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Tree basal area averaged 219 cm2 (.24 sq. ft.) throughout all the stands <br />saaQled. The largest tree sampled had a basal area of 2884 cm2 (dbh = <br />60.6 cm). The age-size regression model for aspen would predict an <br />age of 184 years for this large aspen, the largest tree cored was. <br />116 years and average age of aspen fell in the range of 31-75 years. <br />Average height of the shrub strattan in aspen was 143.6 cm. The largest <br />shrubs were Gambel oak and chokecherry, 372.9 and 287.0 cm, respectively. <br />Shrub height was greater in aspen for individual species than in the tc.,o <br />major vegetation types on the study area, reflecting the increased <br />moisture regime in aspen. Average age of the shrub stratum was also <br />the highest within aspen stands on the study area. <br />Aspen areas on Seneca II were wnsidered a subtype within the mixed <br />brush vegetation type. All aspen areas sampled supported an understory <br />vegetation identical to that of the mixed brush vegetation type, thus <br />the aspen subtype did not require a specific reference area. The <br />reference area for the mixed brush type/aspen subtype vegetation type, <br />of which the aspen subtype is a part, was systematically sampled and <br />these results are presented in the paragraphs that follow. <br />The mixed brush type/aspen subtype reference area comprises approximately <br />4.7 acres and is located in an area not proposed for development just <br />off the southwestern edge of the study site (Map 1, Appendix A). <br />T~aenty~ne species were encountered in mover quadrats and the site had <br />a diversity index of 2.26. Total vegetation basal cover on the site <br />was 12.8, The grass stratum exhibited the highest percent basal <br />cover with 6.4~ as opposed to 3.0 and 3.4o basal cover for the forb <br />and shrub strata, respectively. Comrron herbaceous understory species <br />included slender wheatgrass (1.7°s cover and 52o frequency) and comcron <br />yarrva (1.2$ cover and 48% frequency). Snowberry was the frost comronly <br />encountered shrub on the control site (68~ frequency) and had the <br />highest basal cover of any shrub althouch both servioeberry and Gambel <br />oak evidenced higher canopy cover (14.9 and 12.30, respectively). <br />1 • <br />-58- <br />