This undated file photo shows the scenery of the Saihanba forest in Weichang Manchu and Mongolian Autonomous County in Chengde City, north China's Hebei Province. Saihanba is a vast forest covering nearly 75,000 hectares. It was a piece of barren land 55 years ago, but decades of afforestation efforts have turned it into an important ecological shield for Beijing and Tianjin. (Xinhua/Xin Zhiyou)