CH 



THINNINGS AND PRUNING 243 



principal species has been attained, the crop resolves 

 itself into a storied forest, the upper story of which is 

 pure or nearly so, and composed of the crowns of the 

 principal with some auxiliary species, while the acces- 

 sory species form one or more stories below them. It 

 is evident, however, that, in order to bring the principal 

 species into the upper tiers, the leaf-canopy has to be 

 opened out sufficiently, and that this may lead to the 

 deterioration of the soil unless the operation is most 

 carefully conducted. Although in Europe the isolation 

 of certain selected trees, for the production of large 

 timber, is sometimes begun early, this is not to be 

 recommended as a rule in tropical forests, where the 

 intensity of the sun's rays and the scorching power of 

 the hot winds are much greater, and where not only the 

 isolated trees are liable to deteriorate, but the soil is 

 likely to be invaded by weeds and creepers of all sorts. 



In a crowded wood composed entirely, or nearly so, 

 of coppice-shoots, it may become necessary to make at 

 least one thinning, in order to give the strongest shoots 

 more room. This will not be necessary, however, in 

 coppice worked on a very short rotation, which is only 

 intended to give wood of very small dimensions. But 

 with the coppice-crops intended to give cord-wood, mine- 

 props, etc., it has been found that by cutting out the 

 weaker stool-shoots the remaining stems benefit materi- 

 ally and give a better out-turn at the time of exploitation. 

 In a coppice under standard thinnings are necessary (as 

 well as cleanings) in order to free such seedling growth 

 as is intended to develop into standards. This is all 



I the more necessary because, at the outset, the growth of 

 coppice-shoots is much quicker than that of seedlings. 



In a forest composed of trees of different ages the 

 thinnings will have to vary in character and intensity 

 from place to place, according to the character of the 

 crop. They will be heavy where the trees have attained 

 their full height, and light where they are young ; a 

 mixture will also regulate the heaviness of the thinnings 

 according to its requirements. 



