Chinese President Xi Jinping (1st L, front) talks with other participants during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top Communist Party of China (CPC) and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Chinese President Xi Jinping (2nd, L) plants a sapling during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top Communist Party of China (CPC) and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Chinese President Xi Jinping (3rd, R) plants a sapling together with pupils during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top Communist Party of China (CPC) and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Chinese President Xi Jinping (2nd, R) talks with other participants during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top Communist Party of China (CPC) and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Chinese Premier Li Keqiang (2nd, L) plants a sapling during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top Communist Party of China (CPC) and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Zhang Dejiang (C), chairman of the Standing Committee of China's National People's Congress, plants a sapling during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top Communist Party of China (CPC) and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Yu Zhengsheng (L), chairman of the National Committee of the Chinese People's Political Consultative Conference, plants a sapling during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top Communist Party of China (CPC) and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Liu Yunshan (2nd, L), a member of the Standing Committee of the Political Bureau of the Communist Party of China (CPC) Central Committee and secretary of the Secretariat of the CPC Central Committee, plants a sapling together with pupils during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top CPC and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Wang Qishan (1st R, front), a member of the Standing Committee of the Political Bureau of the Communist Party of China (CPC) Central Committee and secretary of the CPC Central Commission for Discipline Inspection, plants a sapling during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top CPC and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua

Chinese Vice Premier Zhang Gaoli (2nd, R), also a member of the Standing Committee of the Political Bureau of the Communist Party of China (CPC) Central Committee, plants a sapling during a tree-planting event in Sunhe Township of Chaoyang District in Beijing, capital of China, April 3, 2015. Top CPC and state leaders Xi Jinping, Li Keqiang, Zhang Dejiang, Yu Zhengsheng, Liu Yunshan, Wang Qishan and Zhang Gaoli attended a tree planting event in Beijing on Friday. Photo: Xinhua