22 IPostelsia 



BroiJius paclficus Tanacetum huroneiise 

 A mm ode 111 (I Did jar Aster foliaceus 

 N'abiilits (licit lis Alia phut is subalpiiia 



Son eh us as per 



In very severe storms it may happen that 

 there is i^jrcat addition to, or a considerable 

 shifting of the (h^iftwood de})osit and when this 

 occurs, a readjustment of the society naturally 

 ensues. New conditions arise and a response to 

 these will show itself in new arrangements. The 

 beach at the head of San Juan Harbor is a com- 

 [)arati\ely wide sandy waste. Its slope is very 

 gradual and during high seas the waves wash 

 nearly up to the forest edge. Vegetation is 

 therefore extremely scanty and is confined to a 

 narrow strip of tlie l)ack beach where the most 

 typical plants are the following xerophytes:- 



Aira caryopliyUa Carex maeroeephala 



Deschampsia caespitosa Artemisia suksdorfii 



b. Small inlet beach. 



Upon the small sand beaches at the mouths 

 of ravines it is perhaps more difhcult to dif- 

 ferentiate between the front and back regions 



