The most extensive river red gum (E. camaldulensis) forests in Victoria are located on the flood plain of the Murray River below Tocumwal.
The river red gum forests are very tall forests for an environment with relatively low average rainfall, and they rely on regular flooding to supply the necessary moisture requirements for vigorous growth. River red gum has a number of characteristics which may be adaptions to the flood plain environment. These include sensitivity to damage by even low intensity fires, absence of lignotubers, high natural seed fall in the spring, and the capacity for vigorous germination when temperatures are relatively high following flood recession in spring and early summer.
The regularity with which the river red gum forests are flooded has declined with the advent of river regulation, and it now appears likely that a full flooding will occur only in years when winter/spring rainfall is well above average (Dexter 1978). Furthermore, when floods do occur, drainage of the low and middle level forests may be delayed with water receding in summer rather than spring. The silvicultural techniques necessary to achieve the establishment of a satisfactory density and distribution of regeneration following timber utilisation depend on the silvical characteristics of the species and the expected environmental conditions. In the case of the river red gum forests, the natural flooding regime has been modified and this must be taken into account in the silvicultural practices.
Although prolific germination occurs following flood recession in the spring, research (Dexter 1967) has shown that useful germination occurs on unflooded areas in winter and early spring during periods of regular rainfall, and that sites favouring the establishment of seedlings were mainly disturbed, bare, or burnt areas at least 20m distant from an overstorey tree.
To obtain satisfactory regeneration following timber harvesting in the absence of the natural flooding regime, patch fellings are carried out, a receptive seed bed prepared by slash burning or cultivation, and seed supplied either from retained trees or by direct seeding.
Many regrowth stands are densely stocked, and thinning to remove the less vigorous trees is carried out wherever this is practicable and consistent with the management of other forest values.
Slideshow prepared by Barrie Dexter.
Dexter BD (1978) Silviculture of the river red gum forests of the central Murray flood plain. Proc. Royal Soc. Vic. 90: 175-191
FCV Bulletin No.20