328 The Philippine Journal of Science 
is shown graphically in fig. 2. The dipterocarps, like Podocarpus 
imbricatus, are dominant trees. It will be seen at once that 
five of the different species of dipterocarps show rates of growth 
which are very much more rapid than that of Podocarpus 
imbricatus. The sixth, Dipterocarpus grandiflorus, also shows 
a faster rate of growth than Podocarpus imbricatus. Fig. 2 
would seem to indicate that the rate of growth of the average 
dipterocarp is about 2.5 times as rapid as that of Podocarpus 
imbricatus at the top of Mount Banahao, which is not surprising 
Years necessary for growth from a diameter of 5 centimeters to larger diameters. 
. 60 120 180 240 300 360 
m4 
50 
Diameter in centimeters. 
138 
20 
ye iy 
Fia. 2. Rates of growth of Podocarpus imbricatus on Mount Banahao and of dipterocarp 
species in other parts of the Philippines. 
in view of the fact that Podocarpus is subjected to conditions of 
temperature and light that are very unfavorable as compared 
with those under which the dipterocarp species are found. 
CONCLUSIONS 
Podocarpus imbricatus at the top of Mount Banahao shows 
a very slow rate of growth, a tree 60 centimeters in diameter 
being about 500 years old. The rate of growth of Podocarpus 
is very much slower than that of dominant trees at lower eleva- 
tions in the Philippines and of pines in the United States. _ 
