442 The Philippine Journal of Science isu 



from 50 to 100 meters to elevations of 600 meters, where the 

 dipterocarp forest gives way to mountain-top forms. The topog- 

 raphy of this section of the mountain may be described as a 

 series of radiating, broad, well-drained ridges separated by 

 narrow valleys. 



The forest is located in the center of a well-populated district, 

 and has been subjected to a process of selective logging for many 

 years. The trees most valuable for commercial purposes have 

 been almost entirely removed from the forest at all elevations 

 below 400 meters. The dipterocarps which originally made up 

 a large portion of the forest cover were probably Parashorea 

 plicata (bagtican-lauan), Shorea guiso (guijo), Pentacme con- 

 torta (white lauan), and Hopea acuminata (dalindingan or 

 mangachapuy) . Representatives of these species in the seedling 

 and sapling classes are to be found well distributed over the 

 mountain and in the case of guijo and white lauan in sufficient 

 numbers to indicate that there was a considerable stand of these 

 two species on the lower slopes not over seventy-five years ago. 

 Guijo and white lauan are in great demand throughout the sur- 

 rounding communities for the construction of bancas, and da- 

 lindingan, being a close relative of yacal, is everywhere in 

 demand for house construction., Bagtican-lauan, not being 

 especially desirable for either of the above uses, has suffered 

 less than any of the other dipterocarps, and remains as one of 

 the main species in both the main and the understory of the 

 forest. This condition is not the result of a few years' active 

 logging. The change has come about slowly, and a dipterocarp 

 forest such as the situation indicates probably has not existed 

 on the lower slopes of this mountain for as much as from one 

 hundred fifty to two hundred years. 



As is to be expected, the result of this selective logging has 

 been to favor the species which would normally exist in the 

 understory to such an extent that they occupy the dominant 

 situation normally held by the dipterocarps. Species, which 

 due to their persistence remain as inconspicuous elements in a 

 normal undisturbed forest, without ever becoming entirely elim- 

 inated, have increased in numbers, and others, which under the 

 shade of a heavy dipterocarp crown cover rarely reach notice- 

 able size, have developed so as to become prominent components 

 of the main stand. Thus, the present forest, although possibly 

 not any more complex than originally with respect to the ab- 

 solute number of species, is apparently of very mixed character 

 because so many species have come into the main story. 



The most accessible portions of the forest are those extending 



