Palynological investigations in Western Iran
In this paper the palynological examination of sediment cores from Lake Zeribar and Lake Mirabad in the Zagros Mountains of western Iran is discussed. Radiocarbon dates suggest that the Lake Zeribar pollen record covers the last 40,000 years, that of Lake Mirabad the last 10,000 years.
Topography, climate and natural vegetation of western Iran are briefly reviewed in chapter 2 (figs. 1-3). Information on the coring localities is presented in chapter 3. In chapter 4 short descriptions are given for a great number of pollen types distinguished in the Iranian sediment cores (figs. 10-20).
In the period of c. 40,000 to c. 10,500 B.P. open vegetations, in which Chenopodiaceae, Artemisia, and Umbelliferae played a predominant part, prevailed in the Zagros Mountains. The high percentages for umbelliferous pollen, among which a fairly large number of types could be distinguished, are a conspicuous feature of the Zeribar pollen diagrams.
Scattered tree stands were present in the Zeribar area in the period of c. 40,000 - 22,000 B.P., whereas between c. 22,000 and 14,000 B.P. trees had disappeared completely from the Zeribar area and probably from the greater part of the Zagros Mountains. Climatic dryness must have been a major limiting factor for tree growth in western Iran in Pleniglacial times.
After 14,000 B.P. pistachio was again present in the Zeribar area. Trees (Pistacia, Quercus, Acer, and others) expanded slowly in western Iran after 10,500 B.P., which resulted in forest-steppe vegetation. The nature of the herbaceous vegetation differed markedly from that in Pleniglacial times. It was not until c. 5,500 B.P. that the present-day natural forest cover had established itself. In the upper sections of the Zeribar and Mirabad diagrams distinct indications of human activity are recorded.
A comparison of the Zeribar pollen record with that of sites in Greece, southwestern Turkey, and western Syria indicates that rhe Pleniglacial climate of continental western Iran must have been more adverse to tree growth than that of areas near the Mediterranean coasts. Most pollen diagrams from the Eastern Mediterranean area suggest that the early Postglacial climate was drier than that of today. Whether this was due to lower precipitation or to drier summers (higher temperatures, longer rainless period) is not yet clear. Finally same archaeological implications of the results of the palynological investigation are discussed.