Establishment of vegetation on serpentine asbestos mine wastes, southeastern Quebec, Canada.
The serpentine tailings from asbestos mines in southeastern Quebec cover 5.5 km2 and are largely devoid of vegetation. The tailings have a high pH, very low macro-nutrient contents, low Ca:Mg and K:Mg ratios, large amounts of Ni and Cr and a low available water capacity. Vegetation cover has persisted for three years with applications of at least 1 kg/m2 of NPK and 4 kg/m2 of farmyard manure or sawdust. However, deficiency symptoms of N and Ca occur by the end of the second season. Heavy metal toxicity is a minor problem, but might become more important if the tailings are acidified below pH 8.0-8.5. Germination and growth are reduced during dry weather. The most successful species were Lolium perenne, Poa pratensis, Elymus junceus, Bromus inermis, Medicago sativa, Trifolium hybridum and Melilotus alba. The estimated cost, at present prices, of treatments necessary to promote sustained growth is CAN $2960-3460/ha.