It is reasonable to believe that barb wire strung at or around neck height on a well defined quad/motorcycle trail is a negligent/reckless act on the part of the property owner. Cases such as this have been litigated before and it never plays out well for the property owner. My advice would be to contact the law enforcement agency that has jurisdiction in your area and refer the problem to them. I would post the property with marked
"no trespassing" signs with proper capitalization and punctuation.