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IRIS <br />MITIGATION AND DESIGN, INC. <br />SCHWARTZWALDER MINE PHASE 1 - UPSTREAM CUTOFF WALL AND LOW FLOW BYPASS <br />PIPELINE - BIOLOGICAL ASSESSMENT <br />4. ENVIRONMENTAL BASELINE <br />4.1 Overall Habitat Description <br />The Site is located in the foothills of the Colorado Front Range. The Site extends along 4,500 feet of a <br />largely undeveloped portion of Ralston Creek. Ralston Creek is located in a narrow valley formed by <br />foothills rising relatively steeply on either side (see Appendix B — Photo Log). <br />The Site is located in a transitional zone between the plains grasslands to the east and the lower <br />montane forests to the west. This transitional zone exhibits a relatively high diversity of flora <br />representing both grassland and lower montane forest plant communities. The diversity of flora is <br />further enhanced by the varied topography found at the Site. A mosaic of habitat types, including <br />riparian, grassland, shrubland, and forests, is found within a relatively small area. <br />The northeast- facing slopes and gullies are dominated by Douglas -fir (Pseudotsuga menziesii) forests <br />while the southwest and west- facing slopes are dominated by ponderosa pine (Pinus ponderosa) <br />forests. The south, east, and southeast - facing slopes tend to be dominated by the shrub species <br />mountain mahogany (Cercocarpus montanus) while grassland plant communities are found on all <br />slopes to varying degrees as an understory habitat. Grasslands comprise the primary habitat on less <br />steep gradients. As expected, a narrow riparian corridor of dense vegetation surrounds much of <br />Ralston Creek. An additional habitat type is best characterized as "previously disturbed habitats." <br />These areas are dominated by introduced and native weedy species that are able to rapidly colonize <br />disturbed areas and often out - compete more desirable native species. Previously disturbed habitats <br />are common along roadways and other areas where the soil surface has been disrupted. <br />4.1.1 Upland Habitat <br />As mentioned above, the north and north - facing slopes of the area support Douglas -fir forests. <br />Sheltered areas along the creek also support communities of Douglas -fir (see Figure 2 and Appendix <br />B). These forests tend to be quite dense, exhibiting a relative cover averaging 70 to 92 percent. The <br />forest floor is comprised of 45 to 65 percent litter and 15 to 25 percent bare ground. Other plant <br />species found in the Douglas -fir forests include: common juniper (Juniperus communis), ponderosa <br />pine, red cedar (Juniperus scopulorum), Rocky Mountain maple (Acer glabrum), mountain mahogany, <br />and prairie sage (Artemisia ludoviciana). <br />Page 23 August 2011 <br />