240 SYLVICULTURE IN THE TROPICS 



the crown lengthens upwards, the sunlit portion of the 

 crown being only capable of assimilating food for the 

 branches down to a certain depth ; the branches not so 

 nourished die down and drop off before they have 

 attained sufficient dimensions to form any material knots 

 in the timber. If, on the other hand, direct light is let 

 in on these lower branches, they are capable of feeding 

 themselves, and they grow and thicken to the detriment 

 of the quality of the timber. 



If the object be to obtain a large crown and to get 

 a material thickening of the bole as quickly as possible, 

 the length of the bole not being of any great importance, 

 then the crowns should be given as much room as they 

 require for a full development. Such might be the case, 

 e.g., in a rubber plantation. 



If a young crop has been planted it will usually 

 require thinnings later and not so heavy as a crop 

 derived either by sowing or by natural regeneration, in 

 which the young trees will come up in places much 

 thicker than those which have been planted. In the 

 latter, however, the thinnings will probably be more 

 uniform. In the same way crops on good soils can be 

 dealt with with a heavier hand than those on poor soils, 

 and those in dark or sheltered localities than those in 

 exposed or well-lit situations, and shade-avoiding species 

 than trees which are shade-enduring. There are also 

 certain species, such as many of the Meliaceae, which, 

 although they are shade-avoiding during the greater 

 part of their existence, require shelter during early life. 

 These can be dealt with lightly at first, and with more 

 vio-our later on. In fact, the execution of thinnings 

 requires such a thorough appreciation of a large number 

 of factors, especially in a mixed forest, that it should 

 never be entrusted to ignorant subordinates, but 

 only to fully competent foresters. It should always 

 be borne in mind that although it may only take a 

 certain number of minutes to cut a tree down, it 

 will take as many years, or more, to grow another 

 to replace it. 



