Nice photos you have here 🙂
I will use one photo from my walk in the forest on Fruška Gora, Serbia, this weekend, 12/16.
In a valley, I came across a tree with an interesting hollow. a cut part of the tree, and the water that has deepened it for years, will cause the center to be hollowed out, so that water is retained. Water that froze, meaning the temperature was not above freezing, even though the air temperature was around 2°C.