  We study entanglement dynamics of pure three-qubit
Greenberger-Horne-Zeilinger-type (GHZ-type) entangled states when one, two or
three qubits being subjected to general local noise. Employing a lower bound
for three-qubit concurrence as an entanglement measure, we show that for some
many-sided noisy channels the entanglement dynamics can be complete described
by the evolution of the entangled states in single-sided channels.
