Study suggests that greenhouse gas pollution will have a fundamental impact on plant-nutrient cycles and food production
FRISCO — Increased concentrations of atmospheric carbon dioxide is hindering some plants from absorbing nitrogen, the nutrient governing crop growth in most terrestrial ecosystems.
Concentrations of nitrogen in plant tissue is lower in air with high levels of carbon dioxide, regardless of whether or not the plants’ growth is stimulated, University of Gothenburg (Sweden) researchers found in a new study, published in the journal Global Change Biology.
The study examined various types of ecosystems, including crops, grasslands and forests, and involves large-scale field experiments conducted in eight countries on four continents.
“The findings of the study are unequivocal. The nitrogen content in the crops is reduced in atmospheres with raised carbon dioxide levels in all three ecosystem types,” said researcher Johan Uddling. “Furthermore, we can see that this negative effect exists regardless of whether or not the plants’ growth increases, and even if fertiliser is added, This is unexpected and new,” said Uddling, senior lecturer at the Department of Biological and Environmental Sciences at the University of Gothenburg.
When carbon dioxide levels in the air increase, crops in future will have a reduced nitrogen content, and therefore reduced protein levels. The study found this for both wheat and rice, the two most important crops globally. The study also reveals that 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,” says Johan Uddling.
“Future studies should look at what is causing the effect, but it appears to be linked to plants’ capacity to absorb nitrogen rather than to changed levels in the soil,” Uddling concluded.