Medieval Relict Beaver Ponds in the Polish Plain: Studies from the Tuchola Forest

Abstract

Beavers have lived in the territory of Poland since the beginning of the Holocene, as testified by bone remains found in archaeological sites of different ages. The area inhabited by these animals has experienced continuing transformations of terrain relief, geological structure, hydrology and plant cover. In Poland, beavers are partially protected and their population has spread in virtually every part of the country (except in the highest mountain ranges). The authors of this paper wish to present the results of field works carried out since 2006 in the Tuchola Forest (Polish Plain). This paper aims to identify the potential sediments of relict beaver ponds and their sedimentological features. The studies are also backed up with a description of radiocarbon dating of samples. The results indicate that beavers used to live in the Tuchola Forest in the Middle Ages, as shown by the radiocarbon dates and sequences of mineral–organic deposits found in exposures and geological boreholes. The spatial distribution of organic and mineral deposits in wider sections of river valleys can be explained by the avulsion of the riverbed downstream of the pond and by the distribution of ponds in the Gołyjonka valley. The discovery of relict beaver pond sediments suggests that the activity of these mammals in the Middle Ages played a major part in shaping the landscape of the valley. The results of studies clearly indicate that analyses of the valley sediment facies of small watercourses should take into account the role beavers played in the past in shaping the landscape of the analysed valley. This highlights the insufficiency of studies concerning the activity of beavers in river valleys.