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Natural sprouts were growing at random spacing, about 1 ft to 8 ft apart. Natural sprouts selected for measurement were thinned to no closer than 5 ft spacing. The potted and natural trees in all locations were from unknown genotypes, likely different from the irrigated study transplants. Data Collected - Prior to bud break, height of each tree, number of branches, disease and insect infestation, and length of terminal leader dieback was recorded for each tree. Water status and tree growth were measured periodically throughout the experiment. Physical measures of growth were height (cm), basal caliper (mm), number of basal sprouts (count), length of the terminal leader (cm), and length of each of the next three sprouts on upper portion of tree (cm). Disease and insect infestation were recorded again at the end of the growing season. Water status, or leaf water potential, of the plants was measured on June 22, July 21, and September 20 as near to dawn as possible (''/z hr predawn to''/2 hr after sunup) to capture the minimum stress before rapid morning transpiration has depleted leaf moisture. One afternoon measurement was also conducted on August 18 to indicate maximum stress under high radiation loading when transpiration would be highest. Treatment, ambient temperature, time of sampling and exuding pressure level was recorded. Leaves were collected from the different treatments at random to minimize time of sampling biases. Leaf water potential will increases as water is withheld from the plant and plant water stress increases. Water status measurements required removing one fully matured leaf randomly selected from trees in each treatment and measured for water holding capacity using a Plant Water Status Con:;ole. The leaf was removed from the plant and immediately placed in a sealed chambs~r with the petiole extending through a sealing hole in the chamber. A fresh slightly anctled cut was made and nitrogen gas was delivered to the leaf under slowly increasing pressure until water exudes from the petiole surface. The pressure necessary for this to occur is an indication of the leaf water potential or water holding capacity of the leaf, an indication of the water stress and thus physiological stress of the plant. Different plants from each treatment were selected at each testing to minimize leaf loss from sampling. From 2-3 total measurements were made from each treatment such day of measurement. Number of measurements depended on the time necessary'for each measurement, so that all measurements fall within the dawn-time window. Each day of measurements included leaves from all irrigation treatments. Size of sampled leaf was recorded as length from tip to petiole (mm), and maximum width (mm). An empirical equation was developed to relate width and length to actual leaf area. Results -Although the study was primarily conducted to demonstrate the effectiveness of supplemental irrigation on growths and survival of transplanted cuttings, several conditions were actually examined: irrigation (four levels of watering), soil type (roto-cleared, dozer-cleared, ar undisturbed), plant type (transplanted rooted sprouts, natural sprouts, potted plants) and fencing (fenced or not fenced). Since not all treatment combinations existed and none of the treatments were replicated, statistical analyses and inferences are limited. For example, differences in growth or survival between Yoast, II-W roto-cleared soil sprouts, and II-W irrigated treatments may be due to differences in soil disturbance, genetic stock of aspen, transplant type, fencing, or microclimatic differences between sites, treatments not independently