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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 />Drier, less protected slopes support ponderosa pine forests. These forests are found throughout the <br />area's draws and slopes, with the exception of north - facing slopes (which support Douglas -fir forests). <br />Ponderosa pine trees are also found scattered throughout other habitat types. In well- defined stands, <br />ponderosa pine habitats are characterized by a relative cover of 60 to 85 percent, a litter cover of 25 to <br />35 percent, and bare ground averaging 25 to 30 percent. Other plant species found in ponderosa pine <br />forests include: Douglas -fir, red cedar, mountain mahogany, ninebark (Physocarpus monogynus), wax <br />currant (Ribes cereum), boulder raspberry (Rubus deliciosus), golden aster (Heterotheca villosa), <br />fringed sage (Artemisia frigida), and prairie sage. <br />Shrub - dominated plant communities are found in areas having a greater exposure to wind and soil <br />textures unfavorable to tree and grass growth. These conditions often exist on west and east - facing <br />slopes. Rocky outcrops also commonly occur in these habitats. The relative cover in a stand of "pure" <br />mountain mahogany is 75 to 95 percent. Mixed shrub - dominated communities also include: snowberry <br />(Symphoricarpos occidentalis), wax currant, skunk brush (Rhus aromatic), wild rose (Rosa woodsiâ–º), <br />and yucca (Yucca glauca). <br />A grassland plant community comprises the understory of many of the habitats listed above. <br />Grasslands also comprise the most extensive and diverse upland habitat at the Site. The habitat most <br />commonly manifests as a short-grass plant community with heights less than 1 -foot. Grass species <br />commonly found in this very diverse habitat include the following: crested wheatgrass (Agropyron <br />cristatum), smooth brome (Bromus inermis), needle and thread (Stipa comata), Canada wildrye <br />(Elymus canadensis), orchardgrass (Dactylis glomerata), side -oats grama (Bouteloua curtipendula), <br />blue -grama (B. gracilis), mountain muhly (Muhlenbergia montana), and cheatgrass (Bromus tectorum). <br />Forbs scattered throughout the grassland include: fringed sage, prairie sage, and broom snakeweed <br />(Gutierrezia sarothrae). <br />Another common upland plant community occupying significant portions of the area is previously <br />disturbed habitat. This habitat supports species introduced from Asia or Europe along with more <br />invasive native plant species. As mentioned above, the area's roadsides and the margins of settling <br />ponds comprise previously disturbed habitats. Species common in these areas include: gumweed <br />(Grindelia squarrosa), giant ragweed (Ambrosia trifida), burning -bush (Kochia iranica), goosefoots <br />(Chenopodium spp.), western ragweed (Ambrosia psilostachya), sticky aster (Machaeranthera <br />pattersonii), common mullein (Verbascum thapsus), musk thistle (Carduus nutans), sweet clovers <br />(Melilotus spp.) plantains (Platitago spp.), cheatgrass, Canada wildrye, and amaranths (Amaranthus <br />spp.). <br />Page 24 August 2011 <br />