The impact of beech and riparian forest herbaceous plant species with contrasting traits on arbuscular mycorrhizal fungi abundance and diversity

The impact of forest herbaceous plant species identity on arbuscular mycorrhizal fungi (AMF) communities in relation to vegetation and soil chemical properties has rarely been studied in temperate forests. We thus compared abundance and diversity of AMF in two deciduous forests, in the plots with herbaceous plant species of contrasting traits (morphology, phenology, reproduction, and ecology), including Allium ursinum and Dentaria enneaphyllos in a beech forest, as well as Aegopodium podagraria and Ficaria verna in a riparian forest. Plots with a mix of herbaceous plant species and bare soil were also studied. We found low values of AMF root colonisation degrees in both forests. In total, the spores of only 13 AMF species were detected; 12 species occurred in the riparian forest, whereas 6 were found in the beech forest. AMF species composition differed between forest types. Higher AMF root colonisation degrees and soil concentrations of PLFA 16:1?5 AMF structural lipid marker were found in the riparian forest. There were no differences between the plots in AMF abundance and species richness in both forest soils. With regard to environmental variables, the number of arbuscular mycorrhizal (AM) tree species, plant cover, moisture, the concentrations of C, Ca, K, Mg, and N had, in general, a positive effect on AMF abundance in soils. We showed that despite AMF ubiquity, these fungi can be present at low densities in some habitats, such as beech and riparian forests. Higher AMF abundance and diversity in the riparian forest were probably related to larger numbers of AM tree and herbaceous plant species in this forest. Although the herbaceous plant species had contrasting traits, they had little effect on AMF abundance and diversity.