By Adam Cox

STOCKHOLM (Reuters) - The world's tiger population may have halved in the past quarter of a century and at least one of the remaining five sub-species is in danger of becoming extinct, World Wildlife Fund (WWF) experts said on Tuesday.

Chinese demand for tiger parts used in traditional medicines and habitat destruction are the two greatest perils facing the big cat, scientists and conservationists said.

Speaking in Sweden at a seminar featuring experts from Asia, Africa and Europe, they said the South China tiger could soon be extinct and the Sumatran tiger population was the next most threatened sub-species.

!ADVERTISEMENT!

But WWF officials also said with proper measures, tigers could thrive and increase their numbers by thousands, and they believed the species would survive.

"In many ways the tiger stands at a crossroads between extinction and survival, and which path it takes is totally dependent on us," said Sujoy Banerjee, director of WWF India's species program.

The WWF's tiger coordinator based in Nepal, Bivash Pandav, said he believed there were some 3,500 tigers left in the world. That compared with rough estimates of about 5,000-7,500 in 1982.

Pandav said in Sumatra, Indonesia, the number of tigers had dwindled to about 400 and the situation was now critical as forest areas have been decimated.

In 1982 most of the Indonesian island's forest land was intact. By 2004 less than half of it was left, Pandev said.

He said estimates are that by 2050, based on current trends, more than 90 percent of its forests may be gone due to the logging industry, a potentially disastrous outcome for Sumatran tigers which depend on the forest for their survival.

Pandav said one way conservationists had combated forest destruction was to buy up land concessions from the government. "There is hope to save animals in this place," he said.

ONE TIGER A DAY

In India, the tiger population has dwindled to about 1,400, 60 percent fewer than in 2002. Some 40,000 tigers were thought to be in India at the start of the 20th century, but now an estimated one tiger per day is dying there.

Indian farmers, dependent on livestock for their survival, are one threat to tigers, Banerjee said. "Whenever there is human-tiger conflict, the ultimate loser is the tiger."

But additional pressure on governments to stop poaching, in particular from China, and other conservationist measures such as habitat protection could make a huge difference, he said.

"We can easily have 10,000 tigers, if everything goes as per our wish," said Pandav, adding that could be achieved in as little as 10 years.

"I firmly believe that tigers will continue to survive in certain pockets. They're not going to become extinct," he said.

Sarah Christie, a program manager for the Zoological Society of London, highlighted work being done by zoos to protect tigers, saying nearly a 10th of the money spent on tiger protection came from zoos. She said in the case of Sumatra, the total was 60 percent.

Christie said the world's focus on climate change offered a chance to help the tiger.

"Tigers are indicators of eco-system health, they are indicators of forest health. Saving the tiger is a test. If we pass, we get to keep the planet Earth."

(Editing by Janet Lawrence)