Finding flowers more difficult: The increasing air pollution from ground-level ozone threatens plant health and changes the plants’ signals to potential pollinators, as scientists report. According to this, ozone can, among other things, reduce the quantity and quality of pollen and change the color and chemical signals of the flowers – and thus disrupt the orientation of the pollinators. Direct damage to the leaves of the plants is also possible.
Ozone can be a curse or a blessing for our planet, depending on where it is located. In the stratosphere at an altitude of twelve kilometers, the protective ozone layer shields us from excessive UV radiation from the sun. On the other hand, in layers of air near the ground, in the troposphere, the gas is a pollutant that is known to affect human health. Ground-level ozone is created by the reaction of nitrogen oxides, which occur, for example, in road traffic, and volatile organic compounds, which are given off by plants, among other things, and are also contained in substances such as paints and aerosols.
In a scientific report, a team led by Evgenios Agathokleous from Nanjing University in China points out that ground-level ozone is not only harmful to human health, but can also lead to difficulties in plant pollination. The air pollutant thus disrupts the spread and reproduction of plants and thus interferes with a process that is crucial for humans, animals and ecosystems.
According to the authors, ozone pollution in the troposphere has increased significantly over the last few decades, so that today it is having an impact on plant health in many places. Several studies have already shown that an excessively high ozone content in the ambient air leads to damage to the leaves, which manifests itself in the form of discoloration, among other things. As a result, the plant is less able to photosynthesize to provide itself with energy.
The ozone also appears to disrupt the chemical signals that plants send out in the form of volatile organic compounds to alert potential pollinators to their flowers. “Changes in the composition of volatile compounds could also have serious consequences for pollinators, as they may no longer recognize host plants and their traits in the same way they once did,” says Agathokleous.
Ozone pollution can also disrupt visual cues for pollinators because, among other things, it can contribute to flower changes in color. “In addition, it can also react directly with the pollen and reduce its quality, or change the amount of pollen through indirect effects,” says Agathokleous. “Moreover, ozone pollution can affect the timing and duration of flowering in such a way that the occurrence of flowering no longer coincides with pollinator activity.”
Because ozone formation requires sunlight, ozone levels are typically lower at night. However, measurements now show that the nightly ozone concentration has also increased significantly. Thus, it could have a greater impact on nocturnal pollinators than previously thought.
“There is a lot of reporting on the direct impact of agrochemicals on pollinators, an issue that society is paying a lot of attention to. But it is now emerging that ozone is a silent threat to pollinators, and therefore pollination,” says Agathokleous. “These effects of ozone have long been overlooked.”
According to the scientists, a new generation of interdisciplinary research programs is needed to assess the resilience of plant-pollinator interactions in ozone-polluted areas. “Things to consider are the adaptability of pollinators, the responses of wild and cultivated plants, and the possibility that plants evolve new chemical signals that are less affected by ozone,” say Agathokleous and his team. (Trends in Ecology
Quelle: Cell Press
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This article was written by Nadja Podbregar
The original to this post “These effects of ozone have been overlooked for a long time” comes from scinexx.
