IX, A. 6 



Brown and Mathews: Dipterocarp Forests 



431 



with a central volcanic cone rising to an elevation of about 1,400 

 meters. This region differs from northern Negros in that 

 it lacks the broad coastal plain, the ridges sloping directly to 

 the sea. The ridges are narrow and steep, and the interior is 

 badly broken up into knifelike ridges, running up to elevations 

 of over 1,000 meters and separated by deep narrow valleys with 

 steep rocky sides. The climate at elevations below 500 meters 

 has a rather pronounced dry season lasting from December to 

 the beginning of May. At higher elevations this is less notice- 

 able. Whitford " gives the rainfall for this part of the province 

 as follows : 



Table IV.- 



—Rainfall, 



in miUimeters, at Lamao, Bataan, and at Manila for 

 parts of the year 190^-5. 



Month. 



Lamao. 



Manila. 





trace 



20.2 



0.0 



2.8 



1.1 



»173.8 



24.0 



346.2 



£94.4 



212.8 



239.6 





February _ . 



0.0 



0.8 



127.0 



38.1 



497.2 



1,071.8 



270.5 



426.4 



March _ - - _ - - 



April . . — . 



May— - 



June 



July 



August 



September . 













■ The excessive rainfall for April is the highest ever recorded. It is mainly the amount 

 which fell during the typhoon which visited the Islands on the 80th of that month. 



The soil is a stiff loamy clay of volcanic origin, similar to 

 that of northern Negros with the exception that it is probably 

 less heavily charged with humus. Owing to the occurrence of 

 a pronounced dry season, the surface layers of the soil are 

 frequently much dryer than in northern Negros. 



The forest under consideration lies on the eastern slope of 

 Mount Mariveles to the west of Limay and Lamao barrios of 

 the town of Orion, and extends from within a kilometer or so 

 from the coast to an elevation of about 900 meters up the slopes 

 of the mountain. The forest is distinctly dipterocarp in type 

 at all elevations up to 800 meters, where it grades into a forest 

 of miscellaneous smaller species, to which Whitford ^* has given 

 the name Eugenia-Vaccinium formation, but at no elevation 

 is there so large a proportion of dipterocarps as in the northern 

 Negros forest. 



The systematic composition of this forest has been thoroughly 

 described by Whitford.^' We need, therefore, do no more than 



This Journal (1906), 1, 379. 



Ibid., 652. 



' Ibid., 384-431, 637-679. 



