This aerial photo taken on June 21, 2018 shows a wetland within the Chanba Ecological District in Xi'an, northwest China's Shaanxi Province. Aiming to serve as the "green lung" of Xi'an, the Chanba Ecological District has adopted an eco-friendly approach to its development. So far, six large ecological parks have been built here, covering 1,133 hectares of wetlands and 1,933 hectares of forests that are home to 206 bird species. (Xinhua/Shao Rui)