First insights into lichen symbiont associations along a successional gradient in the glacier forefield of Ödenwinkelkees (Hohe Tauern, Austria)

Although lichens play a central role in primary succession, they have so far been largely overlooked in ecological research on glacier forefields. This study presents the first molecular assessment to investigate association patterns of dominant lichen symbionts along a succession gradient in the glacier forefield of the Ödenwinkelkees (Hohe Tauern, Austria). In a pilot study, lichen diversity and coverage was assessed across 11 permanently marked 1×1 m plots of the Ödenwinkel Research Platform, spanning ~225 years of deglaciation. Dominant lichen symbionts (mycobiont [fungus], photobiont [algae]) were molecularly identified using the classic barcode marker ITS and lichen cover was quantified from rectified top-view images. Assembly- and community patterns were explored using network- and multivariate statistics. A hump-shaped pattern of species richness was observed, peaking at ~100 years since deglaciation. Rock dwelling lichens dominated early stages, while soil dwelling species increased after ~46 years and prevailed at intermediate ages (mean coverage ~36%). Photobiont identity appeared to mediate mycobiont ecological range, with generalist fungi associating with multiple algal partners. Field assessable groups effectively indicated successional stage, and the mean thallus area of yellow Rhizocarpon spp. emerged as a promising proxy for terrain age. This study highlights lichen community turnover and photobiont-mediated filtering along primary succession and provides a basis for future molecular and image-assisted lichenological research in alpine environments.