Old-growth forests vital

Sept 15, 2011: - Undisturbed, old-growth forests are irreplaceable for sustaining tropical biodiversity, according to a study published in the latest edition of Nature magazine.

“Tropical forests are being felled and degraded at an alarming pace,” said co-author Professor William Laurance of James Cook University.

“Some scientists have argued that many tropical species will be able to survive in logged or fragmented forests, but we’ve found that the most vulnerable species must have undisturbed forests to survive.

“We need more reserves, and bigger reserves, to ensure that biodiversity can survive in the long term. There’s really no other choice,” he said.

“Either we conserve old-growth forests or we start getting used to the idea of living in a world without orang-utans, tigers and many other vulnerable species.”

Professor Laurance and colleagues from Singapore, Switzerland, Australia, the UK and USA analysed 128 scientific studies from 28 tropical countries, comparing biodiversity in old-growth forests to those in forests altered by selective logging and conversion to farmland as well as regenerating forests.

“There’s no substitute for old-growth forests,” says Luke Gibson, from the National University of Singapore who led the study. “All major forms of disturbance invariably reduce biodiversity in tropical forests.”

However, the authors said that selective logging, in which bulldozers and other equipment were used to extract a limited number of trees from the forest, had lower impacts on biodiversity than did other land-uses.

“Logged forests can recover in a few decades if they’re not overrun by hunters or converted into farmland,” Professor Laurance said. “This is always a big danger because loggers bulldoze labyrinths of roads through forests, making them vulnerable to colonists and hunters.”

Compared to Africa and the Americas, the scientists found that forests in Asia suffered the greatest loss of biodiversity.

“Southeast Asia has the lowest remaining forest cover, highest rates of deforestation and highest human population densities among all major tropical regions,” said Tien Ming Lee from the University of California, San Diego, who co-led the study.

The authors emphasised that parks and other protected areas are critical for the future, as they are the best strategy to protect old-growth forests.

“But a key problem is that many tropical reserves are being invaded by illegal hunters, miners, loggers and colonists,” Professor Laurance said.

Other members of the research team were from the University of Adelaide, ETH Zurich in Switzerland, the Universities of Cambridge, Lancaster and East Anglia in the UK, and the Heinz Center in the USA. The study was initiated by the late Navjot Sodhi, a world-renowned biologist from the National University of Singapore.

Contact: Professor William Laurance

James Cook University, Cairns, Queensland

Email: bill.laurance@jcu.edu.au

Phones: +61-7-4038-1518 and +61-7-4042-1819

Luke Gibson, Tien Ming Lee, Lian Pin Koh, Barry W. Brook, Toby A. Gardner, Jos Barlow, Carlos A. Peres, Corey J. A. Bradshaw, William F. Laurance, Thomas E. Lovejoy & Navjot S. Sodhi. 2011. Primary forests are irreplaceable for sustaining tropical biodiversity. Nature (doi: 10.1038/nature10425), soon available at www.nature.com/nature.

Issued: September 15, 2011

JCU Media Jim O’Brien 07 4781 4822 or 0418 892449