The Forests of the Philippines. 585 



As its name implies, the principal species represented in this 

 type are tanguile (Shorea polysperma) and oak; of these, the 

 former also occurs frequently in dipterocarp types of the lower 

 altitudes. It is found nearer sea level in regions where the dry 

 season is short than in those where the dry season is longer, but 

 in both its numbers increase with the altitude until the mossy-for- 

 est type is reached. In the higher portions of the tanguile-oak 

 type, it is the only dipterocarp of numerical importance. In the 

 lower limits of the type occur, of course, scattered specimens of 

 the dipterocarps of the bordering types below. This is especially 

 true of the lauans and the apitongs, although the latter are not 

 nearly so abundant as the former. Some species that usually are 

 found along streams in the types of lower altitudes occur in 

 deeper soils of the tanguile-oak away from the streams. Certain 

 species of oak, which occur as scattered trees in the lower types, 

 here become more abundant, and in some places give a decided 

 tone to the vegetation. Many of the species occurring in this type 

 also occur much dwarfed in the mossy forests higher up. Indeed, 

 the type is the meeting ground of a number of the species which 

 are found in the types both above and below. So far as is known, 

 there are no species of trees that reach large size that are peculiar 

 to this zone, with the exception, perhaps, of certain species of 

 oaks. A number of species, however, reach more successful de- 

 velopment, both as regards numbers and size, than in the other 

 types in which they are found. Open places occur in this as in 

 other types, giving rise to many subtypes. The undergrowth trees 

 are numerous, but the composition is not so complex as the types 

 below. The closed portions of the type are comparatively free 

 from large lianas other than rattans, so that the only difficulty in 

 penetrating the forest in any direction is encountered in the 

 tangled growth of the open places. 



In the high plateau regions, between 500 and 800 meters (1640 

 to 2624 feet) of altitude, this type attains heavy stands, but usual- 

 ly the topography is so rough that tall forests, covering large areas 

 without a break, are wanting. Large epiphytic plants, like birds'- 

 nest ferns, are more abundant here than lower down. In the up- 

 per limits, the trees gradually become more dwarfed, and the 

 trunks are covered with mosses and liverworts, until the type 

 gradually merges into the mossy forests above. 



