BOTANY 159 



reference to the then German colonies. The later work by Shantz 

 and Marbut (1923), already referred to in Chapter V, represents an 

 attempt, in a sense premature, to produce a scheme for the whole 

 continent as a working basis. 



South Africa 



In South Africa, after the preliminary work of Marloth (1887), 

 Bolus (1905) and Weiss (1905) in defining the botanical regions, 

 J. W. Bews laid the foundations of plant ecology in a long series of 

 papers written between 191 2 and 1925. These deal with the distri- 

 bution of plants in relation to climate and physiography, plant suc- 

 cession in different types of vegetation, the thorn veld, grassland, 

 etc. Among general studies are those of I. B. Pole Evans (191 8 

 onwards), who contributes a chapter on plant geography in the 

 official handbook of the Union, together with accounts of the pro- 

 gress made by his botanical survey; and Cannon (1924) deals with 

 the relation of vegetation to environment in arid regions. E. P. 

 Phillips (1931 ) has provided a valuable account of the grasses with 

 three chapters on their ecology,bringing out the effects of burning, 

 mowing and grazing; human influence is also stressed by Sim 

 (1926), who concludes that in no locality is the flora natural. The 

 results of burning are described and discussed by Michell (1922) 

 and Levyns (1929a), and J. F.V. Phillips (1930a) analyses the influ- 

 ence of fire in changing plant successions and animal associations 

 in both South and East Africa; his general conclusion is that con- 

 trolled burning has beneficial effects on pasture-land, particularly 

 in regions where valuable grazing would be lost if never fired; but 

 local conditions vary so much that generalizations are dangerous. 

 Important experiments in veld burning have been carried out 

 recently at the Cedara School of Agriculture. Van Zyl (1926) and 

 others have stressed the deficiency of phosphorus in both soils 

 and vegetation. Schonken (1931) points out the results of de- 

 forestation in causing loss of water in the soil, and these and other 

 subjects are dealt with by J. F. V. Phillips (1927, 1928a and b, 

 1931a), whose work may be mentioned as applying thoroughly 

 up-to-date principles in plant ecology. 



For the Cape Province, Adamson (1927 and 1931) has contri- 

 buted technical ecological accounts of the vegetation of Table 



