VEGETATION AND SOIL FACTORS ON A HEAVY METAL MINE SPOIL HEAP

Abstract

The vegetation of a small Scottish metal‐mine spoil heap was sampled by means of 70 0.25‐m2 quadrats and classified into three groups. The most common species were Agrostis capillaris and Festuca rubra which were important constituents of all three groups. Soil samples were collected from each quadrat and analysed for pH, loss‐on‐ignition, heavy metal and nutrient elements in the soil solution and for several physical properties. The mine spoil was physically and chemically heterogenous with many of the soil solution samples having potentially toxic concentrations of copper, lead and zinc. The vegetation data were ordinated: axis 1 of the ordination was significantly correlated (positively) with all three heavy metal concentrations, silt and sand, and (negatively) with loss‐on‐ignition and potassium concentration; axis 2 was significantly negatively correlated with pH and calcium, nitrate and phosphate concentrations. Consideration of this ordination and comparisons between soil parameters associated with each of the three vegetation groups and with non‐vegetated quadrats, suggest that lead and zinc may be the major determining factors of the spoil‐heap vegetation. Low nutrients (except phosphate) and in some cases adverse soil physical factors might be important also. The apparently small influence of copper is discussed. Above‐ground parts of five plant species were collected from the mine spoil and were shown often to have high heavy metal concentrations which differed between species. Finally we discuss some implications of interspecific differences in metal‐mine occurrence within the genera Agrostis and Festuca. Copyright © 1983, Wiley Blackwell. All rights reserved