Arbuscular mycorrhiza status of gold and uranium tailings and surrounding soils of South Africa's deep level gold mines: I. Root colonization and spore levels

Surveys of arbuscular mycorrhiza fungi (AMF) root colonization and spore status of slimes dams of South Africa's deep level gold mines in the North–West province were undertaken in the late summer of 1999. Five indicator host plant species [Asclepias fruticosa L., Cynodon dactylon (L.) Pers., Atriplex semibaccata R. Br., Phytolacca octandra L. and Asparagus laricinus Burch.] were sampled from the surrounding natural soils (veld) and dams of three age categories (recently-revegetated-RV, old-revegetated-OV and never-revegetated-NV) within the different zones of each dam (top, lower slopes, retaining wall, toepaddocks). Host species and broad substratum type (slimes, slimes-polluted veld and veld) showed significant effects on AM root parameters. Overall, A. fruticosa and A. laricinus were the most mycotrophic hosts on RV, OV and NV slimes and C. dactylon and A. semibaccata in the veld. On RV sites there were negligible differences between host species and zones in mycorrhizal parameters, whereas on OV and NV sites most parameters were significantly different, with significant interactive effects between host species and zones. No differences in spore densities between host species or age categories were found but total spore densities between zones were significantly different. NV slopes had the lowest pH, aerial cover, organic matter and total P but highest potential acidity and weak relationships were found between zone pH and mycorrhizal colonization parameters. These results are discussed in relation to the factors affecting distribution of AMF on these sites and the options relating to AMF inoculum introduction in rehabilitation programmes.