5/8 Forestry Quarterly. 



ill-formed boles, much smaller in diameter and length. Under- 

 neath the dominant and sub-dominant species are a large number 

 of undergrowth tree species which do not attain more than lo 

 centimeters in diameter when mature, and a height of lo meters 

 or less. From a botanical point of view, these add greatly to the 

 complexity of the forests, but for commercial considerations they 

 should be called undergrowth trees. Within the forests there are 

 comparatively few shrubs, or bushes, and herbs. 



All the types of dipterocarp forests contain climbing palms 

 (rattans), but the number and size of other large vines (lianas) 

 seem to diminish with the prominence of the dipterocarps. Arti- 

 ficial and natural openings in the forests are often covered with 

 a jungle of climbing bamboos and other large lianas, and the edges 

 of the forests, especially along the streams, present breastworks 

 of twisted vines which are very difficult to penetrate ; but as soon 

 as the interior is reached it is easy to pass through the forest with 

 only the occasional use of a bolo (machete). 



Practically all the dipterocarps are evergreens, for the new 

 leaves are formed before the old ones drop. In some of the types 

 discussed below, a few of the dipterocarps and many of the other 

 tree species are partially deciduous, dropping a portion of their 

 leaves during the dry season ; some species, including one diptero- 

 carp, may become entirely defoliated for a period varying from 

 one day to two months. 



These dipterocarp forests show more or less distinct types 

 which are here given the common names of the most numerous 

 species found within them. These, in turn, might be divided into 

 subtypes but, except in limited regions where intensive work has 

 been done, little attempt has been made to distinguish them. 

 The following division of the dipterocarp types is provisional 

 only, but it is believed that the classification will in general hold 

 good, and that future changes will be mainly in the nature of a 

 division into subtypes. 



Lauan type. — To this type is given the name "lauan" because 

 several species producing similar woods having the trade name of 

 lauan predominate. It represents the most successful commercial 

 forests in the Philippines, and is confined to regions with a short 

 or no dry season. It reaches its best development on the more 



