The mine industry produces an important amount of residues, which are stored in tailing storage facilities. By causing land-use change, tailings induce a loss of biodiversity and carbon sink, as well as dust dispersion in the surrounding environment. Revegetating mine tailings by planting trees could mitigate ecosystem degradation and recreate carbon sinks. However, mine tailings physicochemical properties make them unfavorable environment for the establishment of forests. An interesting solution to improve mine tailings support capacity is to use industrial organic waste from such as paper mill biosolids (PB). Recycling PB as a soil amendment would also be an efficient alternative to their burial, which causes greenhouse gas (GHG) emissions. In order to assess the feasibility of this approach, an experimental design was established in 2012 on the mine tailing facility of Niobec (St-Honoré, QC, Canada). To determine the most efficient reclamation method, we planted three tree species (paper birch, tamarack and red pine) in combination with a mix of red and white clover with two levels of PB (0 and 35 t ha-1).
Results/Conclusions
5 years after the establishment of the experimental design, PB applications increased significantly tree height, but not survival rate or root and above ground biomass. Higher trees are more efficient at reducing wind erosion. Consequently, it appears that BP application could be an efficient way to reduce dust dispersion, a major problem on mine tailings. Tamarack and red pine showed higher growth rates, biomass and survival than that with paper birch. PB applications increased soil organic mater decomposition, which suggests higher microbiological activity, allowing better nutrient availability for tree growth. However, neither PB applications nor tree species affected measured soil physicochemical properties. In conclusion, PB applications on mine tailings paired with the use of tamarack and red pine seem to be an efficient way to promote vegetation establishment on tailings facilities, potentially increasing carbon sequestration, biodiversity and reducing GHG emissions from PB burial.