In the heart of the dense forests of the Greater Hinggan Mountains, as the first rays of morning sunlight pierce through the trees, forestry police officer Zhao Xiaohui and his colleague Li Hui start a day's patrol in the mountainous area of Alongshan town, Genhe in the northeast of the Inner Mongolia autonomous region.

"The work of forest police is different from the police officers in cities," Zhao says.

"For us, the lush forest with various wild animals running around carefree is our mission, which is also the value of our job."

Stretching from northwestern Heilongjiang province to the east of Inner Mongolia, the Greater Hinggan Mountains are home to the country's largest forest. Zhao and Li's branch oversees an area of 357,427 hectares, with forest covering 339,520 hectares, which means a climate of unpredictable extremes throughout the year. The region has harsh, lengthy winters and short, hot summers, with drastic temperature variations between day and night. With winter temperatures plummeting to — 50 C, it stands as one of the coldest areas in the country.