BRITISH FOREST TREES 159 



variety of humus or mould, which modifies and improves 

 all classes of soil with respect to their physical properties. 

 Though it extracts a considerable amount of mineral 

 nourishment from the soil, it replaces this again by the 

 humus formed from the fallen leaves, for most of the 

 mineral matter is left in the foliage during the natural 

 process of assimilation. It is therefore by no means an 

 exhausting forest crop ; it is on the contrary, on good soils 

 certainly an improving one. 



Requirements as to Light. Among the broad-leaved 

 trees no species equals the beech in density of foliage, or 

 in its capability of bearing shade ; but the extent to which 

 it is endowed with this capacity varies within considerable 

 limits, being dependent both on the degree of shade to 

 which it is subjected, and on how far soil and situation 

 favour its growth in general. Under certain circumstances 

 it thrives normally even after having been kept in shade for 

 twenty to thirty years, whilst under other less favourable 

 circumstances an insufficient supply of light for only a few 

 years shows its evil effects throughout the whole remaining 

 life-period of the crop. 



'Under normal circumstances beech seedlings do well 

 after remaining under the shade and shelter of their parent 

 trees and protectors against frost for about ten to fifteen 

 years, towards the end of which period a gradual clearance 

 of the standards takes place. The shade of lightly foliaged 

 trees, like the oak, ash, larch, or Scots pine, can be borne 

 by it without injury for a longer time ; localities on which 

 such moderate shade seems injurious to the thicket of seed- 

 lings, can in reality form no suitable situation for the beechl 

 Attainment of Maturity and Reproductive Capacity. 

 The beech begins to bear seed or mast, beech-nuts, in fair 

 quantities sufficient for reproductive purposes, in forests of 

 about sixty to seventy years of age, after the activity of 



