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Baseline Technical <br />Report <br />ARCADIS <br />Report for Soils and <br />Biological Resources, <br />Cresson Mine Life Extension <br />Project Area <br />construction lumber, and were thus left standing when larger trees were logged <br />towards the end of the nineteenth century. <br />4.1 VEGETATION COMMUNITY TYPES <br />Descriptions of the vegetation community types that occur throughout the District and <br />the Study Area are described below. Appendix A includes the common name and <br />scientific nomenclature for each species identified within the Study Area. Taxonomic <br />names conform to Weber and Wittman (1996). <br />4.1.1 Aspen-dominated Woodland <br />Occurrences have a somewhat closed canopy of trees of 15 to 65 feet (5 to 20 <br />meters) tall, dominated by quaking aspen (Populus tremuloides). Conifers that may <br />be present but never codominant include subalpine fir (Abies bifolia), Englemann <br />• spruce (Picea engelmannii), Colorado blue spruce (Picea pungens), ponderosa pine <br />(Pinus ponderosa), and Douglas fir (Pseudotsuga menziesh). Conifer species may <br />contribute up to 15 percent of the tree canopy before the occurrence is reclassified <br />as a mixed conifer occurrence. Common shrubs found in the Study Area within this <br />community include serviceberry (Amelanchier alnifolia), common juniper (Juniperus <br />communis), and wood rose (Rosa woodsh). The herbaceous layers may be lush and <br />diverse. Common grasses may include blue wild-rye (Elymus glaucus), bearded <br />wheatgrass (Elymus trachycaulus), and Arizona fescue (Festuca arizonica). <br />Associated forbs may include yarrow (Achillea millefolium), larkspur (Delphinium <br />spp.), meadowrue (Thalictrum fendlen), fringed sage (Artemesia frigida), cinquefoil <br />(Potentilla ovina), and golden banner (Thermopsis Montana). <br />Distribution of this ecological system is primarily limited by adequate soil moisture <br />required to meet its high evapotranspiration demand, and secondarily is limited by <br />the length of the growing season or low temperatures. Climate is temperate with a <br />relatively long growing season, typically cold winters and deep snow. The mean <br />annual precipitation for most aspen dominated areas is typically more than 15 inches <br />(38 centimeters), except in semi-arid environments where occurrences are restricted <br />to mesic microsites such as seeps or large snow drifts. The mean annual <br />precipitation in the Study Area from 1966 through 2006 was 18.4 inches (Comer, T. <br />2008). <br />• <br />CCV Final Technical Report (3-28-08).doc 9