Ye Dahua, deputy head of the Beijing International Horticultural Exhibition Coordination Bureau, said that the expo promotes horticultural exchanges between China and other countries. It also shares the latest achievements in green development among countries.

Hans d'Orville is chief adviser to the International Center for Creativity and Sustainable Development under the auspices of UNESCO. After looking around, he said that it is no doubt a world-class horticultural expo. He added that it shows that biodiversity is the basis for the survival and development of human society.

On a visit to a small courtyard at the expo, which demonstrates Yanqing's environmental changes over the past 70 years, the visitors were impressed by the district's achievements in ecological construction.

Before the 1990s, Yanqing residents were exposed to deserted land, stripped ground and sparse vegetation. The adverse environment and severe sandstorms endangered the survival of locals and limited the economic development of the district.

With the environmental efforts of governments and locals for almost 70 years, the desert in Yanqing has been repelled. The forest coverage rate in the district has increased from less 7 percent to more than 60 percent.

Yanqing has stepped up efforts to promote the development of three key industries: modern horticulture, tourism and ice-and-snow sports.

Smiljana Vlajic is director of the Cultural Center in the Autonomous Province of Vojvodina, Serbia. She said: "It's unbelievable to see the changes that have happened in Yanqing district. I can't imagine what kind of energy pushed the residents to plant trees for so many years."