Southeastern Washington and Adjacent Idaho. 33 
the principal trees, but a considerable amount of white fir and 
some spruce (Picea engelmanni) are also present. The under- 
growth is rather sparse. 
The evaporation in the cedar forest was always lower than that 
in the preceding developmental communities. The data taken in 
the cedars are shown in Fig. 9. Those of the other forest sta- 
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Fic. 9. Combined he showing the average daily evaporation rates 
at all the stations in the prairie, pine, and fir-tamarack communities on the 
buttes and mountains. The lowest graph gives the average daily evapo- 
ration in the Thuja consociation. 
tions are shown combined with all other readings taken in the 
fir-tamarack forest. For the sake of comparison, the chart also 
gives combined graphs showing the average evaporation rates in 
33 
