224 AFRICA 



apparently been beyond the powers of the Somalis, whose 

 thinly scattered tribes continue to tend hungry cattle, 

 and to hunt among the rich scrub. 



Light Forests and Parks of Tropical Africa. The 

 savana does not pass abruptly to the high tropical 

 forest: with the gradual increase of rainfall and the 

 appearance of a double wet season, the vegetation slowly 

 grows more luxuriant ; patches of woods become at once 

 more extensive and more frequent ; while the park aspect 

 is emphasized. Yet woodlands do not attain to the height 

 and wealth of the equatorial selvas : a good many trees 

 still shed their foliage or possess leathery leaves : and 

 lianas and epiphytes, except in the river- forests, are 

 comparatively small and scarce. In short, there is a 

 distinct belt of transition from the savana to the selva, 

 consisting of light kinds of tropical woods mixed with 

 grass-lands of the savana type ; but by reason of the 

 universal practice of burning the grass yearly in the 

 dry period, the savana has, in most cases, been extended 

 right to the margin of the selva, and, in many instances, 

 has indeed largely encroached upon its limits by the 

 destruction of the belt of light woods, which are easily 

 set on tire. Cultivation is also responsible for much of 

 the damage to the light forests. Thus it is that, in 

 tropical Africa, this belt has been largely transformed 

 into a savana. Distinct traces of it may be found in 

 the hinterland of Upper Guinea (the Ivory and Gold 

 Coast, Togo, and Nigeria), on the watersheds of the 

 Shari, Bahr-al-Ghazal, and Congo basins ; and the great 

 Ituri forest passes to the savana through such a margin 

 of light deciduous tropical woods interspersed with 

 grass-lands. 



In Upper Guinea, representative growth- forms of the 

 selva are present throughout this belt. Oil and borassus 



