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of the plant. Different plants from each treatment were selected at each testing to <br />• minimize leaf loss from sampling. From 2 -3 total measurements were made from each <br />treatment each day of measurement. Number of measurements depended on the time <br />necessary for each measurement, so that all measurements fall within the dawn -time <br />window. Each day of measurements included leaves from all irrigation treatments. Size <br />of sampled leaf was recorded as length from tip to petiole (mm), and maximum width <br />(mm). An empirical equation was developed to relate width and length to actual leaf area. <br />Results (2005 -2006) -The first two years of the study have provided significant results <br />worth reporting here. Supporting data have been presented in earlier reports. The study <br />was initially conducted to demonstrate the effectiveness of supplemental irrigation on <br />growth and survival of transplanted cuttings; but additional experimental conditions <br />allowed examination of additional factors. Factors examined in the experiment were: <br />irrigation (four levels of watering), soil type (roto - cleared/fresh, dozer - cleared/stored, or <br />undisturbed), plant type (transplanted rooted sprouts, natural sprouts, potted plants) and <br />fencing (fenced or not fenced). Since not all treatment combinations existed and none of <br />the treatments were replicated, statistical analyses and inferences are limited. For <br />example, differences in growth or survival between Yoast, II -W roto- cleared soil sprouts, <br />and II -W irrigated treatments may be due to differences in soil disturbance, genetic stock <br />of aspen, transplant type, fencing, or microclimatic differences between sites, treatments <br />not independently replicated for this study. <br />This study was considered a case study relevant only for this one location. Nevertheless, <br />several observations were evident from the study that might be helpful for future aspen <br />management and to identify areas for additional research. <br />I. Irrigation treatment - For this experiment rainfall was plentiful and not typical for the <br />first two years during the study and soil moisture was relatively high even in un- irrigated <br />plots, as indicated by soil moisture matrix potential values and low leaf water potential <br />data for all treatments. This prevented a good examination of the irrigation treatment <br />effects. Aspen growth and survival did not appear to be dependent on, or in some cases <br />consistent with, irrigation treatment, suggesting that soil moisture from the frequent rain <br />events was sufficient even in the non - irrigated plots. The supposition of adequate <br />moisture available to all trees is further evident in that there appeared to be no <br />relationship between irrigation treatment and average leaf area, total leader growth, <br />terminal leader growth, stem diameter growth or caliper, or survival (data previously <br />shown in earlier reports). Growth of second, third, and fourth lateral branches appeared to <br />be similar for all treatments, but are reflected in total growth. Pre -dawn leaf water <br />potential levels also indicate moisture stress was generally less than 8 bars (0.8 mpa) <br />pressure, and did not appear to be related to irrigation treatments during the years when <br />these measurements were taken. <br />II. Transplant type -The aspen saplings used in the irrigation study that were transplanted <br />from the Yoast site exhibited considerably more injury and had considerably more <br />disease infections than natural sprouts arising from buried root segments or potted plant. <br />• Transplant shock was evident only the first year. Leaf area growth, leader growth, stem <br />