Someone must own that land. There is no such thing as open land anymore. It could be the county, or even a person who is a 100miles away. I'm just saying, someone owns that land, and if you're 100% sure that this person doesn't own it, then you don't have to listen to him, but someone owns it.

Maybe this dude is homeless living in these woods...? Maybe you were getting too close to his outdoor living space? Who knows, but i say it's none of your business what's out there. Obviously someone doesn't want you out there, so just forget it.