RESULTS 



Because of the sampling technique, the 1965-1966 sample provides only the relative 

 vertical distribution of root mass. Variation of root weights is high for layer 1 (table 

 1), as is to be expected in an open plant cover of widely spaced individuals. Coarse 

 and medium roots were more abundant in some sampling units than in others even though 

 sample columns had been located so as not to be directly beneath aerial plant crovms . 

 Root weights in layer V are also quite variable. Some units contained more of the 

 calcic, sometimes gravelly, horizon that begins in this level than others did. Layer 

 III, which is in a soil horizon homogeneous throughout the sample and deep enough to 

 be relatively free of the influence of plant spacing, is the least variable. Variation 

 in the seventh and deeper layers reflects the stratification and irregular calcification 

 of the alluvium. 



Weights of roots (by size class) and of other organic material in the three upper 

 levels sampled in 1970 are shown in table 2. Total root weights are similar for these 

 levels, but the proportion of coarse roots diminishes rapidly with increasing depth 

 (from 71 percent in layer I to 3 percent in layer III) . 



Fine roots constituted 16 percent of the mass of roots in layer I . They were much 

 more common in the lower part of this layer than near the surface. In layer II, fine 

 roots comprised 75 percent of the total roots and in layer III they were 80 percent of 

 the total roots. 



Because almost all coarse roots are near scattered shrubs, variation of coarse 

 root weights is high in the surface horizon and remains high in samples of this small 

 unit size (0.0113 m.^) for the three layers (table 3). Horizontal distribution of fine 

 roots is much more even at all levels. Because fine roots comprise the major portion 

 of the total roots in layers II and III, horizontal variability of total roots drops 

 off rapidly (fig. 1). 



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