Personally, I don't think a great amount of detail is needed in the truck on the tree. However, snow detail IS needed, but the black tree acts as a simple compositional form and having detail would not reveal anything that the viewer would be missing when the tree is pure black. In fact, I would probablly burn down that one little light branch in front of the tree truck that slightly breaks up the form of the black tree trunk.
Carl, There is minimal detail on the negative(i placed the trees low on zone 3) and I plan to print them black. This is a negscan until I finish developing all my film from the trip.
Ryan, I agree entirely about leaving the tree black and there is some lovely detail in the snow that doesn't translate through this scan, although some of the interesting shadows are visable. I will certainly burn the branch you are refering to when I start printing.