554 The Philippine Journal of Science lai* 



The humidity and soil moisture under the forest are always high 

 and the rate of evaporation is low. The environment of the 

 dominant story is much dryer than that of the undergrowth. 

 The rate of evaporation, even in the top of the dominant story 

 during the dry season, is not high when compared with evapo- 

 ration rates in deciduous forest regions in the United States. 

 Environmental conditions in the forest are apparently favorable 

 for growth throughout the year. The result is that such a dense 

 vegetation is produced that the rate of growth of the individuals 

 is greatly lowered. 



10. The total growth of whole forests in the Philippines will 

 in many instances be greater than that in a temperate hardwood 

 forest, but the volume production of commercial timber will usu- 

 ally be lower. 



11. Clear cutting over large areas will, in most instances, elim- 

 inate dipterocarp species from any forest. Clear cutting oii 

 small areas will, in many instances, result in a satisfactory stand 

 of dipterocarp reproduction. Selective cutting and culling, if 

 not severe, will merely lower the volume production without 

 seriously changing the species composition, but if continued over 

 long periods will result in the elimination of all dipterocarp 

 species which are cut. A partial cutting followed by a long 

 period of closure seems to be the most satisfactory method of 

 cutting over a dipterocarp forest. 



12. Present experience seems to indicate that planting of 

 dipterocarps will not be successful in open lands and probably 

 only moderately successful in second-growth forests or in open- 

 ings in the high forest. If planting is to be attempted in the 

 Philippines at the present time, species which are easier to handle 

 than dipterocarps and more valuable at maturity should be 

 chosen. 



13. Heavy stands of dipterocarp forest which are largely 

 overmature will have to be managed under some modification of 

 the clear-cutting system. Those which contain distinct second 

 and third stories composed partially of dipterocarps and par- 

 tially of miscellaneous species can be most successfully managed 

 under the shelter-wood system. Those in which there is a sat- 

 isfactory distribution of dipterocarps throughout all size classes 

 can be satisfactorily handled under either the shelter-wood sys- 

 tem or the selection system with a diameter limit. Those which 

 have been very heavily cut over under a diameter limit that 

 was too low should be protected from all cutting until the small 

 dipterocarps in the lower stories become large enough to bear 

 seed. 



