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The growth data suggest that roto-cleared soil could have provided additional nutrients or other <br />benefits, perhaps mycorhizae, for tree growth. Weed growth appeared greater on roto-cleared <br />soil than dozer-cleared soil (data not shown). <br />IV. Fencing -Fencing is necessary to obtain an adequate stand of aspen, regardless of the sources <br />of the trees. The unfenced Yoast site had severe damage from ungulates, including breakage of <br />stems, browsing, and rubbing damage. Most trees at this site had some form of injury. Yet, <br />growth and survival of these trees was good, suggesting that the undisturbed soil presence of an <br />extensive parent root system is ideal for growth of aspen. Nevertheless, fencing of these trees is <br />recommended to produce an adequate stand of mature aspen. <br />CONCLUSIONS (2005-2006): <br />1. Growth and survival did not appear to be related to irrigation treatment, likely a consequence <br />of the high rainfall during the 2005 and 2006 growing seasons. <br />II. Best growth appeared to be on natural root segment sprouts on roto-cleared soil for the first <br />year. Transplanted trees grew well after the first year's transplant shock. <br />III. Transplanted sprouts showed considerable transplant injury their first year, regardless of <br />irrigation treatment in this relatively wet. Growth and survival was relatively low and diseases <br />were higher in transplant cutting plots compared to natural sprouts and potted plants. Recovery <br />of surviving transplant trees was good and growth was good the second year. <br />IV. Potted aspen from nursery stock planted on dozer-cleared soil grew well and had high <br />survival the first year. <br />V. Fencing is necessary to protect small aspen trees from browsing injury. <br />EXPERIMENTAL PROCEDURES/METHODOLOGIES FOR 2007 <br />Study Design: <br />Based on the important finding for 2005-2006 summarized above, several new questions <br />regarding aspen growth and survival on reclaimed lands arose, and follow-up research was <br />conducted using the same II-W Mine plots where the 2005-2006 study was conduced. Our <br />intention was to utilize the existing study design and sampling regime to collect third year <br />survival and growth data from trees sampled in 2005-2006. OSM funding was used for data <br />collection during 2007 and for data analysis and preparation of the final report. Details of <br />operation of the irrigation system, types of planted aspen studied and sampling procedures <br />remained as previously described. Deviations and additions to the original study design are <br />described below.