In New Caledonia, rain forests with an upper canopy dominated by single species of Nothofagus occur next
to mixed-canopy forests, without discernible environmental cause. A potential explanation is that they are different
successional stages. To test this hypothesis and predict long-term change in canopy dominance, population size
structures of 61 canopy species were analysed in six Nothofagus-dominated forests and three adjacent mixed rain
forests. Weibull analysis suggests that these Nothofagus forests are secondary forests, with recruitment insufficient to
maintain monodominance, except at a high-altitude site. At low- to mid-altitudes the Nothofagus canopy is predicted to
develop into amixed canopy, unlessmoderate to severe disturbance occurs within its reproductive lifespan. However,
adjacent mixed rain forests are also secondary, with 85% of analysed species showing no evidence of continuous
regeneration. Fifteen species from both forest types showed reverse-J curves suggesting continuous regeneration, but
only Calophyllum caledonicum did so consistently. Since few canopy species showed evidence of high shade tolerance
and persistence, a small number of shade-tolerant species is predicted to dominate both forests in the long term,
in the hypothetical absence of disturbance. Hence, temporal factors associated with disturbances play a key role in
determining dominance in these forests.
