IX, A, 6 Brown and Mathews : Dipterocarp Forests 553 



it has been removed from considerable areas. This is especially 

 the case in regions in which the dry season is pronounced. 



3. Due to the fact that the forest occurs in dense stands of 

 a few species which may be logged at a low cost, it is capable 

 of furnishing large amounts of construction and finishing lumber. 



4. The chief difference between the dipterocarp forest and a 

 hardwood forest of the temperate zone lies in the several-storied 

 arrangement of the dipterocarp forest, with an accompanying 

 greater density of foliage, and in the presence of a much larger 

 number of minor tree species. 



5. Dipterocarp forests vary from dense stands in which the 

 main story is composed entirely of mature and overmature dip- 

 terocarps to more open stands in which the main canopy may 

 contain more individuals of other species than dipterocarps. 



, 6. The volume of a dipterocarp forest may be greater than 

 that of an all-aged managed stand in Europe, but is usually 

 less. When the volume is great its distribution is usually un- 

 satisfactory from a management standpoint, as the bulk of it 

 is contained in large mature and overmature individuals, the 

 removal of which causes the destruction of the forest. 



7. If the dipterocarp forest is removed and the land is not 

 cultivated, the forest is replaced by a noncommercial one of a 

 totally different type in which the trees are small, softwooded, 

 rapidly growing species. If, after the removal of the forest, 

 the land is cultivated and later abandoned, it usually grows up 

 in grass which maintains itself as long as it is burned over at 

 more or less frequent intervals. 



8. Dipterocarps growing in virgin forests in the Philippines 

 undergo an extremely long suppression period. After this sup- 

 pression period Parashorea plicata, the most rapidly growing 

 dipterocarp measured, appears to grow about twice as fast as 

 yellow poplar in virgin stands. The average of the dipterocarps 

 measured shows rates of growth, after the suppression period, 

 about equal to those of hardwoods in virgin forests in the central 

 hardwood region of the United States. Parashorea plicata, on 

 Mount Maquiling, shows distinct seasonal rates of growth, there 

 being two periods of slow and two of rapid growth. One period 

 of slow growth coincides with the dry season, the other with the 

 height of the rainy season when the sky is overcast for a large 

 portion of the time. 



9. The temperature in the dipterocarp forest of Mount Maqui- 

 ling is very uniform and not particularly high. The daily range 

 is much greater in the dominant story than in the undergrowth. 



