Arboreal pollen indicates surrounding forest presence: evidence from the eastern Tibetan Plateau

Assessing the spatial representation of pollen assemblages from lake sediments remains a fundamental challenge in palynology. This study integrates 871 modern pollen assemblages, four fossil sequences from alpine lakes, and topographic gradients on the eastern Tibetan Plateau to quantitatively estimate the effective dispersal distances of five major arboreal pollen taxa (Abies, Betula, Picea, Pinus, Quercus) by correlating pollen abundances with distances to optimal growth elevation. Results indicate that although Pinus exhibits relatively high dispersal capacity, the upper limits of effective dispersal distance is estimated as 56 km, with other arboreal taxa exhibiting shorter ranges (24 km for Abies; 25 km Picea and Betula; and 18 km for Quercus). This finding aligns well with established pollen transport mechanisms and supports their application in regional past vegetation reconstruction. This discovery establishes a taxon-specific, spatially explicit framework for regional vegetation reconstruction based on lake sediment records on the eastern Tibetan Plateau. It highlights the importance of accounting for the influence of surrounding topographic features when interpreting exogenous pollen signals and offers new insights into the scale of pollen-vegetation relationships in complex mountainous terrains.