208 



EDGAR NELSON TRANSEAU 



moner secondary species. In part they are remnants of the Jun- 

 cus-gerardi Association. The remainder are the fresh water 

 swamp pioneers. The evaporation in this association is only 

 two-thirds of that occurring at the outer margin of the salt marsh. 

 In the middle of the succeeding swamp formation the evaporation 

 is further reduced to one-third. The influence of the salt on the 

 relative humidity of the marsh air is very clearly indicated, for 

 the wetness of the substratum is about the same in both the marsh 

 and the swamp. 



T 



t 



riNE Bmo; forpation 



Prunua-n&ritinia Asoociation 



Annophlls Axoelatlen 



. futreme Vde Uiie 



— — f- Eaectaarls Attselation- 



Selrpua AeMelatlon 



• Xanthlum-Ati'lplcx Assoolatlan 



■o 



Hift Vd* Life 



Oasya AsMclation 

 Sand and Onrel 



Exposed 



Prat»(rt«d 



Fig. 8. Diagram to show the successional relationship of the several plant 

 associations. 



THE UPPER BEACH 



The AMMOPHrLA Association. Beyond the reach of the waves 

 except during violent storms lies the upper beach. The principal 

 agency concerned in its building and modification is the wind. Its 

 soil is uniformly sandy and only slightly saline. There is usually 

 some humus present. Deposition by the wind is often going on in 

 this formation, resulting in the building up of this belt as an ele- 



