A late Pleistocene long pollen record from Lake Urmia, Nw Iran

Abstract

A palynological study based on two 100-m long cores from Lake Urmia in northwestern Iran provides a vegetation record spanning 200 ka, the longest pollen record for the continental interior of the Near East.During both penultimate and last glaciations, a steppe of Artemisia and Poaceae dominated the upland vegetation with a high proportion of Chenopodiaceae in both upland and lowland saline ecosystems. While Juniperus and deciduous Quercus trees were extremely rare and restricted to some refugia, Hippophaë rhamnoides constituted an important phanerophyte, particularly during the upper last glacial sediments. A pronounced expansion in Ephedra shrub-steppe occurred at the end of the penultimate late-glacial period but was followed by extreme aridity that favoured an Artemisia steppe. Very high lake levels, registered by both pollen and sedimentary markers, occurred during the middle of the last glaciation and upper part of the penultimate glaciation. The late-glacial to early Holocene transition is represented by a succession of Hippophaë, Ephedra, Betula, Pistacia and finally Juniperus and Quercus. The last interglacial period (Eemian), slightly warmer and moister than the Holocene, was followed by two interstadial phases similar in pattern to those recorded in the marine isotope record and southern European pollen sequences.1 This work is dedicated to Sytze Bottema for his outstanding contribution to late Quaternary palynology of the Near East.2

A 94–10ka pollen record of vegetation change in Qaidam Basin, northeastern Tibetan Plateau

“…The rivers then transported the Artemisia pollen to the lake. The expansion of an Ephedra shrub-steppe during the glacial stage was also recorded in Lake Urmia, NW Iran, and the analog of Ephedra and Artemisia dominated vegetation type in the present was reported from the foothills of Iran in an arid area (Djamali et al, 2008). Thus, herein we infer that the relatively dry climate at that time led to increased evaporation and a drop in effective humidity, thus promoting the development of Ephedra because the drop in the lake level led to a low water table in the basin.…”

Hydrological variability in the Northern Levant: a 250 ka multi-proxy record from the Yammoûneh (Lebanon) sedimentary sequence

“…This is exemplified (Fig. 11a-c) by pollen records from Albania (L. Ohrid, Lézine et al, 2010), Greece (Tenaghi Philippon, Tzedakis et al, 2006) to NW Iran (L. Urmia, Djamali et al, 2008). During glacial periods, steppe landscapes took place under cool, dry conditions.…”

“…During glacial periods, steppe landscapes took place under cool, dry conditions. Nevertheless, several east Mediterranean lakes (e.g., Konya in Turkey, L. Urmia) have experienced relatively high level stands attributed to substantial temperature lowering reducing evaporation loss and enhanced runoff when an open vegetation cover prevailed (Roberts et al, 1999;Djamali et al, 2008). During interglacial peaks, maximum tree pollen percentages reflect warm conditions and higher precipitation from the mid-latitude westerly system.…”

Fire, climate and the origins of agriculture: micro‐charcoal records of biomass burning during the last glacial–interglacial transition in Southwest Asia

“…If correct, then fire frequencies may have been significantly higher during the Lateglacial and early Holocene than during the early parts of previous interglacial periods (cf. Djamali et al, 2008;Litt et al, 2009), when anatomically modern humans were absent or rare in Southwest Asia. Because fire frequencies increased at those times and in those areas where the human 'ecological footprint' was greatest, it is difficult, indeed probably futile, to try to partition burning regimes between natural and cultural drivers, since they operated synergistically.…”