Tree fossil tells the story of environmental changes in the Andes

Hyperaxion Aug 31, 2020

Scientists hope the fossilized trunk will give them a glimpse of South America’s climate in the past and what the future may hold.

At 4,000 meters (13,123 feet) above sea level in southern Peru, researchers from the Smithsonian Tropical Research Institute (USA) and other institutions found a fossilized tree that reveals important information about how the climate in the Andes has changed dramatically over the past 10 million years.

The findings were published last week in the journal Science Advances.

Tree fossil tells the story of environmental changes in the Andes
(Credit: Rodolfo Salas Gismondi / Smithsonian Tropical Research Institute).

“This tree and the hundreds of fossil wood, leaf and pollen samples we collected on the expedition, reveal that when these plants were alive the ecosystem was more humid—even more humid than climate models of the past predicted,” said Camila Martínez, one of the study’s authors. “There is probably no comparable modern ecosystem, because temperatures were higher when these fossils were deposited 10 million years ago.”

The fossil found is very similar to that of trees that exist today in low-elevation tropical forests – which makes a lot of sense. As the experts explain, at that time the region was at an altitude of just 2,000 meters (6,560 feet) above sea level.

Other 5 million-year-old fossils found at the site fit into a type of ecosystem known as a puna, which now dominates the highlands of the Andes mountains.

5 million-year-old leaf found in the region.
5 million-year-old leaf found in the region. (Credit: Camila Martínez / Smithsonian Tropical Research Institute).

The youngest pollen samples come from grasses and herbs, common to the puna ecosystem. The leaf material was from ferns, herbs, and shrubs.

For researchers, the fossil record in the region indicates that both altitude and vegetation have changed dramatically in a relatively short period. These observations, in turn, support the hypothesis that the tectonic uplift in the region occurred in rapid pulses.

The findings will help scientists better understand the relationship between Andean uplift and changes in South America’s climate over the years.

The puna ecosystem.
The puna ecosystem. (Credit: Camila Martínez / Smithsonian Tropical Research Institute).

Furthermore, according to Martínez, understanding what the region was like in the past can help us “predict the future”.

“By the end of this century, changes in temperature and atmospheric carbon dioxide concentrations will again approximate the conditions 10 million years ago,” Martínez explained. “Understanding the discrepancies between climate models and data based on the fossil record help us to elucidate the driving forces controlling the current climate of the Altiplano, and, ultimately, the climate across the South American continent.”

Related topics:

Andes Fossil

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