The impact of wildfire and mammal carcasses on beetle emergence from heathland soils

Wildfires alter the composition of insect communities due to fire-induced mortality, and the post-fire vegetation and soil conditions also affect the initial re-colonisation and subsequent local emergence of adults from burnt soils. However, the impact of wildfires on re-colonisation and emergence of carrion-associated scavenging species from soils has previously been neglected. We established an experiment in an unmanaged heathland area that was affected by a severe wildfire in 2017 by adding wild boar carcasses to burnt and unburnt areas 204 days after the wildfire. Adult beetles were then collected with emergence tents at paired sites with and without carcasses and in burnt and unburnt areas from 27 April to 10 August 2018. The wildfire did not significantly affect the diversity or abundance of soil-emerging beetles. Community composition in the burnt area differed significantly from the unburnt area with higher numbers of Staphylinidae and lower numbers of phytophagous beetle families (Curculionidae and Elateridae) emerging from soils, probably reflecting the structurally simpler vegetation and reduced litter one year after the wildfire. Scavenging beetles generally colonise mammal carcasses in burnt areas to the same extent as in unburnt areas, but the post-fire conditions favoured some species with very specialised habitat preferences. A few rare species of conservation concern almost exclusively occurred in the burnt area and in most cases in combination with the presence of a carcass. This result highlights the joint importance of heathland wildfires and carcass resources for species conservation in beetle communities.

Automated summary

Wildfires affect insect communities and the re-colonisation of species from burnt soils, but the impact on carrion-associated scavenging species has been neglected.