IX, A. 5 



Broion and Mathews: Dvpterocarp Forests 



433 



250 and 800 meters a decided dipterocarp type with patches 

 where dipterocarps, especially Shorea polysperma (tanguile) and 

 Dipterocarpus grandiflorus (apitong), occur in almost pure 

 stands. However, the average stand covering fairly large areas 

 does not show the predominance of dipterocarps common on 

 areas of equal extent in Negros. Table V, computed from val- 

 uation measurements taken on 18.12 hectares, in one solid block, 

 at elevations varying from 400 to 500 meters on the slopes of 

 Mount Mariveles, Bataan, shows the volume and species com- 

 position of a typical stand (Plate VI, fig. 2). 



Table V shows that in the Bataan forest the great bulk of 

 the timber is between 50 centimeters and 100 centimeters in 

 diameter, indicating that the trees do not attain the large 

 diameters in this forest which are so commonly encountered in 

 the forest of Negros. The fact that the forest of Bataan does 

 not produce a uniform stand of exceptionally large-sized, over- 

 mature trees and that the main canopy is not so exclusively 

 dipterocarp are the two main points of difference between this 

 forest and that of Negros. The reason is, of course, that the 

 site as a whole is not as favorable for the growth and develop- 

 ment of dipterocarps as is the low, rolling, well-watered and 

 well-drained plain of northern Negros. This less desirable site 

 has resulted in giving an opportunity for other species, which 

 are not the equal of the dipterocarps on the best sites, to develop, 

 come to maturity, and reproduce themselves. The rough topog- 

 raphy has resulted in a very uneven development of the stand 

 in different situations, there being some exceptional patches 

 which compare favorably with the average for northern Negros 



Table V. — Stand in 1 hectare based upon 18.12 hectares computed from 



valuation surveys in Bataan forest, showing number and volume of 



trees, 



[Volumes are given in cubic meters.] 



Species. 



Dipterocarpus grandiflorus (apitong) 

 Dipterocarpus vernicifluus (panao) . - . 



Anisoptera thurifera (paloeapis) 



Shorea polysperma (tanguile) 



Hopea acuminata (dalindingan) 



Pentacme contorta (white lauan) 



Shorea guiso (guijo) j __. 



All other species .., 



Total - 



Total dipterocarps 



Diameter class in centimeters. 



30. 



40. 



60. 



Trees. 



Vol- 

 ume. 



Trees. 



Vol- 

 ume. 



Trees. 



Vol- 

 iime. 



1.76 



1.05 



1.87 



2.44 



1.60 



3.44 



3.75 



2.25 



2.53 



3.22 



1.93 



4.15 



1.32 



0.86 



1.59 



1.19 



1.04 



1.35 



2.42 



1.65 



2.15 



2.68 



1.71 



3.45 



0.98^ 



0.16 



0.55 



0.60 



0.38 



0.78 



1.76 



1.32 



1.65 



2.22 



1.43 



3.20 



1.32 



0.87 



0.77 



0.99 



0.38 



0.78 



13.96 



6.16 



8.88 



8.91 



5.40 



10.44 



27.27 



14.32 



19.99 



22.25 



13.87 



27.59 



13.31 



8.16 



11.11 



13.34 



8.47 



17.15 



