Real Christmas trees are beautiful. They smell good. They look classy as hell. They are not made of plastic and imported from China like most of the fake trees you can buy. They are not fake, which means they are easily assumed to possess that most coveted trait of all, authenticity.
But they have a finite lifespan, and after the holiday is over you're left with a decaying tree corpse that must be disposed of before rot and stink and needles happen everywhere. Sure, they're biodegradable, but if you're going to buy a tree specifically chopped down to be ornamental, it's good to figure out something useful to do with it instead of tossing it in with your gift wrap and leftover cheese dip.
Lots of people chuck their used trees in the trash, praying that Santa will forget their wastefulness by the time the next Day of Presents rolls around, but it doesn't have to be that way. There are a few good options for recycling your tree.
Most cities offer programs that will turn your de-tinseled tree into mulch. In New York for instance, the MulchFest program lets you drop your no-longer-wanted tree off at a bunch of different locations throughout the city at the beginning of January. There are also certain areas that will chip your trees and give you a bag of mulch to take home, and a curbside collection program if you're too lazy to lug your dying tree around (you will have to take the tinsel off first).
Chicago, LA, Atlanta, and other major cities offer similar mulching and chipping programs. In rural areas, people are more likely to own their own chippers, to make DIY mulching easier. Unless you live in a coastal area, this is the best option for recycling your tree. Do it!!!!
Restoring coastal marshes
Old Christmas trees are a valuable resource on the coasts. In Louisiana, people can put out their trees for curbside pickup and they are dropped in fenced areas on the coast to prevent erosion. The trees help curb saltwater from seeping inward and turn into sediment. This stops the coasts from getting eaten by the sea.
The Louisiana National Guard helps arrange the trees in Jefferson Parish, an area south of New Orleans. Over 60,000 trees are placed as natural barricades every year. In New Jersey, old Christmas trees to help prevent erosion on sand dunes. The trees are laid on top of the dunes to minimize damage from winter winds.
Feed the animals?
A website I found called "How and Where to Recycle or Dispose Your Christmas Tree" has been an invaluable resource in writing this article. But it gives some dubious advice, advocating for putting fresh orange slices and popcorn on your tree and turning it into a freestanding bird feeder until it is brittle enough to break apart by hand. I do not advocate this approach, because it is a waste of tasty orange slices and it sounds too complicated, and also sounds like you will be breaking apart an old tree covered in bird poop.
Still, it's an option. Merry Christmas!