Warm Younger Dryas summers and early late glacial spread of temperate deciduous trees in the Pannonian Basin during the last glacial termination (20-9 kyr cal BP)

Abstract

This paper focuses on the last glacial termination vegetation and climate reorganization of the Eastern Pannonian Plain via the multi-proxy paleoecological analysis of Kokad mire in Eastern Hungary. Grains size, sediment chemistry and magnetic susceptibility records are compared with the pollen and plant macrofossil records on the basis of which biome and quantitative summer mean temperature reconstructions are provided and discussed with other climate records of the region. Biome assignments indicated (graminoid and forb) tundra vegetation from 19,440 cal yr BP with the local presence of Betula pendula, B. pubescens, B. nana, and Pinus sylvestris. A rapid biome shift to cool coniferous forest took place at 16,200 cal yr BP, and a second biome shift was identified at 14,740 cal yr BP when cool mixed forest developed and persisted into the Early Holocene. The most prominent feature of the record was the early post last glacial maximum (LGM) establishment (17,700 cal yr BP) and expansion (14,700 cal yr BP) of elm (Ulmus) and hazel (Corylus) supporting the phylogeographical evidence for extra-Mediterranean refugia in the Pannonian Basin. The fungal spore record indicated the presence of large grazing mammals locally after the LGM until ?16,780 cal yr BP. Their disappearance predated the biome shift to cold coniferous forest and the final increase of forest fires. Pollen based summer temperature reconstruction suggested relatively warm summers (?14.5 °C) by 19,440 cal yr BP, and buffered July mean temperature fluctuations throughout the last glacial termination in this region with < 1 °C decrease in summer mean temperatures during the Younger Dryas stadial, and ?2.2 °C warming in the Early Holocene. Our comprehensive summary of the basin’s Late Pleniglacial (24,000–14,600 cal yr BP) and late glacial paleoenvironmental and paleoclimate records showed a partially wooded landscape with higher woody cover in Western Hungary. Several loess and lake archives confirmed that in this region of Europe the warming after Heinrich event 1 (around 16,200 cal yr BP) had similar amplitude to the late glacial warming.