484 



The Philippine Journal of Science 



1914 



those indicated by the curves, but for the practical management 

 of existing forests this treatment has been justified (see page 

 476). 



Shorea polysperma, which in northern Laguna is considerably 

 slower growing than Shorea teysmanniana in the same area, 

 is the fastest-growing species measured on type area B, Bataan. 

 However, it shows a slower rate of growth on type area B than 

 in northern Laguna. Thus, in one hundred twenty-seven years 

 it grows from 5 to 50 centimeters in northern Laguna, while it 







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Fic. 3. Rates of growth of dipterocarps. Type area B, Bataan Province, Luzon. 



requires one hundred fifty years to make the same growth on type 

 area B, Referring to fig. 6, in which are presented the average 

 curves of growth for the dipterocarps of each area, it will be 

 seen that the curve for type area B lies below that of northern 

 Laguna. This would seem to strengthen our conclusion that 

 dipterocarps as a class grow slower as the density of stand 

 increases. It does not follow from this that the volume of timber 

 produced per year in the denser stands will be less than that 

 in open stands, as the greater number of individuals in the 

 denser stands may more than make up for the slower rate 

 of growth of the individual trees. 



