A Study of the Vegetation of 



Fig. 4 shows the comparative average daily evaporation rates 

 during 1913 in the three communities, respectively. These data 



FIG. 4. Average daily evaporation rates in the Agropyron, Festuca, and 

 Pinus communities during 1913. 



are averages of six stations located in the several communities. 

 The water content of the soils at the preceding stations at Col- 

 fax is indicated in Fig. 5. . A glance shows that the soils covered 

 by the Agropyron consociation had at all times the lowest avail- 

 able water content. Those of Pinus and Festuca communities 

 are approximately the same, and indeed this condition has been 

 found to exist elsewhere in several similar situations. Isolated 

 determinations at the same stations at various intervals during 

 the following season showed a similar water content relationship. 



KAY 



AU1US7 



c on SOL 



ic/f/o, 



-7 LUf 



const 



\ 



\ 



FIG. 5. Graphs showing the march of soil water to a depth of 10 inches 



in various plant communities at Colfax, Washington. 



24 



