Why can't you share the land and work together? I dont' want to sound like an arse, but he does appear to have the same right as you to hunt the land. I understand the fact that he should have consulted with you about it since you have been there 15 years as a courtesy. But, being there 15 years unfortunately doesnt' give you ownership of the land or any leverage IMO. I'd try to keep it civil and see if you can work something out without it turning into a war.