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May Day and Idaho Mine Complex 112 (d) Permit Application <br />Mixed deciduous and coniferous forests have a greater biodiversity than most other forests be- <br />cause of their multiple layers of canopy and dense understory. This creates a heterogeneous, di- <br />verse stand structure as can be seen in Table 2. Three plant species dominate the mountain <br />slopes of this landscape: Douglas fir (Pseudotsuga menziesii), quaking aspen (Populus tremu- <br />loides), and gambel oak (Quercus gambelii). Douglas fir is widespread throughout the entire <br />southern Rockies, where moisture is abundant. Douglas fir is not a true fir; it has similarities to <br />spruces and hemlocks as well as firs. Narrowleaf cottonwood (Populus angustifolia) and willow <br />(Salix sp.) are the dominant overstory vegetation interspersed with blue spruce in the riparian <br />zone along the La Plata River. <br />Table 2. Estimates of cover and height for principal species in vegetative life forms <br />• <br /> <br /> Cover* (%) height <br /> MCF MD/CF FR AF/MSM MSM <br />Tree 70 65 45 35 0 <br />Douglas fir 40 35 10 70-80' <br />Quaking aspen 20 35 25-35' <br />Ponderosa pine 25 75-90' <br />Limber pine 5 2 30-40' <br />Blue spruce 2 5 25-35' <br />Cottonwood 35 40-50' <br />Tall shrub 15 50 35 30 65 <br />Gambel oak 20 20 55 15-20' <br />Willow 20 <br />Rocky mtn 10 10 10 10 10 5-15' <br />maple <br />chokecherry 10 6-25' <br />serviceberry 8 8 15' <br />Low Shrub 10 40 15 50 40 <br />Wood's rose 2 1-2' <br />Mtn snowberry 5 24' <br />Grass" 20 30 20 10 10 <br />Herb** 20 20 25 10 15 <br />* Due to multi-tier vegetation cover, numbers may add to more than 100% ground cover <br />MCF = Mixed Coniferous Forest, MD/CF = Mixed Deciduous/Coniferous Forest, FR = Fo- <br />rested Riparian, AF/MSM = Aspen Forest/Mountain Shrub Mix, MSM = Mountain Shrub <br />Mix <br />* * The grass and herb understory was diverse in species without obvious dominance by few <br />species, a list of species present is in Attachment J-1. <br />Quaking aspen is serial in this system, and in the absence of fire, the system will succeed to con- <br />ifer-dominated forest (Mueggler, 19884). Nearly a hundred years of fire suppression and lives- <br />4 Mueggler WE 1988. Aspen community tunes of the Intermountain Region. Ogden, UT: USDA, USFS, Intermoun- <br />tain Research Station; Report nr USDA Forest Service General Technical Report INT-250. 135 p. <br />May Day Idaho Mine Complex 112(d) Permit Application <br />September 21, 2010 <br />3