Bioindication of heavy metals using bryophyte communities in the Songtao manganese carbonate ore region, China

Mining and mineral processing are often associated with heavy metal pollution. To reflect the environmental conditions of manganese carbonate ore deposits and of the area surrounding an electrolytic manganese plant, we analyzed the composition and species diversity of bryophyte communities and determined the differences in bryophyte communities related to the content of heavy metals in the substrate. We found that Pottiaceae and Bryaceae were the dominant families in the study area. The species abundance index of bryophyte communities at different locations was in order: vicinity of the mine > mine site > herb-shrubland > electrolytic plant > electrolytic waste dump. The species diversity of bryophyte communities at different locations was in order: herb-shrubland > vicinity of the mine > electrolytic waste dump > mine site > electrolytic plant. Significant differences between heavy metal contents of the substrate were found among the different locations with the exception of Co (p < 0.05). Mn contents were significantly different at each location (p < 0.05). CCA showed that Mn, Cd, Hg, and Pb content in the substrate were the major factors affecting the characteristics of the bryophyte communities. From the combination of CCA with the correlation heat map, it can be inferred that Hg, Mn, and Cu all have an adverse effect on bryophyte communities in the vicinity of the mine and in the herb-shrubland. Thus the determination of the characteristics of bryophyte communities allows ready identification of the impact of heavy metals on the environment, in turn providing a mechanism for decision-making in terms of pollution management and biodiversity protection.