Relationships of vegetation to copper and cobalt in the copper clearings of Haut Shaba, Zaïre

Abstract

The vegetation of two copper clearings at Tenke Fungurumi in Zaire is described. The copper content ol the soil varied between 1000 to 130,000 ppm. Areas of highest soil copper (above 6–7000 ppni) were colonized primarily by grasses particularly Eragrostis boehmii, Sporobolus rangei and Loudetia simplex but also by other specialized cupriferous species including Becium aureoviride, Dasystachys pulchella, Anisopappus hoffmannianus and Pandiaka metallorum. Soils with 1000 to 7000 ppm copper were colonized by a community dominated by Loudetia simplex and a morphologically distinct form of Cryptosepalum maravieme. The percentage cover of Cryptosepalum was negatively correlated with soil copper. Uapaca robynsii, the most copper-tolerant woody plant, grew below 1500 ppm copper and was normally replaced by other species below approximately 1000 ppm. The gross morphology oi Xerophyta equisetoides on three sites at Dikuluwe was investigated in relation to the soil characteristics. The growth form on Dikuluwe Hill (11,000 to 111,000 ppm copper) and a nearby non-cupriferous hill (100–200 ppm copper) were basically similar, although the morphology of the Dikuluwe Hill population was probably affected by soil copper and water stress. A distinct morphological form grew on a cupriferous (4000–5000 ppm copper) dembo site.