Old-growth forest and sacred landscape with Middle Neolithic non-megalithic barrows in western Poland during the 4th millennium BCE

The introduction of agriculture, herding, and permanent settlements during the Neolithic initiated the spread of human-shaped landscapes in Western, Central and Eastern Europe. Funnel Beaker culture (TRB, German: Trichterrandbecherkultur ) is listed among the groups responsible for the first major forest clearances and subsequent landscape transformations. In this article, we verify the hypothesis that TRB economy stayed in equilibrium with forest ecosystems in lowland areas, by examining the site in western Poland (Central Europe), located at the centre of this cultural phenomenon. High-resolution multi-proxy palaeocological research on the rich fen deposits (former lake), uniquely situated in the proximity to TRB long barrow graves, provided a deep view into interactions between TRB people and the environment. Our study revealed that TRB people intensified forest clearing for crop fields and wood pastures more than 100 years before the construction of barrows at ca. 3660 cal. BCE, which was simultaneous to an increase in fire activity affecting mostly grassland habitats. During this time, people probably tended to cut shrubs and young trees, as they were easier to fell. This, subsequently, provided better light availability for canopies of old-growth trees, stimulating them to produce more pollen (extraordinarily high values of pollen accumulation rate (PAR)) at ca. 3680–3540 cal. BCE. Afterwards, PAR declined, probably due to the climate cooling. In that lowland area, TRB people probably adopted the model of a quasi-sustainable economy, applying a rotational land use system in which they avoided extensive use of fire. Nonetheless, they might have stimulated erosion accelerating lake transformation toward the wetland, which is still present in the landscape.