Late survival of woodland contrasts with rapid limnological changes following settlement at Kalmanstjörn, Mývatnssveit, northeast Iceland

This work was funded by the NSF‐IPY (International Polar Year; ref 0732327), a Ph.D. studentship from the School of Geography and Sustainable Development, University of St Andrews, and the Quaternary Research Association.The settlement of Iceland is known to have had profound impacts on vegetation and landscape stability, but there remain uncertainties around the spatial variability and timing of environmental change, and the impacts of settlement on aquatic ecosystems. Here a new multiproxy palaeoenvironmental reconstruction spanning the last 3000 years is presented from Kalmanstjörn, a small lake in Mývatnssveit, northeast Iceland. Sedimentology, pollen and non‐pollen palynomorphs, and geochemical proxies, dated using tephrochronology, are used to reconstruct terrestrial vegetation, landscape stability and aquatic ecosystems. The data reveal complex environmental dynamics after settlement. At this site, substantial tree populations persisted until the late 15th century, in strong contrast to the rapid deforestation shown by almost all other records from Iceland. The eventual loss of woodland may have been caused by changes in direct human activity and the location of extensive grazing, in combination with Little Ice Age climatic cooling. The loss of woodland was accompanied by increased soil erosion. Conversely, the lake ecosystem showed an immediate response to settlement, becoming more productive for several centuries, perhaps in response to increased availability of nutrients from grazing herbivores. The late persistence of woodland in the Kalmanstjörn record adds to our understanding of the spatial variations in ecosystem responses to settlement in Iceland, while the evidence for decoupling of the aquatic and terrestrial systems suggests that palaeolimnological reconstructions focusing on aquatic ecosystem responses may be important new sources of information on the wider ecological consequences of human settlement.Publisher PDFPeer reviewe