CHAPTER VI 



TROPICAL SAVANAS AND DESERTS 



In the tropics the steppes of temperate latitudes are 

 represented by what are called savanas, which are 

 regions where grass occurs, mingled with arborescent 

 or shrubby vegetation. Sometimes we have in these 

 regions scattered trees only ; sometimes clumps of 

 trees occur, separated by regions without trees, giving 

 a characteristic park-like appearance to the landscape. 

 Elsewhere the trees follow the courses of the streams, 

 forming the so-called gaUery forests. Such savanas y' 

 occupy large stretches in the tropical regions of Africa, 

 South America, and Australia, and have a highly 

 developed and characteristic fauna. 



The typical savana climate is tropical. The rain 

 comes in the hotter season of the year, and there is 

 a well-marked dry season. Where the rain is deficient 

 the savana passes into desert, as we see in passing 

 northwards from the Sudan to the Sahara, or inland 

 from the Australian bush to the central desert. On the 

 other hand, where the rainfall is abundant the trees 

 increase in number, and the savana passes into the 

 tropical rain-forest, through the intervention of the \^ 

 savana wood, with its numerous trees. The period of 

 greatest vegetative activity accompanies or follows the 

 rainy season, and the dry season may witness an almost 

 complete cessation of activity. This, like the similar 

 conditions in the steppes, involves a certain amount of 

 migration among the inhabitants of the region. Further, 



