The park has 326 species of jujube trees, about half of all the species found in China. Staff members have conducted research on the rejuvenation and revitalization techniques of the ancient trees. Age determinations and classifications have also been carried out.

In addition, studies on growth indicators and the economic characteristics of the fruits have been conducted. Among the trees in the park, the most unique species is the long jujube, whose fruit is a specialty and a national geographical indication product in Lingwu.

Compared to winter jujubes, long jujube trees are tall and upright. The fruit has a short ripening period, early maturity and high productivity, and is large and elongated or cylindrical in shape, according to Tang Wenlin, senior forest engineer at the Lingwu Natural Resources Bureau.

Fresh long jujubes have 25.3 percent sugar, 68.6 percent water and contain 378.8 milligrams of vitamin C per 100 grams of fruit. They also have a large amount of adenosine triphosphate, a nucleotide that helps stave off cancer, Tang said.

The Lingwu jujube tree has been cultivated for 1,300 years and was used to pay tribute to the imperial court during the Tang Dynasty (618-907). Since 2003, this ancient variety has been massively developed, with a total planting area of about 4,533 hectares.

"In recent years, sales of Lingwu jujubes have been booming and have played a significant role in promoting economic development," Tang said. "We have training classes for farmers to improve taste and production, and we sell the fruit both online and offline. The products have been sold across the country and to Thailand and Russia."