Holocene vegetation and climate changes in the central Mediterranean inferred from a high-resolution marine pollen record (Adriatic Sea)

Abstract

The high-resolution multiproxy study of the Adriatic marine core MD 90-917 provides new insights to reconstruct vegetation and regional climate changes over the southcentral Mediterranean during the Younger Dryas (YD) and Holocene. Pollen records show the rapid forest colonization of the Italian and Balkan borderlands and the gradual installation of the Mediterranean association during the Holocene. Quantitative estimates based on pollen data provide Holocene precipitations and temperatures in the Adriatic Sea using a multi-method approach. Clay mineral ratios from the same core reflect the relative contributions of riverine (illite and smectite) and eolian (kaolinite) contributions to the site, and thus act as an additional proxy with which to evaluate precipitation changes in the Holocene. Vegetation climate reconstructions show the response to the Preboreal oscillation (PBO), most likely driven by changes in temperature and seasonal precipitation, which is linked to increasing river inputs from Adriatic rivers recorded by increase in clay mineral contribution to marine sediments. Pollen-inferred temperature declines during the early-mid Holocene, then increases during the mid-late Holocene, similar to southwestern Mediterranean climatic patterns during the Holocene. Several short vegetation and climatic events appear in the record, indicating the sensitivity of vegetation in the region to millennial-scale variability. Reconstructed summer precipitation shows a regional maximum (170-200 mm) between 8000 and 7000 similar to the general pattern across southern Europe. Two important shifts in vegetation occur at 7700 cal yr BP (calendar years before present) and between 7500 and 7000 cal yr BP and are correlated with increased river inputs around the Adriatic Basin respectively from the northern (7700 event) and from the central Adriatic borderlands (7500-7000 event). During the mid-Holocene, the wet summers lead to permanent moisture all year resulting in a homogeneous seasonal precipitation regime. After 6000 cal yr BP, summer precipitation decreases towards present-day values while winter precipitation rises regularly showing the setting up of Mediterranean climate conditions. Multiproxy evidence from core MD 90-917 provides a deeper understanding of the role of precipitation and particularly the seasonality of precipitation in mediating vegetation change in the central Mediterranean during the Holocene

Eastern-Mediterranean ventilation variability during sapropel S1 formation, evaluated at two sites influenced by deep-water formation from Adriatic and Aegean Seas

“…This conforms with a suggested re-oxygenation of bottom waters in the central and South Adriatic Sea for this period [e.g. Artizegui et al, 2000;Piva et al, 2008;Vigliotti et al, 2011;Siani et al, 2013;Combourieu-Nebout et al, 2013;Goudeau et al, 2014]. However, from our detailed record it is clear that this does not mark the end of sapropel deposition but rather the partial re-oxygenation of the bottom waters.…”

Early and mid-holocene environmental conditions in the eastern Adriatic recorded in speleothems from Mala Špilja cave and Velika Špilja cave (Mljet island, Croatia)

“…As it is already shown by numerous researches (e.g. Bar-Matthews et al 1997Magny et al 2009;Bar-Matthews & Ayalon 2011;Brayshaw et al 2011;Giraudi et al 2011;Peyron et al 2011;Roberts et al 2011;Zanchetta et al 2011Zanchetta et al , 2014Zanchetta et al , 2016Rudzka et al 2012;Combourieu-Nebout et al 2013;Finné et al 2014) the Adriatic and Mediterranean basins are highly sensitive to climate changes and significant differences between the eastern and western basins are evident. Although stalagmites MSM-1 and VSM-1 have longer depositional period, the purpose of this paper is to give preliminary results for the Holocene environmental settings.…”

A long hard road… Reviewing the evidence for environmental change and population history in the eastern Adriatic and western Balkans during the Late Pleistocene and Early Holocene

“…This seems to be contrasted by a humid phase recorded in Lake Ljubljanska (Andrič et al, 2008) and a less distinct signal in the Adriatic, with evidence for only slightly decreased temperature and precipitation coupled with a decline in Quercus (e.g. Combourieu-Nebout et al, 2013).…”

“…During this time, average temperatures declined significantly, especially for the winter, as did overall precipitation, leading to an expansion of the dry steppe and a concomitant fragmentation of the boreal forest (Willis, 1994, Feurdean et al, 2014. Pollen from pine, Artemesia and chenopods in a southern Adriatic core dated to the end of GS-1 in the region suggest very dry conditions characteristic of steppe environments (Favaretto et al, 2008; see also Combourieu-Nebout et al, 2013). At Lake Prespa, there is a marked decrease of Pinus from 13.2 cal BP (i.e.…”

“…The nature of water circulation is important to consider when interpreting paleoenvironmental proxies from Adriatic sediment cores, especially pollen. Much of the freshwater input into the Adriatic from the east coast is via the subterranean flow of water through carbonate rocks (Poulain and Raicich, 2001), but its overall contribution remains minimal when compared to the input of the Pô river (Combourieu-Nebout et al, 2013). Cores from this region are considered useful for reconstructing regional environment because the northern Adriatic behaves as an open sea during fall and winter, with less movement of water occurring during spring and summer, during most pollen production (Artegiani et al, 1997).…”