Use of microarthropods to evaluate the impact of fire on soil biological quality.

Edaphic (i.e. soil dwelling) microarthropods play crucial roles in soil ecosystem services. Fire is a widespread form of disturbance with severe effects on soil invertebrates. Research on the effects of fire on soil arthropods, however, has been mostly focused on surface-active species. Information on the effects of fire on strictly edaphic invertebrates is limited. Thanks to their variable degree of specialization to the edaphic life, soil microarthropods can be used to evaluate soil quality and how it is affected by disturbance. We used an index of soil biological quality based on microarthropods (QBS-ar) to assess the effects of wildfire in three habitats (a natural beechwood, a grassland and a conifer reforestation) in a burnt upland plain in Central Italy, one year after the fire event. Fire affected significantly soil biology quality. In all habitats, burnt soils had a biological quality about 1.4 lower than the respective unburnt soils. Sampling period did not affect QBS-ar values. QBS-ar values varied among habitat types, being highest in the beechwood, lowest in the pinewood, and intermediate in the grassland. These findings indicate that the QBS-ar approach can be profitably used to evaluate the impact of fire on soil biology quality and stress the poor performance of planted conifers in terms of soil quality.