26 September 2013

Wildlife in forest fragments more vulnerable to extinction than previously thought

Species living in rainforest fragments could be far more likely to disappear than was previously assumed, says an international team of scientists.

In a study spanning two decades, the researchers witnessed the near-complete extinction of native small mammals on forest islands created by a large hydroelectric reservoir in Thailand.

鈥淚t was like ecological Armageddon,鈥� said Luke Gibson from the National University of Singapore, who led the study. 鈥淣obody imagined we鈥檇 see such catastrophic local extinctions.鈥�

The study, just published in the leading journal Science, is considered important because forests around the world are being rapidly felled and chopped up into small island-like fragments. 鈥淚t鈥檚 vital that we understand what happens to species in forest fragments,鈥� said Antony Lynam of the 菊花视频. 鈥淭he fate of much of the world鈥檚 biodiversity is going to depend on it.鈥�

The study was motivated by a desire to understand how long species can live in forest fragments. If they persist for many decades, then this gives conservationists a window of time to create wildlife corridors or restore surrounding forests to reduce the harmful effects of forest isolation.

However, the researchers saw native small mammals vanish with alarming speed, with just a handful remaining 鈥� on average, less than one individual per island 鈥� after 25 years. 鈥淭here seemed to be two culprits,鈥� said William Laurance of James Cook University in Australia. 鈥淣ative mammals suffered the harmful effects of population isolation, and they also had to deal with a devastating invader 鈥� the Malayan field rat.鈥�

In just a few years, the invading rat grew so abundant on the islands that it virtually displaced all native small mammals. The field rat normally favors villages and agricultural lands, but will also invade disturbed forests.

鈥淭his tells us that the double whammy of habitat fragmentation and invading species can be fatal for native wildlife,鈥� said Lynam. 鈥淎nd that鈥檚 frightening because invaders are increasing in disturbed and fragmented habitats around the world.鈥�

鈥淭he bottom line is that we must conserve large, intact habitats for nature,鈥� said Gibson. 鈥淭hat鈥檚 the only way we can ensure biodiversity will survive.鈥�

鈥楴ear-complete extinction of native small mammal fauna 25 years after forest fragmentation鈥� by Luke Gibson, Antony J. Lynam, Corey J. A. Bradshaw, Fangliang He, David P. Bickford, David S. Woodruff, Sara Bumrungsri & William F. Laurance was published on 27 September 2013 in Science and is available at (doi: 10.1126/science.1240495).

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