Mediaeval climatic warming recorded by radiocarbon dated alpine tree-line shift on the Kola Peninsula, Russia

Studies of the tree-line history in northern Fennoscandia provide useful evidence about the Holocene environment and the region's climatic history. Here we report on late-Holocene alpine tree-line movement in the Khibiny low mountains on the Kola Peninsula, northwestern Russia. A highly representative collection of subfossil woods above the modern tree-line was obtained and 49 pine samples were radiocarbon dated. Their radiocarbon ages range from c. 1400 to 3000 yr BP with a distinct maximum between c. 800 and 1000 yr BP (about cal. ad 1000 to 1300). We conclude that, especially during the Mediaeval climatic optimum, pine forests grew at least 100–140 m above the modern pine tree-line in the Khibiny mountains.