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Keywords:

  • Trees;
  • Vigour

Abstract

Forests of river red gum (Eucalyptus camaldulensis Dehnh.) occur along the River Murray in Australia. These forests are important for biota, recreation, grazing, and wood products. They occur in a sub-humid to semi-arid environment and require flooding for adequate growth and regeneration. The largest continous area is the Barmah (Victoria) and Millewa (New South Wales) forest near Echuca (Vic.). Information from maps showing the extent of inundation of Barmah Forest for particular floods was related to flow data upstream of the forest, and maps showing the distribution of vegetaton and forest site quality. Vegetation associations were shown to occur in characteristics flood frequency ranges, with red gum being the dominant species on all but the highest and lowest flood frequency sites. In general, higher red gum site quality was associated with higher frequency of flooding. The extent of flooding depended on the magnitude of peak flows in the river. Regulation of the river since the first filling of Hume Dam in 1934 has caused a reduction in the frequency of flows associated with partial flooding and an increase in the occurrence of small summer floods. Areas with a high flood frequency were most affected. It is possible that the forest may change to types associated with reduced duration of inundation in the long-term unless ameliorative action is taken.