Vegetation dynamics in the Northeastern Mediterranean region during the past 23 000 yr: insights from a new pollen record from the Sea of Marmara

Abstract

Abstract. High-resolution pollen analysis of core MD01-2430 from the Sea of Marmara (40 • 47.81 N, 27 • 43.51 E) allows us to reconstruct the vegetation response to climatic changes during the past 23 cal ka in the Northeastern Mediterranean. Variation in mesic/temperate forest cover indicates major climatic shifts connected to Heinrich Stadial 1, Bölling-Allerød, Younger Dryas and to the onset of the Holocene. Pollen-anthropogenic indicator approach was used to recognize human-induced landscape changes in the Sea of Marmara. The pollen-inferred onset of the Holocene occurs at ca. 11.5 cal ka, indicating that the Northeastern Mediterranean region represents a transitional zone where higher moisture availability supported an earlier forest expansion than the borderlands of the Aegean Sea and Black Sea. Two major forest retreats occurred during the Holocene at ca. 5.5 and 2.1 cal ka. The Holocene forest setbacks are in phase with previously published alkenone-inferred seasurface temperature decreases in the Sea of Marmara reconstructed from the same core. Our new pollen record testifies the sensitivity of Mediterranean forests to changes in moisture availability, which is driven by changes in highlatitude atmospheric processes (North Atlantic Oscillations and/or Siberian High).

A Late Glacial to Holocene record of environmental change from Lake Dojran (Macedonia, Greece)

“…The reed beds, however, did not lead to less supply of clastic material (high K, Fe and sedimentation rates), probably because human-induced wood clearance and anthropogenic impact in the catchment increased (cf. Athanasiadis et al, 2000), as it is also reported from other records in the eastern and northeastern Mediterranean region (Willis, 1994;Denèfle et al, 2000;Kotthoff et al, 2008a;Bordon et al, 2009;Valsecchi et al, 2012). A lower lake level could also have promoted the occurrence of shells and shell redeposition (Bially and Macisaac, 2000) by greater exposure of the shell beds to wave action.…”

“…Emeis et al, 2000). However, a separation in two phases such as indicated by Co1260 is not evident in other terrestrial records from Greece or in marine pollen records from the Aegean Sea and the Sea of Marmara (Rossignol-Strick, 1993;Digerfeldt et al, 2000;Lawson et al, 2004Lawson et al, , 2005Kotthoff et al, 2008aKotthoff et al, , 2011Valsecchi et al, 2012). At least the particular dry phase described from the northern Aegean region around 11 800 cal yr BP (Kotthoff et al, 2008a corresponds with the low OM content and low TOC/TN ratios in Co1260 between 11 800 and 11 600 cal yr BP.…”

“…A lake-level lowering of 6 m between 1955 and 2000 was mainly caused by irrigation and canalisation of the former outlet, River Doiranitis (Griffiths et al, 2002;Zacharias et al, 2002;Sotiria and Petkovski, 2004;Manley et al, 2008). This lake level decrease led to eutrophication and is well recorded in the chemical, biological and stable isotope data of the surface sediments (Veljanoska-Sarafiloska et al, 2001;Griffiths et al, 2002). Increasing anthropogenic influence at Lake Dojran from the mid to late Holocene has been inferred from pollen assemblages in sediment cores recovered close to the lakeshore (Athanasiadis et al, 2000).…”

“…Overall cold and dry climate between 12 500 and 11 500 cal yr BP at Lake Dojran can be attributed to the Younger Dryas, when 6 • C lower temperatures and arid conditions with 50 % less annual precipitation compared to modern conditions are reported from the northern Aegean region (Kotthoff et al, 2008a, the Sea of Marmara (Valsecchi et al, 2012), and from other terrestrial records in Italy (Allen et al, 2002), Macedonia (Bordon et al, 2009;, and Greece (Digerfeldt et al, 2000;Lawson et al, 2004). However, the cold and dry climate during the Younger Dryas is barely visible in geochemical and hydrological data from lakes Prespa and Ohrid (Fig.…”

North–south palaeohydrological contrasts in the central Mediterranean during the Holocene: tentative synthesis and working hypotheses

“…39 • N) supports these conclusions with phases of shallower water around 5500 and 4000 cal BP. As discussed by Joannin et al (2013), if we take into account the radiocarbon age uncertainty (standard deviation), the lowering which developed between 2500 and 1800 cal BP may be equivalent to the well-known phase identified around 2700-2500 cal BP at the Subboreal-Subatlantic transition (van Geel et al, 1996). Another relevant interpretation, if we consider the relatively northern latitudinal location of Lake Trifoglietti at more than 39 • N, may be to infer a possible slight migration south to 40 • N of the boundary between the north-and the south-central Mediterranean sectors characterised by contrasting palaeohydrological patterns.…”