XVI International Botanical Congess

Long term survey of mycorrhiza of plants invading disturbed soils in degraded or man-made ecosystems showed that mycorrhiza is affected by successional stage, plant species and amounts of infective propagules of arbuscular mycorrhizal fungi (AMF). The AMF isolates from disturbed soils can tolerate adverse conditions but at the same time the plasticity of AMF is high thus some AMF from undisturbed soils can also sustain severe edaphic stress. The AMF can penetrate and sporulate massively in the cavity of dead seeds of Chenopodium album, a nonmycorrhizal species and the cavity probably provides to the AMF a shelter against soil toxicity. This phenomena is related mainly to the indigenous AMF isolates and probably only to certain species and could be accounted to ecophysiological adaptations of AMF in disturbed soils. The findings are in contrast to often reported negative effects of non-host plants on the populations of AMF. Research was financed by the Grant Agency of the Czech Republic, grants 526-99-0895, 526-99-PO32.