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<br />6.2 Biology Monitoring <br />6.2.1 Terrestrial Vegetation <br />Pursuant to BlM and Colorado DMG requirements, vegetative production, and percent <br />crown cover were sampled in 1991 through 1998 for native undisturbed areas. As a result <br />of minimal change in production and cover from June to July, the June sampling was <br />discontinued in 1997-1998. <br />Circular Random Plots : The Total 1998 grass and forbs production was similar to 1995, <br />See Table 6-18 for 1992 through 1998 summary. July total production was above average <br />• as a result of above average precipitation. July open plots compared to July caged plots <br />indicated a difference of +12% for caged plots. Cattle were not on the mine site in the late <br />spring or summer of 1997-98, but many horses and rabbits were observed thus offering a <br />possible explanation for the difference between caged and open plots. Herbaceous <br />production (grass and forbs) per species is shown on Table 6-19, with western wheatgrass, <br />June grass, Phlox hoodii, and globemallow the most productive species. Figure 6-16 <br />illustrates 1993 through 1998 production for July open and caged (to exclude grazing). <br />Percent cover data for July caged compared to July open indicated minor differences (see <br />Figure 6-17). The percent cover of grass was higher when grazing was restricted and <br />shrubs, trees, bare, rock, and litter were lower as a result of higher density of grass. Forbs, <br />shrubs and trees were similar for caged and open plots. <br /> <br />84 <br />