32 A Study of the Vegetation of 
this station in the fir-tamarack community was 60 per cent., that 
of the prairie and pines about 45 per cent. On August 14, 1914, 
the water content at each station was found to be somewhat 
lower than on the same date of the preceding year. Samples 
taken to a depth of 3 feet in the prairie showed that all of the 
available water had been used. Indeed, at this time, practically 
all of the vegetation except Hoorebekia racemosa, Solidago mis- 
souriensis, Carum gairdneri, and a few other serotinal bloomers 
had dried up. An examination of the root-systems of numerous 
prairie species shows, however, that many of them obtain water 
at much greater depths than 3 feet (Figs. 15a, 15b, and 15c). In 
the underlying rocky soil on this butte itis probable that consider- 
able water ‘was still available at this date. Because of the rocks, I 
was unable to secure samples at greater depths than 2 feet in the 
pine community, but these soils on August 13, 1914, were even 
drier than those in the prairie. Likewise, the deeper soils in the 
fir-tamarack community were very dry. 
The close similarity in water content between the soils of the 
prairie and pine communities is just what one might expect when 
the latter consocies was still quite open and only small amounts 
of organic matter had been added to the soil. There is a close 
similarity between these graphs and those obtained at Colfax in 
communities of about the same stage of development. 
In order to determine the relation between the evaporating 
power of the air and the water content of the soil in the cedar 
community as compared with earlier stages in succession, a Series 
of stations was maintained on Cedar Mountain during the sum- 
mers of 1913 and 1914. A station was maintained in an area of 
the climax cedar forest which occupied a north slope and a ravine 
through which flows a small stream. This forest is over 95 per 
cent. pure cedar, mostly large trees from 2 feet to more than 3 
feet in diameter. The rest of the trees are large white firs, most 
of which are dead. The characteristic undergrowth of meso- 
phytic shrubs and herbs need not be described here. 
About 700 feet beyond the station in the cedars and occupying 
a slope somewhat above the latter, a station in the fir-tamarack 
community was maintained. The Douglas fir and tamarack are 
32 
