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Validation of botanical and organic geochemical proxies in a low CO2 world
Project leader: Dr. W. M. Kurschner
Researcher(s): MSc A.J.C. Hincke
Starting date:

Abstract
Low CO2 levels prevailed during most of the Pleistocene. For most modern plants a minimum concentration of about 160 ppmv atm. CO2 represents the limit of natural growth conditions. It has been suggested that CO2 starvation has had a direct effect on plants, limiting growth and water use efficiency. Low CO2 and associated water stress may have caused extinctions of plant species during the Pleistocene. However, little is known about the impact of these extreme environmental conditions. The validity of palaeoclimate reconstructions based on botanical or org. geochemical proxies has been questioned, as they do not consider the direct effect of low CO2 on plant growth. Growth experiments, which could be used to quantify the low CO2 on plants, are extremely rare. Therefore, the main aims of the present project are to perform growth experiments at a series of subambient CO2, in order to validate botanical (pollen and seed productivity, stomatal frequency) and organic geochemical proxies (stable isotopes). Moreover we will study glacial plant macro and pollen records. The combination will allow us a better understanding of the impact of low CO2 on plants during the Pleistocene.

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