Grazing by collembola controls fungal induced soil aggregation

Fungi affect soil aggregation and hence soil structure. Soil aggregation by saprotrophic fungi has been linked to various fungal traits but not tested during interactions with other organisms such as grazing soil fauna. Here we investigated how fungal identity and traits such as mycelial extension rate and biomass production affect aggregation across 49 fungal species isolated from sandy soils with different land uses. We tested each fungus and its effect on aggregation in the presence and absence of a grazer (Folsomia candida). We show that fungal species vary widely in their ability to aggregate soil, that the ability to aggregate soil was not phylogenetically conserved and the best trait predictor for aggregation was mycelial extension rate. Moreover, we show that the interactions between fungi and collembola affect the ability of fungi to aggregate soils. We conclude that identity of fungal species and their interaction with grazers affects soil aggregation and thus soil structure.