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• V. ASPEN CONIl1-IUNITY ASPEN COMNIIJNITY: GENERAL DESCRIPTION The aspen community is the second most prevalent vegetation community within the Sylvester Gulch study area and the mine permit area. It is predominant on terraces and tceslapes of mesic north and northwest facing slopes above the drainage bottom of Sylvester Gulch. Aspen communities aze found in close association with both the Douglas fir community at higher elevations within the study area and adjacent to the riparian community along the Sylvester Gulch drainage at lower elevations neaz the center of the study azea. The aspen community appeazs to require deep soils for maximum development and is associated with moderate to fine-grained deep colluvial mineral soils. This community also requires a mesic moisture regime, and is never located on steep sideslopes within the study area. Populus tremuloides (aspen) dominates the community, forming a tall open canopy above the understory of shrubs, graminoids and forbs. The understory contains four subdominant shrubs which form a medium level stratum from one to three meters in height. These shrubs include Amelanchier alnilolia, Quercus gambelu, Prunus virginiana, and Symphoricarpos rotundifolius. A low (<0.5 meter) herbaceous stratum is dominated by graminoids, • including Carexgeyeri (elk sedge). Numerous forbs are also present in the herbaceous layer, but collectively represent only one percent of the total vegetation cover. QUANTITATIVE SAMPLING RESULTS Aspen communities within the Sylvester Gulch study area were composed of dominant Populus tremuloides trees forming an open canopy. The understory was variable in both species dominance and composition. In one sample location the overstory of Populus tremuloides was relatively dense, occluding sunlight. At this location the shrub understory was nearly absent, and the low herbaceous layer was weakly developed. In the majority of locations, the canopy was more open (especially when compared with the oakbrush community) and both the understory shrub layer and the low herbaceous layer were both well developed. Amelanchier a/ni(olia, Quercus gambelu, and Prunus virgrtiana were the prevalent species in the mid-level shrub layer (1-3 m.). Carex geyeri dominated the low herbaceous layer, though many herbaceous species were present in this community (20 species total). Four lifeforms were encountered during the sampling of the aspen community. They included graminoids, forbs, woody shrubs, and trees. Thirty-four individual plant species were identified during sampling. Of the different lifeforms, five species were graminoids, fifteen were forbs, thirteen were shrubs, and one was a tree. The shrubs were divided into low, medium, and tall shrubs, with Mahonia repens and Paxistima • myrsinites (mountain lover) being characteristic of the low shrubs, Ribes parvi6orum (gooseberry) and Rosa rwodsii characterizing the medium shrubs and Amelanchier -12-