ECOLOGICAL 97 



FROM POLE TO POLE 



Let us make a short selection in simple illustration of the way in 

 which living creatures must be considered in their geographical 

 environment. 



The Northern Forests. — With our eyes shut we should be 

 able to see from Pole to Pole — the Arctic Ocean with its icebergs 

 and bird-islands, the Barren Grounds or Tundra, the great Conif- 

 erous Forests, the Steppes, the arable midlands and meadows, the 

 hot deserts, the Tropical Forests, the southern Steppes or Pampas, 

 and the Antarctic continent. According to the meridian that we 

 select, the sequence will differ in detail, but there is a general resem- 

 blance in the succession from Pole to Pole. Even over the waters 

 of the ocean there is a zoning, so that we are surprised to find, as 

 Bruce of the Scotia did, Arctic terns within the Antarctic Circle, 

 or an albatross in England. 



The zone we wish first to get glimpses of is the Northern Forest, 

 a vast belt, as everyone knows, to the north of Europe, Asia, 

 and America, sometimes 800 miles in width. It lies between the 

 Barren Grounds to the north and the Steppe Lands (or meadow- 

 lands) to the south. In Siberia, where it stretches for over 3,000 

 miles, from the Ural Mountains to the Pacific Ocean, it is called 

 the Taiga. 



As contrasted with the warm rain-forests, of which Mr. Beebe 

 has given us such vivid pictures, where vegetation reaches its 

 climax, both in luxuriance and variety, the northern forests consist 

 of only a few different kinds of trees — ^largely conifers. This means 

 that the severity of life-conditions has greatly restricted the number 

 of possible tenants. There is a check to the ascent of sap, for the 

 soil is cold through half the year, the water is sour with humic acid, 

 and there is not much evaporation from the thick-skinned leaves 

 into the cool air. Thus growth is slow. Difficulties are increased by 

 the fierce winds of winter, and the heavy snows have eliminated 

 those trees with spreading foliage that do not allow what falls to 

 slide off easily. In a southern region, where snowstorms are rare, 

 it is interesting to observe after a heavy fall that cedar-like trees 

 stand uninjured, while many of their broad-leaved neighbours are 

 borne to the ground or badly maimed. So in the northern forests 

 there is a predominance of pine and spruce, larch and cedar. Shooting 

 up in the thick shelter between these conifers there are slender, 

 long-drawn-out birches, rowans, alders, and hazels, which could 

 not survive by themselves. In her Forest, Steppe, and Tundra, Miss 

 Haviland compares these stripling trees to the lianas and climbers 

 of the tropical jungle. "They grow as straight and close-set as the 



VOL. I H 



