Vegetation response to the ∼14.7 and ∼11.5 ka cal. BP climate transitions: is vegetation lagging climate?

Abstract

The transition from the Last Glacial towards the Holocene is marked by two rapid increases in temperature. These climate transitions are recorded in detail in the Greenland ice-cores, and these records reveal that the climate shifts around 14.7 and 11.5 ka cal. BP seem to have occurred within a few years only. In this paper it is argued that vegetation did respond directly to the climatic warming round 14.7 and 11.5 ka cal. BP. The response of vegetation must, however, not be regarded as an immediate establishment of forests. It is most likely to assume that vegetation present at the moment of climatic improvement, responded by increased flowering, which thus should be reflected in the palynological record as an increased presence. These palynological events occur at approximately 14.8 and 11.7 ka cal. BP, based on calibrated radiocarbon ages. From the palynological evidence, which is available from numerous terrestrial records, the vegetation response to the climate changes seems to be quite different for both transitions. As climate remained relatively warm since the climatic improvement, forests could develop. In the early Lateglacial, it took some time for a dense forest to develop, due to both migrational lags and the delayed response of permafrost melting. For the Early Holocene, forest stands were relatively near, relict permafrost did not occur, and hence vegetation could recover quickly after the climatic improvement.