Christmas trees from the garden of Eden

A few days ago I came across this early christian relief from Naxos depicting the nativity (birth) of Jesus scene. Unlike the later representations of the Nativity which take place in a manger, the Nativity scene on this early marble slab is framed by two trees, which means that the scene is taking place in a forest, a grove. The two trees are the pine and the oak, the two main European Christmas trees.

This image made me ask myself these questions:

What is the origin of Christmas trees? We can read that the Christmas tree customs are the Christianized versions of the older pagan Winter Solstice customs involving evergreen trees. But why are the two main European Chrismas trees Oak and Pine (Spruce, Fir)? Are these two trees somehow connected to the ancient idea of the garden of Eden, the Golden age "when humans enjoyed the spontaneous bounty of the earth without labor in a state of social egalitarianism"?

Oak and Pine were the main original sources of starch food during the Upper Paleolithic, Mesolithic and early Neolithic, before the addoption of grains as the main source of starch food. Is this why these two trees are depicted on the Naxos relief? Is the Garden of Eden, the Golden Age the post glacial Mesolithic northern hemisphere where food literally grew on trees?

You can read more about this here:

Merry Christmas.