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sunlight to the forest floor best meets these requirements. However, young aspen suckers are <br />susceptible to competition from other understory plants and herbivory from browsing ungulates, <br />even if abundant suckers are present. <br />Having access to a well developed parental root system gives aspen sprouts a great advantage <br />over other plants. The parent roots supply carbohydrates and access water deep in the soil profile <br />allowing sprouts to grow rapidly, out-compete other vegetation, and withstand frequent droughty <br />conditions in the West. <br />Re-establishing aspen on surface-mined lands is therefore problematic, since the parent root <br />systems are destroyed when topsoil is removed. Planting aspen in a non-irrigated location in a <br />Colorado study was not successful (Shepperd and Mata 2005). Transplanting greenhouse or <br />nursery-grown aspen seedlings into the field has similar problems to those of natural seedlings, <br />indicating that the small root mass of transplanted seedlings is insufficient to absorb enough <br />moisture to maintain the seedlings during periods of summer drought in the wild. <br />In contrast, transplanting sapling-sized aspen in irrigated urban landscapes has not been a <br />problem, because the abundant supplies of water in lawns and landscape beds enable the <br />transplants to thrive. Although aspen is somewhat tolerant of drought conditions (Lieffers et al. <br />2001), irrigation could benefit growth and survival of planted aspen stock, because moisture <br />stress negatively affects aspen response to nutrient uptake (van den Driessche et al. 2003). Water <br />deficit stress also reduces stomatal conductance, root hydraulic conductivity, and shoot leaf <br />water potential in aspen (Siemens and Zwiazek 2003). Irrigation has been shown to increase <br />growth of hybrid poplar, a closely related species (Hansen 1988; Strong and Hansen 1991). <br />Therefore, it seems reasonable to conclude that supplemental irrigation of aspen planted on <br />reclaimed surface-mined lands could increase initial survival and allow trees to grow sufficient <br />root systems to ultimately survive without additional water and establish new self-regenerating <br />clones on mined lands. Testing this hypothesis, gaining additional knowledge about different <br />planting methods, and documenting factors that potentially limit the re-establishment of aspen is <br />crucial to re-establishing aspen on surface-mined lands in the and west. This research was a <br />collaborative three-year effort, with 2005 and 2006 funding from Seneca Coal Company; and <br />2007 funding from Seneca Coal Company and OSM-NTTT. The US Forest Service contributed <br />cost share funding for the project 2005-2007. <br />PRELIMINARY STUDIES: <br />A pilot study was funded by Seneca Coal Company in 2004 to examine the feasibility of using <br />supplemental drip irrigation to establish aspen on reclaimed coal mine overburden soils. <br />Overburden and top soils are normally stored for a number of months before landscape <br />resurfacing and planting. The study, established on reclaimed lands owned by Seneca near <br />Hayden, Colorado (Figure 1), examined for the 2005 and 2006 growing seasons the growth, <br />survival, and water status of aspen trees planted on reclaimed soils during the fall of 2004. <br />The objective of this study initially was to examine the survival, growth, and water status of <br />irrigated aspen transplants on two types of topsoil, placed over coal mine overburden material