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-1) to determine (1) whether the land application of
biosolids on mine tailings, seeded with agronomic grass-legume mixture, affects
long-term plant community responses, (2) how application rates and soil texture
influenced plant community responses and community structure, and (3) 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 percent cover to the lowest taxonomical 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.