THE PLANT ECOLOGY OF THE COAST BELT OP NATAL. 449 



Voacauga ch-egei, Ficus spp., etc., remain dominant, but 

 soon other species arrive and scrub begins to develop around 

 the margins. This gradually advances up the slopes, and 

 between parallel tributaries the intervening ridges gradually 

 get covered. Forest follows the zone of scrub. Islands of grass 

 veld may be found surrounded by scrub and in a wider circle by 

 forest (text-fig. 2).^ The advance has been from two parallel 

 streams on opposite sides of the island, and sufficient time has 

 not elapsed to cover completely the intervening ground. A 

 transect taken across a forest-clad valley shows the oldest 

 trees at the valley bottom, and all the stages of the succession 

 from the initial to the climax are shown along such a transect. 

 ^J''he succession is most clearly marked on rather drier ridges, 

 for there it takes some considera.ble time for scrub to give 

 way to forest. In moister situations, and especially near the 

 streams themselves, the early scrub stages are more transitory 

 and the tree species may appear before the shrubs — the type 

 of succession seen in tree veld. The drier ridges, however, 

 can only be conquei-ed by pioneer scrub composed of some- 

 what xerophytic light-demanding shrubs and small trees, 

 which prepare the way for the taller-growing, more hygro- 

 philous, more shade-loving forest species. The ultimate 

 stages are dominated by species which are shade-bearers in 

 their early stages and light-bearers at maturity. They them- 

 selves throw dense shade, which easily kills out the seedlings 

 of competitors and in many cases even their own seedlings. 

 The forest has then reached a stable climax condition at 

 which it remains, until the death of old trees begins to leave 

 gaps which admit light and give an opportunity for the 

 seedlings of such species as show the best powers of regenera- 

 tion to grow up. A succession of extra dry years often leads 

 to many old trees dying at the same time, and at such times 

 fires are especially dangerous. As a rule the forest is too 

 moist for wholesale destruction by fire, but if it contains 

 much dead wood a fire may sweep through. 



Regeneration in the open spaces of a forest is not always 

 ' Cf. Henkel, J. S., loc. cit. 



