Record U.S. and Australian fires raise fears for many species

doi:10.1126/science.370.6512.18

GSTDTAP > 气候变化

DOI	10.1126/science.370.6512.18
	Record U.S. and Australian fires raise fears for many species
	John Pickrell; Elizabeth Pennisi
	2020-10-02
发表期刊	Science
出版年	2020
英文摘要	For the past 3 months, arachnologist Jess Marsh has been searching for the Kangaroo Island assassin spider. Early this year, during the worst fire season ever recorded in Australia, a wildfire charred the spider's only known home on an island off the nation's south coast. Now, Marsh fears the tiny, rusty brown arachnid is another of the many Australian species that the blazes have put on a path to extinction: Countless hours of scouting haven't revealed a single survivor. “Its habitat is completely incinerated,” says Marsh, who is affiliated with Charles Darwin University. She isn't the only field biologist worried that the record wildfires around the globe are inflicting lasting damage on species and ecosystems. Even as Australia tallies the damage from its blazes, the worst fires in more than 70 years are burning in California, Oregon, and Washington; so far, they have consumed some 2 million hectares, killing at least 35 people. As in Australia, scientists fear the loss of habitat has threatened species with small populations or restricted ranges, and could potentially lead to permanent ecological changes if burned landscapes fail to rebound in a warming climate. “We are in uncharted territory here,” says ecologist S. Mažeika Patricio Sullivan of Ohio State University, Columbus. “We just don't know how resilient species and ecosystems will be to wildfires of the magnitude, frequency, and intensity that we are currently experiencing in the U.S. West.” Australia's postfire experience offers cause for anxiety, researchers say. From September 2019 to March, more than 11 million hectares burned, mostly in the continent's southeastern forests, killing at least 34 people. More than 20% of the nation's total forest cover was lost, researchers at Western Sydney University reported in February. Even normally fire-proof rainforests and wetlands were scorched ( Science , 20 December 2019, p. [1427][1]). By one estimate, released early this year by the Australian government, 114 threatened plant and animal species lost 50% to 80% of their habitats; 327 species saw more than 10% of their ranges burn. Those estimates, however, were based on satellite data, says John Woinarski, also at Charles Darwin University. To get better assessments, researchers have been trying to visit burned sites, an effort complicated by the COVID-19 pandemic. In some cases, they've reported good news. There was grave concern for the endangered Kangaroo Island glossy black cockatoo after 75% of its habitat burned. But observers have seen large flocks move to unburned areas of the island, says Karleah Berris of Natural Resources Kangaroo Island. And many of the birds appear to have bred and fledged young. “It seems they are coping with the reduction in food by [moving] to where the food is,” she says. Researchers were also worried about the Kangaroo Island dunnart, a shrew-size carnivorous marsupial. Even before the fires, just 500 or so remained, and they lost 95% of their habitat to the flames. But automated cameras have revealed that at least some dunnarts survived, and managers moved quickly to build fences to protect the remaining animals from feral cats. Other findings are more ominous. In New South Wales, fires killed about one-third of the state's koalas, a government inquiry found in July. It warned that the marsupial would be extinct in the state by 2050 if dramatic measures are not taken to conserve it. And in the state's Nightcap National Park, a survey found that fires destroyed 10% or more of the remaining stands of several critically endangered rainforest trees. Some species were down to fewer than 200 trees before the fires, says botanist Robert Kooyman of Macquarie University; they are now “certainly a few steps closer to extinction.” Such concerns have prompted scientists to ask Australia's government to expand its endangered species list. At least 41 vertebrates that were not endangered before the fires now face existential threats, Woinarski and others reported in July in Nature Ecology & Evolution . An additional 21, already tagged as threatened, might need greater protection. Marsh has recommended adding 16 invertebrate species found on Kangaroo Island to the list, including the assassin spider. “That species is really hanging in the balance,” she says. In the United States, researchers say it's too soon to know how many species the fires have put in jeopardy. But there are already worrying reports. In Washington, biologists estimate the fires have killed 50% of the state's endangered pygmy rabbits, which inhabit sagebrush flats that burned this year. They believe only about 50 of North America's smallest rabbit remain. Officials estimate the flames have also killed 30% to 70% of the state's sage grouse and sharp-tailed grouse, birds that also depend on sagebrush. In California, the impact of fires in 2014 may offer a preview. After flames swept through habitat of the endangered spotted owl, many of the birds abandoned nesting sites, biologists Gavin Jones of the U.S. Forest Service's Rocky Mountain Research Station and M. Zachariah Peery from the University of Wisconsin (UW), Madison, found. In 2015, some 22% of nesting sites used by the birds in 2014 were not reoccupied and still are empty, Jones says, and this year's fires could add to the losses. Western fires also threaten the white-headed woodpecker, found only in pine forests in the Pacific Northwest and California, and the Grace's warbler, limited to pine and oak forests in the southwestern United States and northern Mexico, says wildlife biologist Vicki Saab, also at the Rocky Mountain Research Station. Plants that have small ranges and are found in burned areas, such as the Coulter pine in California, might also face trouble, says Camille Stevens-Rumann, a fire ecologist at Colorado State University, Fort Collins. “California especially has a lot of endemic plant species that could be very much impacted,” she says. The longer term consequences for ecosystems are harder to predict, researchers say. In both Australia and the Western United States, many ecosystems are adapted to fire and even require it to thrive. “Many of the old-growth forests we know and love in the Pacific Northwest were born of large and severe fires centuries ago,” says Brian Harvey, a wildfire ecologist at the University of Washington, Seattle. Fires can also help create a mosaic of habitats that support a wealth of species, he and others note. But climate change adds to the uncertainty about how forests will respond this time. “The postfire climate is likely to be warmer and drier than when the parent trees established long ago,” Harvey says, making it harder for ecosystems to recover, and boding more fire in the future. “Just a little more drought can lead to much bigger fires,” says Monica Turner, a fire ecologist at UW who calls climate change “a threat multiplier.” Already, some ecosystems in North America that have had frequent or intense burns are not regenerating. In some places, such as the sagebrush ecosystem of the Great Basin west of the Sierra Nevada mountain range and forests in the Klamath Mountains along the California-Oregon border, invasive shrubs or grasses appear to have taken over. Because the invaders burn frequently, they appear to be preventing seedlings from maturing. In Australia, researchers have similar concerns. In the state of Victoria, forests of alpine ash, a towering eucalyptus tree found in moist regions, historically experienced fires less than once a century or so. Now, some forests have been hit by five fires in the past 20 years, and scientists fear some of the stately groves will disappear for good. [1]: http://www.sciencemag.org/content/366/6472/1427
领域	气候变化 ; 资源环境
URL	查看原文
引用统计
文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/298034
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	John Pickrell,Elizabeth Pennisi. Record U.S. and Australian fires raise fears for many species[J]. Science,2020.
APA	John Pickrell,&Elizabeth Pennisi.(2020).Record U.S. and Australian fires raise fears for many species.Science.
MLA	John Pickrell,et al."Record U.S. and Australian fires raise fears for many species".Science (2020).