CHAPTER II 



RELATIVE VALUE OF PURE AND MIXED CROPS 



The great advantage which pure crops have over mixed 

 crops is that, especially if they are regular, they are 

 much easier to work and easier to regenerate than those 

 which are mixed. Even where they are irregular, 

 there is not the necessity, which may often arise in 

 mixed woods, of sacrificing a valuable tree for the 

 sake of another of a still more valuable species. 



Nevertheless, generally speaking, mixed crops are 

 preferable to pure ones. The soil varies in composition, 

 depth, and hygroscopicity from point to point, and thus 

 also varies in its suitability to different species. Then, 

 also, in a mixed forest the component species fit into 

 each other more closely, and are able to protect and 

 improve the soil to a greater degree than in a pure 

 crop where all the trees have the same requirements 

 and habit. Especially in the case where the principal 

 species is shade-avoiding, it is necessary to have in 

 mixture some shade-enduring species, which are soil- 

 improving and can fill up the interstices in the leaf- 

 canopy, or exist under the cover of the shade-avoiding 

 trees. No doubt in the early stages of growth the 

 struggle for existence is more complex ; the principal 

 species may be shade-avoiding, and becomes easily 

 dominated and finally suppressed by other less valuable 

 species, and it is necessary to carry out sometimes 

 often-recurring operations in order to keep their crowns 

 free. In the same way regeneration fellings are almost 



no 



