RESEARCH METHODS IN STUDY OF FOREST ENVIRONMENT. 89 



2. The group averages for the loamy spruce soils and the granitic 

 gravels are essentially the same. It therefore seems entirely legiti- 

 mate to consider both groups together and, as shown in diagram 4, 

 to express the relation of wilting coefficient to capillarity by a straight 

 line. The nineteen cases show an average variation of 0.0333 from 

 the mean ratio of 0.202, or 16.5 per cent variation. 



3. Both from its mean value and from the fact that the graph 

 which expresses this relationship passes through the main axis of 

 the system of coordinates it is evident that the capillary moisture as 

 it has been measured by the method described above is an entirely 



MEAN 













































DIAGRAM 4 



RELATION OF 



WILTING COEFFICIENT TO CAPILLARY MOISTURE 



IN 10 SPRUCE SOILS AND 9 GRAVELS 



LEGEND 



2.75 Humus percentage 

 O SPRUCE GRANITIC LOAMS 



6 50 Solutes,ppm of soil wi 

 o GRANITIC GRAVELS 

















































































o 



I1S0 



cnl 

























; 



1 

















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J 











































u I 











































i - 















II U 





'o 15 























g 







fc 5!L«- 



6I> 



55 





























-s I 







*"no 



M5 

































£ ^ 



IB 



































^ri 



\l ifi 2 



'■ ! 



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A i 



cLiii, 



iry 



1oist 



1 t 



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; 5 



•erce 



2 5 



nt. 



6 i 



6 



S « 



8 1 



z 7 



4 .» 



> a 







different expression from that used by Hilgard and by Briggs and 

 Shantz. 



4. The relatively high wilting coefficients of the loamy soils having 

 the largest humus contents are believed to result from experimental 

 errors, largely unavoidable, and due to the lack of capillary con- 

 ductivity in soils which are particularly loose. This lack permits a 

 seedling to succumb in one region of the soil, while there may be 

 considerable free moisture elsewhere. The two gravelly soils which 

 show similarly high willing coefficients also have high moisture 

 equivalents, and it is thought from this that they were probably 

 richer than usual in permeable feldspar, which could not hold much 

 water hut would probably hold it very firmly. 



