Forests of the tropical eastern Andean flank during the middle Pleistocene: An insight of how highly biodiverse forests lived without us

Photo taken close by the study site. The road that pass through Eastern Andes, and the magnificent Montane forest of western Amazonia behind. (Photo by M. L. Cárdenas)
Photo taken close by the study site. The road that pass through Eastern Andes, and the magnificent Montane forest of western Amazonia behind. (Photo by M. L. Cárdenas)

Who would have thought that building a road in Andes would have allowed us to gain new and unique insight of pristine western- Amazonian forests? (I would have thought completely the opposite). Initially Patricia Mothes, chief of the volcanologist section of the Intituto de Geofisica in Ecuador, was called to look at sediments exposed by road works on the eastern flank of the Ecuadorian Andes. Arriving at the site she found thick (>20 vertical meters) deposits of grayish and dark brown interbedded layers of sediments which looked like they have been recently deposited. At closer inspection Patricia discovered that there were even wood pieces and leaves within the dark sediments (now known to be highly organic) that had the appearance of have been deposited within modern time. She wanted to know more. So a PhD student was recruited (a.k.a. Macarena Cárdenas) to work with the sediments at the Palaeoenvironmental Change Research Group at the Open University under the supervision of Dr William Gosling… And so the study began.

After several years spent dating the sediments, analyzing their composition (physical and elemental) and the fossils (pollen and wood) contained within them preliminary insights into vegetation change on the eastern Andean flank during the middle Pleistocene (c. 200,000-300,000 years ago) were revealed and published (Cárdenas et al., 2011a; Cárdenas et al., 2011b). Further work covering stratigraphically lower sediments (older than those previously published; c. 500,000 year) and more detailed sedimentary and fossil analysis of the entire sequence completed a PhD thesis (Cárdenas, 2011).

I am now pleased to announce that the extended work included in my PhD thesis has now been published in a new article in Palaeogeography, Palaeoclimatology, Palaeoecology (Cárdenas et al., online). The new paper is an extended version from previous publications from the same research and provides further evidence of the unique insights that can be gained from palaeoenvironmental studies in this region. These are some of the oldest Quaternary sediments ever discovered and studied from the mid-elevation eastern Andean flank / western Amazon and upon their analyses we were able to get for the first time an insight of how human-untouched Amazonian forests were back in time (up to 500,000 years ago!), how was their diversity and how they responded to intense volcanic activity and climatic change.

By Dr Macarena L. Cárdenas

REFERENCES

Cárdenas, M.L. (2011) The response of western Amazonian vegetation to fire and climate change: A palaeoecological study. In: Department of Earth & Environmental Sciences, p. 242. The Open University, Milton Keynes

Cárdenas, M.L., Gosling, W.D., Pennington, R.T., Poole, I., Sherlock, S.C. & Mothes, P. (online) Forests of the tropical eastern andean flank during the middle pleistocene. Palaeogeography, Palaeoclimatology, Palaeoecology. DOI: 10.1016/j.palaeo.2013.10.009

Cárdenas, M.L., Gosling, W.D., Sherlock, S.C., Poole, I., Pennington, R.T. & Mothes, P. (2011a) The response of vegetation on the Andean flank in western Amazonia to Pleistocene climate change. Science, 331, 1055-1058. DOI: 10.1126/science.1197947

Cárdenas, M.L., Gosling, W.D., Sherlock, S.C., Poole, I., Pennington, R.T. & Mothes, P. (2011b) Response to comment on “the response of vegetation on the Andean flank in western Amazonia to Pleistocene climate change”. Science, 333, 1825. DOI: 10.1126/science.1207888

 

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