Southeastern Washington and Adjacent Idaho. 



with a consocies of yellow pine, above which, and still on the 

 north slope, the Festuca consociation continues. The atmometers 

 in the Agropyron community were installed about half way up 

 the bank of the canyon. Those in the pines were placed in a 



ST 



40 



fesfa 



V CO/ J3OCA if ion 



com oc/es 



3O 



25 





ZO 





fS 







N 



N 



FIG. 3. Evaporation rates in the Agropyron, Festuca, and Pinus communi- 

 ties at Colfax, Washington. 



similar position on the opposite bank, and about 60 feet beyond 

 these a station was established in the Festuca consociation. 

 Graphs of the data from these instruments have been plotted in 



Fig. 3- 



These graphs show a striking decrease in the evaporating power 

 of the air as the progressive stages of vegetational development 

 are approached. During 1912 preliminary measurements indi- 

 cated just such conditions in these communities. Stations main- 

 tained at Pullman during 1913, showed similar differences in 

 evaporation between the Agropyron and Festuca consociations, 

 while during 1914 further data at Colfax confirmed in general 

 the above results. 



23 



