Lipschitz continuity and composition operators in pluriharmonic Bloch spaces

We study the Lipschitz continuity of pluriharmonic Bloch mappings in the unit ball ${\mathbb{B}}^n$ with respect to the Bergman metric. We apply this to obtain a sufficient condition such that the composition operator on the pluriharmonic Bloch space is bounded below. As a partial converse, we also give a necessary condition for the boundedness (from below) of the composition operator on the Bloch space of holomorphic mappings in ${\mathbb{B}}^n$.