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most saline (Figure 12), with an EC of > 3 dS/m for those plots receiving the highest <br />amount of irrigation. It is known that aspen trees are sensitive to saline conditions. EC <br />levels > 3 dS/m are considered saline. Our data confirm the findings of Van Cleve et al. <br />(1993) and others who found that saline soil conditions inhibited the growth of aspen. <br />The data suggest that care must be taken when deciding appropriate sources of water <br />for irrigation of plantings on reclaimed mine lands. Salinity of irrigation water should be <br />monitored before it is used. <br />Pre-dawn leaf water potential levels were only monitored on two occasions <br />during 2006 and these data indicate moisture stress was generally less than 8 bars (0.8 <br />mPa) pressure, and was not significantly different among irrigation treatments (data not <br />shown). Moisture was sufficient during most of the 2006 growing season that even the <br />non-irrigated controls did not seem to experience water stress conditions. However, <br />there were likely times during the season when moisture stress apparently limited <br />growth of aspen (see weeding treatment discussion below), but unfortunately we were <br />unable to schedule leaf water potential measurements during those times when rainfall <br />was limited. <br />Plant type: <br />The aspen saplings used in the irrigation study that were transplanted from the <br />Yoast site exhibited considerably more injury and had considerably more disease <br />infections than natural sprouts arising from buried root segments or potted plants in <br />2005, the first year after transplanting. However, the trees that recovered and survived <br />into 2006 showed little injury and disease during the second (2006) growing season <br />(data not shown). There were a larger number of branches (Figure 8b) and more basal <br />sprouts (data not shown) on natural sprout trees than on transplanted or potted trees. <br />Potted trees generally grew as well as transplanted trees; but potted trees grew less <br />than natural sprouts (Figures 6b, 8b, 9b), except for crown height (Figure 10b). Basal <br />caliper growth of potted trees, natural trees on fresh soil, and irrigated trees on stored <br />soil were similar (Figures 7a, 7b). Best basal caliper diameter growth was on low <br />irrigation or non-irrigated weeded trees on roto-cleared/fresh soil and on weeded natural <br />14 <br />