The contribution of pollen analysis of sediment from the sebkha boujmel (Southeastern Tunisia) in reconstructing holocene paleoenvironments and palaeolandscapes in arid land

Pollen analyses are undertaken on Mid-to Late Holocene sediments and on surface samples from the sebkha Boujmel. Preliminary results highlight vegetation changes with large pollen taxono mic diversity and the vegetation response to both palaeoclimate change and human impact. From ca. 7000 to 4000 cal. BP, during the humid Mid-Holocene episode, a grass steppe was widespread in the Jeffara coastal plain while a Mediterranean shrub covered the mountaino us hinterland. At that time, human impact remains limited and major vegetation changes were triggered by climate forcing. At the Mid-to Late Holocene transition, the decrease of Mediterranean vegetation and both spreads of Artemisia and desert taxa may be related to increasing aridity. The surface samples reflect how human pressure is responsible for modern landscapes. The desert taxa develop while Olea and other pollen indicators attest to the increasing human activity on local ecosystems. Furthermore, pollen records stress the complex Artemisia dynamic and point to the lack of evidence towards an Acacia steppe in the southern pre-Saharan Tunisia during the Holocene.