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ARBORETUM AND FRUTICETUM.

PART 111.

this subject we refer to the history of the larch plantations at Athol andDunkeld, given at the end of this article.

Thinning and Pruning. Where the object is timber of large size, the treesought to be thinned out soon after the branches at the lower part of thetrunk interfere with one another to such an extent as to destroy all vegeta-tion on the surface of the ground beneath them ; but, where they are intendedfor poles, fencing, or other minor country purposes, they ought to be allowedto stand thick, so as to be drawn up clean, slender, and straight. De Can-dolle thinks the plantations of larches in Britain much too close. Thetrees are generally at the distance of 3 ft. or 4 ft. from each other, whichis much closer than the Continental practice; and he recommends double,or even triple, that distance. Air and light would thus penetrate betteramong the trees, and would correct the defects arising from the want ofevaporation, and the decomposition of the carbonic acid. You should not,he adds, “ begin planting at the distance of 10 ft.; but you should begin thin-ning out gradually, so as to bring your trees to the distance of 10 ft. apartwhen 20 years old. Considering the atmospherical circumstances of Britain,larch trees should be at a greater distance than they are in Switzerland,and yet they are at considerably less; he therefore strongly recom-mends thinning; and this recommendation, he says, is supported by thejudgment of the most judicious observers, viz., M. De Charpentier andEmmanuel Thomas (the latter a nurseryman and seed dealer at Berg, in theCanton de Valid, and the former the author of a work on the Pyrenees).These persons propose the distance of 1.5 ft., instead of 10 ft., from observingwhat takes place in the Alps, where the larches generally make forests veryfar from close. {Quart. Journ. of Agr., vol. v. p. 409.; and liibl. Univ. deGeneve, Feb. 1835.) Very little pruning is required for the larch. Accord-ing to Mr. Sang, the pruning of larch trees growing in masses, and intendedto attain a timber-like size, should be commenced about the sixth year oftheir growth; and no more than one, or at the most two, tiers of branchesshould be removed at a time, otherwise the trees will be much retarded intheir growth. After this, a tier of branches may be cut off annually, takingcare that, in all larches 20 years old and upwards, not more than two thirdsof the trunk should be clear of branches. The branches should be cut offclose to the stem, in order that the wound may be speedily healed over bythe bark. The time of pruning is the winter season, when the sap is in itsleast active state. The larch trees at Dunkeld seem scarcely to have been-pruned at all; and,indeed, the tree having naturally only small branches,which never attain a timber size, less pruning is required for it in a state of artthan for any other trees, except, perhaps, the spruce and the silver firs. Mr.Pontey has shown, in his Forest Primer, ed. 4., p. 71., by a diagram, of whichJig. 2265. is a reduced copy, that even the dead branches of the larch, when

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enclosed in the trunk of a tree, remain sound in it; and, consequently, whenthe wood is sawn up into boards, it does not produce rotten knots, as isfrequently the case when dead branches have been enclosed by growing overin the evergreen Abietinte; and as always happens in similar cases with thecommon broad-leaved trees. Fig. 2265. represents a piece of larch board,taken from the root end of a tree above 2 ft. in diameter : a shows he core