IX, A, 6 Brown and Mathews: Dipterocar'p Forests 537 



significance of this astonishing reduction both in the total number 

 of seedlings and in the number of seedlings of dipterocarps is 

 very clear. The destruction of a portion of these seedlings was 

 probably due to mechanical injuries incident to the logging 

 operation. The great m.ajority, however, have died because of 

 the excessive insolation they received during the period just 

 after the main canopy was removed. A discussion of what this 

 change in temperature and atmospheric conditions may amount 

 to has been given in another portion of this paper. The results 

 brought out there show very clearly that the conditions are so 

 changed that seedlings which have developed in dense shade are 

 placed at an immense disadvantage. 



As an example of what happens during the period subsequent 

 to logging, Table XLIX is presented, which shows the stand of 

 seedlings on an area of 250 square meters one year after it was 

 logged under the same conditions as those described on page 536. 

 The total number of dipterocarp seedlings in this area is 94. 

 However, 79 of these are of one species, Pentacme contorta. 

 This one species alone seems able to exist under the general 

 unsatisfactory conditions incident to a heavy opening of the 

 crown. However, as against the 94 dipterocarp seedlings exist- 

 ing on this 250 square meters, there are 430 seedlings, other 

 than dipterocarps, less than 10 centimeters in diameter, and 

 435 seedlings of miscellaneous intolerant weeds and vines. It 

 is clear from this that the dipterocarp element will be very in- 

 conspicuous in the forest which is developing on this area. On 

 areas logged two years ago there are only 2 dipterocarp seedlings 

 to 25 square meters. As in the case of the northern Negros 

 forest, it has been shown in the discussion of cleared areas that 

 logging in Bataan with a diameter limit of 50 centimeters has 

 resulted, in the past, in the destruction of the dipterocarp forest. 

 In Bataan the forest has been replaced by a bamboo thicket. It 

 may be that at the higher altitudes, about 500 meters, at which 

 the cutting is now being carried on, the moisture or other condi- 

 tions may make it possible for Pentacme contorta to compete 

 with the weed species. 



The conclusion to which one is forced, from a consideration 

 of the above data, is that an attempt to limit the cutting in a 

 virgin stand of dipterocarp forest by means of a diameter limit 

 of any reasonable size usually does not limit the cutting at all, 

 but results in a clear cutting operation. This is probably true 

 at least for most areas where intensive utilization is practiced, 

 and where logging is carried on in an intensive manner over 

 large areas. 



