158 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



the roots are allowed to take up their natural position, fixing 

 the trees more firmly in the soil. 



When forming margins of plantations, it is generally advisable 

 to plant moderately close, as this will provide a better selection 

 for thinning. 



Of whatever species the margins are formed, the thinnings 

 ought to be at all times most carefully performed. The 

 commercial value of the marginal trees should never be 

 considered, as in every case their growth should be encouraged 

 in such a manner as to produce the greatest amount of shelter. 

 Each tree must, therefore, be allowed sufficient space for its full 

 development of side branches and root ramification. 



Thinning in this case must, therefore, commence before the 

 side branches interlace each other, so that these branches may 

 be preserved alive and thus present a full and close barrier 

 to the wind. 



A number of trees have the power of retaining their side 

 branches alive to the ground for a number of years if provided 

 with sufficient growing space. But all trees will ultimately 

 degenerate into open order by losing their lower side branches. 

 It is, therefore, necessary that the trees forming the extreme 

 margin should not only have the peculiarity of growing bushy 

 and retaining their side branches very low, but should consist 

 of a kind which, on being pruned or cut back, will shoot afresh 

 from the root or cut surface. 



Whenever the species forming the outer margins develop into 

 tall, scraggy trees, or show signs of decay by losing their foliage, 

 they should be immediately cut back, part only being cut at a 

 time. Young growths will then shoot out anew, and fresh green 

 branches will be formed. 



When this cut part has become sufficiently developed to 

 protect the interior, other parts, if necessary, may be treated 

 in the same manner. Such a margin should consist of three 

 descriptions of trees. 



For the principal or inside row perhaps no other trees are 

 so well adapted as the common beech or the sycamore. The 

 oak may often be found a good substitute for the beech on 

 account of its deep-rooting qualities; other trees will thrive 

 better underneath its shade. 



The front or outside rows may then consist of several or all 

 of the following species intermixed together : — beech, hornbeam 



