Grassland reclamation of a copper mine tailings facility: long-term effects of biosolids on plant community responses.
Aim: We explore long-term plant community responses 17 years after a one-time application of biosolids (0, 50, 100, 150, 200, 250 dry Mg/ha) to determine: (a) whether the land application of biosolids on mine tailings, seeded with an agronomic grass-legume mixture, affects long-term plant community responses; (b) how application rates and soil texture influenced plant community responses and community structure; and (c) whether native plant species have colonized and contributed to the reclaimed plant community. Location Two tailings deposits (sand and silt loam) generated by a copper-molybdenum (Cu-Mo) mine in southern British Columbia, Canada. Methods Plant communities were sampled by visual evaluation of cover percentage to the lowest taxonomic level possible. Vegetation surveys were completed on two mine tailings deposits within the storage facility that have different soil textures (sand and silt loam). Results Results showed that the interaction of biosolids applications and soil texture impacted multiple community plant responses, including increasing plant cover at both sites, and increasing richness, evenness and diversity at the sandy site. Biosolids application enhanced the performance of spontaneously established species (volunteer species) and non-native/naturalized grasses. Conclusion Our study demonstrated that biosolids application facilitates ecological succession by enhancing the establishment of non-native volunteer species over the long term, which increases vegetative cover on both deposits and promotes plant communities' diversity on sites with sandy soil texture.