Post-fire Succession and Soil Chemical Properties Shape Soil Fungal Community Structure and Diversity in Hemiboreal Scots Pine Forests in Estonia

We investigated the short- and long-term effects of forest fires on soil fungal communities across a forest fire chronosequence of Pinus sylvestris-dominated stands in northwestern Estonia. Soil fungal communities were characterized using PacBio sequencing of the ITS1-5.8 S-ITS2 genomic region. These effects were studied in seven different sites that differed in time since the last fire (1, 14, 25, 40, 71, 82 and 185 years ago). Overall and saprotrophic diversity was highest at the burn site where fourteen years had passed since the last fire. Ectomycorrhizal diversity was highest at the one-year-old burn site. Overall diversity of vascular plants was negatively correlated with overall diversity of fungi. Time since fire was the most significant factor in shaping overall fungal diversity and community structure. EcM and saprotrophic fungal diversity were more influenced by soil chemical properties such as pH, C,N content and Mg.