SYNTHETIC CHARACTERS OF THE COMMUNITY 



65 



factors than the indifferent species, they react to much hner differences 

 and are therefore more precise indicators of the optimum conditions 

 for the community. An example of this would be the distribution of 



JnH-ial-Phase 



OpiimahPhase 



Consfani species 



o 

 o 



1 

 4 



6.8 5.7 J.6 6.5 J.V 6.3 5.2 5.1 6.0 ^.9 V.(J V.7 VSpH 

 Fig. 38a. — Idealized curves of the constant and the characteristic species in the 

 Curvuletum: Heavy line, normal facies; light line, Campanula scheuchzeri-Alchemilla 

 glaberrima facies. Each circle and each triangle represent a stand examined. {Braun- 

 Blanquet and Jenny.) 



the characteristic species and of the species of highest degrees of 

 constancy of the Caricetum curvulae and the Elynetum in relation to 

 such a dominant factor of the habitat as the soil reaction (Figs. 

 38a, h). 



6.0 



5.5 



5.0 ^.8 V.J 



V.<7 

 PH 



Fig. 386. — Curves for the pH variations for Carex curifula (I), and for the Curv- 

 uletum (//). (Tests from 100 individuals or stands.) Ordinates, frequency; abscissae. 

 pH values. {Braun-Blanquet and Jenny.) 



From the shape of the curve it is seen that the greatest accumula- 

 tion of the characteristic species occurs on soils of pH 5.1 to 4.6. This 

 optimum of the association corresponds to the optimum of the 

 dominant species Carex curvula, as determined by 150 pH tests (Fig. 



