IX. A, 5 Brown and Mathews: Dipterocarp Forests 477 



conception and plotting the curve of growth for Parashorea with 

 that portion of the curve below 5 centimeters omitted, we see 

 that the species does not compare unfavorably with those of the 

 temperate zone for virgin forest. Referring to fig. 8, page 496, 

 in which curves of this character are presented, we find that 

 the curve for bagtican-lauan lies below that of white oak only 

 up to the 32d year and below that of the yellow poplar up to 

 the 63d year. Above these points the curve rises rapidly until 

 the trees attain diameters of 80 centimeters in the same period 

 of time, one hundred thirty-nine years, as it takes yellow poplar 

 to attain a diameter of 62 centimeters and white oak to attain 

 a diameter of 46 centimeters. 



From the above, it would seem that a forester working with 

 rapidly growing species, such as Parashorea plicata, should ob- 

 tain better results with regard to total volume production per 

 year than could be obtained in temperate zones. It should be 

 remembered, however, that dipterocarp forests contain a great 

 mass of foliage that is not producing commercial wood, with 

 the result that they are not as heavily stocked with dipterocarp 

 species as are hardwood forests of temperate zones with species 

 comparable to dipterocarps. As has been shown above, the 

 forest of Mount Maquiling is not by any means a good dip- 

 terocarp forest, and the species, Parashorea plicata (bagtican- 

 lauan), standing almost alone in the dominant tree class, is 

 growing under much more favorable conditions than it would 

 were it a component of the first story in a heavily stocked dip- 

 terocarp forest. The rates of growth which are shown by 

 Parashorea under the above-mentioned conditions apparently are 

 not duplicated by other species of the family Dipterocarpaceae 

 growing in denser forests. A study of growth in other forests 

 makes this apparent. 



Measurements of growth were made in the forests of northern 

 Laguna at an altitude of approximately 500 meters for the 

 period from April 6, 1913, to April 6, 1914, for the following 

 species: Shorea squamata (mayapis), Shorea teysmanniana 

 (tiaong), Shorea polysperma (tanguile), Hopea pierrei (dalin- 

 dingan-isak) , and Dipterocarpus spp. (apitong and panao) . The 

 results of these measurements are given in Tables XVIII to 

 XXII. From these tables the ages of trees of different diameters 

 were calculated, and the results are plotted in fig. 2. In this 

 figure also appear the same curves for white oak and yellow 

 poplar as were plotted in connection with that for Parashorea 

 plicata on Mount Maquiling. In all of these the growth below 5 

 centimeters was omitted. A comparison of figs. 1 and 2 shows 



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