We are studying the distribution of microorganisms, mainly bacteria, in the Atacama Desert. We identify the bacteria that live in the dry and salty soils as well as in association with hosts, such as plants and beetles. We then compare the bacterial colonization patterns in these different habitats among each other and with the distribution patterns of their hosts, which allow us to better understand the microbial colonization of the desert. On top of that, we are performing experiments in order to determine to what extent bacteria in soils are alive and can be reactivated upon soil wetting. Our results will give valuable insights into how bacterial life in such an extreme environment functions. We collected samples from all over the Atacama Desert, which means that we will create an inventory of bacterial life in this particular ecosystem.

“Handling the samples in the laboratory is challenging, because of low microbial abundance and the salt content in the soil. So we had to modify quite a few of the existing protocols in our laboratory. Now we are looking forward to bringing the data from the different subprojects together”

– Wiebke Sickel, PostDoc in B4

Thus, we will be able to study the similarities and differences in microbial colonization of the different habitats in the desert and to compare it with desert colonization of higher organisms. Our ‚activity experiments‘ will furthermore answer the question, to what extent the bacteria in soil can react to rare rain events in the desert, which so far remains largely unclear.

Publication

• https://www.sciencedirect.com/science/article/pii/S0038071717306284

Contact

Prof. Dr. Claudia Knief
Phone: +49 (0) 228 73-2555
E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Two grants were approved for the Z2 project, which is very much appreciated. The first grant is the TanDEM-X Global DEM for the whole study area by the TanDEM-X Science Team. This very accurate digital elevation model will give us the opportunity to derive geomorphometric data for many applications within the CRC, such as catchment analysis, landform classifications and drainage system analysis.

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Deciphering the evolution of the alluvial fans [between 21°S and 25°S – the interplay between climatic and tectonic control]

The project C2 focuses on alluvial fans – special conical sedimentary landforms typical along mountain fronts – in the coastal Atacama Desert. They emerge from the steep Coastal Cordillera and spread over a narrow plain to the Pacific Ocean. By studying the architecture, timing, and drainage basin characteristics of the alluvial fans along a South-North gradient of increasing dryness (‘aridity’), we aim at deciphering the different impacts of climatic and geologic controls on fan evolution. This knowledge is crucial to understand fluvial transport and sedimentation (river deposits) in this unique, extremely dry (‘hyperarid’) landscape. This is particularly important under changing climatic conditions.

“Unique about this project is the combination of different geomorphological, sedimentological, and geochronological approaches allowing us to reconstruct the evolution of such a special coastal environment – being special due to its aridity and steep relief.”
– Prof. Dr. Frank Lehmkuhl

So far, very little research focused on alluvial fans interacting with the marine environment in hyperarid regions. The coastal alluvial fans in the Atacama Desert are especially interesting because they differ considerably in their architecture, age, and activity from the interior fans of the Atacama Desert. The coastal fans are comparatively short (few hundreds of meters to maximum three kilometers) due to erosion by wave action but thick. Rare but extraordinary rainfall events, like the one in March 2015 (see link below), affect in particular the coastal region by severe debris flows.

Moreover, we use and compare a wide range of numerical dating techniques to get first age information on alluvial fan activity in the coastal Atacama during the late Quaternary. In contrast to the interior fans which date back to the Miocene-Oligocene (9 to 34 million years ago, e.g. Dunai et al., 2005, Ritter et al., 2018), fan deposits at the coast are as yet exclusively dated by us to be younger than the last interglacial (last 100,000 years). 

“The ability to see stunning landforms and deposits of various geomorphological processes in a hyperarid region with barely any vegetation is like looking at the evolution of Earth’s naked skin.”
– Prof. Dr. Helmut Brückner

Publication

• Scientific article:
  https://www.tandfonline.com/doi/full/10.1080/17445647.2019.1611499
• The March 2015 flood event in the Atacama Desert:
  https://www.munichre.com/topics-online/en/climate-change-and-natural-disasters/natural-disasters/floods/floods-in-atacama-desert-2015.html

Other references

• Dunai, T.J., González López, G.A., Juez-Larré, J., 2005. Oligocene-Miocene age of
            aridity in the Atacama Desert revealed by exposure dating of erosion-sensitive
            landforms. Geology 33, 321–324. https://doi.org/10.1130/G21184.1
• Ritter, B., Stuart, F.M., Binnie, S.A., Gerdes, A., Wennrich, V., Dunai, T.J., 2018.
            Neogene fluvial landscape evolution in the hyperarid core of the Atacama
            Desert. Sci. Rep. 8, 13952. https://doi.org/10.1038/s41598-018-32339-9

Contact

Prof. Dr. Frank Lehmkuhl
Phone: +49 (0) 241 8096 064
E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it.