From lake to river. The Weichselian Lateglacial and early Holocene palaeoenvironmental development of the Moervaart region (northwestern Belgium): a synthesis on vegetation patterns, climate, abiotic landscape and human occupation

In this paper, a synthesis is given of a large multi-disciplinary project, which included physical, botanical, zoological and archaeological studies, accelerator mass spectrometer (AMS) 14C and Optical Stimulated Luminescence (OSL) dating and chemical analyses from numerous locations in and along the extensive Moervaart palaeolake (NW Belgium), south of the Maldegem-Stekene Coversand Ridge. This rich dataset enabled a detailed reconstruction of climate, vegetation development and human presence in the period from the Weichselian Lateglacial and early Holocene. In addition, this dataset was used to make spatial reconstructions of the vegetation patterns in the direct surroundings of the Moervaart palaeolake for seven time slices and artist impressions for three moments in the archaeological record. These vegetation maps and the high resolution data on climate and the abiotic landscape are compared to former human occupation patterns to give insight in these early human presences in NW Europe. The first evidence for human presence, after a long period of absence, was found from the Allerød period. During this period, hunter-gatherers of the Federmesser culture were present in encampments along the northern shore of the Moervaart palaeolake which had developed during the Bølling period. Both the improving climate and the availability of a fresh water source stimulated human presence. The vegetation transitioned from a tundra landscape in the Bølling period to a boreal forest with birch and pine in the Allerød. During the following cold period of the Younger Dryas, forests retreated and tundra vegetation redeveloped. At the same time, the Moervaart palaeolake and most of the surrounding dune ponds turned dry. Evidence of human presence in the region during the Younger Dryas period is scarce, presumably related to the colder climatic conditions and the strongly reduced availability of fresh water sources. Due to climate warming during the early Holocene, boreal forests expanded again. However, evidence of human occupation of the area remains scarce. The Preboreal forest expansion was shortly interrupted by another cold reversal, the so-called Preboreal Oscillation or 11.4 event. After this event, hunter-gatherers returned to the area, then settling preferably along the dry banks of the Kale/Durme river, a tributary of the Scheldt river, which was the only source of fresh water in the region. During the following Boreal, coniferous forests were gradually replaced by deciduous forests which had developed initially with hazel, elm and oak, but later (Atlantic) also with lime, alder and ash. Hunter-gatherer site-density was highest during the first part of the Boreal, when hazel dominated the landscape. Afterwards, site-density dropped considerably; however, it is not clear whether this reflects a marked population reduction or rather points to changing mobility in response to a changing environment.