Impact of Invading Brushtail Possum Populations on Mixed Beech- Broadleaved Forests, South Westland, New Zealand

The impact of browsing by introduced brushtail possums on mixed beech—broadleaved forests in South Westland was estimated from the amount of conspicuous canopy dieback present in 1989- 1990. Aerial and ground-based reconnaissance in all catchments indicated most canopies (84%) were intact. The remaining 16% of canopies were affected by conspicuous dieback, principally of southern rata (Metrosideros umbellata) and/or fuchsia (Fuchsia excorticata).

Magnitude of Canopy Dieback and Implications for Conservation of Southern Rata-Kamahi (Metrosideros umbellataWeinmannia racemosa) Forests, Central Westland, New Zealand

The amount of conspicuous canopy dieback in all central Westland southern rata-kamahi forests east of the Alpine Fault, between 500 m altitude and treeline, was assessed and mapped from aerial photographs taken in 1984-85 and verified by aerial reconnaissance of selected areas in 1988. At least 20% of all canopy trees, predominantly southern rata (Metrosideros umbellata) and Hall's totara (Podocarpus hallii), were dead in 1984-85.