SOIL HEAVY-METAL CONCENTRATIONS AND EROSION DAMAGE IN UPLAND GRASSLANDS IN THE PENNINES, ENGLAND

The relationship between grassland stability and soil concentrations of Pb, Zn and Cd and soil pH were determined at two abandoned heavy metal mine complexes in the Yorkshire Pennines, England. A process of vegetation change, in which degenerative stages are currently predominant occurs on the finer textured spoils, which are physically and chemically extremely heterogeneous. Physical disruption of closed grassland and floristic changes are involved in this process. There was little evidence that soil heavy metal concentrations, with the possible exception of Zn, were involved in initiating the process. Soil pH was unrelated to metal concentrations or to the disruption. Causes of initiation are not yet known, but these results indicate that more than one factor is involved. There was evidence that later stages of the disruptive process are powered by frost-heave and water erosion.