226 



BOTANICAL GAZETTE 



[SEPTEMBER 



may 



regarded as a type. 



The climax beech-maple forest shows the accumulation of 



cm 



increased to 13.5 per cent at 



cm 



In this association the 

 only every second week, 

 but the graphs (figs. 24, 25) show a constant and generous supply of 



moisture determinations were made 



Fig. 24.— Graphs showing the range of soil moisture in the beech-maple forest for 

 191 1 ; the heavy line at 7. 5 cm. and the light line at 25 cm. depth; wilting coefficients 

 represented by broken lines. 



growth-water, indicative of truly mesophytic conditions. The 

 supply of growth-water is unfailing. As in the other associations, 

 the upper stratum shows the larger amount of variation. A com- 

 parison of the two seasons will show that, while the averages are 

 about the same, the year 1912 shows a much greater uniformity in 

 the range of the moisture supply. 



The results for the pra*irie association are more difficult to inter- 

 pret. The range plotted in lie. 26 is the mean of the two stations 



