Mallee scrub productivity and biodiversity
- Fact sheet
- August 2015
Long-term productivity and biodiversity in the Murray Mallee are under threat. Erosion, salinity and other forms of land degradation, drought, and pests such as environmental weeds and feral animals are all serious problems.
Despite improvements in land management in the Mallee, the unique native species and landscape are under enormous stress. Many native species are still in decline, with some, such as the Striated Grasswren (from the Ettrick area) threatened with extinction
The region’s mallee scrub must be conserved, managed and improved wherever possible. Our challenge is to work towards a balance between our social, economic and environmental needs.
Canopy and sub-canopy
Mallee scrub’s tallest trees are found in the canopy and lower canopy layers. The eucalypts provide ideal conditions for smaller trees, such as Mallee Cypress Pines, shrubs, grasses, herbs, lilies and lichens to establish.
The canopy provides food for many birds that help control pest insects. The flowers in the canopy attract birds, mammals and insects that assist pollination.
Bark
Found at all levels, bark provides lizards, bats, small marsupials, spiders, insects and birds essential habitat. Bark is also one of the vital components of ground litter
Shrubs + grasses
Mallee shrub layers include tall and short shrubs, climbers, and grasses up to a few metres in height. Wattles, hop bushes, turpentine bushes, bush peas, scrubby pines, banksias and tea-trees are just a few examples.
These layers provide structural diversity and important habitat for a broad range of birds. Shrubs are also a food or host plant for a wide range of insects.
Tussocky grasses help to limit erosion and redistribute rainfall and sediments.
Ground + litter
Leaves, twigs, fungi, mosses and lichens protect the underlying soil from erosion. The litter layer also helps maintain soil structure, fertility and moisture levels.
Soil and litter organisms play a vital role in the decomposition of organic material to recycle nutrients and help disperse seeds and spores.
Survival
More than three-quarters of the native vegetation in the Murray Mallee has been removed to make way for agricultural production. The survival of our native plants and animals, as well as our farming systems, depends on retaining as much healthy mallee scrub as possible.
The minimum amount of native vegetation to provide a balance between the needs of landholders and natural systems is estimated at around one-third.
In the Murray Mallee, at least half of the remaining (or ‘remnant’) vegetation occurs within the Billiat and Ngarkat Conservation Parks.
These two reserves are too widely separated to preserve the biological diversity needed to protect our wildlife. Another 250,000 hectares of remnant vegetation on private lands and roadsides plays a crucial role in maintaining biodiversity.
Removing the natural ‘understorey’ of shrubs, grasses, fungi and leaf litter (through grazing or clearing) stops seedlings re-establishing. It creates erosion, compacts soil, encourages dieback, and favours weed species. This has a major impact upon native animals’ habitat and food source
More information
We have developed a range of factsheets about mallee scrub conservation to assist you with good land management. See the related links below.