- A recent study published in the journal PeerJ reports the excavation of fossilized leaves from ancient forests at least 4 million years old in Brunei on the island of Borneo.
- More than 80% of the leaves the team found were from the Dipterocarpaceae family, trees that are still dominant today, confirming their long-standing role in anchoring Borneo’s species-rich ecosystems.
- The authors say the discovery adds to the urgency to protect these forests from logging or development for agriculture because once they are gone, they will be difficult to get back.
On a windless, sunbathing beach in Borneo, paleobotanist Peter Wilf faced one of the biggest challenges in his team’s hunt for plant fossils, which could be used for a new set of tools. Had been. The moist soil they were examining was the remains of an ancient plant never entirely formed in stone, so it crumbled with all but the most delicate touch.
They found that they were doing well if they could get a piece of 30 cm (12 in) – nothing like a 2-metre (6.5-foot) piece of rock wolf used to carve fossil beds in Argentina. it was done. And he had to work with a simple penknife, swapping out the gas-powered drill or even the backhoe that’s part of a paleontologist’s kit in places like the US state of Wyoming.
“You can almost excavate fossils by hand,” said JW Ferry Slick, a botanist from the University of Brunei Darussalam and one of Wilf’s colleagues.
It wasn’t easy, but the team extracted fossilized leaves and other plant matter from two main sites in Brunei, which is located on Borneo’s west coast. The process of drying them and meticulously packing, perming and shipping them in suitcases from Brunei to America was laborious, and took months. But in the end, the evidence researchers unearthed showed that prehistoric forests on the island are still present today, at least 4 million years ago.
More than 80% of the leaves they found were from Dipterocarpaceae, a family of giant rainforest trees that anchor modern forests across the island shared by Brunei, Indonesia and Malaysia.
“This type of forest is ancient, and it has functioned in more or less the same way over a long period of time,” said Wilf, a professor of geology at Pennsylvania State University and a faculty member at the university’s Institute for Energy and Environment. Today, this forest type continues to anchor ecosystems throughout the island that support untold numbers of species.
The team reported their findings March 24 in the journal PeerJ,
Charles Cannon, a botanist and director of the Center for Tree Science at the Morton Arboretum, said, “This is a fascinating description of a paleobotanical study that reconciles long-standing assumptions about the ancient nature of Bornean rainforest communities in their structure and distribution. certifies.” The US told Mongabe in an email. Cannon (no relation to the author of this article), who was not involved in the study, said he would love to see the specimens more thoroughly identified, but said he was surprised the team was able to find plant macrofossils. Was. these conditions. ,
The study shows techniques that can unravel the region’s ancient history, said Robert Morley, a geologist at consultancy Palinova Ltd., who was not involved in the research.
“The main advantage of this paper is that it shows local potential palaeontologists how to usefully study fossil leaf beds using modern methods,” Morley said in an email.
He said scientists have known about the permanent presence of Din in the region for a long time. Peter Ashton, a professor emeritus in the Department of Biology and Evolutionary Biology at Harvard University who was not part of the study team, similarly said that evidence for dipterocarps from plant parts and pollen dates back to at least the mid-20th century. go.
Still, the study provides further evidence of how long these forests and biodiversity support have been in place, Cannon said.
Today, Borneo’s vast diverse forests are under threat. Cannon said this is partly due to the natural rise in sea level as the world’s glaciers began to melt about 10,000 years ago. As the sea rose, the existing forests were reduced and scattered. Now, logging and agriculture are also leading to erosion or bulk evaporation of swaths of Borneo’s venerable forests. As he and his colleagues argued in a 2009 study published in Proceedings of the National Academy of ScienceIt’s “a double whammy for the overall process of diversification and adaptation,” Cannon said.
Another recent study published in conservation Biologyrevealed that much of the land of important tree species in Southeast Asia is vulnerable.
Now, this new evidence confirming the age and history of these forests makes their conservation even more urgent.
“If this forest disappears, as is currently happening quite rapidly, it will be very difficult to get it back,” Slick said.
Relatively small Brunei remains an outlying region, having isolated forest reserves covering more than half of the country’s land area. But global demand for products such as rubber, palm oil and tropical hardwoods has driven deforestation at a rapid pace throughout neighboring Indonesian and Malaysian Borneo.
“There’s a kind of idea that you can reduce it and it will grow back,” Wilf said. “But that’s not what we see in Southeast Asia.”
The depletion of the region’s forests has increased the urgency to catalog the life supported by them, as well as to understand how Borneo’s vast biodiversity is rooted in its flowering plant life – an idea that inspired Wilf. inspired.
“Even as fossils are disappearing, we don’t really know enough about the history of these places,” he told Mongabe.
Much of what modern paleobotanists know about ancient plants comes from ancient pollen. Often tough-hued and microscopic, these capsules of plant genetic information have the potential to survive in sediments for millennia. Identification by curious scientists in the laboratory then provides an estimate of the makeup of plants that existed at a certain location millions of years ago.
However, in the case of dipterocarps, their pollen does not hold as well with age – one reason why the prevalence of dipterocarps in these ancient forests is not as clear so far.
Earlier research often failed to turn up dipterocarp pollen, Wilf said. This raised questions about their place in ancient ecosystems, adding: “Were they abundant? Were they important?”
At his research sites in Brunei, Slick said, periodic floods in the distant past may have washed parts of the forest floor with finer soil, essentially preserving the leaf deposits more or less as they were at the time.
“Leaf deposits are supposed to be … almost the closest thing to snapshot deposits,” Wilf said. And in these deposits the team excavated, more than 80% of the leaves were from the Dipterocarp family, with even pollen from trees in the family difficult to find.
“These are keystone species,” Wilf said.
The researchers also turned to the possibility of understanding leaves from climbing plants, as well as fungi, ferns, and an ancient group of plants called lycophytes, which includes modern clubmosses.
“We’re starting to get a three-dimensional picture of what the forest was like based on what we found,” Wilf said. “It’s the exciting part when you can put it all together.”
Wilf said he hopes the evidence from the long history of these forests on the island of Brunei and Borneo raises awareness more broadly about their importance – and the consequences if they are allowed to disappear.
“You’re going to lose a unique, highly functional Earth system that supports wildlife, supports humanity, supports biodiversity, supports carbon sequestration,” he said. “And the human population would be too poor for that.”
banner image: A river running through an old-growth lowland rainforest in Brunei. Image by John Cannon/Mongabe.
John Cannon There is a staff feature writer with Mongabe. Find him on Twitter: @johnccannon
Citation:
Cannon, CH, Morley, RJ, & Bush, AB (2009). The present refugee rainforests of Sunderland do not represent their biogeographic past and are highly vulnerable to disturbance. Proceedings of the National Academy of Science, 106(27), 11188-11193. DOI:10.1073/pnas.0809865106
Gesberger, H., Fremout, T., Keitel, C. J., Vincetti, B., Kemalasari, D., Kanchanarak, T., … Jalonan, R. (2022). Valuable tree species of tropical and subtropical Asia are under threat. conservation Biology, E13873. doi: 10.1111/kobi.13873
Wilf, P., Xue, X., Donovan, M. P., Coccis, L., Briguglio, A., Shaw, D., … Lambias, J. J. (2022). The first fossil-leaf floras from Brunei Darussalam show dipterocarp dominance in Borneo by the Pliocene. PeerJ, 10, E 12949. doi:10.7717/pirj.12949
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