Microarthropod responses to fire: vegetation cover modulates impacts on Collembola and Acari assemblages in Mediterranean area

In the Mediterranean region, fire is a recurring disturbance that impacts both surface and underground organisms. While the effects on plants and surface animals are well-studied, the consequences for soil microarthropods are often overlooked. This research addresses the microarthropod responses to fire by comparing post-fire Collembola and Acari assemblages in soils with different vegetation covers. Three years post-fire, surface soils were sampled within the Vesuvius National Park (Southern Italy) from a total of 24 sites, comprising 6 sites each under holm oak (HO), pine (P), black locust (BL), and herbaceous (H) vegetation. Within each vegetation cover, sites were further categorized into three unburnt (NB) and three burnt (B) sites for comprehensive analysis. Collembola and Acari were extracted, identified at the family and suborder level, respectively and analyzed for density and taxa richness.

The results highlighted that fire alone did not impact microarthropod communities, but its effects varied according to the vegetation covers. Microarthropod abundance declined in burnt soils under P, and increased in burnt soils under BL. Furthermore, eu-edaphic organisms (Onychiuridae, Oribatida), typical of stable environments, decreased in soils under P, and increased in soils under black locust.

Fire impact on microarthropod communities changed according to the vegetation covers, highlighting the importance of considering vegetation type when managing post-fire landscapes. The rapid recovery of microarthropod communities under some vegetation covers suggests that fire may not universally impair soil biodiversity in Mediterranean environments.