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May Day and Idaho Mine Complex 112 (d) Permit Application <br />tock grazing have converted much of the pure aspen occurrences to the present-day aspen- <br />conifer forest and woodland ecological system, with conifers increasing in dominance. <br />Threatened and Endangered Plant Species <br />The federal list of threatened and endangered (T&E) plant species for Colorado includes thirteen <br />species of which six are endangered and seven are threatened. Three species of concern are also <br />listed. Of these only one, the Knowlton cactus (Pediocactus knowltonii; endangered), is known <br />to occur in, and is listed for, La Plata County. This cactus inhabits pinyon juniper woodlands <br />with mixed sagebrush. This habitat is not present within the May Day Idaho Mine Complex <br />permit boundary. Therefore no T&E plant species are of concern for this project. <br />6.4.10(1)(b) Relationship of Vegetation Type to Soil Type <br />Soil type is reported by USGS as ten soil mapping units with a single unit, the Nordicol stony <br />loam, comprising the majority of the permit area (Exhibit I - Soils Information). This soil unit is <br />formed on sandstones of the Morrison Formation with slopes approximately 30-35° with wea- <br />thered sandstone predominate throughout the profile and topsoil generally less than 6" mixed <br />with weathered sandstone gravels and cobbles. The second significant soil unit is the floodplain <br />of the La Plata River where the Riverwash soil unit is formed from sandy and/or cobbly or gra- <br />velly alluvium. <br />As detailed above, the dominant vegetation is a mixed coniferous and deciduous forest with <br />. Douglas fir and quaking aspen as the dominant tree species. The vegetation within the flood- <br />plain is predominantly narrowleaf cottonwood with willow tree/shrub and blue spruce. Five ve- <br />getation types were mapped. <br />A comparison of soil types to vegetation types (Figure J-1) does not reveal any correlation be- <br />tween specific soil type and the vegetation type growing within it. <br />6.4.10(1)(c) Potential for Reclamation to Recreational Land Use <br />Reclamation of the affected lands will be to recreational use. For this land use, the disturbed <br />areas will be graded, seeded, and planted to match the surrounding natural topography and vege- <br />tation composition as much as practical. Exhibit E - Reclamation Plan details methods of recla- <br />mation and performance standards for post-mine revegetation. Since future land use is not range <br />or agriculture, an annual production or carrying capacity determination is not relevant. <br />6.4.10(2) Relationship of Vegetation Type to Topography <br />Exhibit C's Figure C-5 provides a map of existing vegetation within the permit area and includes <br />the existing topography. This section relates vegetation type to three aspects of topography: ele- <br />vation, slope, and orientation. The mosaic pattern of vegetation types within the May Day Idaho <br />Mine Complex does not seem related to elevation change other than within the La Plata River <br />riparian zone. The forested riparian vegetation type is only present at the lowest elevation. All <br />other vegetation types are present in relatively equal proportions at all elevation levels with no <br />May Day Idaho Mine Complex 112(d) Permit Application <br />September 21, 2010 <br />4