The effect of zinc contamination from electricity pylons. Contrasting patterns of evolution in five grass species

Abstract

Samples of 8–35 individuals of Agrostis capillaris, A. stolonifera, Anthoxanthum odoratum, Deschampsia cespitosa and Festuca ovina were collected from zinc‐contaminated soils beneath electricity pylons erected in North Wales and Lancashire between 1956 and 1970. Their zinc tolerance was assessed, as was that of two individuals of the same species collected from adjacent uncontaminated soils. Five soil samples from beneath each pylon were collected for evaluating total and extractable soil zinc, soil pH, and soil organic matter. Some degree of zinc tolerance was detected in all five species, suggesting that evolution of tolerance has taken place relatively rapidly, particularly in A. capillaris, D. cespitosa, and Anthoxanthum odoratum. However, tolerant individuals of all species were not found beneath all pylons even when the species was present in the surrounding vegetation. This confirms and extends to other species previous findings in A. capillaris, that the gene or genes necessary for the evolution of tolerance are not universally present within species. Copyright © 1990, Wiley Blackwell. All rights reserved