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Section 779.19 (b) Continued. ~, J here are less well-developed, exhibited by shallower, lighter- colored A horizons which may partially account for the lower pro- ductivity. Treated Sagebrush vegetation type contains three major soil series, the Gelkie, Moraet, and Fluetsch. In 1963 this vege- tation type was sprayed with herbicide to kill sagebrush. Prior to treatment, Sagebrush-grass and Sagebrush-gravel vegetation types occupied the area. Production prior to treatment was predominately big sagebrush, estimated to be 65X of production with grasses contributing 19X (based on 1980 data). These soils now produce 68% grasses and 13% big sagebrush. Plant cover has remained about the same. The Coalmont series supports the Alkali Sagebrush vegetation type. Sagebrush plants growing on this site are low (6 cm) 1n height. Production is 476 lbs. per acre with 35% plant cover. This soil is only moderately deep with a sandy clay loam to clay textured soil and only slight development of the A horizon. The heavy texture of the B horizon presents a very restrictive layer for root penetration. Summary Historic data encompassing seven studies during four separate years from 1966 to 1979 for the Sagebrush-grass and the Alkali Sagebrush vegetation types averaged 758 pounds per acre at 45X cover and 399 pounds per acre at 37.3X cover, respectively. This compares favor- ably with the 1980 data of 709 pounds per acre at 40.9X cover and 498 pounds per acrea at 35.1X cover for the same vegetation types. Comparisons of studies is given in Table 28, Summary of Historic and 1980 Vegetation Data. Relative distribution of the vegetation types in the Kerr Mine Area is presented on Map 18, Kerr Mine Area Vegetation. In Table 31, Acreage of Vegetation Types Disturbed by Year, the number of acres which will be affected during the life of the mine is given. Four • of the seven vegetation types that occur within the proposed permit 779-75