580 



INTERRELATIONSHIPS OF ORGANISMS 



they may continue to effect some changes in soil, shade, humidity, and 

 other conditions, are fitted to maintain themselves in the environment 

 they produce. Such a community is termed a climax and is stable and 

 self-maintaining so long as the general climatic conditions of the region — 

 the average seasonal rainfall and average seasonal temperatures — do not 



Fig. 33.15. The climax association of southernmost Florida. A tropical Everglades ham- 

 mock, showing the abundance of air plants (epiphytes), trailing vines (lianas), and palms. 

 (Courtesy Carnegie Museum, Pittsburgh.) 



change. In the region that surrounds the southern half of Lake Michigan, 

 for example, the climax community is a deciduous forest dominated by 

 beech and sugar maple. 1 By no means all of this region had developed 

 beech-maple forests or had reached this stage before modern civilization 



1 Actually this community comprises a considerable number of characteristic plants 

 and animals, but the beeches and maples and a few other trees largely determine the 

 peculiar complex of physical and biotic factors to which all the members of this com- 

 munity are adapted. 



