AN (ECOLOGICAL SUliVEV OF THE MIDLANDS OF NATAL. 497 



dry season, and a strong- wind is blowing, a grass fire will 

 sweep into the bush and destroy the trees around the margin. 

 Next year the dry and half-burnt trees burn still more 

 readily, and scoi-ch another belt. This goes on, and the grass 

 fires gradually eat into the bush. After a time all that 

 remains is a number of patches in the ravines and on the 

 steeper slopes, where the conditions are such that the fires 

 have less effect. 



The grass fires also affect the thorn veld, where the trees 

 grow isolated in a park-like manner. The young thorn trees 

 are destroyed by the fire, and only a few manage to survive, 

 until they grow tall enough to be able to offer a successful 

 resistance. It is this chiefiy that leads to their growing so 

 far apart. The very thick bark of certain trees in the thorn 

 veld helps them to withstand fire. 



The effect of grass-burning on the veld itself will be 

 described more in detail later when the separate grass 

 associations are dealt with, but here it may be pointed out 

 that Avhen the grass is burned early before it has pi'operly 

 withered, it leads to direct changes in the composition of the 

 grass associations, since certain species are less able to with- 

 stand it than others. On the other hand when the grass is 

 burned in late winter after it is withered the ground is left 

 bare, and when the first heavy rains come the soil is more 

 affected. It is washed away more I'eadily because it is 

 uiiprotected by any covering of vegetation. This fact is of 

 importance as helping to explain the extremely rapid rate of 

 denudation, and the formation of those numerous ravines or 

 dongas on the hillsides. 



The practice of burning tlie grass has been carried on for 

 many hundreds of years by the native. When Vasco de 

 Gama landed in 1497 he gave the name Terra de fume to 

 South Africa. 



Apart from fires there has been much reckless destruction 

 of the bush by the white man cutting out the more valuable 

 timber trees. The native is still more responsible. In form- 

 ing the framework of his huts he lias used millions of young 



