Throughout my travels for the past three weeks I spent time at a lot of parks in Florida and California and there was something similar in both places. It wasn't the landscape, or the climate, or the Flora... It was the amount of trash discarded without regard. And I get it, I used to not understand that leaving orange peels, banana peels and other food scraps behind could be considered a big deal until I lived in the woods and got to see the havoc that well-trafficked areas brought to an eco-system. 

The issue is that the volume of tourists that these beautiful and cool places attract is handling so much more trash than it should. It not only is annoying because you can step in others people's trash, dogs decide to pick up your trash when on walks (and then the owners are dealing with it and throwing it away for you), it gets rinsed into rivers and the ocean and can bring diseases and mess up the water quality and the ecosystem in those rivers.

And depending on your location it attracts bears and then those bears become accustomed to humans, and they die as a result of it. 
This is something that is a very easy, and should be a manageable task. I am constantly shocked by how gross trails and parks are. 
Parks aren't your personal compost bins. If you pack it in, pack it out (food scraps, bags, bones, toilet paper and poop included)