FORESTRY 1 8g 



agricultural ills, though it may be a palliative in some cases by 

 postponing the destruction of the soil, and is a useful and cheap 

 method of artificial regeneration in reserved forests. Clearly its 

 efficacy is dependent largely on local conditions. 



For the purpose of planting up areas vacated by shifting culti- 

 vators, exotic trees such as Cassia and Dalbergia are generally 

 favoured. In many situations the indigenous trees could be used, 

 especially species of Acacia, which, like other leguminous plants, 

 have the property of fixing free atmospheric nitrogen through the 

 agency of bacteria to produce nitrates in the soil. In parts of the 

 Sudan the gum tree {Acacia Senegal), which regenerates naturally, 

 and is sometimes planted on vacated farms, is said to be parti- 

 cularly effective in reconditioning exhausted soil in dry country, 

 and is also of great value in the fixation of shifting sand. 



In territories bordering on the Sahara region, forest destruction 

 is said to be partly responsible for the rapid encroachment of dry 

 conditions from the north, e.g. in the northern parts of Nigeria, 

 the Gold Coast, and northern Uganda. In such dry areas acacia 

 trees are frequently cut down to provide fodder for camels, a most 

 wasteful practice which should be discouraged wherever possible. 

 H. G. Sampson (1936) has recorded a similar method for keeping 

 cattle alive in parts of East Africa where country which was grazing 

 twenty years ago is now devoid of pasture. The destruction of 

 forest in one area may cause change to drier conditions elsewhere; 

 for example in Nigeria and other territories of the Gulf of Guinea 

 it is probable that the belt of rain forest near the coast has a con- 

 siderable effect on precipitation in the arid regions farther north. 

 There is a body of opinion, in fact, which maintains that in order 

 to avoid the menace of the advancing Sahara, the forest reserves 

 in the rain-belt near the coast should be enlarged. 



There appears to be no general published work on these ques- 

 tions which deals expressly with Africa, but attention may be 

 drawn to the discussion on the use and misuse of land by R. M. 

 Gorrie (1935), in which the place of forestry in relation to the 

 planning of land utilization is admirably defined. The place of 

 forestry in land-planning is also considered at some length by 

 Major F. M. Oliphant (1937) in a report on his tour of the East 

 African territories. So important are the questions of the relation 



