It's a tool for keeping Right-of-ways clear under/around lightlines. Tractors are good and fast for small tree sapplings/brush (a few years worth of growth). Everyone I've seen, was pulling a Brown tree cutter made in Alabama. They are caged to protect the tractor and operator from all the abuse they go through.
If the trees are too big for the ROW tractor, mulchers are used because they are better at clearing bigger trees and leaves a finer ground up tree.
