Hu Kaijing, a herdsman in Alxa League in Inner Mongolia autonomous region, shows the Congrong, a kind of herb he plants on the roots of a Suosuo tree, May 16, 2016. [Photo by Ma Chi/chinadaily.com.cn]

As tough a plant as suosuo is, surviving in the desert is not easy. A sandstorm can easily bury a newly planted tree. So a sand barrier made of hay or twigs is laid on the ground to fix the sand and protect young trees.

Hu receives a subsidy from the local government for planting suosuo, and also gets technological support from the Alxa Society of Entrepreneurs and Ecology (SEE), a nongovernmental organization committed to preventing desertification.

Hu has planted more than 666 hectares of suosuo on his lands, which effectively prevents the desert's invasion and also brings economic benefits because of a special parasite, congrong, that grows on suosuo roots.

Congrong has a long history of being used as an herb to treat male sexual dysfunction. Dried congrong is sold for more than 200 yuan ($30.6) a kilogram, and its seed is priced at 20,000 yuan a kilogram.

Hu Kaijing earned more than 200,000 yuan last year from the sales of congrong, much higher than his income from sheep farming.

Many villagers followed Hu's example and planted suosuo. More than 17,000 hectares have been cultivated in the village.

"The environment has greatly improved, and we can see more animals, such as swallows, coming back," said Hu.

"Through the planting of 100 million suosuo trees, we aim to build a green barrier in Alax League, thus preventing the encroachment of desert while improving the livelihood of local herders," Feng Furong, an SEE employee, said.

SEE was founded by a group of entrepreneurs in 2004. In 2014, SEE proposed to plant 100 million suosuo in 10 years in areas threatened by encroaching desert in Alxa League.