Fire and herbivory drive fungal and bacterial communities through distinct above- and belowground mechanisms

Fire and herbivory are important natural disturbances in grassy biomes. Both drivers likely to influence belowground microbial communities but no studies have unravelled the long-term impact of both fire on bacterial fungal communities. We hypothesized that soil change through disturbance-induced shifts properties (e.g. pH, nutrients) while vegetation modification (biomass species composition). To test these ideas, we characterised physico-chemical (pH, acidity, C, N, P exchangeable cations content, texture, bulk density, moisture), plant richness biomass, biomass community composition diversity (using 16S ITS rRNA amplicon sequencing, respectively) six (18 70 years) ecological research sites South African savanna grassland ecosystems. found regimes profoundly modified properties, standing biomass. In all sites, an increase woody (ranging from 12 50%) was observed when were excluded. The intensity direction changes highly dependent topo-pedo-climatic context. Overall, shaped distinct driving forces: edaphic (including Mg, Ca) for bacteria, (herbaceous cover) fungi. explained average 7.5 9.8% variability, respectively, compared 6.0 5.6% bacteria. relatively small due disturbance is stark contrast dramatic suggests communities, having evolved with disturbance, resistant change. This represents a buffer short-term anthropogenic-induced restoration challenge face changes.