Further Details on Holocene Treeline, Glacier/Ice Patch and Climate History in Swedish Lapland
Leif Kullman
Citation :Leif Kullman, Further Details on Holocene Treeline, Glacier/Ice Patch and Climate History in Swedish Lapland International Journal of Research in Geography 2017,3(4) : 61-69.
The present paper reports results from an extensive project aiming at improved understanding of postglacial subalpine/alpine vegetation, treeline, glacier and climate history in the Scandes of northern Sweden. The main methodology is analyses of megafossil tree remnants, i.e. trunks, roots and cones, recently exposed at the fringe of receding glaciers and snow/ice patches. This approach has a spatial resolution and accuracy, which exceeds any other option for tree cover reconstruction in high-altitude mountain landscapes. The main focus was on the forefields of the glacier Tarnaglaciaren in southern Swedish Lapland (1470-1245 m a.s.l.). Altogether seven megafossils were found and radio-carbon dated (4 Betula, 2 Pinus and 1 Picea). Betula and Pinus range in age between 9435 and 6665 cal. yr BP. The most remarkable discovery was a cone of Pice aabies, contained in an outwash peat cake, dating 11 200 cal. yr BP. The peat cake also contained common boreal ground cover vascular plant species and bryophytes. All recovered tree specimens originate from exceptionally high elevations, about 600-700 m atop of modern treeline positions. This implies, corrected for land uplift, summer temperatures, at least 3.6°C higher than present-day standards. The current results, in combination with those from other Swedish glaciers, contribute to a new view on the early postglacial landscape and climate in high-altitude Swedish Scandes