194 SCIENCE IN AFRICA 



savannah areas from end to end each year and thus cause much 

 soil erosion. The proportion of reserved forest to land area is low 

 (see table), but the department have the increase of reserves to 

 2,812 square miles as an immediate object, and hope eventually 

 for 10,000 square miles, being 12-4 per cent of the land area, these 

 figures to include savannah as well as closed forest. 



In Nigeria shifting cultivation along the northern and eastern 

 borders of the closed forest zone is resulting in a recession of forest 

 at the estimated rate of i ,000 square miles a year. This destruction 

 of closed forest is said to have had serious consequences for the 

 cocoa plantations of the western provinces. Taungya methods of 

 regeneration are meeting with some success, but it is very doubtful 

 whether re-afforestation by this means could ever keep pace with 

 destruction. The system of taungya in Nigeria is as follows: the 

 native cultivator is induced to work through an area of forest in 

 a fixed direction, clearing and cultivating a series of plots. These 

 are as a rule left to regenerate naturally, under the supervision of 

 native foresters, who follow behind the cultivator, cutting out 

 creepers and undergrowth, and leaving only the valuable trees. 

 The forest experimental station at Sapoba near Benin has been 

 a site for experiments in natural regeneration as well as silvicul- 

 tural research, and results show how natural regeneration, when 

 controlled in this way, can improve the forests to a marked degree. 



The forest reserves of the Southern Provinces are devoted pri- 

 marily to exploitation, while in the north the first object is con- 

 servation of water-supplies. H. N. Thompson, one of the most 

 distinguished foresters of West Africa, laid down the principle that 

 the minimum area of permanent forest in Nigeria should be 25 per 

 cent of the total land area, and the department is still aiming at 

 the acquisition of reserves on this scale. The proportions in differ- 

 ent provinces would range from 5 per cent to 64 per cent the 

 latter figure applying only to Benin, which is the centre of the 

 valuable timber forests. In certain areas the department's policy 

 is to hand over the reserves to be administered by the native 

 administrations under careful supervision by the forestry depart- 

 ment. 



A special problem in the extreme north of Nigeria is connected 

 with the alleged encroachment of the Sahara, discussed in Chapter 



