Rooted in sustainability

Farmer Liu Jingyi would play at the family chestnut tree just outside their yard when he was a child, climbing up its branches and into the hollow of its trunk.

"It was a big tree, the trunk about a meter wide, probably more than 600 years old and very much a part of our lives," says Liu, now 79.

Liu is a fifth-generation cultivator of chestnut trees in Aiyukou village of the Kuancheng Manchu autonomous county in Chengde, North China's Hebei province.

The village is a center of chestnut cultivation. More than 400 Aiyukou households covering nearly 700 hectares of farmland together yield about 1,000 metric tons of the nuts a year, with many of the trees hundreds of years old. About 50,000 hectares in Kuancheng are used to farm chestnuts, with an annual output value of 860 million yuan ($119 million), according to latest industry figures.