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~, <br />.r,'. ~, <br />Mr. David Bcrry, CMLRD <br />September 10, 1990 -page 2 <br />The impact 2,4-D spraying of [his si[e will have on the long term viability of this reference area is uncertain. <br />[n the short term, one would expect an increase in herbaceous production and cover, primarily from native <br />grasses. Species diversity and woody stem densities would decrease significantly. The overall potential for <br />this area for livestock grazing purposes should be enhanced. <br />As outlined in Section 4.4.1.1 of Trapper's Mining and Reclamation Permit, the cover standard for success- <br />ful reclamation on disturbed areas (rangelands) is not based on a comparison with permanent reference <br />areas or premine areas rather an appropriate standard that soil loss due to sheet and rill erosion will not <br />exceed a maximum permissible value. Likewise, a woody stem density of 400 stems per acre is the estab- <br />lished criteria for woody density success on Trapper's reclaimed rangelands (permit section 4.4.1.3 pg 4- <br />126d). These standards have been reviewed and approved by both the Colorado Mined Land Reclamation <br />Division and the Colorado Division of Wildlife. Thus, the only comparable vegetation parameters to be <br />collected from permanent reference areas when evaluating reclamation success are production and species <br />diversity (abundance). <br />One could speculate that future sampling of herbaceous production and species diversity (abundance) could <br />differ significantly from past sampling results over the long term. Herbaceous production (primarily grasses) <br />would be higher without significant woody plant competition. Species diversity would be lower as the <br />increased vigor of grass species would suppress the reestablishment of fortis and woody plants. If permanent <br />reference areas are used for future vegetation comparisons with reclaimed lands, this potential variability in <br />sampling results should be taken into consideration. <br />David, please call if you have any questions or concerns. <br />Sincerely, <br />i~,~C~~ ~,~~ <br />William Agnew <br />Sr. Environmental Engineer <br />WA/jb <br />[CMLRDGSEPTIOA] <br />Enclosure <br />c: J.M. Mattern <br />W.S. Harding <br />R.L Fanyo <br />file <br />