A debarking blade arrangement is carried by a frame of a tree harvesting head and includes a fixed knife segment that cooperates with three articulated knife segments carried by each of right- and left-hand, articulated debarking arm assemblies which are disposed on opposite sides of a tree stem feed axis. Each arm assembly includes a rear arm section that carries a first knife segment, an intermediate arm section and a front arm section that carries second and third knife segments and is yieldably biased toward the intermediate arm section so as to dispose the second and third knife segments for engagement with a tree stem. A hydraulically-powered arrangement is coupled to each arm assembly for selectively pivoting the entire assembly about a fixed axis and for pivoting the intermediate and front arm sections relative to the rear arm section for keeping the knife segments in debarking engagement with the stem.
