Vegetation, fire and climate history of the Lesser Caucasus: a new Holocene record from Zarishat fen (Armenia)

Abstract

Vegetation, fire and climate history are investigated in the 10 000‐year record of Zarishat fen located today in the steppe grasslands of Armenia (Near East). Pollen‐based climate quantification provides a reconstruction of seasonal parameters. The development of in‐situ water‐dependant plants and of forests at lower altitude at 8200 cal a BP echoes the shift from an arid and cold [annual precipitation (Pann) = 452 mm; mean temperature of the coldest month (MTCO) = −11.1 °C)] Early Holocene to a more humid and warmer (Pann = 721 mm; MTCO = −6.8 °C) Mid–Late Holocene. This marks the onset of lower seasonality, in particular more effective precipitation brought during late spring by the Westerlies. Paralleling the Mediterranean precipitation pattern, precipitation in the Near East and Central Asia decreased during the Mid–Late Holocene in favour of higher seasonality controlled in winter/spring by the Siberian High. Fire history and sedge‐based fen development record drier phases at approximately 6400, 5300–4900, 3000, 2200–1500 and 400 cal a BP, which resemble the precipitation pattern of the South‐Western Mediterranean and contrast with the Holocene pattern in the South‐Central and South‐Eastern Mediterranean regions. Arid phases in Armenia are believed to be related to multi‐centennial‐scale variation of Westerly activity (North Atlantic Oscillation‐like).

Mid Holocene vegetation reconstruction from Vanevan peat (south-eastern shore of Lake Sevan, Armenia)

“…According to Havinga (1984), dominance of Cichorioideae is associated with low taxa diversity and inconsistencies in the pollen assemblage. At Vanevan, taxa diversity is indeed low, but pollen assemblage consistency appears robust as several steppic taxa are observed (such as Artemisia, Chenopodiaceae, Caryophyllaceae, Carduaceae, Rubiaceae …), together with trees such as Ephedra distachya t., and E. fragilis t.. Contemporaneously, similar pollen assemblages existed at Zarishat fen (Joannin et al, 2014) and Lake Paravani (Messager et al, 2013). Therefore, Cichorioideae are widespread before ca.…”

“…is not occupied by aquatic vegetation as only few Cyperaceae grow. Sandy-silt sedimentation, which refrains spreading of hygrophytes, can indicate velocity of moving waters or more likely ephemeral fens on alluvial deposits (as observed in the higher elevated Zarishat fen, Joannin et al 2014). In the first case, relatively deep water coincides with wet conditions pointed out by Roberts et al (2001; for the Early Holocene.…”

“…Winter and late spring precipitation (P win , P May-Jun ; Fig. 7) are the hydrological parameters that are assumed to have the strongest relationship with pollen data in Armenia (Joannin et al, 2014). In southern Georgia also, statistical analysis showed that rainfall was the parameter most strongly correlated with pollen composition (Connor and Kvavadze, 2008).…”

“…7) which has already been tested in Armenia from the Zarishat pollen assemblages (Joannin et al, 2014). In the MAT (Guiot, 1990), the similarity between each fossil sample and modern pollen assemblage is evaluated by a chord distance.…”

Leaf wax <i>n</i>-alkanes in modern plants and topsoils from eastern Georgia (Caucasus) – implications for reconstructing regional paleovegetation

“…n-alkane patterns derived from regional sediment archives. Such lacustrine, loess-paleosol, open-air archaeological or fluvial archives were increasingly investigated during the last years and could potentially be used for n-alkane derived vegetation reconstructions (Messager et al, 2013;Joannin et al, 2014;Suchodoletz et al, 2015;Wolf et al, 2016;Egeland et al, 2016).…”