A 4 million-year-old Alp Forest is Revealed in Borneo's Fossils of Leaves

A 4 million-year-old Alp Forest is Revealed in Borneo's Fossils of Leaves ...

Leaf fossils on Borneo have been studied for the first time, according to researchers, revealing that the rainforests that cover the island have been in place, and that biodiversity has been nurtured for at least four million years.

Researchers claim that the current landscape, dominated by dipterocarp trees, looks much like it would have done during the Pliocene Epoch some 2.6 to5.3 million years ago, and that makes it a valuable ecosystem to preserve for future generations.

Borneo is home to 270 dipterocarp species, which is more than half the total worldwide species. The island has a vital role in sustaining that biodiversity.

A fragment fossil of a huge dipterocarp leaf. (Wilf et al., PeerJ, 2022)

"This is the first demonstration that Borneo''s typical dominant life structure, the dipterocarp trees, was not only present but actually dominant," says the paleobotanist. "We found many more fossils of dipterocarps than any other plant group."

These dipterocarps are among the world''s tallest tropical trees, with some individuals capable of acquiescing to heights of around 100 meters (328 feet).

According to Wilf, rock fossils of their leaves are difficult to discover because to the cover provided by the forests and their soils.

Because dipterocarp pollen decays so quickly, there has been a suspicion that these pollen research haven''t shown the whole picture. Here, the experiment found rocks with many dipterocarp leaf fossils, but little in the way of dipterocarp pollen, which underscores the bias hypothesis.

(Peter Wilf et al.)

This new study combines both leaf and fossil pollen, identifying an ancient world of mangroves and swamps bordered by tropical lowland rainforests, with fern undergrowth and an abundance of climbing plants.

"We''re going to really see what the environment was a thousand years ago," Wilf said. "It was very much like what you can find here now, although those habitats have been reduced across many parts of tropical Asia."

logging and agricultural transformation of the land are putting pressure on the forests, although much of the old-growth forests are still preserved in the island.

Maintaining and expanding that preservation should be a high priority, according to researchers. Dipterocarp trees are responsible for supplying numerous kinds of flora and fauna, including proboscis monkeys, clouded leopards, sun bears, and rhinoceros hornbills.

(Peter Wilf et al.)

According to this latest study, roughly 89 percent of Asian dipterocarp species have near-dangered status, while 57 percent are considered as endangered or endangered. This means that the region''s history should be preserved.

"There are very few fossil evidence from the Asian tropics," says the ecologist Ferry Slik of the Universiti Brunei Darussalam.

"I hope this study will encourage further research on fossils in the tropics, as they will unsave a lot about the natural history of the region."

PeerJ has published the findings.

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