BIOME AND BIOME-TYPE IN WORLD DISTRIBUTION 



585 



covering of feathery fuzz, so that they ap- 

 parently present an instance of the Berg- 

 mann Rule (p. 120). 



The floating polar ice, the northernmost 

 islands, and the icy wastes of the Green- 

 land ice cap form an appendage to the tun- 

 dra. They are by no means lifeless, but the 

 terrestrial animals that invade the "ice des- 

 ert" are either partly dependent on the 

 tundra, like the arctic fox, which crosses 

 great stretches in nomadic wanderings, or 

 dependent on the sea, like the semiaquatic 

 polar bear, whose food consists mainly of 



Antarctic terrestrial life, however, is ob- 

 viously an appendage to the benthic marine 

 community. Even with the sea as an ave- 

 nue of dispersal, the penguin group is strik- 

 ingly fragmented from east to west. Thus 

 the antarctic tundra is not here regarded as 

 a distinct biome. 



THE TAIGA BIOME TYPE 



The coniferous forest belt is known in 

 Siberia as the "taiga." This name we have 

 adopted for the American as well as for the 

 Eurasian biome characterized by the conif- 



Fig. 220. Taiga landscape, Slate Islands, Ontario. The taiga biome is characteristically dotted 

 with small lakes. ( Photograph by R. C. Hosie; Courtesy of National Museum of Canada. ) 



seals. The life of the North Polar area prop- 

 er is to be regarded as an appendage to 

 the tundra biome. 



The southern limit of the continuous 

 principal tundra zone is the fluctuating line 

 of permanently frozen subsoil. Even this 

 relatively sharp and significant definition 

 appears to break down, since there are is- 

 landlike areas of low birch forest enclosed 

 in the tundra, and the sphagnum bog com- 

 ponent of the tundra extends far to the 

 south in the bog-captured lakes and in cer- 

 tain relict bogs in more southern areas. 

 These latter are evidently relicts of the post- 

 glacial period. 



The borders of the antarctic continent 

 and the antarctic islands bear an obscure 

 counterpart of the arctic tundra (Fig. 219). 



erous forest matrix. The taiga is of vast 

 extent, adjacent to the tundra at the south, 

 and continuously circumpolar, except for 

 the interruptions of the Bering Sea and the 

 North Atlantic. It has been discussed by 

 Haviland (1926) and Shelford and Olson 

 (1935), among others. The surplus of food 

 supphed by the wood, leaves, browse, and 

 seeds of the trees, and by the herbaceous 

 plants that live in the deep shade of its 

 forest floor (Fig. 220), supports a notable 

 assemblage of animals strictly associated 

 with the plant-defined biome. Most con- 

 spicuous of the larger animals of this biome 

 is the moose, the range of which in Europe, 

 Asia, and North America coincides closely 

 with that of the taiga vegetation. Fur- 

 bearers of the family Mustelidae are espe- 



