Borneo’s rainforest has stood for millions of years


Dipterocarpaceae have dominated the rainforest on the island of Borneo for four million years. This means that the ecosystem could have existed since at least the Pliocene, 5.3 to 2.6 million years ago: further confirmation that the wet forests of Southeast Asia are among the oldest habitats of this type in the world. This is suggested by a study by Peter Wilf of Penn State College and his research group on fossil leaves from the trees in “PeerJ”.

Dipterocarpaceae are among the tallest trees on earth and play an important role in the rainforest of Southeast Asia. They structure the ecosystem and provide a rich source of food with their seeds. With 270 species, Borneo is home to more than half of the known diversity of this family. Biologists have been puzzled since when they became the dominant group of plants on the island: Previous studies have focused on pollen, which can survive for a long time in tropical soils, but this does not apply to Dipterocarpaceae of all things. Fossil leaves or other parts of plants, on the other hand, are rarely found in the deeply weathered underground.

In Brunei, however, Wilf and Co came across two fossil sites in which leaves had been preserved in addition to pollen. “There is hardly any pollen from these trees in the same rocks from which large numbers of leaf fossils of Dipterocarpaceae come,” says Wilf. “The pollen and spores represent many other plant groups, including a large number of ferns.” This suggests that past studies underestimated the true distribution of the ptusa and thus their important role.

The team also discovered other remains of plants that are still found in the Southeast Asian rainforests today. This also underlines the great age of the ecosystem and its long evolutionary history. “It was very similar to what’s found there today, even though those habitats have been deforested in much of tropical Asia,” says Wilf.



Source link -69