High resilience of soil bacterial communities to large wildfires with an important stochastic component

Abstract

Wildfires alter the structure and functioning of ecosystems through changes in their biotic and abiotic components. A deeper understanding recovery process concerning diverse communities and properties within these components can provide valuable insights into the ecological effects of wildfires. Therefore, it is appropriate to enhance our understanding of the resilience of bacterial communities after wildfires within Mediterranean ecosystems. In this research, soil bacterial community resilience was evaluated in three types of ecosystems for two fire severities, two years after a large wildfire in Mediterranean ecosystems. The resilience of the soil bacterial community refers to its ability to return to original state after disturbance. This capacity can be estimated by the study of its recovery over time. In this study we evaluated the resilience using the variables: alpha diversity, beta diversity and the changes in abundance of both OTUs (Operational Taxonomic Units) and principal bacterial taxa (phyla, classes or orders). Our results showed that resilience depends on fire severity and type of ecosystem. We studied three ecosystems with different stage in the secondary succession: low maturity shrublands and heathlands, and high maturity oak forests. In general, high resilience in the soil bacterial community was observed in heathlands under low and high fire severity conditions. The other two ecosystems were resilient only under low fire severity. Stochastic replacement of the abundance of the OTUs was observed in all three ecosystems, with a notable impact on oak forests, under during high-severity conditions.

Keywords: Burn severity; Recovery of diversity; Resilience; Soil bacterial community; Wildfire.