Caring for preservation - coring for prehistoric life. Revisiting 15 000 years of sedimentation at the Ageröd peatland, Southern Sweden

Abstract

The Rönneholm-Ageröd peatland complex, situated in central Scania, contains numerous archaeological sites discovered since the 19th century. Two sediment sequences were obtained at the Ageröd peatland to compare the sediment stratigraphy with a previous sequence obtained in 1960 to detect any modern-day changes and to establish the Holocene environmental development in the area. To clarify the timing of ceased peat-cutting activities, dendrochronological analysis was performed on trees growing on the peatland. The results indicate that the lake transitioned into first a fen stage and later a raised bog stage, at about 7300 cal BP and 6500 cal BP, respectively. Furthermore, the dendrochronological analysis indicates that peat cutting ceased at least before 1960 in the sampled areas. Depending on e.g. hydrological conditions and human impact, the potential for preservation of organic remains varies greatly within the Rönneholm-Ageröd peatland complex. After peat-cutting activities ceased at the Ageröd peatland, the area was abandoned, without being restored to its original state and the drainage systems were left open but without maintenance. Our results show that these drainage ditches are still effective at the Ageröd peatland, which contributes to an active loss of peat at the top of the stratigraphic sequence. This causes the youngest formed peat layers to degrade, in turn, exposing older layers and reducing the buffer zone above the preserved organic cultural heritage from the lake-phase of the wetland with their destruction. To increase the understanding of modern-day processes affecting the preservation of organic remains in peatlands, continued monitoring and measuring of the peatland preservation status is needed in areas with archaeological deposits. We predict that if we fail to take action and establish a routine for finding and mitigating ongoing wetland degradation, the organic cultural and environmental heritage in them will, in the not-too-distant future, collapse and irrevocably deteriorate.