Flood Resistance of Tristaniopsis laurina and Acmena smithii From Riparian Warm Temperate Rain-Forest in Victoria

The responses of seedlings of Tristaniopsis laurina and Acmena smithii, two important tree species in riparian warm temperate rainforest communities in Victoria, are investigated in relation to flood disturbances. Freshly germinated A. smithii seedlings had died within 5 weeks of complete waterlogging in the greenhouse, and although the young T. laurina seedlings survived waterlogging for 14 weeks, their growth rate was curtailed. Nine-month-old seedlings of both species were found to be relatively tolerant to waterlogging, forming aerenchymatous surface roots after 40 days of flooding. Neither species suffered leaf abscission or demonstrated any other signs of water stress commonly associated with flood intolerant species. In experiments to determine the resilience of these species to physical flood damage, both species also demonstrated a capacity to regenerate vegetatively following the removal of above ground parts in young seedlings. The heartwood of T. laurina was found to be more decay resistant than that of other species in the field including that of A. smithii. The significance of these results are discussed in relation to other factors examined in earlier papers adding to the understanding of the ecological status of these species within the riparian rainforest communities.