You could try one of the Scat Mats -- they make them in a circular pattern to go around Christmas trees. How about spraying the lower branches with Bitter Apple? Does Jeffrey know "leave it"? If so, allow him only in the same room with the tree when you are in there and can catch him if he seems to be taking an interest in the tree.
Frankly, we've given up on trees more because of the cats than the dogs, and the other part is, we don't have any little people (human variety) in the house anymore and generally go to someone else's house to celebrate. We decorate with other things like lights and such, but a tree just isn't always up.