EVAPORATION AND PLANT ZONES IN THE CEDAR 



POINT MARSH.* 



Paul B. Sears. 



Yappi in trying to account for the xerophytic structure of 

 marsh plants by means of evaporation studies has shown a 

 definite correlation to exist between the strata of marsh vegeta- 

 tion and rates of evaporation at corresponding levels. The 

 following studies were made in an attempt to discover what 

 additional correlations, if any, exist between distribution of 

 marsh plants and the evaporational power of the air at different 

 portions of the habitat. While the exact quantitative sig- 

 nificance of such work as the following may be brought into 

 question, as it often is, the striking results obtained by 

 Transeau,^ Livingston,^ Fuller,-* Weaver,^ Yapp,^ and others, 

 show that when such work is carefully done it is of unusual 

 efficiency, considering its extra-laboratory character. 



The studies were carried on in the strip of marsh between 

 Beimiller's Cove and Fred's Cove, at Cedar Point, Ohio. 

 The physiography of this region has been beautifully worked 

 out by Mosely," while we are indebted to Jennings^ for an 

 excellent account of the phytoecology of Cedar Point. A 

 glance at the accompanying maps^ will make clear the nature 

 of the region studied. It is a cove marsh along the inside of 

 the lengthy sand-bar (Cedar Point) which, forming across 

 the sunken mouth of the Sandusky River, has served to prac- 

 tically separate Sandusky Bay from the rest of Lake Erie. 

 Save for the occasional violent northeasterly winter gales 

 which have served to pile up Cedar Point, the prevailing 

 winds here are largely from the southern and western quarters 

 of the compass.^ 



Zonation is certainly the most obvious phenomenon of 

 plant distribution in the marsh, and was chosen as the feature 

 most profitable for investigation. Beginning with the outer- 

 most zone of severely exposed vegetation the following clearly 

 defined zones are encountered in order: 



* Contribution from the Botanical Laboratory of the Ohio State University, 

 No. 93. 



91 



