Two main limitations to shrub establishment at Colorado reclaimed mines are browsing and competition from aggressive herbaceous species.  The goal of this study was to evaluate methods for enhancing shrub establishment after mining.  To meet this goal, study plots were established in 2000 to evaluate reclamation techniques to overcome these obstacles.  The experimental design used large-scale demonstration plots that were constructed with normal reclamation equipment to test shrub establishment techniques that have commercial practicality.  Plots were established at three surface mines (Colowyo, Trapper and Seneca) in northwestern Colorado.  Several treatments were tested to evaluate shrub establishment on spoil material, 15 cm of topsoil, and 46 cm of topsoil.  Plots were strip seeded with native seed mixes, alternating rows of herbaceous species and shrub species.  Native shrub transplants were planted at one mine.  Half of each treatment was fenced to prevent browsing.

In 2007, the vegetation in each test plot was evaluated to determine the relative success of the various treatments for establishing shrubs.  Based on this data collected in the 7th growing season several conclusions can be drawn.  First, shrub establishment is favored by fencing to exclude big game.  However, the long-term potential of shrubs that have established outside the fence, where browsing occurs, is unknown.  Secondly, the use of shrub transplants may increase initial success, but the observed success of seeding several shrub species such as sagebrush and bitterbrush illustrate the potential utility of this less-costly approach.  However, the establishment of tall shrub species such as serviceberry and chokecherry may require the use of transplants and protection from browsing.  Results from this study also indicate that lesser amounts of topsoil (15 cm) appear to be better for shrub establishment relative to deeper topsoil treatments (50 cm) or no topsoil.

Since shrubs are long-lived plants, the establishment and persistence of shrub communities should be monitored over many years in order to make ecologically-relevant conclusions.  Continued maintenance and future monitoring of these demonstration plots may yield valuable insights that are not yet apparent.

Overall, it seems that successful shrub establishment is possible in these habitats so long as important factors that reduce shrub establishment are considered in reclamation planning.  These factors include minimizing shrub damage by wildlife and reducing competition from aggressive invasive or seeded grass species, which might be accomplished by using lesser depths of topsoil.