8 
The Tropic region is sufficiently characterized by name and need be 
only mentioned. 
The Austral region corresponds roughly to the popular geographical 
conception of the Temperate zone. It is divided into three life zones, the 
Lower Austral, the Upper Austral, and the Transition. The Lower Austral 
might be designated as subtropic and extends north including the gulf of 
Mexico and the south Atlantic states, but does not reach Canada. The 
Upper Austral is the first zone in which we in Canada are directly interested. 
In the east, it merely crosses the border on the Lake Erie shore and includes 
the famous Niagara fruit belt. In the west it touches our southern 
boundaries in Saskatchewan and perhaps adjacent parts of Manitoba and 
Alberta and penetrates into British Columbia along the southern fruit- 
growing valleys. The northernmost Austral or Temperate life zone is the 
Transition, which includes the greater part of the highly cultivated areas 
of Canada. In the central provinces it is practically co-extensive with the 
prairies, ceasing against the spruce forest of the north and the slopes of 
the mountains to the west. In British Columbia it follows up the warm 
interior valleys to the vicinity of the Canadian Pacific Railway track and 
along the coast in a narrow belt to a point opposite the head of Vancouver 
island, including also most of the east coast of that island. 
The Boreal region is divided into Canadian, Hudsonian, and 
Arctic zones. The Canadian zone includes the coniferous forested region 
north of the Transition to the northern limit of practical cultivation. 
It sends intrusive fingers far north along Mackenzie valley and 
Peace river and up the west coast, including most of the immediate coast 
and islands of the Alaska Panhandle almost to Skagway. The Hudsonian 
zone is the more northern country of small shrubs and stunted tree growth 
and is generally unsuitable for agriculture. The Arctic zone includes 
the Barren-grounds north to the pole. 
These life zones are based fundamentally on temperature and, under 
ideal physiographic conditions, would be determined by latitude. 
However, they are deflected from their natural east and west sweep by 
various conditions, the shielding effects of mountain ranges, the vicinity 
of large bodies of waters and warm or cold ocean currents, temperature of 
prevailing wind, and elevation. Hence the very irregular boundaries of 
these zones across our continent. 
Elevation is an important factor in the distribution of life. Even in 
the tropics, the top of a mountain high enough will be of extreme arctic 
character with perpetual snow, and down its sides at their proper elevation 
will be found belts of the above zones. This is well exemplified in the 
mountainous region of British Columbia. The mountain tops may be of 
Hudsonian character, their peaks even Arctic, and the valleys between 
may descend to Canadian, Transition, or even Upper Austral. Conse- 
quently, the zones that on the level prairies are separated by hundreds 
of miles may, in this more rugged country, be within a few hours climb of 
each other. Also, scattered here and there in level country, elevations may 
produce islands of more northern associations in southern zones. Thus, 
close along the boundary in the Prairie Provinces, we find Turtle 
mountain and Cypress hills as Boreal islands surrounded by Austral 
lowlands; and a long, narrow tongue of Hudsonian zone following the main 
