The distribution of Agrostis gigantea and Poa pratensis in relation to some environmental factors on a mine-tailings area at Copper Cliff, Ontario

The distribution of two dominant species of grass was related to selected soil characteristics on revegetated Cu–Ni tailings at Copper Cliff, Ont. The tailings area had a wet zone dominated by Agrostis gigantea, a dry zone dominated by Poa pratensis, and an overlapping zone of both grasses. In the overlapping zone the biomass–cover index of both species was lower than in their specific zones. pH ranged from 3.3 to 6.7, and sites of Poa pratensis were generally above pH 5. Tailings Fe, extractable by ammonium acetate, ranged from 5 to 344, Cu from 5 to 15, and Ni from 5 to 80 μg∙g −1 . There were significant differences in Fe, Cu, and Ni between the Agrostis and Poa zones, and between Poa pratensis sites in the Poa and overlapping zones. Concentrations of metal in roots of Agrostis gigantea were 2.7 × 10 3 –46.4 × 10 3 , 216–1289, and 108–826 μg∙g −1 for Fe, Cu, and Ni, respectively; in Poa pratensis root concentrations of metal were 2.2 × 10 3 –20.3 × 10 3 , 100–1589, and 99–795 μg∙g −1 for Fe, Cu, and Ni, respectively. Significant differences in Fe and Cu in roots were found between the Agrostis and Poa zones, and within the overlapping zone. Nickel in roots differed significantly only in roots of Agrostis gigantea from the Agrostis and overlapping zones. Key words: Fe, Cu, Ni, roots; tailings; Agrostis gigantea, Poa pratensis; zonation.