70 PRESIDENTIAL ADDRESS SECTION C. 



that definite information can be given regarding the best procedure 

 in each individual case. This forms one of the most important 

 economic results of our study of ecology in Natal. 



. The analysis of the factors influencing the vegetation, climatic, 

 edaphic and biotic, and the study of the plant succession has 

 gradually led to the evolution of a more or less natural scheme of 

 classifying the vegetation units or plant communities. 



The Main Botanical Regions of Natal. 



There is no doubt that Krauss, and later Thode, were right 

 when they divided Natal, like ancient Gaul, into three parts, viz. : 

 (1) Coastbelt, (2) Midlands, (3) Drakensberg or Mountain. These 

 agree in certain important climatic features, especially in having 

 a summer rainfall, so that Natal may be considered as one botanical 

 region and these as sub-regions. The point is immaterial from our 

 present standpoint. Altitude, however, is not the only possible 

 basis for subdividing Natal. Owing to the rivers of Natal having 

 cut down through the system of terrace plateaux between the 

 Drakensberg and the sea, there is a system of deep valleys which 

 contrast rather sharply with the ridges between them. The former 

 are known as Low Veld, the latter as High Veld. The Low Veld 

 is drier, has greater extremes of temperature, a richer soil which 

 is more compact, and supports a generally more xerophytic vege- 

 tation than the High Veld. The Coastbelt is a distinctly sub- 

 tropical region. Frosts are absent or very rare. The Low Veld 

 on the Coastbelt is not so distinctly marked off from the High 

 Veld as in the Midlands. By a recent downward movement of the 

 continent to an extent of 150 feet or more the river mouths have 

 been "drowned" and extensive alluvial flats have been formed. 

 The whole of the actual coastline itself is covered by a mantle of 

 blown sand to a distance of from half a mile to two or three miles 

 from the shore. Close to the sea the sand has formed a line of 

 dunes fixed by bush. The Drakensberg forms the lofty escarpment 

 of the great inland plateau varying in altitude from 6,000 to 

 11,000 feet. It is a region of highly unstable topography. Though 

 snow only falls occasionally and always melts early in spring, 

 otherwise climate and soil conditions are of the usual extremely 

 variable mountain type. The distribution of the plant communi- 

 ties will illustrate further the differences between the various 

 botanical regions. 



The Plant Communities in Natal. 



Since plant succession is a universal phenomenon and funda- 

 mental in any natural scheme of classifying plant communities, 

 the primitive or pioneer types will be dealt with first and the order 

 of arrangement will, as far as possible, be that of the plant suc- 

 cession in each separate climatic area. 



1. — The Strand Vegetation. 

 On the belt of shifting sand between the line of sand dune 

 bush and the sea a number of interesting species, many of them 

 widespread, represent the earliest stages of succession on sand (the- 



