the plantation arrives at the age of fifty or sixty years, it will be proper to thin 

 more freely, in order to harden the timber ; and that then this may be done with less 

 risk of danger, from the strength the trees will have acquired, than at an earlier period ; 

 but still it should be done^radually. 



3716. Plantations of sprUce and silver firs, intended for large useful timber, should 

 be kept much in the manner above stated, both in their infancy and middle age. . As 



