File photo taken on Nov. 3, 2017 shows a black snub-nosed monkey, also known as the Yunnan golden monkey, climbing a tree in the Yunnan golden monkey national park in Tibetan Autonomous Prefecture of Deqen, southwest China's Yunnan Province. To keep Yangtze River clean and beautiful, efforts to restore ecological environment have been taken in the upper reaches of Yangtze River in Yunnan Province in recent years. (Xinhua/Lin Yiguang)