2010-03-12_REPORT - C1981019 (8)

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intervention is provided. If mitigation in the form of herbicide treatment is initiated before the perennials totally succumb, then the expense of reseeding may be avoided. Therefore it is recommended that Colowyo task their weed control contractor to apply Oust or preferably Plateau in a very carefully controlled manner and at the appropriate time. The best time to spray is very late in the fall when only annual bromes are actively growing, and perennials (grasses, forbs, and especially shrubs) have become senescent. The next best time is very early spring, again when annual bromes begin to become active but the perennials are not. The Fall is a better time to spray for annual bromes because the window of opportunity (where the perennial vegetation is dormant and will not be affected by the spray) is longer than in the spring. Having a longer period to apply herbicide will facilitate better control and allow for a larger area to be sprayed. It has been Cedar Creek's experience that when appropriately applied for one or preferably two seasons in a row, annuals can be sufficiently repressed to allow the perennials an opportunity to recover sufficiently to then hold the annuals at or below the "threshold" level. It is also recommended that Cedar Creek review this unit during the two growing seasons following herbicide application to determine the efficacy of the effort. Recommendation # 2 - Increase Effort for the Control of Noxious Weeds This year (2009) was a prolific year for noxious weeds, particularly Canada thistle, throughout Colorado and Colowyo's reclamation is no exception. Observations of noxious weeds were noted in most areas monitored in 2009. This increase in noxious weed observations is most likely due to these unique conditions, but regardless of cause, extra effort will now be necessary to "reign in" the population before it expands and becomes overly problematic and costly to control. It was unclear to Cedar Creek biologists whether weed spraying had been completed at the time of our fieldwork, but certain observations indicated that it may not have been. For example, along the power line road through East Pit it was noted that only those noxious weeds within 20 feet (+/-) of the road had been sprayed. If weed control had in fact been completed for the season, then the weed control contractor needs to be made aware of the strong need to expand control efforts across all areas and portions of areas in the reclamation. Such extra effort should be budgeted for at least the next two years. Recommendation # 3 - Continue Monitoring CSU Experimental Shrub Plots Again, Cedar Creek's final recommendation is that the CSU experimental shrub plots should continue to be monitored annually and compared against success criteria to better track the value of experimental techniques and allow for modifications as necessary. This effort was initiated in 2005 with the establishment of ten approximately 0.1-acre subplots and then expanded to twenty subplots in 2006. CEDAR CREEK ASSOCIATES, Inc. Page 54 Colowyo Mine 2009 Revegetation Monitoring Report • t • • 0-9 • • • • • • • • • • • • • • • r r