Les analyses polliniques au Moyen-Orient

Abstract

In the Middle East, the pollen analysis are still veryfew and the sequences covering several millennia are scarce. In spite of the fact that they offer some variations due to botanical factors, two types of pollen spectra are complementary : the first one deals with wet places as lakes and marshes, the second one cornes from dry soils which are generally related to archaeological sites. Punctual palynological results concern the last Interglacial and show the diversification of its floristic associations. For the lower and middle Wurm the first analyses display a range of fluctuations with interchanges ofeither wet phases when the for est extends or dry ones, characterized by a steppic landscape. In some regions, particularly in the littoral zone, the alternations between Mediterranean and temperate forest rythm the fluctuations of temperature. The cold-wet maximum seems to be dated around 45 000 B.P. On the other hand, a drastic drought characterizes the coldest wurmian phase, which probably explains the scarcity of the archeaological occupations between 23 000 to 19 500 B.P. Some trees, as lime and Pterocarya, which formerly reached south Lebanon, disappeared then. The late Glacial is interrupted by a few improvements dated to 17 000, 13 500, 12 000 B.P. Then, a richer and more diversified flora shows the beginning of the Holocene time. The desertification of certain regions for 6 000 years is certainly due to the climate. But the increasing density of populations since 10 000 years, the pastoral and agricultural practices have had such an influence on vegetation and soils that it is actually impossible, for the Middle East, to refer, as in Europe, to a Holocene botanical stratigraphy.