Landslides increased Holocene habitat diversity on a flysch bedrock in the Western Carpathians

Landslides are an important natural phenomenon of the flysch Outer Western Carpathians that diversify the local topography and provide valuable microrefugia in the geomorphologically uniform region. For the first time, we reconstructed the continuous history of Carpathian landslide wetland – the Kotelnice mire, which initiated at the Pleistocene-Holocene transition, using joint analysis of abiotic proxies, pollen, plant macrofossils and testate amoebae (TA). We utilised modern training datasets of plants and TA to define ecological requirements of species and to determine indicators of either bog or fen habitats. We further compared pollen representation of selected woody species between two landslide-related wetlands and two spring fens, not related to landslides within the study region. The unique feature of the Kotelnice mire is the development of a nearly ombrotrophic bog at ∼2500 cal BP that was after ∼1500 years reversed to a poor fen by intense deforestation and pastoralism. Pollen analysis and its intra-regional comparison demonstrate a dual refugial role of landslides in the Carpathians. In the Early Holocene and perhaps even in the Late Glacial, landslides provided refugia for warmth- and moisture-demanding species (e.g. lime, elm, hazel, beech, maple). On the contrary, they provided shelter for cold-demanding boreal species (e.g. spruce, Eriophorum vaginatum, Sphagnum medium/divinum) in the Middle and Late Holocene. Because the analogous refugial role of landslides at both the recent and the Quaternary time scales has been reported from the flysch-like and volcanite bedrocks across the Northern Hemisphere, landslides deserve more attention in searching for regionally or even globally crucial refugia.