Development of high diversity beech forest in the eastern Carpathians

Aim: In recent decades, a surge in the number of significant and uncontrolled wildfires has occurred worldwide. Global warming may amplify this trend and threaten most ecosystems worldwide. Deciduous forests are characterized by high plant diversity, and understanding their long term dynamics is crucial to anticipate changes in these ecosystems during ongoing global warming. The aim of this study is to understand how European beech forests have colonized the inner Eastern Carpathians and how changes in fire regime and human activities have affected their biodiversity.Location: Inner Eastern Carpathian Mountains, Slovakia.Taxon: Plantae, gymnosperms, angiosperms.Methods: Peat core was extracted from the centre of Durova mlaka mire in 2018. A multi proxy approach has been applied to investigate the development of beech forest. Charcoal analysis has been done each centimetre to reconstruct the fire signal. Pollen analysis has been done at 2 cm resolution to reconstruct the vegetation composition and dynamics, and the variation in palynological richness (PRI), evenness and turnover has been analysed. Macro-remains analysis has been performed at 10 cm resolution to add more information about the local vegetation.Results: Low diversity spruce forest was dominant until 5200 cal. BP during a fire prone period due to specific climatic conditions (drier climate than the following period). The higher fire frequency and intensity following this period is simultaneous with the first expansion of Fagus which indicate that Fagus could occupy post fire habitats, at least at the local scale. However, its dominance coincided with major gaps in fire events from 3900 cal. BP. The PRI has increased during the transition from spruce to beech forest highlighting the importance of beech forests in maintaining plant biodiversity. However, the stronger increase in the richness is synchronous with the increase in human activities around 2000 cal. BP, and then 350 cal. BP.Main Conclusions: Climate-driven fire frequency has been a natural driver of vegetation changes in the Carpathians by promoting the emergence of high diversified beech forest. These changes were significantly modified by later increase in human activities.