THE DEVELOPMENT OF COMMUNITIES 



321 



important species which take part in the process of development. 

 Even in temperate climates the transition stages are vastly more 

 numerous than the pioneer stages. On the other hand, in each chmat- 

 ically uniform region there is only one climatically hmited terminal 

 stage, only one climax. 



Phase. — Within the hmits of an association, stages of development 

 can be distinguished and can be fioristically and ecologically defined. 

 Speaking of developmental phases of the association, initial, optimal, 

 and retrogressional or terminal phases may be distinguished. The 

 static consideration of vegetation is generally based upon the optimal 

 phases of the associations studied. For dynamogenetic considerations 

 the initial and terminal phases are certainly equally important. The 

 terminal phase of one association (A) is often identical with the initial 

 phase of the succeeding association (B). 



Sere. — The series of genetically related, sequential stages which 

 follow one another regularly is called a "sere." A sere includes at 

 least one pioneer stage, usually several transition stages, and a terminal 

 stage. Whereas several or many seres may lead to the same end stage, 

 or one end stage may be common to several seres, the pioneer stages are 

 mostly different. Furthermore, each sere has a greater or smaller 

 number of transition stages pecuhar to itself. The independence of 

 the sere is measured by the number, the structure, and the duration 



Table 36. — Caricetum Firmae-Curvuletum Meadow Succession 

 Variant A Main sere Variants B and C 



Fcstuca violacca Caricetum curvulae 



Caricetum firmae Caricetum firmae typicum < . 



typicum 



f I I 



Sesleria ^ Drijas ^Carex mucronata Salix-Dryas 



cushion stage stage carpet 



11.1/ 



Thlaspeetum rotundifolii Weathered Hmestone 



(on Hmestone gravel) 



