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• moisture matrix potentials for all treatments (Figure 2). Aspen growth and survival <br />did not appear to be dependent on, or in some cases consistent with, irrigation <br />treatment, suggesting that soil moisture from the frequent rain events was sufficient <br />even in the non-irrigated plots. The supposition of adequate moisture available to all <br />trees is further evident in that there appeared to be no relationship between irrigation <br />treatment and average leaf area (Figure 3A), total leader growth (Figure 4A), <br />terminal leader growth (Figure 5A), stem diameter growth or caliper (Figure 6A), or <br />survival (Figure 7A). Growth of second, third, and fourth lateral branches appeared <br />to be similar for all treatments and data are not shown, but are reflected in total <br />growth (Figure 4A). Pre-dawn leaf water potential levels also indicate moisture <br />stress was generally less than 8 bars (0.8 mPa) pressure, and did not appear to be <br />related to irrigation treatments (Figures 8A -11A). <br />Transplant 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 <br />(Table 1). Leaf area growth, leader growth, stem diameter growth, and survival were <br />considerably less with these plants than with natural sprouts or potted plants. <br />(Figures 3A - 7A, compared with 36 - 7B, note differences in scale of A and B <br />plots). Potted plants survival was 100% (Figure 7B); but growth (Figures 4B, 5B, <br />66), although apparently not as good as natural sprouts, appeared better than <br />transplanted cuttings (Figures 4A, 5A, 6A). Natural sprouts on fresh or stored soil <br />had only one terminal leader with no lateral shoots. <br />Soil type: <br />Fresh soil provided sufficient natural sprouting to provide an adequate stand of <br />aspen trees, and these trees appeared to grow better and survival appeared higher <br />than adjacent transplanted trees growing in the same soil. Stored soil had <br />considerably lower numbers of natural sprouts than fresh soil, and stocking was <br />. sparse (data not shown). Natural sprouts appeared to have greater total leaf area <br />