Erosion or plant succession - How to interpret the presence of arbuscular mycorrhizal fungi (Glomeromycota) spores in pollen profiles collected from mires

The spores of arbuscular mycorrhizal fungi (AMF), microorganisms which occur belowground, are recognized as important indicators of erosion in palaeoecological reconstructions. In this study, the indicative value of the AMF was examined in peat deposits. A combination of palaeoecological methods, involving loss on ignition (LOI) and palynological analysis, and mycological techniques, including the assessment of AMF colonization of roots and AMF trap cultures, was used. A layer with abundant AMF spores parallel to other erosion indicators was thereby examined. The results clearly proved that the application of AMF spores as erosion indicators in peat deposits is highly questionable because the spores may have been produced by mycorrhizal mycelia related to AMF host plants whose roots have grown into the layer where the deposits lie. Nonetheless, AMF should still be considered as important markers of episodes of higher downwash in continuous lacustrine sediments. (C) 2012 Elsevier B.V. All rights reserved.