Beyond hope

时间:2019-03-07 04:10:04166网络整理admin

By Fred Pearce HUGE tracts of rainforest across Southeast Asia may have reached the point of no return. The gloomy report comes from a national park in Borneo where no seedlings have taken root for eight years, apparently because logging outside the park has meant that animals eat all the seeds. The rainforests of Southeast Asia—which are the second largest after the Amazon—are dominated by hardwood dipterocarp trees. The trees produce large amounts of seed-bearing fruit during brief synchronised bursts triggered every three or four years by El Niño and the dry weather that it brings. According to Lisa Curran of the University of Michigan in Ann Arbor, this abundance of seed is essential; otherwise creatures such as orang-utans and parakeets scoff them all. New trees can only germinate when these seed eaters are sated. But despite two major El Ninos, Curran’s study sites in the Gunung Palung national park in Indonesian Borneo have produced no new seedlings since 1991. She blames logging and fires set by plantation owners in the surrounding forest. “A decade of logging has reduced protected forests to islands,” says Curran. This has reduced the number of seeds in the forest to a level where migrating animals can gobble up the lot. “We went from 195 kilograms of seed per hectare in 1991 to 18.5 kilograms in 1998,” says Curran. “Four months after the fruitfall, no new dipterocarp seedlings were found.” She fears this means the system is crashing. If the phenomenon is widespread,