Effects of windthrow on a stand of Eucalyptus delegatensis (Myrtaceae) and early understorey succession at Snowy River National Park, Victoria

Summary

During June 1998 a very strong windstorm at the Snowy River National Park near Mt Gelantipy caused severe damage to a stand of Eucalyptus delegatensis. Little is known about the impact of windthrow on E. delegatensis and subsequent seedling recruitment. This study was undertaken 4.5 y later to examine (i) windthrow damage to E. delegatensis and the understorey Acacia dealbata, (ii) the influence of tree size on the pattern of tree damage, (iii) the undergrowth in the windthrow area compared with that in control plots, and (iv) species composition of the soil-stored seed-bank in windthrow and control plots.

We found that high winds toppled virtually all trees regardless of size and species, damaging 99% of the E. delegatensis. In windthrow plots there were 49 seedlings ha-¹ of E. delegatensis and 2210 ha-¹ of A. dealbata. No E. delegatensis or A. dealbata seedlings were recorded in the control plots. In the soil seed-bank study five species were recovered from soil samples collected from the control, and six from the windthrow-damaged sites. The canopy species E. delegatensis recruited only from the windthrow site. The exotic Rubus fruticosus was found to be colonising the windthrow site, but was not present in the control site. Results show that E. delegatensis recruitment is very poor in the damaged area, and species colonising within that area are light demanding or early succession species. It is proposed that seedling recruitment in the windthrow sites be accelerated by burning the site and broadcasting E. delegatensis seed, or transplanting seedlings.

Keywords:

• seedbeds
• seedlings
• regeneration
• plant succession
• plant colonisation
• wind damage
• alpine ash
• Eucalyptus delegatensis