56 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



of age, 700 to 750 of the best of the stems remained standing; 

 then, ten years later, some 200 to 250 of these might be taken 

 out. Most of these would, it is true, be the worst stems then 

 found in the crop ; but in consequence of the previous thinning, 

 which left but few inferior trees, they would bring in a good 

 revenue. And so for subsequent thinnings. 



Up to the age of about forty years, as a rule, little need be 

 done in a Scots fir plantation but to remove stems which, having 

 been crowded out by their more vigorous neighbours, or from 

 other causes, are either dead or dying. At about that age the 

 thinnings will become somewhat heavier, in order to permit the 

 trees, which have hitherto been encouraged to grow tall, straight, 

 and cylindrical, to develop their girth ; and by timely repetition 

 of such moderate thinnings the final stock will attain the desired 

 condition. If, however, the crop of Scots fir is to be under- 

 stocked, this should be done at that stage in its development 

 (usually between the thirtieth and the fortieth years of age), when 

 the shade given by the canopy of crowns begins naturally to 

 lessen, and thus permits the reappearance of grass in place of the 

 moss which formed the chief soil-covering during the previous 

 period of denser shade. At this time a special thinning must be 

 made, sufficient to enable a young under-crop of shade-bearing 

 species to be successfully introduced by planting, or by sowing in 

 patches; and thereafter, during the progress of thinnings, the light- 

 requirements of this crop must receive due consideration. The 

 under-crop keeps the soil well shaded after the period at which 

 the Scots fir begins to fail in this respect ; and it thus promotes 

 the further development of the remaining trees of the principal 

 species, while it also adds considerably to the value of the final 

 crop. When the time for felling the Scots fir ai rives, the under- 

 crop, which will then be from forty to fifty years old, may either 

 be cut with it and sold as pit-wood, or be allowed to grow on to 

 larger size, as may then seem best. 



The same principle should guide the thinning of young larch 

 woods, the shade given by which usually begins to lessen about 

 ten years earlier than that by Scots fir, and sooner or later 

 becomes so much reduced that, through impoverishment of the 

 soil, the trees composing the crop may begin to fall off in their 

 growth, and may fail to attain the required dimensions. For 

 this reason it is, generally speaking, desirable, in the case of a 

 pure larch crop, to introduce an under-crop of shade-bearers 

 between the twentieth and the thirtieth year. But in view 



