no but really without them the forest floor would smell bad with decaying flesh, rotting fruit, and animal droppings. They are pretty much like community service. In fact, I actually have 10 pet snails myself, and recently they just layed eggs, Ya too much info!
Plant life would dwindle because it would be unable to find nourishment to grow .. Plant life is very foundation of our food chain..If one 'link' in the food chain is removed...all other life would suffer the consequences.
An example of a decomposer: worm, fungi, bacteria, etc. If decomposers were abscent in a forset ecosystem, things would not rot, there would be no regeneration of plants, which would collapse the forest food chain and/or web.