BRITISH FOREST TREES 201 



of the last crop has been made close to the ground, the growth 

 of the shoots is usually so vigorous that close canopy is attained 

 in three to four years, and growth in height is continued 

 thereafter with energy, culminating in the tenth to twelfth 

 year, when the shoots attain the size of small poles. At that 

 age there has of course been a considerable diminution in the 

 number of shoots originally sent out from the stools. The 

 better the situation, the more rapid and the more vigorous is 

 the development of the predominating class of shoots, pro- 

 ducing not only a larger quantity of bark, but also bark that 

 is thicker and finer in quality. Pure oak coppice on the more 

 favourable sites yields about 35 cwt. of bark as well as 

 about 850 to 900 cubic feet of wood per acre, when worked 



with a rotation of sixteen years. . . 



Mixed Forests with Oak as the ruling Species are only to 

 be found to a limited extent on deep fresh soils of the better 

 class, as far as other light-loving species like elm, ash, maple, 

 and sycamore are concerned. In low-lying tracts with deep 

 moist soil, where insolation would not necessarily lead to 

 excessive diminution of the soil-moisture, and where also all 

 these light-loving species are more densely foliaged, and at 

 the same time more capable of bearing shade from above or 

 from the side, forests are often formed with oak as the 

 matrix, and these other valuable woods of our forests as the 

 subordinate species, introduced however as individuals only, 

 and not in groups or patches. As the oak is the principal 

 .species to be favoured at all times, these subordinates arc 

 removed in the course of thinnings whenever, and wherever, 

 they make themselves troublesome or self-assertive ; but in 

 any case they are cut out when about thirty to forty years of 

 age, by which time they may have attained good marketable 

 proportions, whilst the oak also needs somewhat enlarged 

 growing-space for its further normal development; occa- 

 sionally, however, good stems are retained longer for the 



