BIOME AND BIOME-TYPE IN WORLD DISTRIBUTION 



587 



salamander, Plethodon cinereus, to charac- 

 terize the "beech-maple chmax" (Fig. 163). 

 Various other widespread salamanders, such 

 as Ambystoma maculatum and Fletliodon 

 gliitinosus, range almost continuously 

 through this biome. A notable index form 

 among invertebrates is the purplish carabid 

 beetle, Dicaelus purpuratus. In fact, south- 

 eastern North America has preserved a 

 continuous forest through so long a period 



different in biotic composition. At the 

 south, the deciduous forest merges into 

 evergreen broad-leaved forest. It is evident 

 that the complexity and diversity of the 

 biome in question are produced by the 

 {listoric factor. The break-up of the rela- 

 tively continuous Cretaceous forest came 

 early in Tertiary times, and the isolation of 

 its fragments has given time for radical 

 changes by both evolution and extinction 



Fig. 221. Deciduous forest; summer scene with the white-tailed deer, characteristic in the 

 deciduous forest biome in North America. (From habitat group in Chicago Natural History 

 Museum. ) 



of geologic time that the ecological biome is 

 largely coincident with the faunal and floral 

 subregion of southeastern North America. 



The relative simphcity of the tundra and 

 taiga biomes (see, however, the account of 

 alpine and other montane zones, p. 592) 

 is lost in the biome type composed of the 

 deciduous forest biomes of the northern 

 hemisphere. For example, the extensive 

 areas of coniferous forest in the south- 

 eastern United States appear to belong with 

 the deciduous forest, for though the floral 

 distinction is sharp, faunal distinction, ex- 

 cept for monophagous invertebrates, is 

 weak. The deciduous forest of California 

 and British Columbia is isolated from that 

 of southeastern North America and is quite 



in the fragmentary areas preserved to 

 modern times. 



The major areas of deciduous hardwood 

 temperate forest are separated by areas in 

 both North America and Asia where the 

 taiga comes in contact with grassland. The 

 biotic composition of the European oak for- 

 ests is familiar, sometimes through literary 

 sources— the red deer, the roe deer, the 

 wild boar, the gigantic extinct aurochs, and 

 the all but extinct European bison are the 

 large and conspicuous animal forms. It is 

 scarcely necessary to point to the wealth 

 of amphibians and reptiles that characterize 

 the European deciduous forest, many of 

 which are types in the nomenclatural 

 sense—Salamandra salamandra salamandra. 



