ECOLOGICAL SUCCESSION OF MOSSES 213 



Succession, from the sedge mat to the climax. In some stages 

 mosses are relatively unimportant, while in others they form the 

 bulk of the vegetation. 



Mosses play an important part in the successional develop- 

 ment of the climax forest, their principal roles being the accumu- 

 lation of humus and conservation of soil moisture. 



Mosses are of the greatest successional importance as pioneers 

 upon the bare surfaces of the rock shores, in the sphagnum-shrub 

 stage of the Bog Succession, and in the climax forest, the num- 

 ber of species being few in all three cases. They occur in the 

 greatest number of species in the stage just preceding the climax 

 in both successions : the mesophytic boulder-cliff stage . of the 

 Rock Shore Succession and the bog forest stage of the Bog Suc- 

 cession. 



Calliergon Schreberi is the most widely distributed species, 

 and contributes more than any other moss to the establishment of 

 the climax forest, in both Rock Shore and Bog Successions. 



THE PLANT WORLD, VOL. 15, NO. 9, SEPTEMBER, 1912 



