CHAPTER IV 
MOUNTAIN FAUNAS 
THE animals of mountain and plateau regions show 
some interesting conditions which make it worth while 
to consider them separately. Taking mountains first, 
we may note that elevated ranges may be divided into 
three regions, each of which presents peculiar biological 
features. The lowest region is usually clad in forests, 
conifers predominating as we ascend. Ata point which 
varies with the exposure, the slope, and other factors, 
even on a single mountain, tree growth ceases, and there 
comes a zone with steppe characters. The width of 
this band and its nature vary greatly. In e.g. the 
mountain regions of Europe, it is characterized by the 
growth of relatively small herbaceous plants, often with 
large and gorgeously coloured flowers, but with tufted 
leaves and other indications of checked vegetative 
growth. Many of these plants reappear in the Arctic 
tundra, but the fact that they are specially abundant 
in the Alps has led to them being called Alpine plants, 
whether they occur in the Alps proper, on the hills of 
Scotland or Norway, in the Himalayas, or in the Cau- 
casus. 
In tropical regions, e.g. in Africa, this steppe area 
with its Alpine plants is replaced by a band where the 
plants show desert characters ; the Lobelias, Senecios, 
and tree-heaths of the upper zone of Ruwenzori and 
Mount Kenya form good examples. In all regions where 
the mountains attain sufficient elevation, above the 
steppe or desert zone comes that of eternal snow, where 
