He took three photos of Yanmen Pass from the same angle over 20 years, showing the ecological changes and sharing them with others.

Barren, snow-covered mountains jump into view in the first photo taken in the early 2000s, evoking a sense of harsh desolation. The presence of green trees emerges on the mountain slopes in the second photo taken 10 years ago.

In the third photo, taken last year, the trees have grown into a lush forest.

"The Great Wall used to be desolate and imposing. Now it has become gentler and full of vitality," Yang says.

To continuously improve the ecological environment of the Yanmen Pass scenic area and the surrounding Great Wall, Daixian county has implemented afforestation projects in a mountainous area of more than 2,600 hectares in recent years, where pine, spruce, wild apricot and elm trees have been planted.

Yang's contribution has earned him multiple accolades, including the Ten Great Wall Guardian award by the Xinzhou government.

"The Great Wall has given me a mission and greatly enriched my life," Yang says, adding that the awards serve as an incentive for him to carry on.

He says he will keep enrolling people in the Xinzhou Great Wall Society so they can join in the efforts for Great Wall protection and studies.

Yang is now working on compiling years of Great Wall studies into books for the public to understand and appreciate its charm.

"Hopefully, I can offer some useful information on Great Wall protection and utilization," he says.

Contact the writer at yangfeiyue@chinadaily.com.cn