  We study nonuniform lattices in the automorphism group G of a locally finite
simplicial tree X. In particular, we are interested in classifying lattices up
to commensurability in G. We introduce two new commensurability invariants:
quotient growth, which measures the growth of the noncompact quotient of the
lattice; and stabilizer growth, which measures the growth of the orders of
finite stabilizers in a fundamental domain as a function of distance from a
fixed basepoint. When X is the biregular tree X_{m,n}, we construct lattices
realizing all triples of covolume, quotient growth, and stabilizer growth
satisfying some mild conditions. In particular, for each positive real number
\nu we construct uncountably many noncommensurable lattices with covolume \nu.
