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 gallery forests. Such savanas 
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, 
