An employee was standing on an uprooted tree that was lodged in a healthy tree attempting to cut a limb on the uprooted tree. The employee's primary climbing line was attached to the healthy tree and positioning lanyard was attached to the uprooted tree. After making the cut, the employee was walking back to the healthy tree when the uprooted tree became dislodged from the healthy tree. The employee fell approximately 60 feet to the ground with the uprooted tree, suffering a fractured femur, pulmonary and head contusion, and forehead laceration.