224 The Philippine Journal of Science 1917 



forest, as quick-growing trees readily invade the grass areas 

 when there are no fires. The trees have a very rapid rate of 

 growth and are small, usually reaching a height of only 10 

 meters or less. 



Our soil samples from this altitude were taken in a grass 

 area at an elevation of approximately 100 meters. 



DIPTEROCARP FOREST 



At altitudes between 200 and 600 meters the ground is covered 

 by a tall, dense dipterocarp forest. This is composed of three 

 distinct stories of trees, the tallest of which reaches a height 

 of from 35 to 40 meters (Plate I, fig. 2). The most prominent 

 tree in it is Parashorea plicata, which is frequently more than a 

 meter in diameter. The second, or middle story, is composed of 

 medium-sized trees, which spread their leaves under the branches 

 of those of the top story. The second story reaches a height 

 of about 18 or 20 meters. The most prominent species is 

 Diplodiscus paniculatus (balobo), which is represented by many 

 more trees than any other species in the forest and is probably 

 about four times as numerous as any other second-story species. 

 The third story is composed of small trees that reach a height 

 of about 10 meters. 



The presence of the different stories is not evident on casual 

 observation, as the specific composition of the stories is very 

 complex and few of the trees present any striking peculiarities, 

 while smaller trees of a higher story always occur in a lower 

 story and between the different stories. In addition to the above 

 stories of trees there is a ground cover composed largely of seed- 

 lings of tree species and climbing palms (rattans), but also con- 

 taining numerous herbs and shrubs. 



The foliage is so dense that when one walks through the forest 

 most of the large trees are completely hidden from view. Plate 

 II, fig. 1, shows an area from which the undergrowth and small 

 trees have been removed. It will be seen that large trees are 

 much more numerous than would be suspected from an examina- 

 tion of Plate I, fig. 2, which shows a virgin area where there are 

 probably as many trees as in the area shown in Plate II, fig. 1. 



For a fuller discussion of this forest, see an article by Brown 

 and Matthews. 8 



The soil samples in the dipterocarp forest were obtained near 

 the top of a ridge at an altitude of about 300 meters. 



$ Op. cit. 



