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His research was done in Western Australia, where dry land salinity is projected to dominate a third of the state's arable lard in the next 30 years. "Mixed plantings may give better results than singlespecies plots because they tap a larger proportion of the soil profile," says Dr White.
He is using the whole-farm approach to managing waterlogging and salinity in the West Australian wheatbelt, where most of the rain fails in winter. The results of land clearance are that water is either trapped by clay, leading to waterlogged soil that restricts crop yields, or water escapes below the limited root zone of single crops, where It can rise in the water table, leading to salinisation.
As part of the research, Bronte and Peter Rundle have planted four species on their farm near Katanning in southwest Western Australia: Sydney blue gum (Eucalyptus saligna) and river red gum (E. camuldulensis) - which send roots down to the saturated area just above the water table - and yellow gum (E. cleucoxyion) and coastal mort (E. platypus) - which extract water from the much drier soil nearer the surface.
The other research, led by Robert Veressey, is in southeastern Australia, wheres major concern is the water supplies for expanding cities. In a world first, for which he will receive an award from the International Union for Forestry Research in August, Dr Veressey has identified that new forests absorb a lot more water than mature native forests.
While focusing his research in areas of mountain ash in Melbourne's catchment, the theory has been tested in other areas of Australia and produced the same results. "It would be best, in terms of water Production in catchments, to leave our native forests unlogged," says Dr Veressey.
He says that projected global forest product shortages, the opportunity to benefit from development in emissions trading, and salinisation and freshwater shortages means that Australia is in a good position to benefit from forestry production. "The value of timber, and the necessity of water, means there are some really courageous decisions needing to be made," says Dr Veressey.
He agrees that reafforestation is essential through Australia to repair the water balance, but says that even a 3-year-old 'plantation absorbs twice as much Water as a native forest, and resulting water shortages would hinder any reafforestation progress.
Dr Veressey would like to see forestry established in drier areas rather than logging operations continuing in high rainfall areas that are also prime water catchments. "People don't talk about it much, but reafforestation will affect how much water goes into rivers and creeks, which are already strained by agricultural demands," he says.
"It should be possible to work collectively. Using a clever approach
to where end how we develop our forests, we can benefit water productivity
and reduce salinity."
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