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China science

China’s southern island of Hainan born out of Vietnam millions of years ago: study

Most of Hainan’s flora and fauna not even remotely connected with the closest land mass in neighbouring Guangdong, Chinese scientists find

PUBLISHED : Tuesday, 26 April, 2016, 5:43pm
UPDATED : Monday, 12 June, 2017, 12:53pm

Animals and plants on China’s southernmost Hainan island originated in Vietnam, hundreds of kilometres away, a research study suggests.

The study’s findings could help solve a mystery that has long baffled scientists: why are the organisms found on the island – 20km off China’s southern coastline – so different from those found in its neighbouring Guangdong province?

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A team headed by Zhu Hua, a professor at Xishuangbanna Tropical Botanical Garden in Kunming, Yunnan province, compared Hainan’s flora and fauna with those found across the region.

“The flora of Hainan has the closest similarities to that of Vietnam,” Zhu said.

The flora of Hainan has the closest similarities to that of Vietnam
Professor Zhu Hua , lead researcher

The findings were published online in the peer-reviewed PLoS ONE journal.

“If we look at the genera shared between these regions, we can see that 110 are shared between Hainan and Vietnam, but only seven are shared between Hainan and Guangdong. The flora of Hainan is most closely related to Vietnam,” Zhu wrote in the paper.

The same phenomenon was found among fauna as well.

Hainan had the highest proportion of mammals shared with Vietnam, and the lowest with Guangdong, according to the study.

“Among the 41 mammal species in Hainan, 30 can be found in Vietnam,” the study said.

Environment in southwest China ‘overwhelmingly’ shaped by human activity for more than 1,800 years

Zhu’s study postulates that Hainan was physically connected to Vietnam during the Mesozoic era. Also known as the Age of Reptiles, the period saw the rise and extinction of dinosaurs from about 252 to 66 million years ago.

Hainan broke away from Vietnam and drifted southeast after the Mesozoic period until it settled in its present location, according to the study. The separation was triggered by volcanic activities in the Beibu Gulf.

But Hainan might not be tied entirely to Vietnam. For instance, the northeastern tip of the island was connected to Guangxi province at the time, the study added.