Paleoclimate history and its influence on ecosystem changes and human occupation/abandonment of East African high mountain ecosystems in Ethiopia

• Applicant: Professor Dr. Michael Zech
• Subject Area: Physical Geography
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 451220720

Periods of human occupation and abandonment in the afroalpine region of the Bale Mountains, Ethiopia, were very likely triggered at least partly by paleoclimate changes. This is suggested by first results obtained from a previous project. Within this follow-up project proposal, which accompanies the DFG Research Unit 2358 ‘The Mountain Exile Hypothesis’, it is therefore planned to contribute to the paleoclimate reconstruction of the study area. The results will be essential for complementing the full picture of ‘climate-human-environment interactions’ of the Research Unit 2358 and they will be interpreted in close interdisciplinary cooperation with the colleagues from the fields of archeology, pedology, paleoecology and glaciology.Work Package (WP) 1 will continue monitoring the isotopic signature of modern-day precipitation in order to better understand the modern-day atmospheric circulation patterns including their specific isotopic signatures affecting the Bale Mountains. This is justified given that isotope records in East Africa are usually interpreted in terms of ‘precipitation amount’. The actually responsible effect might, however, rather be a ‘source effect’. This is of utmost importance for the correct paleoclimatic interpretation of δ2H and δ18O records from the Bale Mountains as well as of other East African paleoclimate isotope records. WP2 aims at establishing a multi-proxy paleoclimate isotope record. The rationale here is that the so far established δ2Hn-alkane and δ18Osugar records from Lake Garba Guracha may not be unambiguously attributable to aquatic versus terrestrial sources. In order to test this, hyrax middens as unambiguous terrestrial archives (in close collaboration with Subproject P3 Paleoecology of the Research Unit 2358) as well as diatoms and the aquatic-derived biomarker dinosterol will be investigated. Last but not least, we will continue investigating sedimentary archives in close collaboration with the Subprojects P2 Anthrosols and P3 Paleoecology of the Research Unit 2358. Within WP3 we will analyze already retrieved and dated sediment and peat cores from the Wergoba Valley, the Sanetti Plateau and the Harena Forest in order to check for spatial and temporal heterogeneity of our paleoclimate proxy signals; within WP4 we will investigate presumably pre-LGM (last glacial maximum) and LGM cores from Lake Cheleleka in the close-by Arsi Mountains. Last but not least, WP5 will focus at highest possible resolution on the topmost core sections of Garba Guracha, for which human occupation/abandonment is most obviously confirmed by P1 Archeology, P2 Anthrosols and P3 Paleoecology.

• DFG Programme: Research Grants