Forest or tundra? How different vegetation reconstructions of Last Glacial landscapes in Europe may shape our perception of early human dispersal processes

Regional variability and long‐term changes of past ecosystems likely had a strong impact on hunter–gatherer population dynamics, including the expansion of anatomically modern humans and the disappearance of Neanderthals. However, our understanding of these ecosystems remains limited, even when looking at large‐scale patterns, such as the extent and distribution of forested areas. Vegetation reconstructions are key to better understanding ecological preferences and their influence on the spatial distribution and dispersals of early humans. Here, we compare four different vegetation reconstruction techniques, two based on pollen data and two vegetation models, between 70 and 20 thousand years before present in Europe. Absolute values in forest cover can differ by up to 40% between reconstruction techniques, highlighting that the choice of method can make the difference between a boreal forest and a tundra. Besides method‐specific and statistical uncertainties, the reason for such a substantial offset lies in the loose definition of forest cover metrics, rendering a direct comparison between methods impossible. At the same time, we show that all reconstruction techniques accurately reconstruct ecosystem dynamics over time on continental to regional scales. We therefore highly recommend that researchers use relative forest cover measures as the more robust method to estimate past landscapes.