I don't know what state you are in (state laws differ on hte details, but they all have this), but it sounds like he is trying to obtain title to the land through adverse possession. If you own the land or are willing to do the legwork for your landlady, find out exactly what the requirementrs are in your state, and do whatever is necessary to legally protect your land (which, sad to say, could include giving him permission to use your land (of course you can later revoke that permission, but at least it breaks the time that would count towards possession and the clock will restart).
He may feel that the amount of time needed has already occurred. However, for title to change hands, it does have to go to court. The land surveyor would not have that information as the courts would be the ones re-aligning the property lines.