Note: AMS dating of charcoal samples were conducted at Poznan Radiocarbon Laboratory (Poz), Poland. Radiocarbon ages were calibrated using CALIB (Version 7.0.4) (Stuiver and Reimer, 1993; Reimer et al., 2013). The 2 sigma ranges have maximum area under the probability distribution curve. All samples are taken from organic-rich bulk sediment.