Bulletin No. 20
Flooding and regeneration of river red gum, Eucalyptus camaldulensis, Dehn. B.D. Dexter. 1967. Forests Commission, Victoria. 35 pp.
The research described was carried out in Barmah State Forest which forms part of a natural flood control reservoir on the River Murray east of Echuca in Northern Victoria.
Regeneration of riverain red gum forests following utilization has been difficult. This has been due to variable flooding, unfavourable seed-beds, inadequate seed supply, and soil drought induced by high evaporative losses and competing vegetation. In recent years, river regulation has reduced the extent and frequency of forest flooding.
Research has shown that useful germination appears on unflooded areas only in winter and early spring during periods of regular rainfall. Water temperatures during winter are generally unfavourable for germination on flooded sites, but germination is prolific following flood recession in spring. Soil moisture and seed-bed conditions are the main determinants of seedling establishment, although prolonged flooding limits seedling establishment when satisfactory seed-beds have been prepared. Period of flooding is however largely uncontrollable.
Grazing, mainly of cattle, has been carried out in the study area for approximately 130 years. Wild horses, kangaroos and rabbits are also of considerable significance in the grazing balance of the forest. Grazing of cattle aids seedling establishment by significantly reducing weeds and grasses that compete with seedlings for soil moisture. Damage by cattle does not exceed that by insects or prolonged inundation.
Prescriptions have been developed which facilitate the satisfactory regeneration of cut-over river red gum stands.