Soil microbiome drives the recovery of ecosystem functions after fire

Fire is an ecological disturbance that alters soil microbiomes and the functions they mediate in terrestrial ecosystems. Soil microbial diversity in Mediterranean Basin ecosystems shows resilience to fire following the restoration of plant-soil feedbacks. We hypothesised that microbial functions related to organic matter decomposition and nutrient cycling might show similar patterns of recovery. We quantified the rates of microbial respiration and enzymatic activities related to C, N and P cycling in three 20-year fire chronosequences including 150 transects in 50 burned and unburned plots (no historical fire registers) in a paired experimental design. Microbial functions, except for the hydrolysis of N compounds, were sensitive to fire but recovered the levels of unburned plots in approximately 20–24 years. The recovery of microbial functions responded to abiotic and biotic drivers. Total soil nitrogen concentration was overall strong predictor of microbial functions. In addition, fungal phylogenetic diversity significantly explained the post-fire trajectories of potentially mineralizable C, while bacterial diversity was involved in the restoration of organic C and P hydrolysis. Our results suggest that the long-term recovery of soil biodiversity in Mediterranean Basin ecosystems creates resilience to restore essential ecosystem functions after fire.