|
If you looked at the Australian
landscape, you'd think nature grows in straight lines.
We need to replace artificial management structures with
ones reflecting natural landscape processes. We also
must understand the soil itself is a living entity that
drives the production system on which we live.'
Denis Saunders, Deputy Chief,
CSIRO Division of Wildlife and Ecology
- Catchment
and water management that recognises Australia's
variable climate and infertile soils is vital to
restoring our land and water resources. Our ability to
use land resources sustainably relies on an improved
understanding of their condition and productive
capacity.
-
Land clearing and
agriculture have wrought extensive changes through
changed water flows, tillage, fertiliser use, and
pollution from pesticides and herbicides. Further
pressures stem from pastoralism, forestry, mining and
human settlement. In the Murray-Darling Basin, some
80% of average annual water flow is diverted. In dry
times, natural systems are not sustained. Most of the
water is used for irrigation, leading to waterlogging,
salinisation and erosion.
-
Similar problems exist in
dryland agriculture, where soil structure decline
resulting from tillage and overgrazing causes erosion
and run-off, raising salt levels, sediments,
pesticides and nutrients in surface waters. High
phosphorus levels and reduced stream flows cause
blooms of toxic blue green algae. Some 2.2 million
hectares are affected by salinity with a further 1.4
million hectares are at risk. A National Dryland
Salinity Program was established in 1993.
-
Acidification affects
most agricultural land, leading to toxicity, poorer
water and nutrient use and lower yields. Causes
include the use of fertilisers and legumes, and
natural weathering. Applying lime is an effective
remedy, but present rates are inadequate.
Acid-tolerant crops are being developed.
-
Australia's rangelands
cover about 75% of the continent. About 2% of this
region is severely degraded and 15% requires
destocking. Grazing is particularly heavy near water
sources and these may provide a focus for future
conservation strategies.
-
Some 80% of Australia's
forests have been cleared or logged since European
settlement, with severe impacts on biodiversity, soil
and water. The National Forest Policy Statement is
intended to address the issue of sustainable forest
use and regional agreements are improving forest
reserve systems.
-
Introduced animal pests
both consume and damage produce, and degrade the
resource base. CSIRO is involved in the selection,
importation and release of bio-control agents such as
insects and microorganisms to combat pest plants and
animals. Early next century, transgenic viruses and
bacteria are likely to be used against mammal pests.
They include a virus for mice that triggers their
immune system to destroy unfertilised eggs and a bait
containing genetically-modified gut bacteria to stop
foxes reproducing.
- CSIRO
scientists are also working with landholders across
the country to find ways of quantifying, preventing
and reversing land and water degradation and habitat
fragmentation. Australia's Landcare program is
enlisting widespread community support for sustainable
use of land resources, but the approach must be
extended and maintained, with adequate financial and
technical support, to have the necessary impact on
land-use practices.
|
