Huaping county in Lijiang city, Southwest China's Yunnan province, sits near the Jinsha River in the upper reaches of the Yangtze River.

For environmental protection purposes, the local government made a plan to transform its "black" energy-powered economy into a "green" one and began planting trees on the mountains in the 1990s.

The plan was also a response to the central government's campaign to protect the Yangtze River.

"Demand in coal fell off a cliff in the market, and the county was faced with the challenge of transforming Huaping's pillar industry into a high-quality and sustainable one," said Yu Lijun, Party chief of the county.

The local government offered each villager a subsidy of 1,050 yuan ($160) per hectare for them to plant mangoes and taught them farming skills from Southwest China's Sichuan and South China's Hainan provinces for free.

In 2019, 25,200 hectares of mango land in the county generated 2.28 billion yuan in revenue, the local government said.

As the usage of coal declined sharply, the county shifted to hydropower and solar power. In a clean energy industrial park, enterprises manufacture silicon rods for making solar cells and have created jobs for villagers.

In October, the Ministry of Ecology and Environment nominated Huaping and 34 other counties and districts as demonstration bases for other places to learn how to transform green mountains into invaluable assets. The ministry launched the nomination in 2017 to conclude ecological and environmental experience from local governments and set them as examples.