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June pre-dawn and afternoon water stress levels (Figures 8, 11) appeared to <br />be similar for all treatments. The data sugctest that pre-dawn water stress levels <br />as high as 14 bars, and afternoon water stress levels as high as 20-25 bars, <br />were not of sufficiently high levels to cause; enough stress to reduce survival of <br />these trees. <br />Moisture stress appeared to be less. with transplanted sprouts in the <br />irrigation experiment, including the un-irrig,ated controls, than with root sprouts, <br />potted plants, or natural sprouts in July and September (Figures 96 - 10B). It is <br />interesting to note that leaves appeared srnaller and terminal growth appeared <br />less on these apparent less-stressed transplanted trees (Figures 3 and 4), <br />suggesting that growth of root sprouts, potted plants, and natural sprouts was <br />not limited by the apparent higher moisture: stress levels they experienced. <br />Maximum leaf water potentials at mid-afternoon (Figure 11A, 11 B) found stress <br />levels of about 25 bars or less, levels that ,appeared unrelated to treatment, or <br />to growth and survival. <br />The growth data suggest that roto-cleared soil could have provided <br />additional nutrients or other benefits, perhaps mycorhizae, for tree growth. <br />Weed growth appeared greater on roto-cleared soil than dozer-cleared soil <br />(data not shown). Since we weeded around all monitored trees for this <br />experiment, weeds were not a competitor for the aspen in this study. <br />IV. Fencing -Fencing is necessary to obtain an adequate stand of aspen, <br />regardless of the sources of the trees. The unfenced Yoast site had severe <br />damage from ungulates (Table 1), including breakage of stems, browsing, and <br />rubbing damage. Most trees at this site hart some form of injury. Yet, growth <br />and survival of these trees was good (Figures 3B - 76), suggesting that the <br />undisturbed soil presence of an extensive parent root system is ideal for growth <br />of aspen. Nevertheless, fencing of these trees is recommended to produce an <br />adequate stand of mature aspen. <br />Conclusions: <br />I. Growth and survival did not appear to be related to irrigation treatment, likely <br />a consequence of the high rainfall during the 2005 growing season. <br />II. Best growth appeared to be on natural root segment sprouts on roto-cleared <br />soil. <br />III. Transplanted sprouts, regardless of irrigation treatment in this relatively wet <br />year, showed considerable transplant injury. Growth and survival was <br />relatively low and diseases were higher in transplant cutting plots. <br />IV. Potted aspen from nursery stock planted on dozer-cleared soil grew well. <br />V. Fencing is necessary to protect small aspen trees from browsing injury. <br />~o <br />