"DRYLAND SALINITY" - Australia's Growing Crisis

Australia is facing massive economic, environmental and social challenges due to the widespread and growing phenomenon of dryland salinity. More than 80 regional towns and cities (June 1999) have costs related to salinity - and even Sydney is being affected. (see [6], below) The costs include damage to building foundations, bridges, pipelines, roads and land lost to agricultural production [2].

[5]
Road damage caused by high saline watertables (NSW). http://www.dlwc.nsw.gov.au/care/salinity/effects.html

Clean drinking water is also at stake [2]. South Australia is particularly affected in this respect, as the Murray River - a water source for both Victoria and South Australia - flows through badly affected regions. The Murray is South Australia's only large, permanent river - about 90 percent of South Australia's population depends on piped water from the Murray - and it is also the major source of water for agriculture in the state.

The most heavily affected state, Western Australia, in 1996 was estimated to have lost 1.8 million hectares (9.4% of agricultural land), with 6.1 million hectares (31.8% of agricultural land) at risk. It is accepted that one of the major causes of the problem in Western Australia is that of the 25 million hectares of land in south-western Australia previously covered by native perennial vegetation, almost 18 million hectares have been cleared [7].

Pine plantations were first introduced into Western Australia in an attempt to control a naturally occurring problem. Near Bunbury, in 1897, Radiata pine (Pinus radiata) plantations were trialled to control coastal sand dune encroachment. The trials failed - Radiata pine was found to be unsuitable [1].

By 1907, however, it was found that the Maritime pine (Pinus pinaster) was better adapted to these poorer soil types and this became an important plantation species in Western Australia, with radiata pine being planted only on the better soils away from the coast [1].

It is recognised that integrating perennial, deep-rooted plants (trees and shrubs) with agriculture is essential to develop a more sustainable and productive land management system [7].

However, commercial tree crops had been considered unsuitable in areas of Australia with less than 700 mm of rainfall per year or which have less than ideal soil types. Maritime pine tolerates these conditions and also has vigorous tap roots that act like a sponge - these two landcare benefits make it potentially very useful in combatting dryland salinity [3].

So, a farm forestry industry based on Maritime pine has the potential to address some of the land degradation problems, like salinity and wind erosion, with a possible financial return through the production of softwood for industry [4],[7].

As well as providing a wood resource, Maritime pine, like all plants will convert atmospheric CO2 into carbon that is stored within plant tissue. This means that a by-product of Maritime pine plantations is their ability to act as carbon sinks (known as carbon sequestration) which help to reduce greenhouse gases [8].

(Although forestry schemes have significant potential for storing carbon and reducing fossil fuel emissions, drastically cutting carbon dioxide emissions by converting to non-fossil fuels is crucial to our planet's future).

Planting plantation pine trees is a "significant component" of Western Australia's Salinity Action Plan [7].

Land care benefits of planting trees (benefits other than the possible economic benefit of increased return on farmland) include: weed control; improved health of water catchment; to protect crops below the plantation; to assist in controlling the rising water table; control of waterlogging and salinity; increased water use within the catchment and reducing recharge; counteract soil acidification; windbreak and shelterbelt benefits (wind erosion); and to combat water erosion/slope stability.

More Online Information

To read more about greenhouse gases and carbon sequestration follow this link [8].

To read about how Sydney is being affected by dryland salinity, including good background information, follow this link [6].

For a list of WWW hyperlinks regarding Salinity (on the NSW Department of Land & Water Conservation website), follow this link [5]. {Note: There are many worthwhile links here, but a 'must see' is "CSIRO Land and Water – Photo Album: Salinity"}

For an article about salinity (21st Feb 2001), follow this link. (Article copyright AAP News Service).

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Glossary

carbon sequestration: Carbon dioxide gas is removed from the atmosphere and stored (sequestered) by growing trees.

dryland salinity: Occurs in non-irrigated areas where high enough proportions of chemical salts build-up in the soil to the point where it affects the environment.

greenhouse gases: Gases that trap the heat of the sun in the Earth's atmosphere, producing the greenhouse effect. The two major greenhouse gases are water vapour and carbon dioxide. Other greenhouse gases include methane, ozone, chlorofluorocarbons, and nitrous oxide.

perennial: (Botany) Living three or more years.

Citations

[1] Australian Academy of Technological Sciences and Engineering (1988). Technology in Australia 1788-1988 ["Exotic Pines"] [WWW document]. URL www.austehc.unimelb.edu.au/tia/210.html

[2] CSIRO (1999, June). CSIRO Media Release ["SALINITY - AUSTRALIA'S GROWING CRISIS"] [WWW Document] URL http://www.its.csiro.au/news/mediarel/mr1999/mr99139.html

[3] Davis-Hall-Watson, K. (Editor) (2000, May-July). State Forests of NSW Journal: The Bush Telegraph ["Pinus pinaster: the new plantation pine"] [WWW Document] URL www.forest.nsw.gov.au/bush/may00/Features/page13.htm

[4] Davis-Hall-Watson, K. (Editor) (2000, May-July). State Forests of NSW Journal: The Bush Telegraph ["Salinity Summit confirms key role for new forests"] [WWW Document] URL www.forest.nsw.gov.au/bush/may00/Features/page15.htm

[5] Salinity in NSW (NSW Department of Land & Water Conservation) (2000). Salinity Links [WWW Document] URL http://www.dlwc.nsw.gov.au/links/salinity.html

[6] Salt Action (NSW Government) (2000, March). Dryland Salinity Information Sheet: Salinity in Western Sydney [WWW Document] URL www.ndsp.gov.au/15_publications/10_fact_sheets/05_NSW/05_salt_action/salt_action_ca5.html

[7] Trees in Agriculture (Agriculture Western Australia) (1999, April). Salinity in Western Australia - an introduction [WWW Document] URL www.agric.wa.gov.au/progserv/natural/trees/Salinity/salwa.htm

[8] Western Australian Department of Conservation and Land Management (CALM) (undated). CALM Online: NatureBase ["Greenhouse Solutions and Carbon Sequestration"] [WWW Document] URL http://www.calm.wa.gov.au/science/greenhouse_splash.html

Copyright D. L. Christiansen [Last updated February 2001] Images: respective copyright owners noted/cited.

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