What happens to unsold cut x-mas trees?

In my area, there are many man-made lakes. Unsold Christmas trees are
sometimes donated by the tree lot owners to be used as fish habitats.
They also can be ground into mulch.

In Germany, they spend a very dark and forlorn Christmas eve, already
suffering from the rejection of not having been chosen to help someone
celebrate, even more depressed by knowing that the value on their tag
has been marked down.  It is a horrible fate for a big or little tree
that has some growth defect that made it unattractive through no fault
of its own.  And Christmas Day is no better, nor the second day of
Christmas:  no more lights in the lot, feeling its wounded stump
drying out as it imagines how wonderful it would have been to be in a
family home with real candles and hearing the family joyuously
singing:  "O Tannenbaum"  (even it were a blue spruce or a Douglas
fir).
Maybe I will buy one of those this coming week.
But then all the rest disappear, probably the the fate Pinkfreud indicates.  ;-(

This kind of reminds me of the episode of "Friends" where Joey is
selling Xmas trees and Phoebe is shocked (to put it mildly) to find
out what happens to the unsold ones.