Drazha's village has a unique written rule: a villager can only build a new house if his old one is more than 30 years old.

Drazha, a Tibetan farmer, lives in Langrong village in Diqing Tibetan autonomous prefecture of Yunnan province. The village is located in Potatso National Park, a 1,300-sq-km preservation area near Shangri-la city.

"Limiting the number of new houses is part of measures to protect the environment," said Drazha.

Drazha, 52, used to replace his wooden rooftop every summer, but now he uses steel panels. "The wood soaked up water in the summer rainy season, so replacing the roof with steel saves a lot of wood," he said.

The Three Parallel Rivers area, a world heritage site that includes sections of the Jinsha, Nujiang and Lancang rivers, has benefitted from the villagers' environmental efforts.

The 1.7-million-hectare area is rich in plant and animal species. It covers four prefectures and cities in Yunnan: Diqing, Nujiang Lisu autonomous prefecture, Lijiang and Dali. The total population is around 1.3 million.

More than 30 families like Drazha's receive money from the park to compensate them for their environmental protection efforts, such as using solar panels, more efficient stoves, and abandoning herding. Drazha received 75,000 yuan last year in subsidies from the government and Potatso park. He gave up herding and farming long ago and now works as a patroller at the park.

More than 14.4 million visitors came to Diqing in 2014, and the number is growing every year. Zhang Yonglin, deputy director of the Diqing forestry bureau, said by developing tourism on 2.3 percent of park land, the park earns enough to pay farmers and protect the environment.

"The villagers have turned protecting the environment into a volunteer activity," said Hotang, an official with Potatso National Park.

In neighboring Nujiang prefecture, reforestation has been a priority. More than 1,800 rangers have been hired to plant trees, patrol the forest and guard them against poachers.

The prefecture aims to turn at least 40,000 hectares of farmland into forest or grassland in the next five years.

During the past six years, the central government and the province have invested 367 million yuan (about 56 million U.S. dollars) to protect the forest in Nujiang. More than 75,000 hectares of forest have been added.