Beijing, May 28 (Youth.cn) - Photo taken on May 27th in Shuanggui Lake National Wetland Park. Under blue sky and white clouds, wetland, lake, city and grass form a beautiful summer ecological landscape. The wetland park is in Liangping District. As an international wetland district, Liangping possesses 20000 hectares of wetland and its 17.7 billion RMB ecological value. Ecological value of wetland is an important reference for ecological construction of wetland, which is calculated by supply of ecological materials, the value of maintaining water resources and soil, of flood water storage, of carbon sequestration, of purification of water and air, of local climate regulation, and of tourism and sightseeing. Photo/VCG