A controlled lean system for a tree feller-buncher includes a sensor configured to measure an orientation of a boom coupled to the tree feller-buncher, and a felling head operably connected to the boom. A controller is operable to detect a cut tree carried by the felling head and to estimate a quantity of tree lean needed to reduce torsional load during rotation of the boom while carrying the cut tree based at least in part on the measured orientation of the boom.
