588 



THE COMMUNITY 



Bufo bufo bufo, and the like. It is less easy 

 to characterize the mixed hardwood forest 

 of eastern Asia by famiUar forms, partly 

 (and perhaps somewhat paradoxically) be- 

 cause this region is even more modified by 

 man than are Europe and Eastern North 

 America. 



Excluding the Tibetan Plateau and its 

 bordering ranges, the deciduous forest 

 biome of China and Manchuria merges at 

 the north with the Siberian taiga, to the 

 northwest is bounded by steppe and desert, 

 and to the south grades into the tropical 

 forest of the Oriental biotic region. Char- 

 acteristic large predators are the Man- 

 churian tiger (the largest of the tiger 

 races), various wildcats, and a true wolf. 

 Famihar herbivores are the large represen- 

 tatives of the red deer (and the wapiti), 

 and a smaller spotted deer related to the 

 South Asiatic axis deer. The musk deer, the 

 dwarf deer (Elaphodus), and the muntjac 

 by no means exhaust the Ust of deer that 

 take part in this forest biome. Pecuhar 

 types of moles and shrews, and forms of 

 the pan-Asiatic hedgehog, are to be found. 

 The bird Ufe of the east Asiatic temperate 

 forest is a rich and confused mixture of 

 migrants and permanent residents. Among 

 the latter the pheasants form a conspicuous 

 group, including the famihar Reeves, 

 golden, and silver pheasants as character- 

 istic forms. Amphibian and reptiUan hfe is 

 strikingly well developed in eastern Asia, 

 with numerous characteristic types related 

 phyletically to parallel forms in eastern 

 North America. These include pit vipers 

 (Agkistrodon) , chicken snakes (Elaphe) , 

 water snakes (Natrix), grass snakes 

 (Opheodrys), pond turtles (Clemmys), 

 and the Chinese alhgator, the only hving 

 congener of the American alhgator. Among 

 amphibians the giant salamander (Megalo- 

 batrachus) represents the American hell- 

 bender (Cryptobranchus) , and the fire- 

 bellied toads represent the otherwise Euro- 

 pean Bombina. 



THE GRASSLANDS BIOME-TYPE 



The great number of famihar terms ap- 

 pUed to grassland areas in various lan- 

 guages—steppe, prairie, plain, savanna, 

 campo, llano, pampa (often in the plural 

 form)— is an indication of the obviousness of 

 this major formation, made still more famil- 

 iar to man by the distinctive pastoral 



economy and pastoral (often nomadic) so- 

 cial structure developed in primitive 

 peoples and recognizable as late as the 

 cowboy era of the North American West 

 and conspicuous today in many grassland 

 regions of the world. 



The boundary between the deciduous 

 forest biome and the grassland biome, or 

 between grassland and taiga where these 

 formations meet, is often sharp and conspic- 

 uous, and the North American grassland 

 in particular has had much attention as 

 an integrated biome of great geographic 

 extent. Intergradation between grassland 

 and deciduous forest is mainly of the 

 nature of forest islands or even forest pen- 

 insulas enclosed or nearly enclosed by 

 larger areas of grassland, as in the river 

 border forests of the western affluents of the 

 Mississippi. Conversely, prairie peninsulas 

 also extend into generally forested country. 

 The transition from grassland to desert is 

 far more complex. 



The areal extent of grassland biomes, 

 when all the continents are considered, is 

 enormous, and the radical biotic (zoologi- 

 cal and botanical) diflEerences from con- 

 tinent to continent are extreme. Ecologi- 

 cally, these diflEerences are minimized by 

 the concept of ecological equivalence, 

 emphasizing the role of the species in its 

 community and biome, instead of phylo- 

 genetic relations or even general appear- 

 ance, as when the gregarious kangaroos 

 and wallabies are seen to be ecological 

 equivalents of the savanna and plains ante- 

 lopes (Table 35). 



Ecologically, the grassland biome exhib- 

 its surprisingly httle diflFerence in ap- 

 pearance in temperate and tropical regions. 

 Where rainfall is abundant and run-ofiF re- 

 tarded, the animal component of the grass- 

 land is extraordinarily conspicuous, with 

 species of herbivores of large size, vast 

 numbers, and gregarious habits, and attend- 

 ant carnivores. The potential exactness of 

 equivalence of grasslands is shown by the 

 flourishing Tertiary horse populations on 

 the American Great Plains, their disap- 

 pearance, and their prompt reestabhshment 

 from introduced stock in historic times. 



Either directly or with the intermediacy 

 of desert transition areas, the grasslands 

 are continuous from South Africa and 

 Senegal to Mongolia via Central Asia, en- 

 tering Europe proper in the steppe of 

 southeastern Russia. This vast Old World 



