  This paper deals with a transient random walk in Dirichlet environment, or
equivalently a linearly edge reinforced random walk, on a Galton-Watson tree.
We compute the stationary distribution of the environment seen from the
particle of an edge reinforced random walk. We obtain a formula for the speed
and give a necessary and sufficient condition for the walk to have a positive
speed under some moment conditions on the offspring distribution of the tree.
