Contrasting effects of host identity, plant community, and local species pool on the composition and colonization levels of arbuscular mycorrhizal fungal community in a temperate grassland.

Arbuscular mycorrhizal fungi (AMFs) are important plant symbionts, but we know little about the effects of plant taxonomic identity or functional group on the AMF community composition. To examine the effects of the surrounding plant community, of the host, and of the AMF pool on the AMF community in plant roots, we manipulated plant community composition in a long-term field experiment. Within four types of manipulated grassland plots, seedlings of eight grassland plant species were planted for 12 wk, and AMFs in their roots were quantified. Additionally, we characterized the AMF community of individual plots (as their AMF pool) and quantified plot abiotic conditions. The largest determinant of AMF community composition was the pool of available AMFs, varying at metre scale due to changing soil conditions. The second strongest predictor was the host functional group. The differences between grasses and dicotyledonous forbs in AMF community variation and diversity were much larger than the differences among species within those groups. High cover of forbs in the surrounding plant community had a strong positive effect on AMF colonization intensity in grass hosts. Using a manipulative field experiment enabled us to demonstrate direct causal effects of plant host and surrounding vegetation.

Šmilauer P ，Košnar J ，Kotilínek M ，Šmilauerová M ... -  《-》

Host age and surrounding vegetation affect the community and colonization rates of arbuscular mycorrhizal fungi in a temperate grassland.

Arbuscular mycorrhizal fungi (AMF) are important symbionts for the majority of terrestrial vascular plants, yet the drivers of the compositional variation in AMF communities need to be better understood. What effects does the ontogenetic stage of host plants have and do these effects differ between plant functional groups? Are the AMF communities modified by the properties of surrounding vegetation, such as the proportion of different functional groups or nonmycorrhizal plants ? We addressed these questions in a temperate grassland and studied AMF communities using next-generation sequencing and light microscopy, evaluating their composition, taxonomic, phylogenetic and functional diversity, functional traits and root colonization levels. We found important differences between AMF communities and their diversity between seedlings and adults which are larger than the differences among host species or between functional groups. The proportion of nonmycorrhizal plants in the surrounding affected AMF community composition and increased its richness. Our results highlight the need for further investigating the existence of a common mycelial networks. The decision to use seedlings for experimental work can affect the results more than the chosen host species.

Šmilauer P ，Košnar J ，Kotilínek M ，Pecháčková S ，Šmilauerová M ... -  《-》

Arbuscular mycorrhizal fungal communities of forbs and C3 grasses respond differently to cultivation and elevated nutrients.

Šmilauer P ，Šmilauerová M ，Kotilínek M ，Košnar J ... -  《-》

Grazing Intensity Rather than Host Plant's Palatability Shapes the Community of Arbuscular Mycorrhizal Fungi in a Steppe Grassland.

Arbuscular mycorrhizal fungi (AMF) are the predominant type of mycorrhizal fungi in roots and rhizosphere soil of grass species worldwide. Grasslands are currently experiencing increasing grazing pressure, but it is not yet clear how grazing intensity and host plant grazing preference by large herbivores interact with soil- and root-associated AMF communities. Here, we tested whether the diversity and community composition of AMF in the roots and rhizosphere soil of two dominant perennial grasses, grazed differently by livestock, change in response to grazing intensity. We conducted a study in a long-term field experiment in which seven levels of field-manipulated grazing intensities were maintained for 13 years in a typical steppe grassland in northern China. We extracted DNA from the roots and rhizosphere soil of two dominant grasses, Leymus chinense (Trin.) Tzvel. and Stipa grandis P. Smirn, with contrasting grazing preference by sheep. AMF DNA from root and soil samples was then subjected to molecular analysis. Our results showed that AMF α-diversity (richness) at the virtual taxa (VT) level varied as a function of grazing intensity. Different VT showed completely different responses along the gradient, one increasing, one decreasing, and others showing no response. Glomeraceae was the most abundant AMF family along the grazing gradient, which fits well with the theory of disturbance tolerance of this group. In addition, sheep-grazing preference for host plants did not explain much of the variation in AMF α-diversity. However, the two grass species exhibited different AMF community composition in their roots and rhizosphere soils. Roots exhibited a lower α-diversity and higher β-diversity within the AMF community than soils. Overall, our results suggest that long-term grazing intensity might have changed the abundance of functionally diverse AMF taxa in favor of those with disturbance-tolerant traits. We suggest our results would be useful in informing the choice of mycorrhizal fungi indicator variables when assessing the impacts of grassland management choices on grassland ecosystem functioning.

Faghihinia M ，Zou Y ，Bai Y ，Dudáš M ，Marrs R ，Staddon PL ... -  《-》

Abiotic rather than biotic filtering shapes the arbuscular mycorrhizal fungal communities of European seminatural grasslands.

Although it is well known that arbuscular mycorrhizal fungi (AMF) play a key role in the functioning of natural ecosystems, the underlying drivers determining the composition of AMF communities remain unclear. In this study, we established 138 sampling plots at 46 grassland sites, consisting of 26 acidic grasslands and 20 calcareous grasslands spread across eight European countries, to assess the relative importance of abiotic and biotic filtering in driving AMF community composition and structure in both the grassland soils and in the roots of 13 grassland plant species. Soil AMF communities differed significantly between acidic and calcareous grasslands. In root AMF communities, most variance was attributable to soil variables while very little variation was explained by host plant identity. Root AMF communities in host plant species occurring in only one grassland type closely resembled the soil AMF communities of that grassland type and the root AMF communities of other host plant species occurring in the same grassland type. The observed AMF-host plants networks were not modular but nested. Our results indicate that abiotic conditions, rather than biotic filtering through host plant specificity, are the most important drivers in shaping AMF communities in European seminatural grasslands.

Van Geel M ，Jacquemyn H ，Plue J ，Saar L ，Kasari L ，Peeters G ，van Acker K ，Honnay O ，Ceulemans T ... -  《-》