242 CLIMAX AND SERE 



biomes at their borders. No special terms to apply to the range of 

 animals seem necessary, since the significance of the few exceptions 

 to the usual rule can readily be discussed without them. 



The most illuminating facts in regard to the animals of a biome 

 are found in the relation to climax and sere and to permanent bodies 

 of water, such as rivers and large lakes that are not necessarily serai. 

 The relations of plants to early serai stages and to watercourses were 

 long ago recognized in Schimper's (1898) distinction between climatic 

 and edaphic communities. This stands in sharp contrast to the at- 

 tempt of Merriam (1890) and his followers to mix the two and use 

 edaphic or local climaxes species as indicators of life zones supposedly 

 based on temperature. Schimper's suggestions laid the foundation for 

 further development of succession and other dynamic ideas, while the 

 life-zone view has served to confuse values. 



Choice of habitat by each species of animal constitutes an im- 

 portant response, expressed chiefly by the term niche. While Elton 

 (1927) employs this word to sum up the relations to food and enemies, 

 so that it is largely synonymous with coaction, Grinnell (1928) and 

 Park (1931) used it in the sense of place. For purposes of locat- 

 ing the animal in the biotic community and defining its life habit, the 

 space relations, plant matrix, specific plants frequented, and soil and 

 water requirements are of first importance. INIany animals occupy 

 several minor habitats during their life history, a fact well illustrated 

 by the bobwhite, which according to Leopold (1933) requires some- 

 what distinct places for rest, sleep, nesting, drying young, and hiding 

 with and without snow cover, whereas the deer of the Lake States 

 requires five types of places for its different activities. Other animals 

 resemble the deer and bobwhite more or less in this respect, and hence 

 niche is often a compound space concept, to which role of food and 

 enemies must be added, and the term then becomes synonymous with 

 life requirements. 



The life requirements of many large influent species during the 

 yearly cycle include a series of different places, thus bringing them 

 into contact with most of the serai stages of the region and with the 

 climax. Such influents have been termed permeant. On the basis 

 of size, they may be divided into major and minor permeants. The 

 boundary line between major and minor is based on the inability 

 of the major influents to hide in vegetation, hollow logs, etc., while 

 minor influents can do so readily. Influents that are confined largely 

 to the serai stages may be termed serai, those confined to the climax, 

 climax influents. Further, because of the great difficulty of estimating 



