On the number of spanning trees on various lattices

We consider the number of spanning trees in lattices; for a lattice L, one defines the bulk limit z(L) = lim(vertical bar VG vertical bar ->infinity)(log N(ST)(G))/vertical bar VG vertical bar, where N(ST) (G) is the number of spanning trees in a finite section G of L. Explicit values for z(L) are known in various special cases. In this note we describe a simple yet effective method to deduce relations between the values of z(L) for different lattices L by means of electrical network theory.