Researchers discover evidence of prehistoric rainforest on the Falkland Islands | Polarjournal
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Researchers discover evidence of prehistoric rainforest on the Falkland Islands

Julia Hager 18. October 2024 | Antarctica, Science
This is what the rainforest that grew on the Falkland Islands 15-30 million years ago may have looked like. Illustration: Benedikta Rabius

The Falkland Islands, now treeless, looked very different during the Cenozoic period 15-30 million years ago. By chance, researchers in Stanley discovered remnants of ancient tree trunks, pollen, and spores that testify to a diverse rainforest

For tens of thousands of years, the Falkland Islands have been dominated by grasslands, and today, trees can only be found in human settlements. So, Dr. Zoë Thomas, a lecturer in Physical Geography at the University of Southampton, was all the more surprised when she learned by chance about the well-preserved wood discovered during construction work in the city of Stanley, the capital of the Falkland Islands.

“When we first heard that there were large pieces of wood within a peat deposit, we were quite intrigued, but nothing quite prepared us for what we saw when we travelled to the site,” Dr. Thomas describes, still excited, in an email to Polar Journal AG. “We quickly realised that the wood we were handling must be very old indeed, but it was still hard to believe because it was so perfectly preserved. Of course, it wasn’t until we undertook the detailed pollen analysis back in the lab that we were able to ascertain exactly how old the deposit was, but we knew as soon as we saw it that it was a very special discovery!”

The pieces of wood that Dr. Thomas and her team recovered from the peat “were so well preserved, they looked like they’d been buried the day before,” Dr. Thomas said in a press release from the University of Southampton. Photos: Dr. Zoë Thomas

The international research team, led by Dr. Thomas, examined the wood in the laboratory at the University of New South Wales in Australia and found that the radiocarbon method was not sufficient to determine the age. Only the analysis of the pollen found in the same peat layer revealed that the tree trunks and branches hidden at a depth of 6 meters were from the middle to late Cenozoic period, 15 to 30 million years ago.

In the study published in the journal Antarctic Science at the beginning of September, the research team also uses the pollen and spores to draw conclusions about the prehistoric plant species community: the now windswept, barren islands in the southwest Atlantic were once home to cool, moist forests with species from the Podocarpaceae, Nothofagaceae (southern beeches) and Myrtaceae families, among others.

Dr. Thomas explains to Polar Journal AG that many of these species are now extinct and their closest relatives were found in rainforests that covered much of the land masses in the southern hemisphere at the time, for example in South America, New Zealand and Tasmania. The prevailing westerly winds helped to spread the seeds and pollen.

Although the inland glaciation of Antarctica had already begun several million years earlier – 34 million years ago – the climate in the South Atlantic was still significantly warmer and wetter than today and offered ideal conditions for the development of a rainforest. Which animals were associated with the former forest was not investigated as part of the study. However, Dr. Thomas assumes that – like today – seabirds and penguins lived on the islands.

The researchers suspect that the cause of the disappearance of the rainforest and the conversion to peat bogs is a change in climate towards colder and drier conditions.

The Falkland Islands lie to the east of the southern tip of South America, Stanley is located in the east of East Falkland (red marker on the map top left). The site where the tree remains were found is located in the town of Stanley on East Falkland, right by the water (yellow marker). Maps: GoogleMaps

It is a great stroke of luck that the pieces of wood found during excavation work on a construction site for the new retirement home “Tussac House” were scientifically examined at all. Dr. Thomas, who was doing fieldwork in the Falklands at the time, only found out about the extraordinary discovery through word of mouth.

“This discovery was a result of a range of lucky coincidences – there may well be other deposits of this nature but It would be pot-luck to try to find them,” says Dr. Thomas. “I am however planning to return to the Falklands to persue some of my other research which is focused on the more recent past – looking at how the climate and environment has changed over the last 20,000 years (a period with abrupt and extreme climate changes) to help understand the mechanisms and pace of change in the future.”

Julia Hager, Polar Journal AG

Link to the study: Thomas ZA, Macphail M, Cadd H, et al. Evidence for a floristically diverse rainforest on the Falkland archipelago in the remote South Atlantic during the mid- to late Cenozoic. Antarctic Science. Published online 2024:1-20. doi:10.1017/S0954102024000129

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