283 



slopes quite gradually up to the highest point in the center of the 

 clump, from which the slope is more gradual down to the leeward. 

 After severe wind storms the leeward trail may be over a meter in 

 length. A change of wind, however, soon changes its position. 



During the winter the dead standing stems with their leaves pro- 

 tect the dune in a measure from ordinary winds and storms. On the 

 more open upper beach this protection is inadequate, and the return 

 of the growing season finds the sand level with some exposed roots 

 to show the former location of the Calamovilfa dune. But a short 

 time is needed to reconstruct the dune when the growing season is 

 once commenced. In less exposed situations the dunes persist over 

 winter. 



The Calainovilfa dunes are a conspicuous feature of the vegeta- 

 tion of the lake shore in the central part of the region, yet the dunes 

 are never large in size. They spread radially quite easily but they 

 do not grow very much in hight. A Calamovilfa dune a meter high 

 is uncommon. The usual altitude is from three to six decimeters. 

 Higher dunes are formed by plants whose ecesis can be accomplished 

 in a Calanwznlfa dune but could not have been on the normal upper 

 beach. 



The outcome of the growth of these dunes is usually the forma- 

 tion of a ridge running parallel with the line of wave action. As 

 additional ridges are built up nearer the lake, the Calamovilfa remains 

 as a relic along the crest of the ridge. In such places it sometimes 

 exhibits the growth form known as fairy rings. Succeeding associa- 

 tions, however, finally bring about its disappearance. The secondary 

 species of this association are very few in number and, in general, 

 unimportant in value. 



IvIST OF THE SPECIES OE THE CAEAMOVILEA DUNE ASSOCIATION 



Dominant vSpecies 

 Calamovilfa longifolia 



Invading Species 

 Andropogon scoparius Pctalostemmn purpurcnm f. arena- 



Prunus piimila rimn 



Elynms canadensis Quercus vehUina (rarely) 



Salix glancophylla Vitis vulpina (one plant, 3.5 meters 



Popuhis candicans long) 



THE AMMOPHILA ARENARIA DUNE ASSOCIATION 



Because there is so little sand carried from the lake, this associa- 

 tion of dune plants is very scarce in this region. Animophila arcnaria 



