276 SUCCESSION IN EURASIA. 



and strand forest had just made a beginning on one island. In the interior, 

 grass steppe was well developed, while the hills exhibited low-grass vegetation, 

 and the cliffs were still clothed with ferns. Bushes were sparse and trees 

 almost entirely absent, for it seems that many years must pass before the vol- 

 canic surface is sufficiently weathered and humus abundant enough to permit 

 the reconstitution of the original forest. 



Whitford (1906) has described the following formations in the Philippines, 

 with especial reference to their developmental relations: 



(1) Strand, (2) Bambusa-Parkia, (3) AnisopteronStrombosia, (4) Diptero- 

 carpus-Shorea, (5) Shorea-Pledronia, (6) Eugenia^Vacdnium. In the Bawbusa- 

 Parhia formation, the repeated cutting of the bamboo gives an opportunity 

 for the development of other trees and shrubs, giving rise to a curious type of 

 second-growth termed "parang," of which there are several kinds. In the 

 case of clearings for cultivation, grasslands often develop, though in time these 

 become parangs and pass into the climax forest. Strand formations are 

 grouped as follows: 1. Sandy beaches lying above high tide, (1) Pes-caprae 

 formation, (2) Barringtonia-Pandanus; 2. Strand lying below high tide, 

 (1) mangrove and Nipa formations behind sandy beaches, (2) mangrove and 

 Nipa formations not behind sandy beaches, (a) formations at the mouths of 

 rivers, (6) formations at the base of cliffs. As the beach grows, the Barring- 

 Umia-Pandanus formation invades and replaces the Pes-caprae zone, and in 

 the same way the vegetation behind the beach invades the older portions of 

 the latter. The mangrove and Nipa formations are found in lagoons produced 

 by bars on mud-flats and deltas or on protected wave-cut terraces. The tidal 

 estuaries of young rivers are first invaded by Nipa, and this is followed by the 

 mangrove. As the delta grows, the mangrove invades the newer portions and 

 advances steadily seaward. Meanwhile, the swamps are being filled landward 

 by deposition, and the parang advances upon the Nipa and the latter upon 

 the mangrove. 



The author adopts the conclusions of physiographic ecology that the vege- 

 tation will become stable only when base-level conditions are approximated. 

 The canons with mesophytic vegetation and the slopes with xerophytic ones 

 are both regarded as possessing temporary vegetation. The physiography of 

 the entire mountain is very unstable and its vegetation is also temporary. 

 With its destruction it will pass to a more and more permanent condition, and 

 the vegetation will be altered with the change of topography. Just before the 

 death of such a topography, the whole country will be brought nearly to a 

 base-level, with the ground-water not far from the surface. The vegetative 

 conditions will then not be unlike that of the delta region, of which there are 

 many fine examples in the Philippines. At death itself, the mangrove swamps 

 will then prevail. 



Gibhs (1906) has described three formations in the region of Victoria Falls, 

 namely, the veld or tree steppe, the Eugenia guineensis formation, with Phrag- 

 mites, Papyrus and Erianthus, and the Eugenia cordata formation, and has 

 discussed the effect upon the veld of the annual burning by the natives. 



Ernst (1907, 1908) has described the further changes in the vegetation of 

 Krakatoa, which was studied by Treub in 1886 and by Penzig in 1897: 



Two strand formations have now developed. The outer zone is a typical 

 Pes-caprae formation with low creeping grasses, herbaceous plants, bushes, 

 and shrubs. The inner zone is a Barringtonia forest with coconut palms and 



