ii) Acacias as a woodlot

Acacias are a pioneer species. They are usually the first to regenerate from seed or suckers after soil disturbance by fire or cultivation. It is this rapid early growth that makes them so useful for soil stabilisation, visual screens and shelter-belts.
Acacias adapted for drier, saline and waterlogged sites can be used for strategic discharge and recharge planting within degraded catchments.
Acacias are legumes and can use atmospheric nitrogen for their own growth and to return nitrogen to the soil. While rates of nitrogen fixation are low, early results from a mixed planting of Eucalyptus globulus and Acacia mearnsii indicated that the presence of the acacia does improve foliar nitrogen in the eucalypt. Inoculation with rhizobia (soil bacteria) which assist nitrogen fixation is under investigation.

Using acacias
Most acacias make excellent fuel wood and charcoal. Suitable species in this area include A. decurrens, A. mearnsii and A. melanoxylon.
A niche market exists for A. mearnsii posts complete with undamaged bark. They are used in salt water as oyster pegs or racking and have been a stable resource for the south coast oyster industry since World War I.
Aboriginal people have used specific temperate acacias as sources of wood for weapons, implements and fires; leaves for medicinal purposes as a wash or smoke therapy (fumes from heated leaves are a healing agent); seed for food; gums for ointments, infusions and glues; and bark for infusions, bandages, ropes and sandals.
(Source: Suzette Searle, formerly of CSIRO Forestry and Forest Products).

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CASE STUDY:
DIVERSITY = STABILITY One farmer’s story
John Weatherstone of ‘Lyndfield Park’ in Gunning has become an enthusiastic convert to the value of planting native species, including understorey species, on the family farm.
“I believe that successful environmental rehabilitation depends very heavily on inclusion of understorey species.
One of the most important principles in environmental management is that DIVERSITY = STABILITY.
“We fenced off a 15-hectare paddock to revegetate, plus a smaller area for regeneration, a few years ago. Although these areas had been fertilised lightly and grazed for decades, we have been quite surprised at the number of native shrubs that have returned, presumably from seed that had lain dormant in the soil for years. (This would be likely to occur only in areas that were not covered in dense perennial pastures.)
“With the range of wattles and grevilleas we have planted, some are flowering at almost every time of the year, keeping birds in the area.
“Other often-despised plants that are good for birds are the prickly shrubs, such as Acacia genistifolia, Hakea sericea, Bursaria lasiophylla and some of the prickly grevilleas. They provide birds with nesting sites and shelter from feral cats, foxes and hawks.”
John has successfully planted native species shelter-belts for his stock.
“Use some fast-growing wattles but include some long-term trees. Many of the wattles may well replace themselves with seedlings if the area is kept fenced off.
It is also valuable to include some smaller shrubs and understorey plants for stopping draughts and to provide a more diverse habitat for wildlife.”

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