It's just an ecosystem thing - if the ground cover can't handle the leaves it probably should be a different ground cover there. This does remind me of something cool though. I was up in the UP Michigan canoeing and ended up in a forest of maple trees. Their leaves had so completely dominated the ground that it was just a blanket of leaves and sap for miles. Only a few patches of fern could make it there but otherwise there were no (visible) ground plants