512 



The Philippine Journal of Science 



19U 



Table XXXVIII. — Annual diameter growth of trees of Class I. Miscel- 

 laneous species. Trail trees. Bataun Province, Luzon. 



[Diameter and growth 



are given in centimeters.] 







Species. 



Diameter class in centimeters. 



20 to 30. 



30 to 40. 



50 to 60. 



70 to 80. 



Diam- 

 eter. 



Growth. 



Diam- 

 eter. 



Growth. 



Diam- 

 eter. 



Growth. 



Diam- 

 eter. 



Growth. 



Koordersiodendron pinna- 

 tum (amuguis) 



26.7 

 29.2 



0.480 

 0.285 



32.1 

 34.0 



2.610 

 0.689 



53.1 

 57.9 



0.257 

 1.641 







Dracontomelum dao (dao) - 

 Total - 



76.1 



0.732 





0.765 

 0.382 

 i. 1 





3.199 

 1. ."iflg 





1.898 

 0.949 



- 0.7S2 



0.732 



13.6 







Years in class 



2 



6.3 



1 



10-5 





















From the above data it is seen that as long as we maintain 

 the dipterocarp canopy undisturbed the dipterocarps remain the 

 fastest growing trees in the forest. By their existence in the 

 dominant situations they hold down the miscellaneous species 

 growing under them to such an extent that these species cannot 

 enter into serious competition with them. However, a disturb- 

 ance in the main canopy is accompanied, in every instance, by in- 

 creased rates of growth of these species. They are generally 

 more numerous than the smaller-sized dipterocarps, and when 

 the opening in the canopy is large this fact enables such numbers 

 of them to obtain dominant situations that they place many 

 of the young dipterocarps at a great disadvantage. 



Unregulated logging in dipterocarp forests will always result 

 in a gradual change in composition and volume such as that 

 described above. The need of great care in the regulation of any 

 cutting in this forest is very apparent. Success over any large 

 area cannot be expected from a mere rule of thumb, such as a 

 diameter-limit regulation, for this will only accidentally so reg- 

 ulate the cutting in certain places that openings in the canopy 

 will be made which dipterocarps are able to fill, and in a majority 

 of cases will result in so favoring one or many of the minor 

 species that dipterocarps will be placed at a great disadvantage 

 or partially eliminated from the area. 



We have yet to consider what can be expected of the diptero- 

 carp forest at points near its upper limits. At elevations 

 above 600 meters in most parts of the Islands the climate 

 approaches that of the nonseasonal belt at lower elevations in 

 everything except temperature. The rainfall is noticeably in- 



