Hötzel, Sebastian

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PhD Project

Vegetation development in West Africa of the biosphere shiftduring late Miocene to (early) Pliocene

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.

Publications and Manuscripts

Hoetzel, S, Dupont, L., Schefuß, E., Rommerskirchen, F. and Gerold Wefer (in press): The role of fire in Miocene to Pliocene C4 grassland and ecosystem evolution. Nature Geoscience. DOI: 10.1038/ngeo1984
Hoetzel, S., Dupont, L., Marret, F. and Wefer, G. (in prep.): Miocene-Pliocene Stepwise Intensification of the Benguela Upwelling over the Walvis Ridge off Namibia.
Hoetzel, S., Dupont, L. and Wefer, G. (in prep.): Miocene-Pliocene Vegetation change in south-western Africa (ODP Site 1081, offshore Namibia).

Conferences and Workshops

Participation at the Pollen and Spore Master Class, Utrecht, Nl (2013).
Hoetzel, S.. Dupont, L., Schefuß, E. and Wefer, G. (2012): The Miocene to Pliocene Expansion and Establishment of the South West African C4 Grass Savanna (Namibia) (poster presentation). AGU, Fall Meeting, San Francisco, USA.
Hoetzel, S. and Dupont, L. (2012): Late Neogene Vegetation Change of the South West African Tropics (Namibia) and the Expansion of Modern Savanna (oral presentation). The Centenary meeting of the Paläontologische Gesellschaft, Berlin, Germany.
Hoetzel, S. and Dupont, L. (2012): Late Neogene vegetation change of the south west African tropics (Namibia) (oral presentation). Bremen PhD Days, Bremen, Germany.
Hoetzel, S. and Dupont, L. (2012): Late Neogene vegetation change of the south west african tropics (Namibia) (poster presentation). IODP/ICDP Spring Meeting Kiel, Germany.
Hoetzel, S. and Dupont, L. (2011): Impact of Benguela Upwelling (Namibia) - Intensities of the last 10 Ma and Effects on Continental Vegetation (poster presentation). 2nd Young Scientist Excellence Cluster Conference on Marine and Climate Research, Bremen, Germany.
Hoetzel, S. and Dupont, L. (2011): West African vegetation changes (poster presentation). Bremen PhD Days, Bremen, Germany.
Hoetzel, S. and Dupont, L. (2011): Reconstruction of the Benguela Upwelling (Namibia) - Intensities of the last 10 Ma and Effects on Continental Vegetation (poster presentation). 9th International conference on modern and fossil dinoflagellates, Liverpool, UK.

Research Interests

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

Short CV

since 2010	PhD student at the Marum, University of Bremen Thesis: Vegetation development in West Africa of the biosphere shift during late Miocene to (early) Pliocene
9 and 11 2012	Guest student at the School of Environmental Sciences, University of Liverpool (UK)
2007-2010	Master of Geosciences at the Westfälische Wilhelms Universität Münster Master thesis: Palynofacies and Microfacies of a Middle Devonian carbonate succession of the Sötenich Syncline (North Eifel)
2004- 2007	Bachelor of Geosciences at the Westfälische-Wilhelms Universität Münster Bachelor thesis: In situ palynology of some stephaninan fructifications