  We show exactly that the squared entanglement of formation (SEF) obeys a set
of hierarchical monogamy relations for an arbitrary $N$-qubit mixed state.
Based on this set of monogamy relations, we are able to construct the set of
hierarchical multipartite entanglement indicators for $N$-qubit states, which
still work well even when the concurrence-based indicators lose efficacy. As a
by-product, an intriguing analytical relation between the entanglement of
formation (EOF) and squared concurrence (SC) for an arbitrary mixed state of
$2\otimes d$ systems is derived, making the concurrence calculable via the
corresponding EOF. Furthermore, we analyze the multipartite entanglement
dynamics in composite cavity-reservoir systems with the present set of
hierarchical indicators. Moreover, for multilevel systems, it is illustrated
that the SEF can be monogamous even if the SC is polygamous.
