574 Forestry Quarterly. 



seed-bearing centers. Thus so many sub-types exist that it is 

 difficult to make generahzations. Advance stages in the develop- 

 ment of second-growth forests are so mixed with tangles of climb- 

 ing bamboo and other vines that they are difficult to penetrate. 

 Such forests often cover large areas, and are the so-called jungle 

 growths of the Philippines. They often alternate with patches of 

 grass, with which they make the vegetation known as parang. 

 Forest fires such as exist in drier portions of the Tropics and in 

 temperate regions do not exist in the Philippines. Surface fires 

 run through the pine forests, destroying young trees and injuring 

 somewhat the older ones. Outside the pine regions there are 

 practically no forest fires, only "prairie" fires and burnings of 

 timber that has been felled previously. These may injure the 

 edge of the original forests, but do not penetrate them and pro- 

 duce conflagrations such as are known in the coniferous forests 

 of the temperate regions. The parang districts often show ka- 

 leidoscopic changes, due to the rapid development of jungle 

 growth where the fires are checked and the entrance of grass or 

 second-growth forests in newly abandoned caingins. In the 

 more thickly settled portions of the Islands, and along well- 

 traveled trails, practically all the original forests have disap- 

 peared, giving place to grass or second-growth forests. The 

 second-growth forests in newly abandoned caiiigins. In the 

 conveyed the wholly wrong impression that the forests of the 

 Philippines, and, it is believed, of the Tropics in general, are a 

 densely overgrown mass of impenetrable jungle. Little is seen 

 of the original forests of the interior, for the jungle growth on 

 its borders tends to discourage efforts to penetrate within. Over 

 one-half (approximately 68,000 square miles) of the area of the 

 Islands is covered with grass or with second-growth forests. The 

 prevention of further destruction of the virgin forest, and the re- 

 forestation of the grassy regions on non-agricultural lands, both 

 by the prevention of fires and by planting, are the greatest forestry 

 problems of the Philippine Islands. 



4. Virgin Forests. 



Virgin forests are those which either have been undisturbed by 

 man, or have been so little exploited that their original character 



