26 COMMUNITY FUNCTIONS— DYNAMICS OF BIOTIC FORMATION 



CYCLE OF CAUSE AND EFFECT 



Physical Basis of the Biome. Probably the most important modi- 

 fication of concepts that ensues from the recognition of the biotic 

 community operates upon the current meaning of the term "habitat." 

 The accepted division of factors into physical and biotic has been 

 both logical and useful in the past, but with the rise of the biotic 

 concept this no longer holds. With plants and animals regarded as 

 essential constituents of the community, it becomes undesirable, if not 

 actually misleading, to refer to either as biotic factors. The word 

 factor should, in consequence, be restricted to the various physical 

 forces or conditions that constitute the habitat. Such use promotes 

 clarity of thinking as well as of expression, and accordingly is adopted 

 throughout the present treatment. 



The word habitat is deeply rooted in the practice of plant ecolo- 

 gists, but it has been variously applied by systematists and others. 

 It has been employed somewhat less frequently by zoo-ecologists, and 

 chiefly in application to an area with its plants or to the specific 

 "niche" of an organism. It is used here solely in relation to physical 

 and chemical factors. It would be desirable to secure greater uni- 

 formity of usage with respect to the complex of physical factors, to 

 which have been applied a variety of terms, such as habitat, environ- 

 ment, station, and biotope. 



A new term, not only free from these objections but also with 

 merits of its own, is suggested. Such a word is "ece," derived from the 

 Greek, oIko?, home, and already familiar in the derivatives eco- 

 nomics, ecology, ecesis, ecad, ecotone, etc. In addition to its brevity, 

 euphony, and significance, it combines readily with both Greek and 

 Latin stems, yields attractive compounds, and may be adopted into 

 any language without change. In actual use during the past seven 

 years, its value has become more and more apparent, and it bids fair 

 to be of distinct service in connection with the comprehensive analysis 

 of the habitat (Clements, 1925:321). At the same time, habitat 

 remains as a desirable synonym for a term in such constant use, while 

 environment still has a proper role in application to the total setting 

 of individual or organism. 



Nature of the Habitat. In accordance with the preceding, habitat 

 or ece comprises all the physical and chemical factors that operate 

 upon the community. Of these, water, temperature, light, and oxygen 

 are of vast importance to both plants and animals, and carbon dioxide 

 to all holophytes and a few chlorophyll-bearing animals. The raw 

 materials for food making by the plant are obviously ecial factors, 

 but food itself is not, either for animals or hysterophytes. As to the 



