Laserfiche WebLink
Results: <br />This study was conducted to demonstrate the effectiveness of supplemental <br />irrigation on growth and survival of transplanted aspen sapling trees, but the <br />experimental conditions allowed observation on several additional variables. In addition <br />to irrigation (four levels of watering), we were able to observe growth and survival of <br />aspen of different plant type (transplants, natural sprouts, and potted plants), soil type <br />(roto-cleared/fresh and dozer-cleared/stored soil), and weed control (weeded and not- <br />weededj. Since not all treatment combinations existed and none of the treatments were <br />replicated, statistical analyses and inferences are limited. The differences for growth <br />and survival discussed in this report are based on our observation of the dataset and <br />not based on statistical analysis for significance of differences. Even if differences in <br />growth or survival between treatments had been statistically verified, interacting <br />treatment effects confound conclusions that can be drawn. For example, differences <br />between natural sprouts on roto-cleared soil and transplants in irrigated treatments may <br />be due to differences in soil disturbance, genetic stock of aspen, transplant type, or <br />microclimatic differences between sites, treatments not independently replicated for this <br />initial case study designed for this one location. Nevertheless, given all these caveats <br />several observations are evident from the study that can be useful for future aspen <br />management and to identify areas for additional research. <br />Irrigation: <br />Rainfall was well dispersed during the 2006 growing season, except fora 3-week <br />period in June (Figure 3a); but soil moisture appeared to be adequate after spring <br />snowmelt entering this June drought period. Temperatures were moderate during this <br />time period (Figure 3b). Rainfall was different for the two monitoring stations (the <br />experimental site, and near the entrance to the mine access road about 2 km west), but <br />major rainy periods were similarly documented at both sites. For this experiment, there <br />appeared to be an effect of irrigation treatment on soil moisture in the irrigated plots; but <br />soil moisture decreased through the season, especially for non-irrigated controls <br />(Figures 4a). Weeded plots retained more soil moisture (Figure 4b). Highest soil <br />moisture was in the high irrigation treatment, followed by the medium irrigation <br />12 <br />