2010-03-12_REPORT - C1981019 (8)

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of shrubs protected inside the fence is almost twice the average cover of shrubs outside the fence (31.7% vs. 16.3%). In addition, the average density of shrubs inside the fence is substantially greater than the average density of shrubs outside the fence (6,942 vs. 4,661 shrubs per acre). Differences are more apparent with shrubs exhibiting greater palatability. Shrubs such as bitterbrush and Mountain big sagebrush exhibit three times the ground cover inside the fence versus outside the fence. To the contrary, a less palatable shrub, silver sage, exhibits higher cover and density outside the fence. Results provided in the following three paragraphs are based on full sampling from 2008, and are supported by data collected in 2009. Perusal of Table 9 and Charts 17 and 18 indicate that average shrub cover continues to increase in most of the treatments; however Treatment #2 (outside fence) and Treatment #5 (inside fence) saw a decrease in average shrub cover with no explanation other than potential sampling error. The average cover between fenced and unfenced areas was similar until 2002 when fencing was erected. Since 2002, cover values from inside the fence have been increasing faster than outside the fence. Perusal of Table 10 and Charts 23 and 24 indicates that shrub densities have generally been decreasing since initial sampling in 2001. This phenomenon is expected as shrubs become larger and the competition for nutrients, light, and water increases. Furthermore, confidence in the data from CSU's efforts is somewhat reduced given the sampling protocol utilized versus that utilized by Cedar Creek. CSU's sampling protocols incorporate a significant component of undetectable sampling error. Based on these interim results, it appears that 6 inches of topsoil with either one of the seed mixes has outperformed both the non-topsoil and 20 inches of topsoil treatments with respect to vegetation cover and shrub densities and diversity after eight growing seasons. Placing 18-20 inches of topsoil appears to benefit primarily annual and perennial grasses and in this regard increases erosional stability. Controlling access by native ungulates appears to noticeably increase cover (maturity) and densities of shrubs, however, populations of shrubs outside the fenced area are presently far above the success criterion for revegetation. However, results of this study should be viewed with caution as seeding of these plots coincidentally occurred in an "excellent" shrub recruitment year mine-wide (based on observed results for other revegetation efforts during this year). If these plots were seeded one year earlier or later, the shrub cover and densities most likely would have been considerably lower. Continued observation during the next few years will shed significant additional light on the progress of these populations over the longer-term. CEDAR CREEK ASSOCIATES, Inc. Page 33 Colowyo Mine 2009 Revegetation Monitoring Report