Jóla tré (Norse Yule Tree) originally consisted of evergreens, decorating houses and barns, to scare away evil spirits and also to provide a place for birds during Yuletide (Yule time).  

ORIGINS

Yggdrasil, a tree also known as the world tree, in which shadow the world stands, is introduced in Snorra Edda (Prose Edda). Gangleri asks where the favorite or holiest place of the gods is. Hár (High) replies "It is the ash Yggdrasil. There the gods must hold their courts each day". Gangleri asks what there is to tell about Yggdrasil. Jafnhár (Just As High) responds that Yggdrasil is the biggest and best of all trees, that its branches extend out over all of the world, and reach out over the sky.

Ask veit eg standa, An ash I know stands,
heitir Yggdrasill, Its name is Yggdrasil,
hár baðmur, ausinn An immense tree, covered over
hvíta auri; By the white sand;
þaðan koma döggvar Thence come the dew
þær er í dala falla, That falls in the valleys,
stendur æ yfir grænn It stands evergreen
Urðarbrunni. Above the well of Urdal.

Völuspá

CHRISTIANIZATION

Upon Christianization of Nordic countries, the Church attempted to eliminate Jóla tré, seen as a symbol of Pagan worship. This started with missionaries such as Saint Boniface cutting down Yule oak trees in the early 800’s CE. An irony considering Jóla tré is now a symbol of Christmas, a Christian celebration.