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sprouts on dozer-cleared/stored soil (Figures 7a, 7b). Survival was different by plant <br />type, and was particularly influenced by weeding for natural sprouts (Figures 11 a, 11 b). <br />Soil type: <br />Roto-tilled/fresh soil provided sufficient natural sprouting during 2005 to provide <br />an adequate stand of aspen trees, and these trees (when weeded, see below) grew <br />better and survival was higher than adjacent transplanted trees growing in the same <br />soil. Dozer-cleared/stored soil had considerably lower numbers of natural sprouts than <br />roto-cleared/fresh soil, and stocking was sparse (data not shown). Average leader <br />growth was higher for natural sprouts on dozer-cleared/stored soil than irrigated trees <br />on the same soil (Figures 6a, 6b), but crown height was similar (Figures 10a, 10b). <br />Leader growth (Figure 6a), basal caliper (Figure 7a}, crown height (Figure 10a}, and <br />survival (Figure 11 a) of trees were considerably less on dozer-cleared/stored soil than <br />on roto-cleared/fresh soils for the irrigation experiment. These differences cannot be <br />attributed to salinity, since EC of both soils responded similarly to irrigation with the <br />highest EC occurring under the highest irrigation treatments (Figure 12). Whether the <br />growth difference is due to soil type, the storage of the soil before placement at the site, <br />or any compaction/drainage differences of the two soil types is unknown. <br />Other than higher EC and pH in irrigated soils, soil chemistry analyses appeared <br />to show no large differences that might be attributed to irrigation treatment or soil type <br />(Figures 13-21). Perhaps most noticeable was the higher potassium and zinc in the <br />undisturbed aspen stand soils. Soils examined in this study were not sodic (SAR >12, <br />data not shown). <br />Weed control: <br />Weed control during 2006 had a major influence on growth and survival of aspen. <br />Soil moisture was higher in the weeded plots (Figures 4b, 5a, 5b), suggesting more <br />water was available to the aspen trees for growth when trees were weeded. Soil <br />moisture was somewhat higher at 20 cm depth than 40 cm depth for roto-cleared/fresh <br />soils compared to higher moisture at the greater depth for dozer-cleared/stored soils <br />15 <br />