228 



The Philippine Journal of Science 



One of the most striking peculiarities about these tables is 

 the similarity in the amount of moisture in any given soil at 

 different depths. This is apparently due to the fact that the 

 dense covering of the vegetation prevents the surface soil from 

 drying out at a much more rapid rate than the deeper layers. 



The average percentage by months of the moisture in the soil 

 at a depth of 20 centimeters, at elevations of 90, 350, and 725 

 meters, is shown graphically in fig. 1. 



Fig. 1. Average percentage, by months, of moisture in the soil at a depth of 20 centi- 

 meters at different elevations on Mount Maquiling. 



The lowest moisture content is shown by the grassland at the 

 base of Mount Maquiling (Table III). Here, however, the 

 growth of trees is much more rapid than at any of the higher 

 elevations. This is very probably not due at all to soil con- 

 ditions, but to the greater illumination of the individual trees 

 and the rapid rate of growth characteristic of the second-growth 

 species. 



At a depth of 10 centimeters the greatest variation of water 

 content is from 41.3 per cent on November 21 to 24.1 per cent 

 on April 11. The soil samples taken in different places in a 

 very limited area on the same day would, of course, show varia- 



