CPSC Lecture by Christian Körner – University of Copenhagen

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CPSC Lecture by Christian Körner

"Plant carbon limitation in a CO2 rich future"

Christian Körner from Institute of Botany, University of Basel, Switzerland will give a CPSC Lecture on 11 February at 15.00-16.00.

Since it was discovered that plants 'eat air', 220 years ago, it became obvious that CO2 plays a central role for plant growth, ecosystem productivity, crop yield, and more recently, the climate system. As the CO2 concentration continues to rise, the 'staple food' of the planet becomes more abundant. Will this fasten plant growth, 'fatten' vegetation and crops? I will explain, why this is highly unlikely. 

In this presentation, I will challenge some classical concepts of plant growth control that lead to false expectations and misleading carbon cycle models. The predominant view still is that photosynthesis controls growth. I will illustrate that under most circumstances, the controls operate the other way round, very similar to the consumer market, where consumption of goods controls production, at least in our 'western' consumer market.

For plants this means,  that the activity of the sites of carbon investment, that is growing tissues (C-sinks), control the amount of photosynthesis products (sugars; C-source) that can be utilized for growth. This sugar production 'on demand' reflects the need for chemical elements other than carbon to build a healthy plant (element stoichiometry). Most importantly,  environmental stress such as low temperature or drought stress affect tissue growth (sink activity) long before these stresses affect CO2 uptake (source activity), opposite to what text books still suggest and modellers model.

Crop physiologists have long noticed that yield is not related to the photosynthetic capacity of foliage, and modern approaches in crop breeding are focusing on the very nature of the growth of cells and tissues, rather than carbon capture. Not surprisingly, elevated atmospheric CO2 concentrations do not stimulate growth, unless all other controls of growth are artificially optimized. Natural ecosystems are currently not carbon limited.

I will briefly present results of the first and still only CO2 enrichment experiment with mature forest trees in a natural beech-oak forest near Basel. This and grassland experiments showed that water relations of plant species respond differently to the perturbation of their CO2 diet, often leading to unexpected biodiversity effects. I will advocate a shift in paradigm in how we teach, research and model plant growth and productivity.

Reading: Körner C (2015) Paradigm shift in plant growth control. Curr Opin Plant Biol 25:107-114.

Christian Körner is Professor of Botany at University of Basel, Switzerland. He has a PhD from the University of Innsbruck on water relations of alpine plants. He is currently involved in several research projects, among these are: “Effects of elevated CO₂-concentration on plants and ecosystems”, “The Swiss Canopy Crane Project”, “Alpine plant ecology” and “High Elevation Treeline Research”. He is, furthermore, president of the Alpine Research Station ALPFOR on the Furkapass.

Time: 11 February 2016, 15.00-16.00

Place: Thorvaldsensvej 40, 1871 Frederiksberg C. Room: A2-70.03.