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• (Siemens and Zwiazek 2003). Irrigation has been shown to increase growth of hybrid <br />poplar, a closely related species (Hansen 1988; Strong and Hansen 1991). <br />Therefore, it seems reasonable to conclude that supplemental irrigation of aspen <br />planted on reclaimed surface -mined lands could increase initial survival and allow trees <br />to grow sufficient root systems to ultimately survive without additional water and <br />establish new self- regenerating clones on reclaimed mine lands. Testing this <br />hypothesis, gaining additional knowledge about different planting methods, and <br />documenting factors that potentially limit the re- establishment of aspen is crucial to re- <br />establishing aspen on surface -mined lands in the and west. <br />Another issue in transplanting aspen is tolerance of the species to saline soils. <br />Saline condition of the reclaimed soils and /or irrigation water may be important in aspen <br />growth and survival. Aspen has been listed as moderately sensitive (< 3.0 dS /m, <br />Blaylock 1994), sensitive (upper limit EC of 2.0 dS /m, Pearson 2007), slightly tolerant <br />(upper limit of 3 dS /m, USDA 2002), low tolerance (< 4 dS /m, Wentz 2001), or <br />moderately high tolerance (up to 6 dS /m, Swift 2003) to saline conditions. Reclaimed <br />lands that are saline are expected to have lower species richness (Purdy et al. 2005). <br />They suggest that "facilitated colonization" is necessary for re- vegetation on saline <br />overburden soils (Purdy et al. 2005). Van Cleve et al. (1993) found that high salt content <br />of soil inhibited growth of aspen. Renault et al. (1998) report that aspen seedlings <br />irrigated with saline water from mine tailings lost their leaves which were replaced by <br />morphologically different leaves. These trees had increased leaf water potential and <br />reduced transpiration. Saline conditions can cause lower water absorption by plants; <br />and accumulation of salts in plant tissue can decrease leaf water potential (Renault et <br />al. 1998). Knoxfield (1995) suggests that EC > 3.0 dS /m in irrigation water is unsafe, <br />and EC > 1.5 dS /m of potting media is too high. Bauder et al. (2006) indicate that <br />irrigation water with EC > 2.0 dS /m should not be used, particularly on soils with poor <br />drainage. <br />A pilot study was established to examine the feasibility of using supplemental <br />drip irrigation to establish aspen on reclaimed coal mine overburden soils. Overburden <br />and topsoil are normally stored for a number of months before overburden is replaced <br />and then resurfaced with topsoil, then landscape planted. The study described herein <br />0 <br />5 <br />