524 The Philippine Jowrnal of Science im 



the miscellaneous species existing in the forest of northern La- 

 guna, the figures for growth in diameter of tanguile, which were 

 found to be about the average for the dipterocarps, were applied 

 to the volume table for the miscellaneous species in calculating 

 the growth of these species in the stand. These figures are 

 probably erroneous for the higher diameter classes of the mis- 

 cellaneous species, in as much as tanguile probably grows more 

 rapidly than the large classes of these species. However, the 

 majority of the miscellaneous species do not get into the larger 

 diameter classes. 



By reference to Table XLI we see that the greatest amount 

 of growth is taking place in the diameter classes of 40 and 50 

 centimeters. This is due, in part, to the fact that trees of these 

 sizes are growing at a rapid rate, but more largely to the fact 

 that these trees constitute the bulk of the forest. The total 

 amount of growth per hectare per year in this forest is 3.9 cubic 

 meters. Since the bulk of the growth occurs in the lower 

 diameter classes, if all the timber over 60 centimeters in diameter 

 were removed from the forest, it would reduce the growth per 

 hectare per year less than 0.7 cubic meter, and if the rate of 

 growth of the smaller trees did not increase this forest would 

 still be producing over 3.2 cubic meters per hectare per year. 

 The reduction in rate of growth in volume per year would prob- 

 ably be insignificant, as the trees which were left on the ground 

 would probably respond to the removal of the larger trees of 

 the forest by increased rates of growth. Of the total annual 

 production of 3.9 cubic meters per hectare, 0.7 cubic meter is 

 produced by miscellaneous species other than dipterocarps. The 

 balance, or 3.2 cubic meters, is produced by the dipterocarps 

 alone. 



The total growth of 3,9 cubic meters is the annual growth on 

 a capital of 203.9 cubic meters, and is therefore a growth of 

 1.91 per cent. Assuming that the percentage of growth as shown 

 by this forest is approximately normal for equal volumes of 

 timber throughout the Philippine Islands, we are in a position 

 to make an approximation of the total production of timber in 

 the forests. Whitford estimates the total stand of timber of 

 the Philippine Islands as 822,584,000 cubic meters. By applying 

 our percentage growth of 1.91, we can estimate that the total 

 annual production of timber in the Philippine Islands amounts 

 to 15,711,000 cubic meters. 



Statistics from the Bureau of Internal Revenue place the total 

 amount of timber cut in the Philippine Islands per year at 277,171 



