CLIMATIC CONTROLS OF THE MIDDLE MARSH ZONE IN THE BAY OF FUNDY

The ecological importance of Plantago maritima within a salt marsh on the Bay of Fundy is documented through measurements of cover, density, and biomass. During late August 1993, peak standing crops of Plantago were as high as 532 g m(-2), and composed as much as 96% of the bioma ss of a stand of vegetation. Plantago is a dominant component of the m arsh vegetation at an elevation just above the Spartina alterniflora-d ominated low marsh, and is found as a dominant when growing in associa tion with a number of plant species characteristic of the high marsh. We hypothesize that the existence of this community is dependent upon regular ice-shearing of Spartina patens, which would otherwise competi tively exclude Plantago. This hypothesis is supported by the elevation al limits of Plantago dominance and the geographical Limitation of Pla ntago communities to portions of the northwestern Atlantic subjected t o winter temperatures which average below 0 degrees C.