IX, A, 6 Brown and Mathews: Dipterocarp Forests 547 



application of the system should vary in accordance with the 

 data thus collected. 



As has been pointed out the conditions which exist in the 

 dipterocarp forest of Bataan Peninsula differ from those of 

 the northern Negros forest in that the stand is less heavy, the 

 volume distribution by size classes more satisfactory, and the 

 composition of the forest more complex. Furthermore, the to- 

 pography, consisting of a series of radiating steep ridges sep- 

 arated by rather narrow valleys, is a great disadvantage from 

 the logging standpoint. Clear cutting in strips on this area 

 might be successful in certain patches of the forest where excep- 

 tional overmaturity exists, but in the main the logging difficul- 

 ties which will arise in the application of such a system make 

 it inadvisable. On the other hand, the more uniform distribu- 

 tion of volume through the different size classes, the presence 

 of adequate reproduction on the ground in virgin stands, and 

 the presence of distinct second and third stories make the pos- 

 sibility of some modification of the shelter-wood system worth 

 considering. In applying the shelter- wood system to mature and 

 overmature stands, an attempt is made to remove the bulk of 

 the mature and overmature timber within a restricted period 

 and to replace it with a new, more or less even-aged stand which 

 develops uniformly over the logged area under the shelter of a 

 portion of the stand which is left on the ground. This system, 

 when practiced in temperate zones, aims to remove all of the 

 mature and overmature timber, leaving on the ground only the 

 most thrifty and rapid-growing trees. To meet the problems 

 of utilization, this system will have to be modified for use here. 

 The most overmature timber in our forest is often so defective 

 that it can only be logged out at an actual loss, and the timber 

 which composes the bulk of the second and third stories is not 

 marketable. The timber that it is possible to log at a profit 

 is exactly the portion of the stand which from the forester's 

 standpoint would be most desirable to retain on the ground. In 

 the practice of this system here, the forester is compelled to 

 resort to the expedient of removing the best timber in his forest 

 and of leaving on the ground for his shelter wood his second 

 and third stories, with such overmature specimens of his main 

 species as are too defective to prove of value commercially. 

 These last may be used as seed trees. Were it not for the very 

 satisfactory stand of dipterocarp seedlings existing in the ground 

 cover, the system would hold out but little promise of success, 

 as the seeds distributed from the overmature trees which it is 

 possible to leave would probably not be sufficient to insure the 



