Articles | Volume 12, issue 6
Clim. Past, 12, 1339–1359, 2016

Special issue: Human–land–sea interactions in the Mediterranean...

Clim. Past, 12, 1339–1359, 2016

Research article 15 Jun 2016

Research article | 15 Jun 2016

Environmental changes, climate and anthropogenic impact in south-east Tunisia during the last 8 kyr

Sahbi Jaouadi1, Vincent Lebreton1, Viviane Bout-Roumazeilles2, Giuseppe Siani3, Rached Lakhdar4, Ridha Boussoffara5, Laurent Dezileau6, Nejib Kallel7, Beya Mannai-Tayech8, and Nathalie Combourieu-Nebout1 Sahbi Jaouadi et al.
  • 1UMR 7194 CNRS, Histoire naturelle de l'Homme Préhistorique, Département de Préhistoire, Muséum national d'Histoire naturelle, Paris, France
  • 2Laboratoire d'Océanologie et de Géosciences LOG, UMR8187, CNRS-Université Lille-Université Côte d'Opale, 59655 Villeneuve d'Ascq, France
  • 3Laboratoire des Interactions et Dynamique des Environnements de Surface (IDES), UMR8148, CNRS-Université de Paris-Sud, Bat 504, 91405 Orsay CEDEX, France
  • 4Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisia
  • 5Institut National du Patrimoine, 4 Place du Château, 1008 Tunis, Tunisia
  • 6UMR 5243 CNRS, Géosciences Montpellier, Université de Montpellier, Montpellier, France
  • 7Université de Sfax, Faculté des Sciences, Laboratoire GEOGLOB, BP 802, 3038 Sfax, Tunisia
  • 8Université de Tunis El Manar, Faculté des Sciences de Tunis, 2092 Tunis, Tunisia

Abstract. Pollen and clay mineralogical analyses of a Holocene sequence from Sebkha Boujmel (southern Tunisia) trace the climatic and environmental dynamics in the lower arid bioclimatic zone over the last 8000 years. During the mid- to late Holocene transition, between ca. 8 and 3 ka BP, a succession of five wet–dry oscillations is recorded. An intense arid event occurs between ca. 5.7 and 4.6 ka BP. This episode marks the onset of a long-term aridification trend with a progressive retreat of Mediterranean woody xerophytic vegetation and of grass steppes. It ends with the establishment of pre-desert ecosystems around 3 ka BP. The millennial-scale climate change recorded in the data from Sebkha Boujmel is consistent with records from the south and east Mediterranean, as well as with climatic records from the desert region for the end of the African Humid Period (AHP). Eight centennial climatic events are recorded at Sebkha Boujmel and these are contemporary with those recorded in the Mediterranean and in the Sahara. They indicate a clear coupling between the southern Mediterranean and the Sahara before 3 ka BP. The event at 4.2 ka BP is not evidenced and the link between events recorded in Sebkha Boujmel and the North Atlantic cooling events is clearer from ca. 3 ka BP onwards. These variations indicate the importance of climatic determinism in the structuring of landscapes, with the establishment of the arid climatic conditions of the late Holocene. It is only from ca. 3 ka BP onwards that the dynamic of plant associations is modified by both human activity and climatic variability. The climatic episodes identified during the historic period indicate strong regionalisation related to the differential impact of the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) on the Mediterranean Basin. The local human impact on regional ecosystems is recorded in the form of episodes of intensification of pastoral and/or agricultural activities. The development of olive production and of several taxa associated with agriculture attest to increasing sedentism among human populations during classical antiquity. The significant increase in Artemisia (wormwood) between ca. 1.1 and 0.8 ka BP (850–1150 AD) is linked to intensive pastoral activity, associated with heightened interannual and/or seasonal climatic instability. A complete reshaping of the landscape is recorded during the 20th century. The remarkable expansion of the olive tree, and the deterioration of regional ecosystems with the spread of desert species, is linked to recent local socio-economic changes in Tunisia.

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