Dynamics of Nothofagus-dominated rainforest on mainland Australia and lowland Tasmania

Cool temperate rainforest in Australia is commonly dominated by Nothofagus species. In Victoria and Tasmania, Nothofagus cunninghamii dominates old rainforest on optimal sites and is able to regenerate continuously. Size structure analysis of the major lowland tree species in this forest suggest that no major changes in species composition or dominance are occurring. This contrasts with the status of Nothofagus in lowland rainforest in New Zealand and rainforest below about 1000 m a.s.l. in south-central Chile. N. cunninghamii is a relatively light-demanding species, and is maintaining its dominance by seedling regeneration in canopy gaps created by the death of old individuals. The dynamics of the cool temperate rainforest in northern New South Wales are more complex. These forests are dominated by Nothofagus moorei, and size structure analysis indicates that persistence of this species within the rainforest is dependent on vegetative regeneration. On some sites this rainforest is being actively invaded by warm temperate and sub-tropical elements from lower altitudes. In these areas N. moorei in unable to regenerate beneath the canopy.Nomenclature follows Curtis (1963, 1967), Curtis & Morris (1975) and Williams (1982).We thank Mr. A. Floyd of the N.S.W. National Parks and Wildlife Service for his assistance in identifying species from the N.S.W. rainforests, and Mr. J. Hickey of the Tasmanian Forestry Commission for suggesting study sites in north-west Tasmania. Thanks are also due to the N.S.W. National Parks and Wildlife Service for allowing us access to National Parks for the purpose of this study. J. R. is supported by a Commonwealth Forestry Post-graduate Research Award.