Fire on the ground: Wildfires impacts on soil health and biodiversity - A review

The increasing occurrence of fire events is of great concern, as these events promote intense changes in soil environments, altering their physico-chemical composition and severely damaging organisms through a wide range of effects. Therefore, this review aimed to understand the different types of effects promoted by fire events on the soil and its organisms. Bibliographic searches were performed on different platforms, which returned a total of 109 investigations, which were grouped into different thematic axes. Fires promote extensive changes in soil composition, including by decreasing nutrient concentrations. In addition, an increase in toxic substances, such as PAHs, heavy metals and contaminants resulting from water used to control fires, was identified. Few studies have been carried out with the aim of understanding the ecotoxicological effects of contaminants generated by fires, with the majority of studies involving leachate, observing mainly acute mortality effects. Most of the studies found focused on understanding changes at the ecological level, with a special focus on microorganisms and animals, with few studies on plants. This review highlights the urgent need for ecotoxicological studies on the effects of fire-derived contaminants, particularly on soil organisms. There is also a pressing need for more ecological studies that adopt an integrated approach, incorporating multiple soil-dwelling species from different taxonomic groups to better reflect the complexity of natural ecosystems.