GRASSHOPPERS IN RELATION TO PLANT ASSOCIATIONS. 147 



bery. In more open parts of the hardwood forest, and near the 

 edges of clearings, most of the grasshopper species that are 

 common in clearings were also found, in very small numbers, 

 however. 



Ravine Forest Association (Gates, '13: 66-70). This associa- 

 tion is best developed in the ravine occupied by what is locally 

 known as Big Springs. A number of springs, fed by the under- 

 ground drainage from Douglas Lake, to the north, form the head 

 of Carp Creek, which runs south to Burt Lake. The ground is 

 very wet, and is occupied by bog plants and deciduous forest 

 undergrowth. Trees are Tilia americana, Tsuga canadensis, 

 Fagus grandifolia, Ostrya virginiana, Betula lutea, Acer saccharum, 

 Abies balsamea. Succession has proceeded from the coniferous 

 bog forest toward the beech-maple association. Podisma gla- 

 cialis variegata, recorded from Carp Creek, probably was taken 

 in this ravine forest, Melanoplns islandicus probably also occurs 

 in the same association. 



Local Associations. 



Dry Beach Associations (Gates, '13: 55). Quite a number 

 of the strand plants of the sandy margins of Douglas Lake 

 belong to an assemblage which is characteristic of the sand shores 

 of the Great Lakes. Three of these independently form associa- 

 tions in the region. These are Elymus canadensis, Ammophila 

 arenaria, and PotentUla anserina. Elymus forms a low, narrow 

 dune about one eighth mile long, at the southeastern end of the 

 lake. It and Ammophila are found just above the level of wave 

 action at many places on the shore. Sandbars on the north 

 shore were partly covered by Potentilla growth. In these beach 

 associations the soil is pure sand, dry and shifting, with full 

 exposure to sun and wind. The vegetation is dry and scanty. 

 Grasshoppers typical of these situations are : Melanoplns atlanis, 

 M. angustipennis, M. bivittatiis, Camnula pellncida, and Disso- 

 steira Carolina. Two species not taken at Douglas Lake, Spharage- 

 mon wyomingianum (Thomas), and Trimerotropis maritima 

 (Harris), are very characteristic of beaches and dunes of the 

 Great Lakes ; both are recorded by Shull from the Saginaw Bay 

 region ('n: 225-226). 



Marsh Associations (Gates, '13). Communities of marsh 



