Brushtail possums (Trichosurus vulpecula) tend to eat young canopy foliage in southern rātā (Metrosideros umbellata), and browsing tends to be concentrated on only a few trees.
Increased dieback in Westland rata (Metrosideros umbellata)-kamahi (Weinmannia racemosa) forests has been linked to the build-up of populations of the Australian brush-tailed possum (Trichosurus vulpecula). Within these forests young even-aged stands are observed to be more resilient to dieback than older stands. The effect of possum browsing on individual rata trees was related to the level of defoliation. Trees which had been not or only lightly browsed maintained intact canopies.
