Most WWF campaigns put images of animals front and center, and these ads to save the trees are no different, although they are a little more abstract than usual.
The minimalist black and white posters are set up so that they mimic the face of a panda, the eyes and snout of a polar bear and the rear end of a hippo. Each of the shapes that makes up these abstract animals is a little tree, which reiterates the cycle of how "Trees save wildlife. Wildlife saves trees." The simple ads might take some squinting and head-tilting to see, especially if you're in close proximity to the ads, but the print ads would be pretty eye catching from a distance.