Zoom in on the tree leaves, it's very visible on those. They appear as green rings, slightly lighter on the edge, giving it the appearance of a ring. You can also see it very clearly in the spots of sky between the leaves, they appear grey with an almost white outline.

Zoom in on the large tree in the background. It looks as if it has ornamental balls hanging off it.

A good video from a pro going through why someone might deliberately choose characteristics like this: https://www.youtube.com/watch?v=O0zH7J_Vmg4 (4:47)