IX. A, 5 Brown and Mathews : Dipterocarp Forests 475 



lack of light. At the base of Mount Maquiling on the north- 

 eastern side is a very small pure stand of Parashorea, in which 

 none of the trees is more than 14 centimeters in diameter. 

 This stand is at the edge of the forest near a large seed tree, 

 and probably became established under a canopy which has since 

 disappeared. The straggling individuals near the edge of the 

 stand are in an exposed situation; they are smaller than those 

 in the main stand, and show a slower rate of growth. While 

 thus too great an exposure appears to be injurious to young 

 plants of Parashorea, they show a much faster rate of growth in 

 the open than in the forest, as is shown by a comparison of Table 

 XVI with Table XVII, in which are given the rates of growth 

 of trees in this stand in the open for the period from January 

 13, 1913, to January 13, 1914. The upper curve in fig. 1 is 

 plotted to represent the age of different diameter classes of 

 Parashorea, the age of classes below 20 centimeters being based 

 on the rate of growth of the trees in the open, while the time 

 required for trees to pass through the larger classes is taken 

 from the table for Parashorea in the virgin forest. Assuming 

 that this curve would represent approximately the age of differ- 

 ent diameter classes of Parashorea, if grown in the open, we 

 find that it takes in the open less than half the time to reach 

 any diameter up to 65 centimeters that it does in the forest. 

 The greatest difference is, naturally, in the smaller classes, 

 which in the forest are most heavily shaded. Thus, a tree 20 

 centimeters in diameter is 23 years old if grown in the open and 

 106 years old if grown in the virgin forest. 



The curve for Parashorea grown in the open shows a much 

 more rapid rate of growth than do any of the temperate zone 

 species which we have considered. The most rapid growing 

 of the latter is yellow poplar, which is 183 years old when it 

 reaches a diameter of 70 centimeters, while Parashorea, grown 

 in the open, attains the same size in ninety years. These facts 

 indicate that if foresters in the tropics were able to follow the 

 German practice and plant solid dipterocarp forests of rapid- 

 growing species, such as Parashorea pUcata, they would easily 

 surpass the results obtained in managed forests in the temperate 

 zone. As will be shown later, however, environmental consider- 

 ations make the planting of dipterocarps on any large scale an 

 impracticable proposition, and foresters in the Philippines must, 

 for the present at least, deal with species as they occur in virgin 

 or partially cut-over forests. They will, therefore, have to 

 accept as inevitable a long suppression period in all of their 

 dipterocarp species, and cannot hope that the rate of growth 



