Is plastic harmful to a forrest, as it is to the oceans?

My Observations (n=1) suggest otherwise and i don´t know what to do of it.

Everyday i steal myself a half an hour of fresh air and wander through the office´s nearby forest. From the beginning i noticed an uncommon amount of litter on the trail. Mostly candy-wrappers from the nearby school but also bottles and cans. So since this week i started to pick it up and throw it away.

But does that really do any good? I´m no ecologist but if plastic doesn´t compose and rot, than it´s nearly than same as rock. Even more with the glass bottles and metal cans. Animals and plants seem to find their way around it.
Yesterday i even pulled some big trash bag from the roots of some fern.