Dendrochronological analysis of subfossil fraxinus and quercus wood excavated from the Kegai mire in Lithuania

Abstract

Dendrochronological investigations on subfossil Fraxinus and Quercus wood found in the Kegai mire in Western Lithuania are discussed. Radiocarbon dating has revealed that the trees grew in the Middle and Late Holocene (Fraxinus approximately from 4700 BC to 1500 BC and Quercus from 3400 to 2300 BC). These trees were slow-growing (on average less than 1 mm per year) and usually with a less pronounced age trend in comparison to living trees. The subfossil Fraxinus lived longer (131 years) than modern ash trees (76 years). It is supposed that their growth was limited by humid periods. The raise of soil water induced a long downward trend in ring width of ash and oak. This was followed by an abrupt reduction (up to 51%) in ring width before the die-off of ash trees. Up to now, forest history in Lithuania relied mostly on palynological studies, thus our results extend the current knowledge on the distribution of deciduous trees in the Baltic region in different periods of the Holocene.