EEPHODTJCTIOlSr OF WESTERN YELLOW PINE. 



65 



TRANSITION ZONES. 



The above test applies to areas either well within the zone of 

 maximum root activity or entirely beyond the reach of tree roots, 

 that is, within a radius of 30 to 40 feet from living trees on one 

 hand and the same distance from the stumps of felled trees on the 

 other. Obviously there are transition zones intermediate between 

 these extremes. In order to secure some idea in regard to the effect 

 of cutting in different conditions of root activity, samples were 

 taken in 1919 at various points in transects extending from groups 

 of freshly cut stumps, across openings, and into groups of living 

 trees. Two such transects were made, one on a light limestone- 

 sandstone soil and another on a heavy clay loam derived from 

 basalt. In both instances from 75 to 80 per cent of the timber had 

 been logged off within a few months or a year previous to the soil 

 sampling. Wilting coefficients were not determined, and therefore 

 the results are expressed in terms of total rather than net available 

 moisture content. In view of this fact, care was exercised to secure 

 samples of apparently uniform texture, especially with reference 

 to clay content. This necessitated omitting a few of the selected 

 sampling points. 



Table 18. — Soil moisture in varimis sones of root activity. 



Limestone-sandstone soil, 1919. 







Total soil moisture, per cent. 





June 13. 



June 28-30. 



From trees. 



From stumps. 



6 inches . 



12 inches. 



6 inches. 



12 inches. 







10.1 



8.4 

 6.5 

 4.7 

 5.6 

 7.2 



7.0 

 4.6 

 4.3 

 3.7 

 3.8 



6.2 



90 feet west 



35 feet east 



4.9 



40 feet west 



85 feet east 



4.8 

 4.9 

 7.0 



4.1 



20 feet west just outside of crowns 



Under trees 





3.2 



120 feet east 



3.9 









Basaltic Clay loam soil, 1919. 



Distance of sampling points. 



Total soil moisture, 

 per cent. 



From trees. 



From stumps. 



June 14, 



depth 



6 inches. 



July 1, 



depth 



6 inches. 



55 feet west 



60feet east. .. . 



19.8 

 17.8 

 20.7 

 15.0 

 19.7 

 21.0 

 22.4 



14.2 



20 feet west just outside of crowns 



90 feet east 



14.6 



Under trees 





14.8 



20 feet east, just outside of crowns 



90 feet west 



11.3 



50 feet east 



60 feet west 



12.9 



80 feet east 



30 feet west 



18.0 



llOfeeteast 



In group of stumps 



19.7 









Note. — In both soils the moisture content is higher directly imder the trees than at a distance. This 

 is evidently due to shade. 



904°— 23 5 



