A retired Chinese forestry official who became an environmental activist campaigning against deforestation and overdevelopment on China’s southern Hainan Island was put on trial this week for illegally publishing and distributing books on environmental protection, his friends and associates said.

Liu Futang, 65 and in poor health, faces as much as five years in prison. Under the Chinese legal system, defendants are considered guilty when brought to trial — there is no presumption of innocence — but family members said they are petitioning the court to free him on medical grounds. No date has been set for his sentencing.

Liu came from northeastern China more than two decades ago to work in the provincial Forestry Ministry in Hainan, at China’s southernmost tip. He became chief of the Forest Fire Prevention Bureau and then stayed on trying to protect the island province’s natural ecosystem — especially its coastal forests, which were being uprooted to make way for luxury seaside hotels, apartments and golf courses as part of the Chinese government’s quest to turn Hainan into an international tourism destination dubbed the “Hawaii of the East.”

“Hainan is a real-life example of that film ‘Avatar,’ ” Liu said in a 2010 interview with The Washington Post about the deforestation that was underway. “Except in ‘Avatar,’ they could organize together to fight back.”

Of Hainan’s prospects, Liu said, “I don’t have much hope. Nothing can stop this change.”

Liu started a microblog and became a “citizen journalist.” His efforts were rewarded in April with a China Environmental Press Awards prize, co-sponsored by Britain’s Guardian newspaper, the nonprofit group Chinadialogue and the online media company Sina.

Liu’s son, Liu Yin, and others say that Liu’s latest book, “The Tears of Hainan II,” upset some powerful entrepreneurs who are trying to build a coal-fired power plant in the township of Yinggehai over the objection of residents.

Liu was arrested in July while hospitalized with high blood pressure and diabetes. He was officially charged Sept. 19 with running an illegal business — specifically, printing his environmental books without a license.

He spent about $30,000 of his retirement savings to publish the three books and gave away most of the copies.

Liu’s three-hour trial was held Thursday in Haikou, the capital of Hainan. About 20 activists from the province and elsewhere in China showed up outside the People’s Court, some holding a banner that read, “Protect Liu Futang,” friends and supporters said.

Friends and relatives who saw Liu in court Thursday said he appeared sick and frail.

“His cheeks were sunken, and he could barely stand,” Liu Yin said. “He was weak, and didn’t have any strength, and he couldn’t hear clearly due to tinnitus,” a condition Liu suffers from that involves ringing in the ears.

The younger Liu said his father became so depressed while awaiting trial that he attempted suicide; family members still worry about his mood.

Chinese Internet activists have begun using Twitter-like microblogs to demand justice for Liu. One activist said he started a microblog account called “Protect Liu Futang” that immediately attracted 700 followers.

Wang Juan in Shanghai contributed to this report.