22,3 Reyes: Woods of the Philippine Dipterocarps 293 



species of lauaans. But in the inventory and development of 

 the natural resources of the Islands, finer distinctions must be 

 drawn. Woods which superficially seem alike may prove to 

 differ widely in their physical properties, when more thoroughly 

 studied. Closer utilization entails an accurate knowledge of 

 the anatomical features and physical properties of the wood 

 of the various forms. The following studies, based on gross 

 and minute anatomy, aim to distinguish the commercial species. 

 This has never been attempted previously, and the present work 

 is in the nature of a preliminary survey. 



In approaching the subject it has seemed desirable first to 

 discuss the wood of a typical dipterocarp at some length, since 

 this would not only acquaint the reader with the general features 

 of the timbers of this family, but at the same time would offer 

 a logical starting point for the remainder of the study. For the 

 purpose in view, it was thought that Parashorea maUmnonan 

 (Blanco) Merrill 7 (Parashorea plicata Brandis) would best 

 serve, owing to its wide distribution and abundance throughout 

 the Islands and the fact that its wood seems to incorporate best 



7 Bagtikan (Parashorea malaanonan Merrill) (Plates 1, 2, 6, 7, 8, 22) 

 is one of the largest of the dipterocarps and is found on all the large 

 islands of the Archipelago from northern Luzon to Mindanao. In virgin 

 forest it is not uncommon to find trees 40 to 50 meters in height with a 

 diameter at breast height of 2 meters. As is characteristic for the trees 

 of this family, the bole is tall and often unbranched for 20 or 30 meters 

 and bears the crown far aloft. Under forest conditions the latter becomes 



Parashorea malaanonan is one of the faster-growing dipterocarps 



as is often the case in such trees, avoids habitats like the western part 

 of Luzon, where there is a pronounced dry season. It undergoes suppres- 

 sion well, but the growth is then much restricted. According to Brown 

 and Matthews, Philip. Journ. Sci. § A 9 (1914) 475, those trees which 

 grow in dense forests undergo a long suppression period in contrast to 

 those which are exposed, and require fully twice the time to reach any 

 diameter up to 65 centimeters. Trees 20 centimeters in diameter average 

 twenty-three years of age when grown in the open, while forest-grown 

 specimens of like diameter average approximately one hundred six years. 



Further researches have also shown that bagtikan exhibits periodical 

 fluctuations of growth intensity. There are two distinct periods of slow 

 and two of rapid growth. The first period of inhibited growth occurs 

 during the height of the dry season when transpiration is at a maximum, 

 the second during the mid-rainy season when the sky is overcast during 

 a large portion of the day. -The fir Z./'SSJ lit 



earlier part of the rainy season and is 

 close of the rainy season when insolation i 



