COMMUNITY SUCCESSION AND DEVELOPMENT 



577 



land biome and the eastern deciduous 

 forest biome, the convergence may end in 

 either a climax prairie or in a climax forest 

 (Figs. 211 and 214)." 



With the principle of convergence in 

 mind, several general aspects of succes- 



synthetic productivity relationsliips, there is 

 (1) an initial, relatively brief period of 

 oligotrophy, followed by (2) a rapidly in- 

 creasing productivity until a eutrophic 

 equilibrium is reached. The duration of this 

 high productivity period depends upon the 



/ CLIMATIC 



RSH-»MOIST rOREST MARCIN-fcFOBEST MARGIN 

 OR THICKET * OR THICKET 



CthICKET- -■V THICKET ■ ROCK 



V 



■T — GRAVEL 



/ \/ 



Fig. 214. Diagram of convergence of seres in central North America in the forest-border re- 

 gion into either prairie or forest climax. Compare with Figure 211. (After Shelf ord.) 



sional phenomena deserve attention. In the 

 first place, some data suggest a correlation 

 of successional position with community 

 productivity and eflBciency. Lindeman 

 (1942) has suggested that productivity 

 increases in the early stages of a lake suc- 

 cession, or hydrosere, dechnes with senes- 

 cence of the lake community, and rises 

 again as the edaphic lake sere converges 

 in the terrestrial sere, through a bog forest, 

 and eventually into a climax forest (Fig. 

 215). That is, in terms of probable photo- 



** A discussion and evaluation of the details 

 of development, sere structure, and the as- 

 sociated nomenclature, lie outside the scope of 

 this book. This subject can be pursued by the 

 interested student in the following refer- 

 ences: Braun-Blanquet (1932), Cain (1939), 

 Clements (1928), Clements and Shelf ord 

 (1939), Cooper (1926), Du Rietz (1930, 

 1930a), Egler (1942), Gleason (1926), Han- 

 sen (1921), Klugh (1923), Nichols (1917), 

 Costing (1948), Phillips (1934, 1935), Shel- 

 ford (1931, 1932), Shelford and Olson (1935), 

 Smith (1928), Tansley and Chipp (1926), 

 Taylor (1927), Warming (1909), Weaver and 

 Bruner (1945), Weaver and Clements (1929), 

 Woodbury (1933). 



mean depth of the lake basin and upon the 

 rate of sedimentation. The plateau of high 

 productivity continues until (3) the lake 



OUGOTROPHY 



SENESCENCE 



Fig. 215. Hypothetical increase in productiv 

 ity in early stages of lake succession and de- 

 velopment in cold temperate regions; decline as 

 the lake becomes senescent, and increase again 

 as the edaphic hydrosere passes through a 

 bog-forest stage, and eventually into the 

 regional climatic climax forest. See also Figure 

 212. (After Lindeman.) 



community becomes too shallow for a 

 maximum growth of phytoplankton in the 

 upper strata, or the shallowness of the lake 

 prevents optimal regeneration of nutrients 

 from the bottom ooze. This decHne in 



