SHADE-BEARING TREES 95 



a canopy is formed, without interruption ; and, by the time 

 natural pruning begins, these branches are already big and 

 formidable. 



(4) The Shade-bearing or Light-demanding 

 Qualities of Trees. 



It is very necessary to pay great regard to this matter. 

 If a mixture be planted, it is imperative that, if the 

 species chosen have not the same height growth, the species 

 that grow the slowest are capable of withstanding the shade 

 of the quicker growing species. So also, when underplanting 

 is adopted, only the shade-bearing trees can be used. Any 

 disregard for this question must result in absolute failure. 

 Care must also be taken when underplanting, that the under- 

 crop does not catch up the over-crop before it is desired to 

 fell the latter. 



The most light-demanding trees are : Larch, Birch, Scots 

 Pine, Oak, Acacia (Robinia), Corsican Pine, Poplars, Willows, 

 and Elm ; also, Ash and Spanish Chestnut when mature, 

 though these latter too, and especially Spanish Chestnut, will 

 bear considerable shade when young, or when grown as 

 coppice. 1 



The trees that will bear the greatest amount of shade 2 

 are : Silver Fir, Cupressus macrocarpa, Beech, Nordmann's 

 Silver Fir, Hornbeam, Thuya gigantea ; and, next in order, 

 come Sitka Spruce, Sitka Cypress, Douglas Fir, Weymouth 

 Pine, Spanish Chestnut (when young), Hazel, and Lime. 



The Norway Spruce will only bear shade when the con- 

 ditions for its growth are quite favourable ; otherwise it is 

 quite intolerant of shade. 



The shade-enduring trees are all thickly foliaged, and 

 their canopy is complete, and no soil deterioration should 

 take place under them ; but the light-demanding trees are 

 thinly foliaged, and, as maturity approaches, their canopy 

 becomes broken, and the humus disappears and the soil 

 becomes covered with a rank growth. The fall of leaves 



1 As to the suitability of trees for coppice, vide Chapter X. 



2 Vide also Chapter VIII. 



