FOREST COMMUNITIES 439 



erous forest or taiga. The northern limit is set by the summer warmth; 

 the southern depends on rainfall, absence of drying winds in winter 

 when the ground is frozen, and character of the soil, which favors 

 the growth of conifers if peaty or sandy. The leaves remain on the 

 trees the year around; the trees often carry nuts, berries, or seeds, 

 which are present above the snow for animal food. The coniferous 

 trees provide more shelter than the deciduous hardwoods. 



The coniferous forest is particularly liable to forest fires and has 

 been so in all ages. Now as in preceding periods they may be started 

 by lightning. The effects produced are of importance to the forest 

 animals, for in the burnt-over areas grow berry bushes of many sorts 

 which provide much food. Willows and birches are common along 

 streams, and poplars occur locally (also after fires), so that the forest 

 is not completely monotypic. Lianas and creepers are absent. 



Many animals of the deciduous forests extend into the northern 

 coniferous ones. The most important mammals are the ungulates, 

 rodents, and carnivores, with a few bats and insectivores. Deer are 

 characteristic; antelopes are absent. Contrary to usual opinion, the 

 wild ungulates are increasing in numbers in this region in America 

 since man has been holding the wild carnivores in check, and probably 

 there are more moose, caribou, and mule deer in these forests now than 

 when the white man first came. The distribution of many of these 

 animals is determined almost as much by the distribution of their 

 feeding grounds in forest openings as by the conifers themselves. 



Ungulates which occur in the tropical rain-forests are mostly small 

 with laterally compressed bodies which can glide through the tangled 

 plant growth. But those of the coniferous forest are large, often with 

 spreading antlers in the males, suggesting that they have only recently 

 moved into the forest. In both Canada and Eurasia one finds caribou or 

 reindeer, moose or elk, and representatives of Cervus (the red deer 

 in Europe corresponding to the wapiti in America). These are mainly 

 forest-browsing forms that eat twigs, leaves, berries, nuts, lichens, 

 and mosses, grass being a less important food. All may range south- 

 ward, but they find their best development in this belt. The woodland 

 caribou are larger than the barren-ground form of the tundra to the 

 north, being better fed and better protected. 



The important rodents are the squirrels, beaver, varying hares, 

 and Canadian porcupine. This last is largely arboreal, although it 

 nests on the ground. These northern forests show a paucity in true 

 cats, which are abundant in tropical forests. An abundance of mem- 

 bers of the weasel tribe replaces the tropical cats and civets. Bears 

 are characteristic, although they occur elsewhere. In both America 



