‘Maintain the diversity of Asian forests to avoid the impact of climate change,’ new study suggests

A team of international scientists, led by Dr Rebecca Hamilton from the University of Sydney, has discovered that instead of the dry savannah of Southeast Asia that dominated during the Last Glacial Maximum more than 19,000 years ago years ago, there was a mosaic of various closed and open areas. types of forests, overturning the previous scientific consensus.

The results suggest that Asia’s tropical forests could be more resilient to climate change than previously thought, provided that landscape diversity is preserved. They further show that humans and animals migrating through the region would have had a more diverse resource base than previously thought.

The research is published in the Proceedings of the National Academy of Sciences.

Dr Hamilton, from the University of Sydney’s School of Geosciences, said as climate change accelerates, scientists and environmentalists are concerned about the impact it will have on Australia’s tropical rainforests. regions like Southeast Asia.

“Maintaining forest types that facilitate resilience should be a conservation goal for the region. Our work suggests that prioritizing the protection of forests above 1,000 meters (“montane forest”) alongside Seasonally dry forest types could be important in preventing future “savannization” of Asia’s tropical forests,” she says.

Savanization refers to the metamorphosis of a landscape, usually a forested area, into a savannah ecosystem, which usually includes open wooded plains. Change is generally induced by climate variations, human interventions or natural ecological dynamics.

The researchers analyzed records from 59 paleoenvironmental sites across tropical Southeast Asia to test the so-called savannah model, which assumed a vast, uniform grassland extended across the region during the Last Glacial Maximum.

They found that records of pollen grains preserved in lakes show that forests persisted during this period alongside an expansion of grasslands, indicated by other biochemical signatures.

Dr Hamilton said: “We put forward the idea that these apparent discrepancies could be reconciled if, during the cool, seasonal climate of the Last Glacial Maximum, montane forests (above 1,000m) persisted and expanded into high altitude regions, while the lowlands experienced a shift towards seasonally dry forests, which have a naturally grassy understory. »

The team also included scientists from the Max Planck Institute for Geoanthropology in Jena, Germany; Flinders University; Purdue University in the United States; University of the Philippines; and the Australian National University.

The researchers said they expect the statistical methods developed to compare the many paleoecological records will be useful for regionally testing other past ecological changes.