8o 



VICTOR E. SHELFORD. 



within its limits there was throughout the summer season a 

 continuous stress rather than a series of violent extremes. On 

 the whole it shows a water demand of little more than half of 



Cottonwood dune 

 Pine dune -__._. 

 Oak dune 

 Beech -maple forest 



FIG. 2. Mean daily evaporation rates (cc. per day) in the ground stratum of four 

 of the animal communities. (Courtesy of G. D. Fuller and the Botanical Gazette.) 



that occurring in the cottonwood dunes. Its greatest divergence 

 is plainly due to the evergreen character of its vegetation and is 

 seen on its low range in May and the first part of June, and again 



