Tolerance of grasses to heavy metals and microbial functional diversity in soils contaminated with copper mine tailings

Copper (Cu) mine tailings, because of their high content of heavy metals, are usually hostile to plant colonization. A pot experiment was conducted to determine the tolerance of four forage grasses to heavy metals in Cu mine tailings and to examine the variation in the microbial functional diversity of soils from the tailing sites in southern China. All the four grass species survived on Cu mine tailings and Cu mine tailing-soil mixture. However, on pure mine tailings, the growth was minimal, whereas the growth was maximum for the control without mine tailings. The tolerance of grasses to heavy metals followed the sequence: Paspalum, notatum > Festuca arundinacea > Lolium perenne > Cynodon dactylon. The planting of forage grasses enhanced the soil microbial biomass. The Biolog data indicated that the soil microbial metabolic profile values (average well color development, community richness, and Shannon index) of the four forage grasses also followed the sequence: P. notatum > F. arundinacea > L. perenne > C. dactylon. Thus, P. notatum, under the experimental conditions of this study, may be considered as the preferred plant species for revegetation of Cu mine tailing areas.