172 WEST AFRICAN FORESTS AND FORESTRY 



the natives have directly helped in this process, by leaving some 

 of the less straight and more branched Iroko-trees standing. They 

 have used the best for canoe-making. In this manner seed-bearing 

 trees have been available, and with part of the ground having been 

 cleared for farms, the conditions have been most suitable for the 

 reproduction of the tree. Subsequently the farms have been abandoned 

 and the young trees have grown up amongst the weeds, creepers, 

 and other inferior tree species, such as Albizzia, just according sufficient 

 shade and protection for the young Irokos, and yet not too dense or 

 thick to prevent them from sooner or later emerging and overgrowing 

 the rest of the trees. Although, of course, many trees growing up under 

 these conditions branch somewhat low down, they do not suffer 

 nearly to the same extent, and sometimes not at all, from the attacks 

 of the leaf coccus. This has two effects : not only does it not hinder 

 and retard the sapling's growth, but also all the sooner it reaches the 

 higher zone or greater distance from the ground (as far as its upper 

 foliage is concerned), so that these attacks do not occur. Again, the 

 competition of the various weeds, Albizzias, creepers, etc., has the 

 effect of so stimulating the growth of the young Iroko that in such 

 positions it reaches a much greater height in a quicker time than 

 when planted in jDure plantations. From numerous observations it 

 appears that after the first year the height growth may exceed 6 feet 

 in one season. Even later this is kept up, and if the rest of the forest 

 growth remains comparatively thick, no side branches can be formed 

 on the bole of the Iroko, so that clean-stemmed trees are the result. 

 As it gets older the Iroko stands less shade, and thus any small branches 

 which do form are soon killed by the surrounding trees. Thus it is 

 seen how we find these very straight, long-boled Irokos in the forests. 

 Again, too, it is not very expensive, and at least much cheaper, to 

 undertake partial cleaning and pruning amongst the self-sown Iroko- 

 trees, especially to eliminate forks low down in the stem. Various 

 experiments undertaken in the Ikrigon, Olokemeji and Mamu Reserves 

 showed how quickly the sapling Irokos respond to this treatment. 

 In some cases, trees only 2 inches in diameter and forked have reached 

 nearly 4 inches in diameter and nearly doubled in height in one year. 

 Another advantageous feature of the Iroko is the rapid, satisfactory, 

 and smooth way in which the occlusion of the wounds made bj^ pruning 

 takes place. Even in the case of a very crooked tree covered with several 

 branches, in fact almost forming a crown, these may be marked but not 

 all cut until the following year. Surfaces of less than 2 inches will be 

 nearly occluded over, and a tendency of the tree towards a crown will 

 be almost obliterated at that point and be forming much higher up 

 the tree. 



Apparently, the more northward the tree is found the less liable 

 it is to attack by the leaf coccus. Whilst it is found in the Olokemeji, 



