METAL TOLERANCE IN AGROSTIS-SCABRA FROM THE SUDBURY, ONTARIO, AREA

Acid, metal-contaminated soils are frequently colonized by plant species that have evolved tolerance to metals. Agrostis scabra (tickle grass) grows at several such sites in the Sudbury area. To test whether these populations were tolerant to metals, three experiments were performed. A hydroponic root growth experiment, in which clonal ramets from contaminated and uncontaminated sites were grown in metal-amended nutrient solutions, showed that plants from the Sudbury area had greater tolerance indices than those from outside Sudbury. A seed-based hydroponic experiment, where seeds were germinated in metal solutions, showed that metal-tolerance indices calculated from root growth were mostly greater for populations from Sudbury but that leaf growth was not a good indicator of metal tolerance. A seed-based soil-bioassay experiment, in which seeds were germinated on soils covered with filter paper, showed that seeds from contaminated sites performed better on contaminated soil and a 50:50 soil mixture (contaminated-uncontaminated) than those from uncontaminated sites. Populations of A. scabra growing on contaminated soils in the Sudbury area therefore appear to have been selected for metal tolerance. Ecological aspects of metal tolerance and the possible role of A. scabra in the revegetation of the Sudbury area are discussed.