Tropical Forests 



But at Sierra Leone there is a distinct change in the 

 vegetation even towards the summit of Mt. Sugarloaf : 

 the high winds and exposure prevent the continual 

 moist hot-house heat which is required for its true 

 development. But along a great river valley such as the 

 Congo, the wet-jungle slightly modified may be continu- 

 ous, extending up the tributary rivers and their small 

 streams just so far as they remain so sunk below the 

 general level of the country as to preserve this moisture. 

 Even at about 7000 feet in the Wimi valley on Ruwen- 

 zori, one is reminded at every turn of the coast jungle 

 at Sierra Leone. 



This is not at all surprising, for there is a nearly con- 

 tinuous series of hot, moist, forest-clad slopes or steamy 

 valleys right across Africa from Ruwenzori to the Congo 

 mouth, and thence along the shore to the Sierra Leone 

 peninsula. In the Amazon valley, so far as I can under- 

 stand Dr. Ule's description, the entire valley and its tribu- 

 taries are clothed with essentially the same wet-jungle 

 forest up to the eastern slopes of the Andes in Peru.* ^ 



But in such an aeroplane as has been suggested, one 

 would pass sometimes over plateaux, or perhaps over 

 slightly undulating ground, with here and there a range 

 of mountains rising well above the general level of the 

 country. These plateaux will not be covered with the 

 true wet-jungle, which begins to fail a little before the 

 crest-line of the coast mountains. Most of them will 

 be savannahs covered by tall *' elephant grass," or even 

 by low steppe-like grasses with a few scattered trees. 

 Occasionally the rolling hills and valleys will be '^ park- 

 like," or it may be wooded, but the trees are not tall, 

 and there is nothing like the rich undergrowth and 

 riotous vegetation of the true wet-jungle. Every river 

 will usually have its fringe of wood or <^ gallery wood." 



* The inundated forest of the Amazon is different, as one would expect, 

 frem that which is above the annual floods. 



