Long-term post-fire recovery of oribatid mites depends on the recovery of soil properties in a fire-adapted pine forest

Fire is a highly important factor affecting the forest structure as well as its functions. The understanding of the post-fire recovery mechanisms could be especially useful in the face of globally increasing fire frequencies. Fire-adapted forests in Minnesota provide a unique opportunity to study these recovery mechanisms due to their long and well-documented history of prescribed burnings and wildfires. We investigated oribatid mite (Acari: Oribatida) assemblages along a 126-year post-fire chronosequence, together with soil physical, chemical and microbial properties (e.g. bulk density, organic matter content, C, N and P content, microbial biomass). Whereas the effect of prescribed burning was negligible, the wildfire decreased oribatid density (–86 %) and diversity (–38 %) for at least 13 years. The recovery of oribatid mites corresponded to the changes in soil properties, being correlated negatively to bulk density and positively to organic matter content, water holding capacity and microbial activity and biomass. The recovery did not depend simply on the time elapsed since fire, but it was rather a complex response to long-term (15–20 years), fire-induced changes in the soil environment.