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systems is necessary for aspen survival. A study has been funded by the Department of <br />the Interior, Office of Surface Mining (DOI OSM) National Technology Transfer Team <br />Applied Sciences Program, to complete this aspect of the study during the 2007 <br />growing season. <br />For 2005, all aspen trees were weeded (2m weed -free area around each tree) to <br />eliminate the effects of weed competition on aspen response to treatment. During the <br />2006 growing season a weeding treatment was added to the experiment. For the <br />irrigation experiment, the north 25 of each group of 50 trees on the roto - cleared soil and <br />the south 25 of each group of 50 trees on the dozer - cleared soil were left un- weeded. <br />Exterior sides were selected for weeding to avoid disturbance of the soil sensors which <br />had been located nearer to the middle of the study plot. For the natural sprouts growing <br />on roto - cleared or dozer - cleared soil, half of the trees were randomly selected for <br />weeding (2m weed -free area) while the other half remained un- weeded. Weeds were <br />removed mechanically. This allowed a comparison of the effects of weeding on tree <br />growth and survival. <br />• Natural sprouts were growing at random spacing, about 1 ft to 8 ft apart. Natural <br />sprouts selected for measurement were thinned to no closer than 5 ft spacing. The <br />potted and natural trees in all locations were from unknown genotypes, likely different <br />from the irrigated study transplants. Treatments examined are as follows: <br />1. II -W mine, fenced site 1, transplanted aspen plants, roto - cleared /fresh topsoil, <br />high irrigation <br />2. II -W mine, fenced site 1, transplanted aspen plants, roto - cleared /fresh topsoil, <br />medium irrigation <br />3. II -W mine, fenced site 1, transplanted aspen plants, roto - cleared /fresh topsoil, <br />no irrigation <br />4. 1I -W mine, fenced site 1, transplanted aspen plants, roto - cleared /fresh topsoil, <br />low irrigation <br />5. II -W mine, fenced site 1, transplanted aspen plants, dozer - cleared /stored <br />topsoil, medium irrigation <br />6. 11 -W mine, fenced site 1, transplanted aspen plants, dozer - cleared /stored <br />r� <br />U <br />topsoil, no irrigation <br />D <br />