Space-Age Christmas, The Doctor Who Annual 1974
I wish I'd known about this before doing a Who Christmas Special set on a colony spaceship in the future.
"If pollution and the effects of the population explosion go on at the present rate, there will probably be very few trees left in the world, and any forests which do still exist will be protected by stringent laws." Yikes!
"But let’s hope that all that’s best about our traditional Christmas will stay, and that it will still be the same festival of happiness and goodwill that it is today." Ahh...
I went more than twice as far into the future to be on the safe side. And I don’t remember specifying if the tree on the colony ship was real or plastic - real could work considering the need for air cleaning and such, although they’d probably focus on more multi-purpose plants than fir trees.