Lichen community development along a post-fire chronosequence in a Scots pine-dominated hemiboreal forests

Lichens are key components of forest ecosystems, contributing to biodiversity and serving as sensitive indicators of environmental change. Their post-fire dynamics can provide valuable insights into habitat resilience, succession processes, and the ecological impacts of fire. Understanding lichen responses to fire is therefore essential for informing conservation and management in fire-affected forests. This study addresses a key knowledge gap by investigating the recovery dynamics of lichen communities across a post-fire chronosequence in Scots pine-dominated forests in hemiboreal Estonia. Using a space-for-time substitution approach, we examined lichen community composition and richness in stands that experienced stand-replacing fires at different points in time – specifically 16, 27, 42, 73, 84 and 187 years since fire. Lichen communities were surveyed across different substrate types in 18 study plots (each 100 m²), alongside measurements of stand structure and soil characteristics. In total, 96 lichenized taxa (lichens) were recorded in post-fire forest stands, including 10 of high conservation value. The time since the fire was associated with shifts in lichen species composition, however it was not a significant predictor of community-level species richness or Shannon diversity, according to linear mixed models. Richness, diversity, and composition of lichens were significantly influenced by several stand characteristics. In particular, our results highlight the importance of substrate heterogeneity, particularly the availability of deadwood and tree species diversity, in maintaining lichen richness in fire-affected forests. To conserve lichen diversity across landscapes, it is crucial to retain a mosaic of successional stages, as different species thrive at different points along the post-disturbance gradient. • Lichen communities shift compositionally along the fire chronosequence. • Deadwood and tree diversity are key drivers of post-fire lichen richness. • Post-fire forests host lichens of high conservation value. • A mosaic of successional stages is needed to conserve lichen diversity.