SHADE-BEARING TREES 167 



cleared, the canopy always becomes broken towards the end 

 of a rotation (except where the rotation is very short, as for 

 instance, Larch grown for pit timber), and thus necessitating 

 underplanting if the land is to be kept clean. The degree to 

 which the partial clearance should take place will vary greatly. 

 If it is desired that no trees forming the overwood should be 

 removed until the undercrop is grown into strong stout poles, 

 it must of course be much heavier than if several successive 

 partial clearances are made whilst the undercrop is growing. 

 Provided the underplanting is done thick enough, this latter 

 method is far preferable, since the removal of older trees from 

 amongst a young crop which is thick in the ground, does not 

 do an enormous amount of damage, if the older trees are well 

 grown, and have not unduly large crowns. 



When pure crops of thinly foliaged trees are thus under- 

 planted, a two-storied high forest is the result. 



If the undercrop be subsequently coppiced, it would bring 

 about the system of high forest with coppice ; though this 

 system is best brought about, except in the case of Oak on 

 stiff soils, by arranging a proper mixture at the time of 

 planting, and subsequently, say at 16 or 20 years of age, 

 coppicing those trees planted for that purpose. 



Scots and Corsican Pine can be underplanted, but usually 

 the growth of these pines should be confined to the poor dry 

 soils, where underplanting would be a failure, and where a 

 fairly short rotation is indicated. 



The trees used for underplanting must l*e able to bear 

 shade, at any rate whilst they are young and during the pole 

 forest stage. 



Silver Fir, Cupressus macrocarpa^ Beech, Nordmann's 

 Silver Fir, Hornbeam, and Thuya gigantea (plicata) will bear 

 the greatest amount of shade of any timber trees. Sitka 

 Spruce 1 (Picea sitchensis], Sitka Cypress 1 (Cupressus 



1 A great deal more experience is required with these trees 

 in this country before they can be recommended largely for underplanting. 

 Cupressus macrocarpa seems peculiarly suitable, as it will then escape its 

 greatest enemy cold, dry, east winds ; intense frost will kill the tree. It 

 will bear a very great amount of shade. 



