Unless they are destroying them or exporting them far, far away, then it's still a net increase in the number of trees in a certain area, no?
Or maybe they steal them in order to sell them back to you?
That may not be good for your pocket book, but it still doesn't decrease the number of trees in a certain area.
Similarly, I wonder how long durable water-collection pots would stay scattered around trees in impoverished, drought-stricken areas.
Someone came to my grandma's garden in the dark of night and stole all of her flowers. Apparently, some horticulturists are thugs.
Perhaps some horticulturists are rabbits? My wife planted about 120 tulip bulbs, which was nice the first year but by the second the rabbits found them, from there on all we ever saw was stems and leaves.
Some of them were in pots on the porch. The pots disappeared as well. One was more or less a little tree. This has happened at several homes throughout the neighborhood. God help us if these rabbits develop a taste for human flesh.