Sebastian Hötzel

• Palynology of Africa (dinoflagellates and pollen)
• Climate development of south tropical Africa
  
• Development of the African savanna

The Miocene-Pliocene is the major time of the savanna grassland expansion in Africa and is followed or accompanied by the expansion of the so-called C4 plants which are adapted to dry warm conditions. The driving forces for this expansion are still unknown. Increased climatic seasonality, increasing general aridification, cloud cover, intense herbivory, and fire abundance are discussed to play important roles. It is mostly believed that strong upwelling attended with decreasing sea-surface temperature (SST) plays a major role in desiccation of the African continent. However, direct evidences for this link have been rarely reported so far and it is still poorly known how the tropical vegetation changed north of South Africa and especially how the tropical savannas developed.
This PhD project aims to understand and link the Neogene evolution of vegetation of western tropical Africa with sea conditions (e.g. Benguela Upwelling) by studying palynomorphs of marine sediments containing both marine as well as terrestrial organic microfossils. The main scientific objective by studying the vegetation history of western Africa is to gain insights in the variability of the tropical vegetation and its driving forces.