An Ecological Study of Buckeye Lake. 69 



lake. At each margin stands a large dead maple. Water at the 

 entrance is two feet deep and clear of vegetation, June, 191 1. 

 The associations included in the transect are : 



I. A zone with an association of floating and one of fixed 

 aquatics : A narrow fringing border, two feet wide, of Potamo- 

 geton lonchites associated with P. pectinatus, P. pusillus, P. zos- 

 terifolium and the floating aquatics Spirodela polyrhiza, Lemna 

 trisulca and Spirogyra sp. This zone is but poorly developed 

 and lies close to the shore. 



II. Mixed zone of high shrubs and marsh plants : This zone 

 covers a belt 30 feet broad and is very typical of the margin of 

 the island. An Alnus-Rhus society is the dominant one in the 

 shrub and a Typha latifolia in the marsh association. The soil 

 in the border, which is covered by the marsh and shrub associa- 

 tion, is of an entirely difl^erent consistency from that of the 

 Sphagnum mat. It is compact, has become compressed by the 

 weight of shrubs and trees and no longer responds to the alter- 

 ations in water level of the lake. Consequently when the water 

 rises in the lake it rises over the border of the island, and the 

 trees and shrub's at the margin stand in water; if this condition 

 continues long enough they are killed, hence the prevalence of 

 dead wood at the margin of many parts of the lake. On the 

 other hand, when the water sinks in the lake, the island margin 

 does not respond and a peat shelf is exposed. Depressions have 

 arisen in the shrub border by the permanent sinking due to 

 settling of the soil ; these are filled with water when the general 

 water level is high and become dry during periods of low water. 



The water in the depressions of zone II is from 6 inches to 

 I foot deep, and the surface is covered with a dense growth of 

 Lemna trisulca and Spirodela polyrhiza. At the bases of several 

 shrubs are small hummocks on which is a thin growth of Sphag- 

 num. At the extreme margin of the lake is a more distinctly Typha 

 border, interrupted, however, by a Rosa Carolina at the eastern 

 margin of the transect, several dead and one living Alnus 

 fugosa, two Rhus vernix and a clump of Peltandra at the 

 western margin, four small Cephalanthus occidentalis, the 



