Interest of hydrogeological modelling in the interpretation of pollen proxies for palaeo-climate reconstitution: example from Senegalese niayes
Résumé
Niaye ecosystems shelter an azonal relic guinean vegetation under sahelian climate. Pollinic proxy records in cores show that a guinean closed forest installed at 10500BP* during the African Humid Period (AHP), and thrived under a somewhat degraded state until 2500 BP. Sub-surface water flow brings today the necessary water to these interdunal depressions, keeping some of them flooded, with a distribution linked to water stress. But the equilibrium was different in the past between underground water availability, surface run-off, varying regional hydrogeology, sea level.
and distance, and pluviometry (annual and seasonal). This study aims at:
- explaining how gallery forest persisted through the mid-Holocene dry episode (7500-4000BP), though in a degraded state,
- examining the dynamics of the end of the Tafolian humid pulsation (4000-3000BP), when vegetation turned to sahelian
- weighting the relative strength of the different forcings, notably the transience of higher-scale hydrogeology
- finally, examining the pertinence of a (sometimes assumed) distinctive relationship between observed pollens and regional climate.
Domaines
Milieux et Changements globaux
Origine : Fichiers produits par l'(les) auteur(s)