How forests rose again after the planet’s most extreme extinction

Earth has faced many climate challenges, but none compare to the catastrophe that unfolded 250 million years ago. The End-Permian Event (EPE) stands as the most severe extinction in history, wiping out more than 80% of marine species and devastating life on land.

Scientists have extensively studied its effects on ocean ecosystems, but the impact of mass extinction on forests remains less clear.

A team of researchers from University College Cork (UCC), the University of Connecticut, and the Natural History Museum of Vienna has uncovered how plants responded to this crisis.

Their findings reveal that ecosystem recovery was slow, complex, and shaped by extreme climate swings.

By studying fossilized plants and rocks from the Sydney Basin in Australia, the team reconstructed a multi-million-year journey of forest survival, extinction, and eventual regrowth.

Worst mass extinction in history

The End-Permian Event, which occurred around 252.3 to 251.9 million years ago, caused the collapse of gymnosperm-supported ecosystems.

Over 80% of ocean species vanished, making it the most severe mass extinction ever recorded. While its effects on marine life are well documented, its impact on land ecosystems has remained unclear.

Researchers examined fossilized plants and rocks from eastern Australia’s Sydney Basin, a region that was once located near the South Pole (∼70°S).

Using sedimentology, biostratigraphy, and stable carbon isotope analysis, they traced the timing and sequence of gymnosperm reestablishment across different latitudes.

The results of the analysis highlight the staggered nature of recovery, rather than a smooth, uninterrupted process.

Cooler temperatures helped forests recover

After the End-Permian Event, the first plants to return were peltasperm seed ferns. They managed to build stable ecosystems, holding on for about 200,000 years.

But nature didn’t stand still. Over time, voltzialean conifers took over, spreading across the land and thriving for an impressive 1.5 million years.

Then, disaster struck again. Around 250.3 to 249.6 million years ago, global temperatures soared during the “Late Smithian Thermal Maximum.”

The heat was too much for the conifer forests, and they collapsed. Their disappearance left space for a new kind of survivor – pleuromeian lycophytes. These plants were tough. They didn’t need much to grow, making them perfect for harsh conditions.

For 800,000 years, these small, shrubby plants dominated the land. But nothing lasts forever.

As temperatures finally began to drop during the “Smithian-Spathian Event” around 249.6 to 249.2 million years ago, the environment shifted once again, opening the door for a new wave of plant life to reshape the world.

Forests recover, but extinction is forever

The SSE brought much-needed relief to struggling ecosystems.

As the climate cooled, a new kind of plant took over – umkomasialean seed ferns. These plants thrived and spread across the high-latitude forests of Gondwana, shaping the landscapes of the Middle and Late Triassic. They helped stabilize ecosystems that had been in chaos for millions of years.

But recovery didn’t happen the same way everywhere. In many parts of the world, pleuromeian lycophytes – a type of tough, shrubby plant – quickly spread after the End-Permian Event. However, in the polar south, this process was much slower.

It took around 1.7 million years for these plants to finally establish themselves. This delay reveals that recovery from mass extinction wasn’t simple or predictable. Some places rebounded faster than others, while some struggled for much longer.

Even though forests eventually grew dense again, they were not the same. The plants that filled these new ecosystems were completely different from those that had dominated before the extinction. Nature rebuilt itself, but in a way no one could have expected.

“The term ‘recovery’ can be misleading. Forests recover eventually, but extinction is forever,” said Dr. Chris Mays, leader of the Mass Extinction Group at University College Cork.

Lessons from ancient forest extinction

Studying how ancient ecosystems recovered from extreme climate shifts gives us clues about what might happen to plants today. The way they adapted back then can help scientists predict how modern plant life will respond to environmental changes.

Plants do much more than just grow. They form the foundation of nature’s balance, providing food for animals and humans alike.

They also help regulate the Earth’s climate by absorbing carbon dioxide and producing oxygen. When plants thrive, ecosystems stay stable. When they struggle, the entire planet feels the impact.

“This research highlights how crucial plants are, not just as the base of land food chains, but also as natural carbon sinks that stabilize Earth’s climate,” explained UCC researcher Marcos Amores, the study’s lead author.

“The disruption of these systems can have impacts lasting hundreds of thousands of years, so protecting today’s ecosystems is more important than ever.”

Earth’s past reveals a clear lesson: nature can recover, but it takes time. The resilience of plant life has shaped the world we know today, making conservation efforts essential for the future of our ecosystems.

The study is published in the journal Geological Society of America Bulletin.

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