Forest threat

Report: Anita Hadi
Photography: Dr Cathy Yule

A scientist at the Monash Sunway campus in Malaysia is helping unlock the secrets of one the world's least understood forest ecosystems.

Tropical peat swamp forests are unique wetlands found mostly in Malaysia and Indonesia and are refuge to a high percentage of globally-threatened species.

They are little understood, vital shelters for endangered animals and have the potential to affect ecosystems throughout the world.

Peat swamp forests make up about 75 per cent of Malaysia's wetlands, covering an area of more than two million hectares. They are one of the last refuges of orang-outangs, Asian elephants, Sumatran rhinoceros, tigers, clouded leopards, and Malayan tapir. More than 65 species of mammals, reptiles and birds in Malaysian peat swamp forests are listed as threatened.

Tropical peat swamp forests have been formed over thousands of years, typically as sediment and debris are trapped on the inland side of mangrove swamps, trapping water and layers of peat up to 20 metres thick.

Their ecology has been the work of Monash graduate and fresh water biologist Dr Cathy Yule since 1996. She said there was relatively little understanding of this complex ecosystem.

"Although the environment of a peat swamp is quite extreme with low pH level, low oxygen and low nutrients, it is also surprisingly diverse and productive," Dr Yule said. "Water is rich in bacteria, forming the basis of the ecosystem and supporting hundreds of fish species."

Dr Yule has worked with her students to collect bacteria samples from the surface and at depths of 10, 20 and 50 centimetres for further study. Work with the University of Mississippi has involved the extraction and amplification of DNA (16S rRNA genes) from bacterial communities. Each sample has shown bacteria are diverse and abundant and the communities vary with depth. They also showed that there are more archaic, anaerobic bacteria at greater depths.

Dr Yule said her research into the decomposition of leaf litter had revealed that the slow rate of decomposition of leaves was due to the physical and chemical properties of the leaves themselves, not the extreme conditions in the peat swamp forest.

"We've concluded that in such poor nutrient conditions, the plants focus on protecting leaves, as well as fruits, from damage caused by herbivores like insects and monkeys. So it is the basic components of the leaves that inhibit decomposition in the peat swamp, not the acidic and anaerobic conditions," she said.

But while Dr Yule and her colleagues continue to understand more about the peat forest swamps, the habitat is being destroyed. The threats mainly come from logging and tin mining, as well as agricultural conversion to palm oil and pineapple plantations.

The swamps are a sink for as much as 20 per cent of global soil carbon and if dried and destroyed by fire, resultant smoke could cause enormous carbon emissions.

"Emissions from fires in Indonesia during 1997 to 1998 alone are estimated to have produced between 0.8 and 2.5 gigatonnes of carbon. That is the equivalent of up to 40 percent of global annual emissions from fossil fuel combustion."

"We are destroying an eco-system we don't understand and one that could have a big impact on ecosystems across the world through climate change. We hope that people will become more aware about the importance of tropical peat swamp forests for the environment. They should realise that environmental degradation is neither an inevitable, nor unimportant consequence of development."