Increased carbon dioxide levels in air, due to global warming, restrict plants' ability to absorb nutrients, reveals a recent study published in the journal Global Change Biology.
Researchers at the University of Gothenburg revealed that the concentration of nitrogen in plants' tissue is lower in air with high levels of carbon dioxide, whether or not the plants' growth is stimulated.
The study was conducted in eight countries on four continents and examined various types of ecosystems, including crops, grasslands and forests.
Researcher Johan Uddling said that the findings are unequivocal. In all the three ecosystem types, the nitrogen content in the crops is reduced in atmospheres with raised carbon dioxide levels.
When carbon dioxide levels in the air increase, crops in future will have reduced nitrogen content, and therefore reduced protein levels.
The study found this for wheat and rice, the two most important crops globally and the strength of the effect varies in different species of grassland, which may impact on the species composition of these ecosystems.
For all types of ecosystem the results show that high carbon dioxide levels can impede plants' ability to absorb nitrogen, and that this negative effect is partly why raised carbon dioxide has a marginal or non-existent effect on growth in many ecosystems, added Uddling.