34 



A Study of the Vegetation of 



the butte-prairie and yellow pine communities. These data show 

 a marked relationship between the evaporating power of the air 

 and the stage of succession. Fuller (4, 5) has determined a simi- 

 lar relationship for the plant consocies which culminate in the 

 beech-maple climax forest. It is interesting to note in this con- 

 nection that the evaporating power of the air in the Thuja climax 

 forest is only slightly greater (0.5 c.c. daily in 1913) than that 

 of the beech-maple forest climax of the East. 



In order to further check these results, evaporation readings 

 were taken again in the cedars and fir-tamarack on Cedar Moun- 

 tain during 1914. To this series of stations was added one in a 

 very open yellow pine consocies on a wind-swept western slope. 

 The results are given in Table IV. 



TABLE IV 



SHOWING THE AVERAGE DAILY EVAPORATION RATES IN THE PINE, FIR- 

 TAMARACK, AND CEDAR COMMUNITIES DURING THE SUMMER OF 1914 



A record of the water content of the soils at the stations in the 

 cedars and fir-tamarack on Cedar Mountain was kept from June 

 14 to September 17, 1913. During 1914 this was repeated for a 

 period, and to this a record of the soil moisture at the station in 

 the pine community was added. The results are shown graph- 

 ically in Fig. 10. A glance shows that the cedars occupy by far 

 the most mesophytic habitat. The high wilting coefficient indi- 

 cates at once a fine textured soil with considerable organic matter. 

 A mechanical soil analysis (Table II) reveals just such charac- 

 teristics. This is in marked contrast to the coarse sandy loam of 

 the station in the pine. Likewise, a chemical analysis (Table III) 

 shows 13 per cent, of volatile and organic matter in soils of the 

 cedar community, and 8 per cent, in those occupied by the firs 

 and tamaracks. The water holding capacity of these soils is re- 

 markably high. It was found to be over 100 per cent, of their 



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