TROPICAL FORESTS AND THE WAR 509 



here and there. On the flood-plains of the Magdalena River the cotton 

 tree (Ceiba pentandra) forces itself on the observer by its symmetric- 

 ally rounded top. In places this tree would constitute at least 50 per 

 cent of the stand, with the remaining 50 per cent made up of a large 

 number of other species. 



The sal forests of northern India are in this class, the sal forming 

 almost pure stands of the upper story. Other dipterocarp forests of 

 the Indo-Malay region are of this character, but sometimes the canopy 

 of the upper story is closed or partially closed, so that the profile is 

 more even. Such is usually the case on the best sites for forest growth. 

 One of the best examples of such a forest that has come under my 

 observation is in northern Negros, Philippine Islands (i). Here the 

 canopy of the upper story is almost completely closed. This makes the 

 volume of such a forest greater per acre in contrast with those where 

 the trees of the upper story are further apart. From cruises the num- 

 ber of trees 16 inches and over in diameter is estimated to be 81 per 

 hectare, of which 73 trees, or 89 per cent, are divided among six spe- 

 cies, all members of the dipterocarp family. Moreover, the woods of 

 five of these species were so near alike that they were placed on the 

 market and sold as two woods. The remaining eight trees per hectare 

 were scattered among many different species, some of which when 

 mature, although reaching a diameter of over 16 inches, were short- 

 boled and would be classed as trees of the third story. This forest 

 contains an average of 30,000 board feet per acre of the diptero- 

 carp timbers alone. In my paper on the dipterocarp forests of the 

 Philippines, it is shown that cruises made in many parts of the Islands 

 demonstrate that the actual volume of lumber in the dipterocarps alone 

 will vary from 54 to 95 per cent of the total stand of timber. Fox- 

 worthy (2) states that in British North Borneo "seven of the ten most 

 abundant commercial woods belong to this family (Dipterocarpacere), 

 and areas which have been studied in detail show 60 per cent of the 

 volume of trees over 16 inches in diameter to be of this group." My 

 hurried observations in the Federated Malay States, and even in the 

 so-called teak forest of Burma, showed that similar conditions obtain. 

 Dutch foresters have told me that the dipterocarp timbers of the Dutch 

 possessions in Sumatra and Borneo are more abundant than all the 

 others put together. The character of the woods of this family will be 

 discussed in another connection. 



In South America the low-lying region beyond the reach of the an- 

 nual floods of the larger rivers is known as the "terra firma." Recently 

 1 had occasion to see something of the tcrra-firma forests of the Mag- 



