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increase, most notably the dominant westernwheatgrass (Agropyron smithii), which increased from 6.0% <br />cover in 1998 to 17.0% cover in 2001. Cover of non - noxious forbs declined over the course of the study <br />(from 8.0% in 1998 to 1.0% in 2001), mostly due to reduced cover of yellow sweetclover (Melilotus <br />officinalis), which contributed 6.0% absolute cover in 1998 and 1.0% absolute cover in 2001. Total <br />vegetation cover appears to have stabilized at around 50 %. <br />Reference Area No. 1 and Adjacent Reclaimed Flat Areas in Sutey Pile Vicinity <br />CONCLUSIONS <br />• Control program objective appears to have been met. Within the sampled reference area, density of <br />noxious weeds declined by over 85% between 1998 and 2001. <br />• A satisfactory vegetation cover has developed, dominated by perennial grasses. <br />• Perennial forb cover declined significantly between 1998 and 2001, but a number of desirableforb <br />species are present in the stand, at low levels. <br />• The biennials plumeless thistle and houndstongue are the primary noxious species remaining in the <br />stand, although at much lower levels than prior to initiation of control. A sparse scattering of Canada <br />thistle plants remain, at a level not detected by cover sampling. <br />RECOMMENDATIONS <br />• Suspend formal monitoring unless conditions change. Perform informal visual reconnaissance <br />monitoring late May /early June each year. <br />• Suspend chemical control with the exception of fall spot spraying of defined patches of Canada thistle <br />noted during annual visual reconnaissance. <br />• Consider continued mechanical control to prevent seed production of remnant noxious plants by <br />chopping with weed whip or other appropriate hand tools annually in late June /early July, possibly as <br />part of an organized group activity. <br />• Document control efforts annually. <br />CONCLUSIONS <br />CONCLUSIONS AND RECOMMENDATIONS <br />Reference Area No. 2 and Adjacent Sutey Pile Slope Areas <br />• The noxious weed reduction objective of the control program appears to have been met. Within the <br />sampled reference area, noxious weed density declined by approximately 75% between 1998 and <br />2001. Most of the decline appears to reflect reduction of the initially dominantplumeless thistle and <br />other biennial species, with minimal impact to Canada thistle. <br />• Several noxious species, including the perennial Canada thistle, and the biennialsplumeless thistle, <br />bull thistle, and houndstongue maintain a significant presence in the stand. <br />8 <br />