They painted in tree holes and tree burls in the eastern suburban district of Tongzhou on February 5, 2017. /CFP Photo

A fox, a frog, a hedgehog, an owl, and other animals are vividly pictured on grey trunks, adding vigor to the once lifeless season. /CFP Photo

The creative idea was first pushed forward by a 23-year-old art undergraduate in Shijiazhuang, Hebei Province, back in 2013. /CFP Photo

Wang Yue, together with her friend, Li Yue, transformed public trees on streets into a pop-up gallery by painting images of animals and natural scenery. /CFP Photo

They had to first find the right trees with smooth surfaces to paint on, composed a digital drawing, and finally painted the image onto the tree. The whole process could take more than a week. /CFP Photo

This form of public art drew wide attention immediately. / CFP Photo

It is reported that the paint is not harmful to trees, but the non-toxic paintings will fade in time. /CFP Photo