578 PRACTICE OF AGRICULTURE. Part III. 



Sect. IV. Of the Mixture of Trees m Plantations. 



3669. The object of mixing trees in plantations is threefold : that of sheltering the 

 weaker but ultimately more valuable kinds by the stronger and hardier ; that of drawing 

 as much profit from the soil as possible ; and that of producing variety of appearance. 



3670. With respect to slielter many situations are so exposed, that it is extremely diffi- 

 cult to rear trees without some mode of protecting them from the cold winds of spring 

 during their early growth. This is sometimes done by walls, the extent of whose influ- 

 ence, however, is but very limited ; by thick planting, or by planting the more hardy 

 and rapid growing species, to nurse up and protect such as are more tender, but ultimately 

 more valuable. The proportion of nurses to principals is increased according to the 

 bleakness of the site : Pontey says, ' Both authors and planters are in the habit of err- 

 ing egregiously, in regard to the proportion of principals and nurses, as they generally 

 use as many or more of the former than the latter, though it is very easy to show, that 

 they ought to use three times as many of the latter as the former. For instance, when 

 trees are planted at four feet apart, each occupies a surface of sixteen feet ; of course 

 four of them will occupy sixty-four, or a square of eight feet ; and, therefore, if we 

 plant three nurses to one principal tree, all the former might be displaced gradually, and 

 the latter would still stand only eight feet apart. 



3671. Nurse plants should, in every possible case, be such as are most valued at an 

 early period of growth. The larch and spruce fir should be used liberally, in every case 

 where they will grow freely ; still it is not intended they should exclude all others, 

 more particularly the bircK, which has most of the properties of a good nurse, such as 

 numerous branches and quick growth, on any tolerable soil or situation. It is not, 

 however, like the others, a wood of general application. {Profitable Planter, p. 113.) 

 Sang also adopts the proportion of three nurses to one principal, and employs chiefly 

 the resinous tribe, and looks to them for reimbursement till the hard timber lias attained 

 to a foot in diameter, under which size hard timber is seldom of much value. His 

 principals are planted at from six to ten feet apart, according to the soil and situation. 

 {Plant. Kal. p. 166. ) 



3 57 2. In procuring shelter much depends on the mode of commencing and continuing 

 plantations on bleak sites. Sang, whohas had extensive experience in this part of planting, 

 observes, that " every plain, and most fields and situations for planting, in this country, 

 have what may be called a windward side, which is more exposed to the destructive blast 

 than any other. It is of great importance to be apprised of this circumstance, and to be 

 able to fix upon the most exposed side of the proposed forest plantation. Fix, then, upon 

 the windward side of the space which is to be converted into a forest, mark off a hori- 

 zontal stripe or belt, at least a hundred yards in breadth. Let this portion of ground 

 be planted thick, say at the distance of thirty inches, or at the most three feet, with a 

 mixture of larch, sycamore, and elder, in equal quantities or nearly so, if the soil be 

 adapted for rearing these ; but if it be better adapted for Scots pines, then let it be planted 

 with them at the distances prescribed for the above mixture. We have no other kinds 

 that will thrive better, or rise more quickly in bleak situations, than those just mentioned. 

 When the trees in this belt or zone have risen to the height of two feet, such hard-wood 

 trees as are intended ultimately to fill the ground sliould be introduced, at the distance of 

 eight or ten feet from each other, as circumstances may admit. At this period, or per- 

 haps a year or two afterwards, according to the bleak or exposed situation of the 

 grounds, let another parallel belt or zone, of nearly equal breadth, be added to the one 

 already so far grown up, and so on, till the whole grounds be covered. It is not easy 

 here to determine on the exact breadth of the subsequent belt or zones ; this matter 

 must be regulated by the degree of exposure of the grounds, by the shelter afforded by 

 the zone previously planted, and by such like circumstances." {Plant. Kal. p. 29.) 



3673. In situations exposed to the sea breeze a similar j^lan may be successfully fol- 

 lowed, and aided in effect, by beginning with a wall ; the first zone having reached the 

 height of the wall, plant a second, a third, and fourth, and so on till you cover the whole 

 tract to be wooded. In this way the plantations on the east coast of Mid Lothian, 

 round Gosford-house, were reared; in Sang's manner, the mountains of Blair and 

 Dunkeld were clothed ; and examples, we are informed, might be drawn from the 

 Orkney and Shetland islands. 



3674. The practice of mixing trees with a view of drawing as much nourishment from 

 the soil as possible, and giving, as it used to be said, more chances of success, was till 

 very lately generally apprpved of. Marshal advises mixing the ash with the oak, be- 

 cause the latter draws its nourishment chiefly from the subsoil, and the former from the 

 surface. Nicol is an advocate for indiscriminate mixture {Practical Planter, p. 77.), 

 and Pontey says, " both reason and experience will fully warrant the conclusion, that 

 the greatest possible quantity of timber is to be obtained by planting mixtures." {Prof. 

 Planter, p. 119.) "We are clearly of opinion," says Sang, " that the best method is 



