44 



The Botanical Survey of Nebraska 



As has been shown conclusively for plains and prairie plants (and 

 investigation will probably show the same holds true for many 

 forest trees) root systems are so much more extensive than here- 

 tofore supposed that too much emphasis should not be placed 

 upon the water content of the surface layers of soil, and certainly 

 not to the degree of neglecting the deeper substrata. Soil mois- 

 ture of the deeper soils is given in the following table. 



TABLE 7 



Total Water Content of the Soil in the Several Forest Communities 

 AT Depths of i to 2, 2 to 3 and 3 to 4 Feet, at Peru, 1917 



Bur oak. . 

 Black oak . 

 Red oak. . 

 Linden. . . 



Bur oak. . 

 Black oak . 

 Red oak. . 

 Linden. . . 



Depth 



l'-2' 

 l'-2' 



2-3' 



2'-3' 



2-3' 

 2'-3' 



July 19 



18.9 

 14.4 

 22.6 

 22.8 



17.7 



15-6 

 20.7 

 23.8 



July 31 



15-8 



13-6 

 16.3 

 18.2 



12.9 

 14.1 

 16.7 

 19-3 



August 18 



12.4 

 II.4 



iS-i 

 16.0 



10.7 

 II. I 



15-9 

 16.1 



Sept. 5 



14.9 

 10.4 

 12.7 

 13-7 



12.8 



9.6 



13-0 



14.9 



July 31 



4-5 



Bur oak. . 

 Black oak. 

 Red oak. . 

 Linden. . . 



12.9 



15-4 

 19.9 



10.7 



13-4 

 15.8 

 18.7 



At depths of 3 to 5 feet the soil moisture increases gradually 

 but directly from bur oak to linden forest. Indeed this holds true 

 throughout every determination and at all depths indicated except 

 in the case of the black oak at depths of i to 3 feet, where the soil 

 is usually of lower moisture content than in the bur oak forest. 

 Indeed this may be the prevailing condition, and only further soil 

 sampling can determine this point. However, from all other evi- 

 dence the writers feel quite certain that future determination will 

 show this consocies to conform to the general law of increasing 

 soil moisture content as succession progresses. 



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