The move follows three decades of indiscriminate Chinese logging and ineffective government efforts at reforestation.
He was jailed for resisting political reeducation and refusing to criticize exiled spiritual leader the Dalai Lama.
A second group comes to protest in support and is also taken into custody, sources say.
Four people avoid jail, but face longer term for property seizure at the heart of the dispute over development.
Relatives and friends are warned they will be held responsible if any photos are taken or circulated following his release.
Replacements are hired based on 'backdoor connections' with influential county officials, sources claim.
Chinese law guarantees the freedom of expression, writer Shokjang says in his petition for release from jail.
They had tried to reclaim land seized for a government development project on which no work was ever done.
A local leader and two others are being held for taking part in a group chat about the Sikyong, Tibet's exile political leader.
Tibetans protesting his death in detention are also taken into custody, a local source says.
Police fire on Tibetan herders after they confront Chinese Muslims caught rustling yaks.