Local soil legacy effects in a multi-species grassland community are underlain by root foraging and soil nutrient availability

1. Plant soil legacies consisting of species-specific microbial communities are hypothesized to play a critical, structuring role in plant species co-existence processes. Plant species are thought to perform worse on soil conditioned by the same species compared to soil of other species, which serves as a self-limitation mechanism and averts mono-dominance of strong competitors. Here we test in a multi-species community setting, whether root colonisation and resource utilisation of soil patches with distinct soil legacies, are consistent with this hypothesis. 2. We grew eight grassland species together in an outdoor mesocosm setup in unconditioned soil and created soil patches in these communities conditioned by one of four plant species, or a soil mixture of all four. During two subsequent growing seasons, we tested the effect of these conditioned soil patches on belowground root colonisation into the patches of each surrounding plant species using a novel sequencing based approach. In...