Bui. 1227, U. S. Dept of Agriculture. 



Plate III. 



Fig. I. — Under Total Protection. 



The difference in the number of fruiting heads under protection and under rodent grazing 

 indicates the difficulties of propagation by seeds when prairie dogs are present. 



Fig. 2. — Under Grazing by Prairie Dogs. 



The grass is thinner and poorer than under protection from the rodents. The background in 

 this figure and in Figure 1 is numbered in feet. 



WHEATGRASS (AGROPYRON SMITHM) UNDER TOTAL PRO- 

 TECTION AND UNDER GRAZING BY PRAIRIE DOG3, COCO- 

 NINO, ARIZ., OCTOBER 29, 1920. 



