A new study led by CREAF reveals that where atmospheric changes are increasing tropospheric ozone levels, the fragrance of flowers is fading.
On the one hand, this fact causes flowers to lose their ability to attract pollinators and their reproductive success diminishes. On the other hand, it harms bees and other insects that cannot find their own food.
Plants depend on odor molecules to attract bees and other pollinators that get food from flowers while they pollinate them. Atmospheric changes make this process more and more difficult, mainly due to ozone that accumulates in the lower layers of the atmosphere and is expected to increase in the coming decades. According to research, led by CREAF and published in the journal New Phytologist, the fragile odor molecules in flowers break down more quickly as they are exposed to higher concentrations of ozone.
"Ozone is a highly reactive pollutant that increases the degradation of all volatile compounds emitted by plants in general and shortens their life", comments the first author of the study, Gerard Farré-Armengol, a CREAF researcher.
If ozone levels rise as planned, the flowers will become less and less olfactory attractive to pollinators. The flowers will not be able to maintain an intense fragrance that can be smelled from a distance and this will end up affecting both the flora and fauna. Pollinators will have trouble finding their food source, flowers, and plants will see pollinator visits decrease and reproductive success drop.
Bumblebees can't find mustard flowers
To carry out the study, the researchers used the bumblebee (Bombus terrestris) as a model, one of the most common pollinators in Europe and the world. According to Gerard Farré-Armengol, the study not only demonstrates how ozone degrades the volatile compounds responsible for the fragrance of flowers, but also relates it to the negative consequences that this fact has on pollinators. The researchers observed that the degradation of flower odors in the presence of high concentrations of ozone reduced the distance at which the flowers could attract bumblebees.
Although the researchers test the effects on the flowers of a single species, black mustard (Brassica nigra), the researchers are convinced that the same phenomenon would happen to the fragrances of other plants in reaction with ozone, since it is a well known physicochemical process.
Researchers from CREAF, the Higher Council for Scientific Research (CSIC) and the University of Eastern Finland (UEF) participated in the study.
Article: Farré-Armengol, G., Peñuelas, J., Li, T., Yli-Pirilä, P., Filella, I., Llusia, J. and Blande, JD (2015), Ozone degrades floral scent and reduces pollinator attraction to flowers. New Phytologist. doi: 10.1111 / nph.13620