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Environmental changes have had an enormous impact on prehistoric hunter-gatherers as they affect the biotic landscape and availability of resources such as freshwater, edible plants, game and fish. To assess whether various innovations that took place in hunter-gatherer communities during the Boreal may be attributed to changes in the vegetation, a high-resolution pollen and macrofossil analysis of a well-AMS-dated Early Holocene peat record from the Grote Nete valley in the Belgian Campine was carried out. Shifts in the pollen assemblages indicate a change from a birch-pine woodland in the late Preboreal to pine-dominated forests in the Boreal. After the initial expansion of hazel, followed by oak and elm from the early Boreal onward, a prominent and abrupt reduction of the pollen concentration, by up to 95% over several spectra, is observed during the second half of the Boreal. This sharp decline affects all taxa and coincides with a decrease in pollen percentages of thermophilous trees and an increase of the cold-tolerant pine. This shift in pollen concentration and vegetation composition likely reflects a climatic cooling at 9.3 ka which is evident in the stable oxygen isotopic record of the Greenland ice cores. On the one hand, the vegetation dynamics are discussed in the light of the Boreal vegetation history in general and this temporary cooling more specifically. On the other hand, we discuss how these changes may have affected past hunter-gatherer communities.

Palaeoecological studies in coversand areas are sparse as organic remains generally do not preserve well in sandy deposits. An AMS-dated Holocene peat sequence in a palaeochannel in a natural depression (the Liereman), flanked by coversand ridges proved to be an exceptional and valuable archive of long-term vegetation dynamics in the Campine (N Belgium). Analyses of microfossils, such as pollen, spores and non-pollen palynomorphs, as well as macrofossils of plants and other organisms have given insight in the vegetation dynamics over the past 11,500 years. Grasslands developed during the Rammelbeek phase of the Preboreal at the expense of the birch woodlands that characterized the Friesland phase of the Preboreal. During the Preboreal the depression was ecologically diverse with abundant resources for human subsistence, such as permanent fresh water, game and edible plants. However, to date no contemporaneous archaeological sites are known in the area. In the woodlands on the coversand ridges pines became the dominant regional vegetation towards the Boreal. The resulting lowering of ground water levels led to a decrease of the water availability and associated resources for hunter-gatherer societies. Yet, (early) Mesolithic hunter-gatherers settled in the area, however only temporarily. During the Atlantic coniferous forests were succeeded by mixed deciduous woodlands, while the freshwater availability decreased further. This possibly explains the near absence of middle and late Mesolithic sites in the Liereman area. From the Subboreal onward deciduous woodlands opened, probably as a result of human activity. Finally, through deforestation the area in and around the Liereman depression was partly cleared for agricultural purposes during the Subatlantic.