Damaged ozone layer may have led to sterilized trees

A new study shows that tree sterilization may have been a major factor in the end-Permian extinction.
By Joseph Scalise | Feb 10, 2018
Researchers at the University of Berkeley have discovered that the end-Permian event -- also known as the Great Dying -- may have sterilized certain tree species across the world, according to a study published in Science Advances.

The end-Permian event, which occurred 252 million years ago, was one of the most deadly extinctions in Earth's history. It killed off seven out of 10 land species and nine out of 10 aquatic animals. However, while scientists have long known about the event, the mechanisms behind the event have been a mystery for some time.

To shed light on the die off, the team in the study found a connection between high levels of ultraviolet radiation and the appearance of malformed pollen. Such a discovery suggests the end-Permian may have harmed forest reproduction on a global scale, which in turn would have negatively affected ecosystems all across the world.

Scientists discovered that, during the event, numerous volcanoes in Siberia erupted. That then damaged or destroyed most of the Earth's ozone layer.Without that protection, harmful rays poured down onto the Earth and damaged many different kinds of wildlife.

"During the end-Permian crisis, the forests may have disappeared in part or fully because of increased UV exposure," said lead author Jeffery Benca, a researcher at the University of California, Berkeley, in a statement. "With pulses of volcanic eruptions happening, we would expect pulsed ozone shield weakening, which may have led to forest declines previously observed in the fossil record."

Researchers analyzed malformed pollen fossils that dated back to the end-Permian event. The remains perfectly matched the decline of forests on a global scale at that time. In addition, the team also created three "mass extinction chambers" where they exposed 60 miniature bonsai conifers to high-intensity UV-B lamps that matched the effects of the Siberian eruptions on the ozone layer.

The team left the trees in the chambers for two months to see if the high radiation levels would cause the bonsai to produce malformed seeds,International Business Timesreports.

After such exposure, the plants were not able to produce any seeds at all. In fact, their seed cones would wither before they had a chance to be properly fertilized, rendering the trees completely sterile.However, once the bonsai were taken out of the chambers, they regained the ability to produce seeds.

This finding could shed new light on an die-off and help researchers get a better idea of the ancient world. Little is known about past extinction events, and this evidence could help uncover other ancient mysteries as well.

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