Relict charcoal hearths as indicators of long-term microbial shifts and functional imbalance in forest soils - data

The study assessed the long-term effects of historical charcoal production on soil properties and on the composition of bacterial and fungal communities in relic charcoal hearth sites in northern Poland. Three microsites were compared—hearth centre, surrounding ditch, and control soil—revealing persistent differences in physico-chemical parameters and pronounced microbial differentiation. Soils from the hearth centre exhibited higher microbial diversity and a more balanced functional profile, whereas the ditch was characterised by reduced diversity and a shift towards stress-tolerant taxa and saprotrophic groups. SEM observations indicated a well-preserved charcoal microstructure with limited microbial colonisation, suggesting that former charcoal hearths leave durable and spatially heterogeneous “signatures” in the functioning of forest soils.