426 ^^^ Philippine Journal of Science isu 



and each forest presents a somewhat individual problem in its 

 management. 



THE FOREST OF NORTHERN NEGROS 



The northern end of Negros is characterized by broad gently 

 slopiag ridges which extend from a broad coastal plain inland 

 to a volcanic cone rising to an elevation of about 1,400 meters. 

 The climate of the region is nonseasonal in character at all 

 points above 100 meters in elevation. The soil is a deep, fer- 

 tile, well-drained clayey loam of volcanic origin. The forest 

 extends on the northern and eastern slopes to within 6 kilometers 

 of the coast, where the altitude is from 30 to 50 meters. It is 

 dipterocarp in character up to elevations of 700 meters and 

 over, where it grades into mountain-top forms, but it reaches 

 its best developement on the lower broad gentle slopes up to 

 elevations of 500 meters. 



On the broad lower slopes the forest is typical of the best- 

 developed forests of the Islands (Plate V). From the stand- 

 point of yield and simplicity of composition, the forest is 

 unsurpassed. The dominant trees, numerically and commer- 

 cially, are only six, and all are dipterocarps. They are Shorea 

 negrosensis (red lauan), Shorea polysperma (tanguile), Shorea 

 eximia (almon-lauan), Pentacme eontorta (white lauan) Para- 

 shorea plicata (bagtican-lauan), and Dipterocarpus spp. (api- 

 tong). These trees are all of large size, attaining an average 

 diameter of 70 centimeters and a height of 50 meters. Indi- 

 vidual trees attain diameters of over 250 centimeters and heights 

 of over 65 meters, and over large areas the average diameter 

 of the 6 species may run as high as 100 centimeters (Plate IV, 

 fig. 1, and Plate V). Owing to the fact that the top story is 

 60 highly developed, the under stories are less prominent than 

 in the average dipterocarp forests. This forest is, therefore, 

 not as typically three storied as are most forests in the Islands. 

 An analysis of the stand shows a striking lack of intermediate- 

 sized trees of the predominant species. The understory is for 

 the most part made up of a great number of minor species which 

 are too small and too varied in quality to be of importance 

 commercially. In other words, the forest approaches an even- 

 aged stand of overmature dipterocarps with a scanty under- 

 story of mixed pole-sized dipterocarps and miscellaneous species. 

 This fact is illustrated by Table II compiled from data given 

 by Everett and Whitf ord ^® in their working plan for this area. 



" Everett, H. D., and Whitford, H. N., A preliminary working plan for 

 the public forest tract of the Insular Lumber Company, Occidental Negros, 

 P. I., Bull. P. I. Bur. Forestry (1906), No. 5. 



