THE BOGS AND BOG FLORA OF THE HURON RIVER 



VALLEY. 



EDGAR NELSON TRANSEAU. 



(WITH SIXTEEN FIGURES) 



[Continued from p. 375.] 

 THE BOG AS A HABITAT FOR PLANTS. 



WHEN we consider the bog as a habitat for plants, there is at once 

 brought to mind the marked contrast between its characteristics and 

 those of the other plant habitats of its vicinity. In both its atmos- 

 pheric and edaphic conditions it is unique. The various factors 

 entering into the plant environment will be discussed as physical, 

 chemical, and biotic agents. 



A. PHYSICAL FACTORS. i. Wind. Because of the fact that so 

 large a number of our bogs lie in depressions surrounded by hills, 

 the influence of the wind is somewhat lessened. It is only in the 

 case of the larger basins that its effects become marked. It has been 

 noted by several students of bogs (41, 5, p. 37; 59, 47) that in the 

 region of prevailing westerly winds the greatest development of bog 

 areas and peat deposits occurs on the western sides of lake basins. 

 Where the deposition has taken place in a large lake basin, which 

 is now only partially filled, we commonly find open water occurring 

 toward the eastern side. The peat deposits at Portage, Parks, and 

 West Lakes in the vicinity of Ann Arbor are massed on the western 

 shores, while the eastern margins exhibit an ordinary lake beach. At 

 the bogs north of Delhi, although nine- tenths of the original basin has 

 been filled, the two small lakes are near the eastern margin. The 

 facts noted in this region all favor the idea of the bog plants being 

 unable to gain a foothold on the eastern side in the presence of wave 

 action. The shoreward thrust of the ice is of importance at times in 

 this connection. 



Farther north in Michigan the wind frequently shows its extreme 

 effect in these bog areas in the presence of " windfalls." Owing to 

 the character of the substratum, such areas are more readily affected 



418 [DECEMBER 



