This annual vegetation uses less water, and a high proportion of rainfall can ‘leak’ into the bedrock, causing major alterations to regional hydrology, mobilising the ancient salt store and bringing it to the surface.(Ref 1)

A Salinity Audit released by the Murray-Darling Basin Commission (MDBC) in October 1999 has shown that salt, previously stored in the landscape, is now being mobilised on a massive scale by rising groundwater tables due to land-use changes across the Basin.

The Audit covered the majority of the area of the Basin — more than one million square kilometres, extending over three-quarters of NSW, more than half of Victoria, significant portions of Queensland and South Australia, and the whole of the ACT.

As a result of the Audit, the Basin Salinity Management Strategy (BSMS) (2001-2015) was formed to guide communities and governments in working together to control salinity; and protect key natural resource values within their catchments.

The Strategy establishes targets for the river salinity of each tributary valley and the Murray-Darling system itself — reflecting the shared responsibility for action both between valley communities and between States.

Targets can be achieved through salinity credits and debits trading schemes using:

o improved land-use to reduce recharge eg native revegetation, perennial pasture, plantation; or

o emergency means such as salt-interception works

The BSMS includes end-of-valley salinity targets for
each tributary valley and a Basin target in Morgan, South Australia. The target at Morgan is supported by a system of salinity credits and debits. The currency through which trade-offs can be accommodated is EC at Morgan. (EC is Electrical Conductivity (uS/cm) as a measure of salinity concentration).

The system of salinity credits and debits is managed through the Commission A Register (for tracking Salt Disposal Entitlements) and the Commission B Register (for actions to address the ‘legacy of history’ – i.e. salinity impacts of past actions).

In order to maintain Morgan salinity at 800EC or less for 95 per cent of the time from 2001-2015, the MDBC Audit found that a reduction in salinity of about 100EC at Morgan will have to be found by new interventions over and above within-valley actions such as revegetation.

One such intervention, salt-interception works, can prevent discharge from an already-mobilised salt store where land use change is too late. Large-scale groundwater pumping and drainage projects intercept saline flows and dispose of them, generally by evaporation.

The partner governments nominated interim end-of-valley targets for stream salinity and salt loads — these were considered by catchment communities during the public comment period for the draft Strategy.

NSW, Victoria and South Australia have indicated they will finalise end-of-valley targets by next month, while Queensland has indicated it will finalise its targets by March 2004.

The real challenge for salinity is to increase ‘perenniality’ in the landscape, to replace leaky annual systems with perennial ones. There are a range of vegetation systems that can do this: native vegetation, perennial pastures, and exotic plantations may all help to increase water use and reinstate natural hydrological cycles.

Areas that were once temperate woodlands are now farmlands. Clearing in the wheatbelt has caused massive biodiversity decline, with many vegetation communities now covering less than 10 per cent of their original area. 
(Ref 3)

The challenge for biodiversity is to restore the remnants of these communities, to expand and link them to achieve a sustainable, biodiverse landscape.

Redesigning farming systems is a part of the Basin Salinity Management Strategy (BSMS).

The BSMS (Section 3.7) addresses ways in which vegetation management can be funded. It proposes the establishment of a Vegetation Bank, which would provide funding for three types of vegetation management activities in the Basin.

o Plantation forestry outside its traditional zone (i.e, in the 500 – 800mm rainfall zone) where it would not be commercial otherwise.

o Native vegetation management, rehabilitation, and land stewardship

o Innovation for short rotation tree crops.

Arrangements for the establishment of the Vegetation Bank are now underway. Given that the Vegetation Bank will initially be established using Commonwealth funding, the NPA is keen to ensure that the whole range of potential activities, including native vegetation stewardship and management, will be implemented in NSW.

In NSW, between 120,000 and 174,000 hectares of land are estimated to be affected by dryland salinity. If we continue to use our land the way we do now, by 2050 the area of affected land in the NSW part of the Murray-Darling Basin could increase to up to four million hectares.(Ref 4)

The MDBC Salinity Audit reports that currently its threshold is estimated to be exceeded in the Macquarie Marshes 4 per cent of the time, and this is predicted to rise to 23 per cent of the time by the year 2100 if we do not change the way we use our natural resources. This would result in a loss of species diversity and composition, as well as salt scalding by about 2020." (Ref 4)

Implications of Salinity – report for ANZECC, South Australia, 2001

A report prepared for ANZECC titled, Implications of Salinity for Biodiversity Conservation and Management (2001) points to the exclusion or unavailability of realistic estimates for the areas of remnant vegetation likely to be affected in NSW. According to the Report, an estimated 10% of the central sheep/wheat belt of NSW to be affected by 2050 does not include isolated trees.

The estimated 10 per cent of national parks and reserves in areas prone to salinity to be affected by salt by 2050 substantially underestimates the areas of native vegetation currently and likely to be affected by salinity. Overall, no information is available on the specific risks to ecological communities or species in NSW from current or future salinity. (Ref 5)

What is known is that native vegetation provides the best ‘filter’ for salinity reduction. How will this preferred solution be applied in NSW, and how will the Vegetation Bank assist the process?

Under the Plantations and Re-afforestations Act 1999, a Plantations Code has been developed. The aim of the Code is to focus plantation development toward ‘essentially cleared land’, defined through the ‘biodiversity protection mechanisms’ of the Code. (Ref 6)

In effect, this means that any clump or ‘patch’ of woody native vegetation less than 1ha in area can be cleared. In the south-west slopes of NSW, more than 55% of Box Woodland vegetation occurs in clumps less than 1 hectare.  
(Ref 3)

The Plantations Code provides for Regional Vegetation Schedules to be developed to further protect vulnerable vegetation communities. For these communities, remnants greater than 0.5 ha must be protected. However, more than 40% of all Box Woodland Vegetation occurs in patches less than 0.5 ha. (Ref 3)

Whilst the conservation movement has often promoted plantations rather than native forest logging, it should not be assumed that plantations will not have biodiversity impacts.

In order to prevent these sorts of impacts on biodiversity from an unbalanced salinity management strategy, the ANZECC Report recommended that:

o States should develop clear and consistent policies that recognise links between salinity and biodiversity, and ensure that biodiversity conservation is adopted as a central objective in integrated salinity management programs

o All proposals and programs relating to salinity management be assessed in terms of potential biodiversity impacts, and seek to achieve positive biodiversity outcomes.

o The National Action Plan for salinity and water quality ensure that biodiversity conservation is addressed as a priority issue and that its outcomes include positive benefits for biodiversity conservation.

NSW was the only State or Territory in Australia not to endorse the ANZECC recommendations. Why?

References:

Murray-Darling Basin Commission Strategy 2001-2015, MDBC, 2001, www.mdbc.gov.au

Dryland Salinity Program Management Plan 1998-2003;

Taking on the Challenge, NSW Salinity Strategy,2000-2010, DLWC, August 2000.

Implications of Salinity for Biodiversity Conservation and Management, prepared for ANZECC by a task force established by the Standing Committee on Conservation, June 2001

www.biodiversity.sa.gov.au/pub.html#salinity

Plantations and Re-afforestations Act 1999 www.dlwc.nsw.gov.au/care/veg/planation/pdfs/pra_code.pdf

Walker, Gilfedder & Williams, Effectiveness of Current Farming Systems in the Control of Dryland Salinity, CSIRO, Land and Water, 1999 www.clw.csiro.au

Gibbons, Phillip and Boak, Miles, Citations: Ecological Management and Restoration, (in press) 2002.

Thankyou also to the MDBC and DLWC for providing background information and images for this report.

Specific References from within the text of this article: