464 



Succession and Fluctuation 



750 1760 1770 1780 1790 1800 1810 1820 1830 1840 

 Time in years 



160 

 140 12 



^ 80,000 



c 



Z" 60,000 

 o 



_g 40,000 



E 



5 20,000 



1930 



1890 1900 

 Time in years 

 Fig. 12.16. Population trends of the Canadian lynx (solid line) graphed against 

 sunspot numbers (dotted line). (Alee et al, 1949 after MacLulich, 1937.) 



modifications brought about by the hfe processes of the inhabitants in 

 their reciprocal relations with the environment cause ecological suc- 

 cession to go forward from the initial colonization of a new biotope 

 to the climax condition. The biomes of the world represent the per- 

 manent establishment of the principal climax communities in general 

 equilibrium with their environment. Within these generally main- 

 tained conditions, however, many seemingly regular and many ir- 

 regular fluctuations continually take place. 



