Rumbling earthmovers carve out a seaside golf course among fallen palm trees on a Chinese island, after authorities silenced the man who spoke out against destroying the tropical forest.

Vast swathes of Hainan in the South China Sea have been cleared -- a quarter of its woodlands in the last decade according to environmentalists Greenpeace -- for golf courses and exclusive hotels in an attempt to create a tourist paradise.

Liu Futang, a former forestry official disgusted by the destruction, campaigned against damaging developments for years.

The People's Daily, China's most circulated newspaper and the ruling Communist Party's mouthpiece, even lauded him on its front page as an "environmental warrior" after he stopped a mining firm cutting down swathes of palms around two kilometres from the golf course site in Wanning.

But Liu now stands as a symbol of Chinese suppression of environmentalist critics after he was tried for publishing books on the subject, jailed, convicted and released on condition he does not speak to the media.

His activist career was terminated after his support on Sina Weibo -- a Twitter-like platform boasting more than 500 million users -- for the villagers of Yinggehai against a coal-fired power station took on overtly political tones.

"To protect Hainan's almost destroyed environment... we need to let officials feel the people's leather shoes pressing against their bodies, and let them feel the power of the people," he wrote.

His social networking account was deleted. Months later, prosecutors in Hainan's capital Haikou, where Liu was being treated for diabetes and high blood pressure, ordered his arrest.

Prosecutors accused him of illegally self-publishing books on Hainan's environmental problems and making 78,000 yuan ($13,000) from doing so -- charges his defence dismissed as absurd.

"If I had wanted to make money, I would never have published the books," Liu told the court, at one point breaking into tears, according to an account of the trial confirmed by Zhou Ze, who was present but said he was not allowed to represent him.

"Liu's publications were not a commercial exercise, he did not pursue profit... and gave away most of his books for free," said Zhou, who is well known in China for his work on human rights cases.

"According to Chinese law, Liu should be free to print his books."

Eventually, after being held in custody for months, Liu -- whose titles include "The Green Dream" and "Hainan Tears" -- was given a three year suspended sentence in December and released, but authorities have silenced him.

"The local security bureau has made him promise not to speak to the media," Zhou said. "It's clearly an illegal violation of his rights."

Neither the security bureau nor the court responded to fax and phone enquiries from AFP.

Hainan's top official Luo Baoming said last year that environmental protection "has always been a priority in the government's work", the state-run China Daily reported.

But in Yinggehai, a poverty-stricken town with unpaved roads, locals said officials had beaten and arrested protesters against the plant last October.

"The government hit people... they just arrested whoever was standing at the front of the protest," said a shopkeeper, who did not want to be named for fear of reprisals.

"We're scared of being arrested, so don't want to talk about the plant," he added, before furtively handing over a copy of a protest rap song.

"No one dares to report it, because of pressure from the centre... those who protect their beautiful home are suppressed," the rapper sings, alluding to press censorship of the protests.

Hainan's undisturbed sandy beaches, lapped by gentle waves, still prove an irresistible lure to developers, who continue to hack down trees that have stood over the shores for years.

"They cut down the forest about a year ago," said Wang Jurong, a farmer in Wanning, as she picked vegetables in a palm-fringed field still ploughed by oxen.

But she would support the development as long as she received a cut, she said. "If you give us a high enough price you can do what you like with the land."

It is an attitude mirrored by officials in Hainan, who last month heard China's new president Xi Jinping declare that "development is still the key to solving all our problems."

"Local governments protect local industries which boost GDP... even using the violent instrument of the law to avoid pressure from people like Liu Futang," Zhou, the lawyer, said. "It makes me very depressed."