105 



soil are hardened, there is a greater run-off of water, and 

 numerous dongas and ravines appear along the sheep or cattle 

 tracks, and the water table is lowered. The surface layers 

 become drier and hard baked, and Karroo conditions are 

 established. There seems to be no doubt that the Karroo has 

 extended rapidly eastward within recent years, and parts of 

 the transitional belt hare become intersected by dongas to an 

 extraordinary degree. Over considerable areas around Tarka- 

 stad, there is very little soil left. Such considerations make 

 the study of the plant succession of vital importance from the 

 agricultural or economic standpoint. 



On the coast belt from Port Elizabeth northwards through 

 the Alexandria and Albany divisions, there is much grass- 

 land, but there is also a great development of succulent and 

 thorny Scrub (Fish River Scrub. Addo Bush, etc.). In this 

 region, too, the eastern boundaries of the S. Western Macchia 

 are reached. From Alicedale northwards to Cookhouse the 

 railway line lies parallel and close to the eastern boundary 

 of Grassveld. From Cookhouse the Karroo extends somewhat 

 irregularly to a point east of Tarkastad, and from there the 

 boundary line more or less follows the mountain ranges. At 

 Steynsburg it is fairly sharply defined, but farther north the 

 Karroo has an eastward extension towards Aliwal North. 

 North of the Orange River in the Free State, it is very diffi- 

 cult within wide limits to draw any boundary line. If the 

 southern Free State is visited after a long spell of dry weather, 

 one would be inclined to classify it all as Karroid. After 

 good rains, on the other hand, the grass grows quickly, and 

 open Grassland developes, dominated chiefly by Eragrostis, 

 Aristida, and Enneapogon. At Hopetown we reach the 

 southern boundary of the Sand Veld rejnon. 



The hydrosere in this region need not be dealt with at 

 length, since it is essentially the same as for the Karroo itself, 

 with a few extra species belonging to the Eastern Grassveld 

 region. The ruderal species are also of the usual widespread 

 types. 



In the early stages of the xerosere a number of species 

 form consocies. Cynodon incompletes (Kweek gras) is one of 

 the most widespread and important. It often forms an almost 

 pure growth over bare, dry slopes. Its prostrate creeping 

 stems, which root at the nodes, enable it to extend rapidly 

 after rains, and it is quickly followed by other species, which 

 gradually take its place, especially species of Eragrostis (eg., 



