416 The Philippine Journal of Science isu 



Java, Borneo, and the Philippines ; and probably also to Celebes 

 and New Guinea, as dipterocarps have been reported from these 

 regions. These forests usually occur below elevations of 1,000 

 meters, and generally show the greatest development at low 

 elevations. They generally occupy the regions best suited for 

 tree growth. Dipterocarp forests usually give place to other 

 types in dry regions, but the requirements of different 

 dipterocarp forests as to moisture and temperature vary greatly. 

 In the constantly humid forests of Sarawak, Borneo, dipterocarps 

 are conspicuous, while in Bengal Shorea rohusta occurs in 

 localities where the dry season is so pronounced that fires cause 

 considerable damage to the forests.^ These two regions also 

 illustrate the differences in temperature endured by dipterocarps, 

 the forests of Sarawak having a continuous high temperature, 

 while Shorea rohusta in Palaman and Hagaribagh Districts 

 of Bengal is repeatedly injured by frost. 



DISTRIBUTION IN THE PHILIPPINES 



According to Whitford,* the dipterocarp forests cover 75 

 per cent of the virgin forest area of the Philippines, or 77,700 

 square kilometers (30,000 square miles), and contain approx- 

 imately 95 per cent of the standing timber. These forests 

 occur on almost all types of topography, but usually grow best 

 on well-watered plains or on the gentle lower slopes of the main 

 mountain masses. On such sites the soil is usually a deep 

 loamy clay of volcanic origin, and as we pass from these situa- 

 tions to soils of a drier nature and of calcareous origin the 

 dipterocarp species give way to a more open type usually 

 dominated by such species as Vitex parviflora (molave). Both 

 dipterocarp forests and the individual trees are best developed 

 at comparatively low altitudes, and as higher elevations are 

 reached the trees become smaller and the dipterocarps less 

 numerous. At elevations of 800 meters or less this type gives 

 way to one in which miscellaneous trees — Quercus and other 

 genera — are more prominent. Dipterocarp forests may extend 

 practically to the sea, where situations favorable to them occur, 

 but they do not grow on sandy beaches or muddy fiats. How- 

 ever, the type is not usually found within 3 or 4 kilometers of 



° Mclntire, A. L., Notes on sal in Bengal, Forest Pamphlet, Calcutta 

 (1909), No. 5. 



'Whitford, H. N., The forests of the Philippines, Bull. P. I. Bur. 

 Forestry (1911), No. 10. 



