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 pure 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 by 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, 
