Johannes Edvardsson

A 1561-year tree-ring width (TRW) chronology covering the period 2668–1108 BC (4617–3057 BP) has been developed from 159 moisture-sensitive peatland pines (Pinus sylvestris L.) sampled at Åbuamossen, southern Sweden. Tree population dynamics and annual growth responses of the trees were shown to reflect and give absolute age to regional hydro-climatological changes. The main wet-shifts recorded in the TRW data were precisely dated to 2150–2100, 1550 and 1230–1150 BC (4100–4050, 3500 and 3180–3000 BP) and are likely to be related to the stepwise Mid- to Late Holocene climate transition, during which the condition changed from relatively warm and dry towards cold and moist in the northern hemisphere. The tree-colonization phase was ended by several long-lasting periods showing depressed annual tree growth and an abrůpt dying-off phase, possibly caused by increasing water level in the peatland as well as the adjacent river Helge A. This study demonstrates that TRW data obtained from subfossil peatland trees can provide detailed information and exact age control on moisture variability in peatlands associated with regional hydroclimatic changes. Moreover, the combined information from the stratigraphical and the TRW analyses enabled a detailed temporal and spatial site development reconstruction.