英文原文链接 NewScientist.com news service
1. FAILURE: Destruction of the Amazonian Rainforest
Currently the Amazon rainforest is being cleared at a staggering rate of 24,000 km2 per year – that is an area about the size of New York’s Central Park disappearing each hour. The Amazon is the world’s largest remaining tropical forest – 40% of the world’s rainforest is now found in Brazil. Other nations, such as the Philippines, have been totally deforested, says Jeff McNeely, chief scientist with the World Conservation Union (IUCN). In total, about 80% of all the forests that covered the Earth 8000 years ago have been cleared or degraded by man.
In 2002 the Chinese government began an ambitious project to reforest 5% of the nation, an area the size of California. The 440,000 km2 project is the largest ever undertaken in history. The aim is to prevent soil erosion, disastrous droughts and floods, and reduce the severity of dust storms. The plan has also called for the creation of nature reserves for pandas, Tibetan antelopes and rare orchids. “The purpose is to recreate forests to influence the hydrological cycle, and stop the encroachment of the desert towards Beijing,” says the IUCN’s McNeely. “It’s remarkable how green China is now.”
3. FAILURE: Saiga antelope
In 1993 more than a million saiga antelope (Saiga tatarica) crowded the steppes of central Asia. However, by 2004 just 30,000 remained, many of them female. The species had fallen prey to relentless poaching – with motorbikes and automatic weapons – in the wake of the Soviet Union’s collapse. This 97% decline is one of the most dramatic population crashes of a large mammal ever seen. Poachers harvest males for their horns, which are used in fever cures in traditional Chinese medicine. The slaughter is embarrassing for conservationists. In the early 1990s, groups such as WWF actively encouraged the saiga hunt, promoting its horn as an alternative to the horn of the endangered rhino. “The saiga was an important resource, well managed by the Soviet Union,” says John Robinson, at the Wildlife Conservation Society (WCS) in New York City, US. “But with the breakdown of civil society and law and order, that management ceased.”
From herds numbering tens of millions, Bison (Bison bison) were hunted down to as few as 750 animals in the 1890s. Between 1868 and 1881, 31 million were slaughtered by hunters and fur traders. However, like the North American gray wolf, the bison has made a remarkable comeback. Through conservation initiatives, re-introduction, population management and the development of the bison meat industry, the population has rebounded to around 350,000 individuals.
5. FAILURE: Northern white rhino
The northern white rhino (Ceratotherium simum cottoni) was once common – and as many as 2250 still remained across five African countries in the 1960s. However the intense pressure of poaching had reduced the sub-species to just 10 animals by February 2005, making it the most endangered large mammal on the planet. About 40 animals still remained as recently as 2003, but the Democratic Republic of Congo’s Garumba National Park has not been able to offer these animals the protection they need. An emergency plan to airlift five animals to Kenya has been scuppered by the DRC’s resentment of outside interference, meaning the animals’ prospects are bleak. “We’ve been losing them one by one,” says Robinson of the WCS, “and a last-ditch attempt to move them into captive breeding has now failed”.
6. SUCCESS: Southern white rhino
In stark contrast to its northern relative, the recovery of the southern white rhino sub-species (Ceratotherium simum simum) is one of the world’s greatest conservation success stories, according to conservation group WWF. In the late 1800s it was considered extinct, but a small population of perhaps 50 animals was rediscovered in Natal, South Africa. The subsequent creation of protected areas and breeding rhinos on private ranches has been a spectacular success. Though poaching is still a problem, the population has swelled to 11,000 and growing, making this the most numerous of all rhino sub-species. The success can partly be attributed to allowing rhinos to be bought and sold for tourism and sport hunting. “Giving them an economic value caused them to bounce back like crazy,” says Robinson at the WCS.
7. FAILURE: Worldwide amphibian declines
Frogs and their amphibian kin are dying in droves and no one really understands why. The first global amphibian survey in 2004 revealed that almost one-third of the 5743 known amphibian species are under threat worldwide, compared with just under one-quarter of mammals and almost one-eighth of birds. Overall 43% of all populations surveyed were declining. “It’s depressing news,” says McNeely of the IUCN. “The survey found that 3% to 4% of amphibians had probably fallen extinct already and that a third of them are threatened.” Climate change, environmental stresses such as droughts and pollution, habitat loss and the fungal disease chytridiomycosis are all suspected causes.
8. SUCCESS: Wildlife reserves cover 10% of the Earth’s land
In 1872 Yellowstone National Park in the US became the world’s first modern wildlife reserve – now there are 44,000. This growth is described as “one of the greatest conservation achievements of the twentieth century” by the IUCN. The areas cover almost 14 million km2, an area equivalent in size to India and China combined. In 2004, Brazil established the world’s largest reserve, Tumucumaque National Park, which is larger than Belgium. The growth in protected areas is because “the public have recognised the impact we are having on the environment”, says McNeely of the IUCN.
9. FAILURE: Orang-utan
Orang-utans (Pongo pygmaeus) declined by more than 90% during the 20th century. As few as 40,000 are thought to remain on the islands of Borneo and Sumatra. About 1000 are currently killed each year in order to kidnap their young, which poachers sell into the pet trade. Loss of habitat is also a big problem. “I expect we may lose them in the wild within the next 10 years,” says Robinson at the WCS.
10. SUCCESS: Golden lion tamarin monkey
Golden lion tamarins are small and striking Brazilian monkeys (Leontopithecus rosalia). They were thought extinct until the 1970s, when 200 were discovered in the Atlantic coastal forest of Brazil. A concerted conservation effort and captive breeding programme, assisted by international organisations, has paid off. The monkey has now been reintroduced to 17 forest fragments and 1200 or more now live in the wild.