Gum trees on a river bank and reflected in the water
River red gums are found growing along the banks of waterways. They shed their bark in long ribbons.

The river red gum, (Eucalyptus camaldulensis) is a common sight along many water courses over much of mainland Australia. It is frequently the dominant tree of riparian1 communities, and is an iconic species of the Murray-Darling catchment.

Habitat features

River red gum forests provide important habitat for fish, reptiles, mammals and birds. Breeding of many species require a certain length of flooding duration and at the right time of year. The river red gum is a unique ecosystem. It is a monoculture with an absence of shrubs. The understorey is dominated by sedges, rushes, herbs and grasses specifically adapted to the annual pattern of spring flooding and summer drought.

Climate

As spring time temperatures increase, winter snow melts causing floods along the rivers leading from the eastern mountain areas. These floods last for several weeks, even months. The long duration of flooding is very important in regenerating the ecosystem. Eroded silt from the mountains is deposited on the floodplain as the waters slowly meander across the flat floodplain after rushing down the river. Years of deposition has built up the floodplain soil. The floods also wash in plant material adding organic matter to the soil and ecosystem.

A vital breeding ground for fish

With the arrival of the annual flood waters, fish are stimulated to commence breeding. The Murray cod in particular times its breeding cycle to the flooding regime. The female lays her eggs to coincide with increasing water levels and temperature. The juvenile fish or fry2 then float onto the floodplain where they remain for several months. Amongst the debris they are protected from predators and able to feast on the available food. Without long flood periods the fry will die.

Birds

Wetland birds also utilize the flood period to breed. If water levels fall too soon many adult birds will abandon the nestlings in search of a reliable water pondage.

Gum tree lifecycle

The river red gum themselves respond to the warm temperatures and water supply during spring. They enter a growth spurt stage and develop seeds that are dispersed onto the freshly moistened soil. The resulting seedlings grow rapidly in an attempt to develop a deep enough root system to survive through the long dry summer period.