IIASA “Special Lecture: On Plants and Carbon”, Christian Körner, Institute of Botany, University of Basel, 6th June 2016

The special lecture in honor of Professor Kurt Komarek is organized by the International Institute for Applied Systems Analysis and the Austrian Academy of Sciences on the occasion of his 90th birthday and will be held in the Festive Hall at the Austrian Academy of Sciences.
Date: Monday, 06 June 2016
Venue: Austrian Academy of Sciences, Doktor-Ignaz-Seipel-Platz 2, 1010 Vienna

 Moderator: Gerhard Glatzel, Chair Austrian IIASA Commission

  • 18:30 Welcome remarks by Anton Zeilinger, President of the Austrian Academy of Sciences, and Pavel Kabat, Director General and CEO of IIASA
  • 18:45 Laudatio by Peter Schuster, University of Vienna: Kurt Komarek – a Life for Science Dorsamy (Gansen) Pillay, National Research Foundation (NRF) of the Republic of South Africa, on behalf of the IIASA Governing Council
  • 19:10 Keynote Lecture by Christian Körner, Institute of Botany, University of Basel: On Plants and Carbon
  • 20:00 RECEPTION (Aula)

Mandatory Registration by 30 May here  
On Plants and Carbon
 About half of the dry matter of organisms consists of carbon (C). The biosphere contains roughly 700 billion tons of C, largely tied to cellulose, the most abundant biological substance on earth. Forests store almost 90 % of the global biomass carbon reservoir. Carbon enters the biosphere by photosynthetic uptake of CO2, and it leaves the biosphere by respiration of all non-green tissue and heterotrophic organisms. The balance between these fluxes was close to zero, before humans started to manage the planet. Now, humans release nearly 10 billion tons of carbon as CO2 every year by burning fossil fuels and destroying forests, almost half of this CO2 remains in the atmosphere, enhancing the green-house effect. Since plants can absorb CO2 and store C, there is a debate on whether plants can mitigate atmospheric CO2 enrichment. I will challenge these views, by recalling the basic rules of element ratios, the stoichiometry of life, and by emphasizing that fluxes of carbon (the carbon cycle) must not be confused with pools of carbon (carbon storage).

 It needs about 25 chemical elements in the right proportion to build an healthy organism. Plants compete for most of these elements (for instance P, K, Mg, Mn, Mo) since they conquered land. Per unit land area, the availability of these elements is finite per unit land area. In contrast, the availability of CO2 is theoretically infinite, and its acquisition is a matter of photosynthetic activity. Plants can absorb atmospheric CO2 only to the extent, the availability of these other chemical elements permit. Only if the availability of all these elements is increasing in proportion to the rise of atmospheric CO2 concentration, plants can capture more C. This explains, why experimental CO2-enrichment of natural vegetation does not enhance plant growth and productivity, but it does, when applied together with a full nutrient solution or compound fertilizer or in very fertile soils, such as under horticultural conditions or in fast rotation tree plantations. Thus, there is no reason to expect a global CO2-fertilization effect in the biosphere.

 This debate is also tied to the still widespread assumption that faster tree growth, for whatever reason, represents ‘carbon sequestration’, i.e. a mitigation of atmospheric CO2 enrichment by permanent C storage in the biosphere. This is as if one assumed cash flow to represent capital in economy. Growth is a process, tied into the global carbon cycle. Growth at one place has to be balanced with mortality or harvest elsewhere, and only if these two parts of the carbon cycle differ, the biospheric carbon capital can rise or fall. Hence, carbon storage of an area is a matter of carbon residence time, of tree age distribution (tree demography), and globally, it is a function of land area covered by high stocking forest, irrespective of the rate at which C cycles through these forests. Quite commonly, very productive forests (e.g. plantations) store less carbon than slow growing old growth forests. So, there is no straight-forward relationship between productivity and C storage. These rather basic aspects of the C cycle will be illustrated by empirical data.
Christian Körner received his academic education at the University of Innsbruck, and is professor of Botany, University of Basel, Switzerland since 1989. He has authored many publications in alpine plant ecology and alpine treeline research including books, Alpine Plant Life and Alpine Treelines, and is coauthor of a publication on botany, Strasburger. Professor Körner is also known for his pioneering CO2-enrichment experiments in natural vegetation of all climatic zones. He is a member of the German National Academy of Sciences Leopoldina, the Austrian Academy of Sciences, and an honorary member of the Ecological Society of America. For further information please visit the webpage