So now I ask....just because there is a 50' ROW you have the right to do anything you wish within that 50' ? Even though your property is part of that 50'ROW ?
From what I understand, the answer is yes. The person who has the ROW can do what he wants inside the ROW to maintain it.
When I lived in CA, a friend had a ROW though a city Park to get to his land, that was 100% surrounded by the Park. The Park wanted his land and started harrassing him. Park Rangers where sent to give him tickets for driving on his ROW, then they installed gates and tried to lock him up, and then sate there and watched him cut their locks, and then wrote him tickets for destroying their locks. He took them to court and won every time because he has a ROW to get to his land.
I forget why, but he decided to widen the road and improve it getting to his land. We cut down all sorts of trees that belonged to the Park and they really freaked out. They sent helicopters with Park Rangers to arrest us, but they also had half a dozen Park Rangers, a Game Warden and several Sheriffs there in their vehicles. The owner of the land was the former city planner for Oakland and he truly enjoyed the game of messing with the Park. He knew his rights, he knew the law, he knew what his easement was, and best of all, they all knew that he knew this. They where bluffing, they tried to intimidate him, and he told them that he needed the road to be able to get a fire truck to his place!!!! That stopped them cold, and sure enough, he had that documentation too. They made us stop working for the day, but by the next weekend, his lawyer had been to the Judge and we where back to cutting down trees and branches with at least two Park Rangers parked up on the hill watching us the entire time.
Eventually the Park took his land through Eminent Domain, and that started another battle on what the land was worth.
I have no idea what the law is in Tennessee, but my guess is that the person with the ROW can do what he wants, and just like a neighbor in a city with a big tree on their side of the fence line, you can cut branches that might lead to the death of the tree, but you cannot cross over the fence to remove the tree. Sounds like he did something like that with the roots of your trees that are on his ROW.