Southeastern Washington and Adjacent Idaho. 31 
here, as at Colfax, the available water was exhausted somewhat 
earlier than in the summer of 1913. On July 14, 1914, and when 
the available moisture of the surface ten inches had been depleted 
in all habitats, samples were taken as usual at a depth of two 
feet in the prairie and fir-tamarack communities respectively. 
These showed that practically no water was available even at this 
depth. 
The relation of soil moisture to plant succession was likewise 
determined at the stations already described near Viola, Idaho, 
during 1913. The results are plotted in Fig. 8. These graphs 
Ss Sa Ce aN a WB, ae 
P2 ons 2) 
Bee 2Zewebs se) 
Bee ll: 
SHB Hest 
ace 
ae a ee es 
Fic. 8. Graphs showing the march of soil water to a depth of 10 inches 
in plant communities at Viola, Idaho. 
appear somewhat different from those at Kamiak. This is due 
in part to the longer intervals between readings. Also the fir- 
tamarack station was somewhat less mesophytic than that at 
Kamiak, but like the former, was covered with a second growth 
of Douglas fir and tamarack. Likewise, the pine community was 
of a much more open type than that on the sheltered base of 
Kamiak Mountain. The water holding capacity of the soil at 
31 
