Salinity Control

Introduction

The Salinity Audit for the Murray-Darling Basin, released by the Murray-Darling Basin Ministerial Council in 1999, predicts the future movement of salt in the landscape and the associated rise in river salinity across the Basin, assuming no new management interventions. The total economic impact of salinity is estimated to have already reached $46 million per year and it is predicted that this will continue to rise as the area affected by salinity increases.

In August 2001, the Ministerial Council released the Basin Salinity Management Strategy 2001-2015 to guide communities and Governments in working together to control the spread of salinity and to protect key natural resource values.

The NSW Government has also recognised the severity of the problem and has endorsed the need for early action. A Salinity Summit was held in Dubbo in March 2000 and Taking on the Challenge: The NSW Salinity Strategy was released in August 2000. The Strategy provides for an additional expenditure of $52 million over four years on salinity management actions.

In both these strategy documents, targets are established for the river salinity of each of the major tributary valleys. If these salinity targets are to be met, there will need to be some fundamental changes in the way we use our land, with greater areas managed under perennial plants. The establishment of new planted forests in key areas within each catchment is therefore seen as an important element in the fight against salinity.

The areas that will need to be planted to control salinity are not traditional forestry areas. Forests NSW has therefore been undertaking a range of work that will help us understand how best to encourage the establishment of new forests in these lower rainfall areas. Both of the strategy documents highlight the possibility of using a market-based approach to address dryland salinity. Some of the work that Forests NSW has been undertaking has therefore been focussed on developing this type of approach. For more information see fact sheet Developing Markets for Salinity Control.

Dryland Salinity Demonstration Trials

In October 1999, Kim Yeadon, the then Minister for Forestry, signed a Memorandum of Understanding with the Minister for Agriculture and the Minister for Land and Water Conservation. As part of the MoU, Forests NSW, in cooperation with the Department of Sustainable Natural Resources, has established 47 demonstration trials of two hectares each within the 500-700 mm rainfall zone. The trial sites are in the area bounded by Narranderra and Wagga Wagga in the south and Inverell and Moree in the north.

The sites will also be used to demonstrate the potential for other commercial and environmental returns including carbon sequestration, charcoal production and fuel for the generation of biomass energy. Click here for more information on the demonstration trials.

Pilot Salinity Control Trade

In October 1999, Forests NSW and Macquarie River Food and Fibre signed a Memorandum of Understanding to conduct a pilot project in the Macquarie catchment. The aim of the project is to develop a cost effective, market-based approach to reducing salinity in the catchment. The project will explore the potential for establishing a system for trading of salinity control credits.

Under the Memorandum of Understanding, Forests NSW has established 100 hectares of new planted forest in key recharge areas in the Upper Macquarie catchment. Macquarie River Food and Fibre will pay a fee for the transpiration service provided by these new forests. The trees have been planted on private land and the owners of the land will receive an annuity from Forests NSW for a minimum of twenty years. In return, Forests NSW will receive the timber and carbon rights associated with the trees. For more information see fact sheet Macquarie River Salinity Control Trade Questions and Answers.

Gunnedah Operational Scale Trial

As part of the NSW Salinity Strategy, Forests NSW is establishing 400 hectares of hardwood planted forests in the Gunnedah area as an operational scale trial.

The plantings are on critical recharge areas within the catchment and are spread across a number of properties on a variety of soil types and in different landscape positions. The plantings vary in size from 10 hectares to 60 hectares. Some of them have been deliberately designed to find out what site preparation, planting density, species mix and layout will provide the best result. For more information, see fact sheet Research into Farm Forestry for Salinity Control.

Properties have been identified with the help of the Liverpool Plains Land Management Committee and the Department of Land and Water Conservation. Four species have been used in the trial – ironbark, spotted gum, red gum and yellow box. Planting on some of the properties occurred in Spring 2001 and the remainder planted in Autumn 2002.

It is hoped that this trial will act as a lever to attract additional investment in new planted forests in the area and that it will stimulate the markets for non-traditional wood products as well as for environmental services. The planted forest will be used to produce biomass for energy generation and charcoal, whilst providing a range of environmental services that include carbon sequestration and biodiversity enhancement in addition to salinity control.

In August 2004, a survey of attitudes towards tree planting for multiple purposes (combining commercial and environmental outcomes) was carried out with landholders in the Liverpool Plains area. The results showed that the Gunnedah Operational Scale Trial had been successful in demonstrating that modern forestry establishment techniques could ensure acceptable tree growth and survival even during prolonged drought.

Landholders' opinions regarding the future for commercial forestry in the area were more cautious, however there was strong support for planting native trees for purpose such as biodiversity and salinity

For more information see:
REPORT ON A SURVEY INTO LANDHOLDER ATTITUDES TOWARD TREE PLANTING FOR NATURAL RESOURCE MANAGEMENT IN THE LIVERPOOL PLAINS (80Kb PDF document)

Benchmarking Salinity Control

As part of the NSW Salinity Strategy, Forests NSW, together with NSW Agriculture, is developing a research project to benchmark salinity control and carbon sequestration from tree plantings in low rainfall areas to provide the necessary basis for trading in these environmental services.

The project aims to underpin the future development of market-based solutions to dryland salinity by:

determining the suitability of transpiration as a trading unit;
providing transpiration rates for important tree species in the western region of NSW; and
developing cost-effective methods for measuring and estimating water use by planted forests.

Measurements of transpiration rate will be taken at a number of sites in the Gunnedah, Wellington and Albury areas using both existing plantings and those to be established as part of the Gunnedah trial. The heatpulse measurement method will be used because it allows the transpiration rate to be continuously estimated without destroying the tree. A small heater and a pair of thermistors are inserted into the stem of the tree. Small pulses of heat are released by the heater and transported in the sap, causing temperature changes in the stem. These temperature changes are detected by the thermistors and recorded. The velocity of the sap flow through the stem can then be calculated. Once the velocity of the sap and the water conducting area (or sapwood area) of the stem are known, the transpiration rate can be estimated.

Tree Planting for salinity affected areas

Various tree species can grow in areas affected by salt and can play an important role in reducing the effects of salinity. Forests NSW' nurseries have identified a range of species that are suitable for planting in such areas and can recommend establishment techniques that will improve the chances of these trees surviving. For more information please contact one of our nurseries.