This result can only have become possible through higher protein production per 

 unit of soil water available for plant growth. Increasing nitrogen concentration and 

 protein formation per unit of water transpired would have been favoured by heavier 

 defoliation (Trumble, 1952), and the greater concentrations of livestock might also 

 have tended to enhance nitrogen enrichment of the soil per se. 



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*i<gt^^ia» 







Figure 6. 

 Heavily grazed bluebush in foreground showing active regeneration of bluebush; moderately 



grazed plot with less regeneration in background. 



139 



