TECHNOLOGY

Ground level ozone is a formidable threat to biodiversity


It is well established that prolonged exposure to high ozone levels poses a serious threat to human health, exacerbates heart and lung problems such as asthma and emphysema, and reduces birth weight. One study found that more than 1 million premature deaths are caused by high levels of ozone worldwide each year.

Studies have also shown that crops and forests are damaged or killed by ozone, directly or indirectly, because ozone makes them more susceptible to insects, diseases and droughts. According to the U.S. Department of Agriculture, ozone harms plants more than all other air pollutants. This gas has predicted a significant decline in global food production. A recent study predicts that by 2050 wheat yields will fall by 13 percent, soybeans by 28 percent and maize by 43 percent as temperatures and ozone rise.

Although it is clear that ozone can affect all organisms, studies have not, until recently, looked at its effects on biodiversity. Scientists believe the effects are substantial. This month the International Union of Forest Research Organizations, a global network of scientists, is holding a conference entitled Plant Ecosystems Threatened by Air Pollution. Ozone tops the list.

In a study published last year, 20 researchers from Europe and Asia, including Agathaclius, modeled what could happen to the ecosystem in the coming decades as a result of ozone pollution. They concluded that ozone “would affect major physiological features by affecting the structure and diversity of plant communities” and could cause changes that reduce biodiversity. In their research paper, the researchers called on officials to consider ozone in their efforts to protect and restore biodiversity, saying its impact should be included in the assessment of atmospheric pollution and climate change.

Studies show that ozone affects plants in different ways.

“It cripples tree stumps, and so they release more water than they take in,” said Howard Newfeld, a plant ecologist at Appalachian State University. The stomata are microscopic openings on the leaf surface where the tree exchanges gases with the atmosphere. Ozone damages them and interferes with various processes, including photosynthesis.

Ozone damages the leaves and accelerates their aging. “Photosynthesis decreases as the leaves are injured; a plant produces less sugar, and has fewer resources,” Newfeld said. “It also affects the roots of the roots, which reduces the growth of the roots, making them more susceptible to drought and malnutrition and disease.”

Ozone damage can change the timing of leaf fall and shrink leaf size, reduce litter volume, and affect decaying microbial communities. Germs in litter and soil are important for nutrient uptake, plant disease prevention and efficient use of water.

The effects of ozone on the soil also affect the rhizosphere – the main system and its associated germs, fungi and other organisms. “When trees respond to ozone, they expend energy,” Agathoclius said. “When they use so much energy, there is less supply for organisms in the soil and the chemical composition can be affected.” Less nutritious leaves can also affect the life cycle of their animals.



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