452 The Philippine Journal of Science lou 



If the land is cleared of forest and not cultivated, it is very 

 quickly covered by second-growth trees. The most prominent 

 are Trema amboinensis (anabion) , Homalanthus populneus (ba- 

 lanti), Macaranga bicolor (hamindang), Macaranga tanariua 

 (binunga), Mallotus ncinoides (hinlaumo), and Mallotus moluc- 

 canus (alim). One of these, particularly one of the first four, 

 may in certain localities form almost pure stands. Thus, a 

 small cleared plot at an elevation of 450 meters on Mount Ma- 

 quiling was very quickly covered by a growth consisting almost 

 entirely of Trema amboinensis, while cleared areas on Mount 

 Mariveles at a similar elevation frequently show practically 

 nothing but Homalanthus populneus. Along with the trees 

 mentioned there may be a number of others, but they usually 

 occur in much less abundance. All of these trees are small, 

 soft-wooded, rapidly growing species. They reach maturity 

 early, are subject to decay and insect attack, and thus are very 

 short lived. 



The future development of these second-growth forests varies 

 with their size and situation. If the second-growth forest is a 

 small patch in a dipterocarp forest or is on an area adjacent to 

 one, some of the species of the dipterocarp forest will invade the 

 second growth. The first invaders are frequently species of the 

 genus Canarium or of the families Meliaceae and Sterculiaceae. 

 The second-growth trees are very intolerant of shade and form 

 only a very light canopy. The conditions under this canopy are 

 very dry as compared with those in the original forest, and 

 especially in regions with a pronounced dry season are apparent- 

 ly not favorable to species requiring the moist conditions of a 

 dense forest. The stages through which the forest passes in re- 

 turning to the original dipterocarp type have not been studied, 

 but the changes must be extremely complex and the time required 

 considerable, for as will be shown later, the trees of dipterocarp 

 forests, unlike those of the second growth, usually develop in 

 dense shade and are very slow growing. 



The second-growth forest will apparently give place to a 

 dipterocarp one much quicker in a region without a pronounced 

 dry season than in one which has a long season of dry weather. 

 Where the dry season is not pronounced, dipterocarps, if there 

 are seed trees present, may seed into the second growth very 

 quickly, and in many cases the seedlings will be able to survive. 

 Climbing bamboos and other vines frequently come into the 

 second-growth forests to such an extent that they form a very 

 dense tangle through which it is difficult to pass. 



