IQI2] 



BRIEFER ARTICLES 



425 



evaporation conditions at different levels in the same plant association 

 may permit plants to grow in close proximity with one another, and 

 yet, vegetating principally in different strata, to be subject to rather 

 widely different growth conditions. Evidence supporting this view has 

 also been furnished by Dachnowski 2 and Sherff 3 from observations 

 extending over comparatively brief periods, all of these observers work- 

 ing in swamp or bog habitats. 



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Fig. i. 



Diagram showing the average daily rate of evaporation in three strata 



of the beech-maple forest association for the growing season of 191 1. 



The present records were obtained during the season extending from 

 May 1 to October 31, 191 1, in some comparatively undisturbed beech- 

 maple forests about 45 miles southeast of Chicago near the little village 

 of Otis, Ind. The forest was of the usual climax mesophytic type. Its 

 vegetation and the methods employed in obtaining the evaporation data 

 by the use of the Livingston atmometers have been described in a 



2 Dachnowski, A., Vegetation of Cranberry Island. Bot. Gaz. 52:126-149. 



1911. 



Sherff 



Bot. Gaz. 53 "4* 5-435- l 9 12 - 



