Shifts in soil traits and arbuscular mycorrhizal symbiosis represent the conservation status of Araucaria araucana forests and the effects after fire events

•Arbuscular mycorrhizal symbiosis is strongly affected by fire in A. araucana forests.•Glomalin-related soil protein was a good indicator of soil stability in unburned areas.•Better performance for A. araucana forests is in the coastal range.•High rates of mycorrhization, fungal structures and enzyme activities were in the coastal range.