Toxic effects of cadmium and zinc on ectomycorrhizal colonization of Scotspine (Pinus sylvestris L.) from soil inoculum

Scots pine seedlings colonized by ectomycorrhizal (ECM) fungi from natural soil inoculum were exposed to a range of Cd or Zn concentrations to investi gate the effects of metals on ECM fungi-Scots pine associations in a realis tic soil environment. Experiments focused on the relationship between the s ensitivity of ECM Fungi and their host plants, the influence of metals on E CM community dynamics on Scots pine roots, and the effects of metal exposur e on ECM colonization from soil-borne propagules. Ectomycorrhizal colonizat ion was inhibited by Cd and Zn, with a decrease in the proportion of ECM-co lonized root tips. Shoot and root biomass, total root length, and total roo t-tip density, however, were unaffected by Cd or Zn. A decrease in the dive rsity of ECM morphotypes also occurred, which could have a negative effect on tree vigor. Overall, colonization by ECM fungi was more sensitive than s eedling growth to Cd and Zn, and this could have serious implications for s uccessful tree establishment on metal-contaminated soils.