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• method. The dozer cleared soil appeared to be more compacted and was less well <br />drained than the roto - cleared soil, and it is expected that these physical characteristics <br />were more important to tree growth than the method of clearing. Also, storage effects <br />on the soil were likely more important than method of clearing. <br />Control of plant competition: <br />The best growth of aspen was with trees that were hand hoed to remove all <br />competing vegetation. This was likely related to lower water stress of the trees, since all <br />other vegetation competed with the trees for the limited water supply. This was <br />particularly apparent on the roto - cleared soils where there was a high biomass of <br />competing vegetation. <br />Root growth: <br />Similar to top growth, root growth on the roto - cleared soil was greater in plots <br />where competing vegetation was removed by hoeing compared to plots where <br />competing vegetation was left intact. Effect of competing vegetation removal on root <br />growth of dozer cleared soils was less evident, likely since amount of competing <br />vegetation was considerably less and growth was less on the dozer cleared soils. Roots <br />in most treatments were of sufficient size but too deep to support suckering. <br />Nevertheless, sucker initiation was likely inhibited by apical dominance of the growing <br />trees. Lateral root extension was progressing, but was considerably slower in the plots <br />on the dozer cleared soils. The upward growth of roots toward the soil surface that was <br />observed indicates that care should be taken in future plantings to plant trees only to a <br />depth of the original root collar. <br />Overall recommendation from pilot study: <br />Best conditions for reproduction of aspen on reclaimed surface mined coal lands <br />resulted from using transplanted saplings obtained from local sources and replanted on <br />freshly placed soil removed from aspen stands. Care should be taken to avoid <br />compaction of the replaced soil. Transplanted trees should be planted no deeper than <br />the original root collar, and competing vegetation should be controlled around <br />individual trees. Irrigation with non- saline water might enhance growth and survival in <br />7 <br />