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• (Figures 5a, 5b), perhaps suggesting poorer drainage of the dozer - cleared /stored soil <br />type. <br />Trees that were weeded generally had greater leader growth and higher basal <br />caliper growth than un- weeded trees for the irrigation experiments (Figures 6a, 7a), <br />particularly on the roto - cleared /fresh soils. Growth differences were not as evident for <br />number of branches, caliper at the base of the crown, and crown height (Figures 8a, 9a, <br />10a). Survival differences in the irrigation experiment was related to the amount of water <br />delivered to the plants (Figure 11 a), and the highest salinity was in the highest irrigation <br />treatments (Figure 12). <br />Natural sprouts on roto - cleared /fresh responded dramatically to weeding, with <br />growth generally higher in weeded plots (Figures 7b, 8b, 9b, 10b). Survival of un- <br />weeded trees on the roto - cleared /fresh soil type was very low, while all weeded trees <br />survived (Figure 11 b). Differences in growth of weeded and un- weeded on the dozer - <br />cleared /stored soil were less obvious, except for the much better basal caliper growth <br />for weeded trees (Figure 7b). As with the roto - cleared /fresh soil, all of the trees that died <br />• on the dozer - cleared /stored soil were un- weeded. Growth of potted plants was generally <br />less than natural sprouts and more similar to irrigated trees. Survival of potted plants <br />was high. <br />An interesting finding was observed in the non - irrigated plots where all of the <br />weeded trees survived while many of the non - weeded trees, particularly those on the <br />roto - cleared /fresh soil, lost their leaves prematurely and appeared to have died (Figure <br />11 b). Leaves on these trees appeared to be green and wilted before dropping, rather <br />than yellow as a sign of early senescence. Whether these apparently dead trees survive <br />from residual live buds and /or roots will be determined in 2007. However, it appears that <br />removing weed competition to insure adequate soil moisture improves the survival of <br />aspen. <br />Conclusions: <br />1. A clear finding from the 2005 field study verified that fencing is important for <br />adequate survival and growth of aspen by preventing wild ungulate grazing. <br />0 <br />16 <br />