Real pine trees are environmentally friendlier than artificial plastic trees unless you reuse an artificial tree for many years.
The case for real trees
Christmas trees are grown on farms like any other cash crop. These trees provide environmental benefits such as cleaning the air, and the very presence of these farms prevents commercial development of the land. Also, once a tree is cut down, another will be planted to replace it keeping plants in existence. Tree farms, unlike manufactured artificial trees, provide local jobs helping the immediate community.
After the season is over pine trees can have a second life as a host of things. Some zoos take Christmas trees because the animals enjoy playing with, and eating, the trees. Most municipalities have some sort of recycling program for trees. NYC has a mulchfest where they recycle old trees providing the city with valuable mulch. Even the Rockefeller tree gets recycled into lumber for Habitat for Humanity homes.
The case for artificial trees
As of 2017, 95 million US households displayed a Christmas tree, and of those 81% were artificial. Artificial trees are frequently made in China with PVC plastic and metal. In addition to the petroleum they are made from, petroleum is burned to ship them to a store near you, and you burn even more petroleum to drive to that store. Even worse, if you decide after a few years you don’t want it anymore, the “tree” becomes that much more plastic in a landfill since most plastic is never recycled. None of this is environmentally friendly.
The primary benefit of an artificial tree, is that its environmental cost goes down the more years you use it. Once you own it there isn’t any fossil fuel involved in getting it out of storage every year (unlike the annual drive to go get a real tree). How many years you need to use an artificial tree for its benefits to outweigh its detractions is debatable. The low-end estimate is 8 years but the high-end estimate is more than 20 years – so it takes 1-2 decades for an artificial tree to become more environmentally sustainable than a real pine tree.
The best tree is the real tree you can buy close to your own home from a local tree farm in your region. Only if you plan on using an artificial tree for many years will it become the more sustainable option.