ECOLOGY OF SALT MARSHES 



329 



become covered by an efflorescence of salt. An examination of the 

 distribution of the various communities on the Norfolk marshes 

 shows that five communities are each confined to one type of habitat. 

 This relationship may be due to: 



(a) Association with a particular phanerogamic community, e.g. 

 Phormidium autumnale (IX) and Ohione portulacoides. 



Shingle 



Escarpment 



Juncetuin 



Plantagetum 



Sea meadow 



General salt m. 



Obioneto-Staticetum 



Obionelo-Glvcerietum 



Obionetutn 



Late Asteretum 



Asteretum 



Creek Asteretum 



Salicornietum 



Sand 



Mud 



Pans 



o 



Fig. 197. Distribution of the algal communities in space at Scolt, Norfolk. 

 (After Chapman.) 



{h) Dependence upon certain edaphic conditions, e.g. Muddy 

 Chlorophyceae (Ic). 



(c) Dependence upon the physical character of the environment, 

 for example slope, exposure, wave action, e.g. Marginal Cyano- 

 phyceae (III), Vernal Ulothrix (IV) and the Pan Association (XVI). 



