Arbuscular Mycorrhizal Fungi in the Rhizosphere of Saplings Used in the Restoration of the Rupestrian Grassland

Arbuscular mycorrhizal fungi (AMF) can optimize nutrient uptake of seedlings in adverse environments. Inoculation with AMF could therefore increase the restoration success of the rupestrian grassland (campo rupestre). We aimed to assess the AMF spore community in the rhizosphere soil of nine important native plant species used in the restoration of the rupestrian grassland and its influence on plant development. We evaluated AMF composition, richness, and density in the rhizosphere of saplings, as well as sapling height and diameter at ground-level. Overall, we sampled 53 AMF species with an average of 55.07 spores/50 g of soil. We found low specificity of AMF to the studied plant species. Only three plant species showed a distinct AMF species composition. AMF species richness was also very similar among most plant species and the control (soil without plants), although AMF density was higher in certain plant species. Sapling development was weakly associated with AMF richness, but positively related to AMF density. Each plant species was affected by the density of distinct AMF species. These results suggest that: 1) the density of certain AMF may be more important for sapling development than the richness of associated AMF, 2) not all AMF species favor plant development, and 3) not all plant species respond to AMF. Given this, saplings used in rupestrian grassland restoration should be inoculated with specific native AMF. We also recommend further investigation into soil conditions and plant traits that could allow associated higher density of AMF species in the rupestrian grassland.