Política energética:

Management of areas with soil erosion needs to be part of a process that includes whole property or catchment management. Areas with minimal erosion may recover in time by manipulating grazing intensity (downwards), through fencing and water availability. Areas with moderate to severe degradation and/or erosion will require more intensive regeneration methods and recovery may take many years.

Soils are most vulnerable to erosion under continuous grazing, and where total grazing pressure from livestock, feral animals and native animals is high. Removal of grazing pressure on a regular basis during seedling establishment will often provide sufficient spelling to encourage plant growth.

Sandy duplex soils (405 and 406) are highly susceptible to erosion after initial soil surface crust decline. Below the topsoil, the clayey subsoil is less fertile and usually more saline. If exposed through erosion, the subsoil may become scalded and sealed, with greatly reduced water infiltration rates and increased surface salinity. This creates a harsh environment for seedling establishment and survival. Similarly, the topsoils of loamy duplexes (506), loamy earths (542 and 544) and clayey soils (602, 621 and 622) have lighter textures than the subsoils and similar scalding can occur as a result of erosion after significant vegetation loss.

Soils with partial topsoil loss will most likely remain viable for seedling establishment providing there is no grazing pressure. Spelling from grazing on a regular basis is the most cost-effective method to regenerate such areas.

Highly saline soils often have very soft puffy soil surfaces with a very thin fragile crust. Immediately under the surface crust, salt grains derived from the subsoil via capillary action may be visible. It is not recommended to cultivate these soils with earth moving machinery, as the soils will be exposed to more erosive forces.

Regeneration of degraded land may require cultivation using heavy earth moving machinery and seeding or planting suitable native or introduced plant species.

Some soils with completely eroded topsoils may have saline subsoils with hard, scalded and sealed surfaces. These soils tend to be salt free on the surface, but are often saline within a depth of 10-20 cm. To encourage plant

establishment on these soils, the prime principle is to reduce the high salinity just below the soil surface.

The use of earth moving equipment to create large water holding ponds will often reduce the surface salinity as the water carries some of the salts to the lower soil profile. However, ponding banks cannot be placed in areas of moderate or intense overland water flow, as breaches of the banks can occur and possibly create further erosion. The construction of ponding banks and ponds is a high cost option for regeneration.

Fencing and shutting off artificial waters to exclude, as much as possible, all grazing animals are the first requirements towards re-establishing vegetation. Suitable niches for seed and adequate soil moisture for plant establishment and growth are the most important factors for successful regeneration. Recovery may require the use of expensive techniques involving earth works and

reseeding/planting of native species, and treatment may need to be repeated over several years.

For more details on methods of regenerating degraded rangelands see Ward (1990), Williams and Shepherd (1991), Payne and Tille (1992), Scholz (1995) and Addison (1997).

References

Addison, J. (1997). A guide to mechanical rangeland regeneration. Agriculture Western Australia, Bulletin 4334.

Bettenay, E., Churchward, H.M. and McArthur, W.H. (1967). Explanatory data for sheet 6 Meekatharra-Hamersley Range area, Atlas of Australian Soil. CSIRO, Melbourne University Press.

Bettenay, E. and Churchward, H.M. (1974). Morphology and stratigraphic relationships of the Wiluna Hardpan in arid Western Australia. Journal of Geological Society of Australia

21: 73-80.

Isbell, R.F. (1996). The Australian Soil Classification. Australian soil and land survey handbook series, Volume 4. CSIRO Publishing, Collingwood, Australia.

McDonald, R.C., Isbell, R.F., Speight, J.G., Walker, J. and Hopkins, M.S. (1990). Australian soil and land survey field handbook. 2nd Edition. Inkata Press, Melbourne and Sydney.

Munsell (1954). Munsell Soil Colour Charts. Munsell Color Co. Inc. Baltimore 18 Maryland 21218, USA.

Overhue, T.D., Muller, P.G., Gee, S.T. and Moore, G.A. (1993). Esperance land resource survey. Western Australian Department of Agriculture, Land Resource Series No. 8.

Payne, A.L. and Mitchell A.A. (1992). An assessment of the impact of the Ophthalmia dam on the floodplains of the Fortescue River on Ethel Creek and Roy Hill stations. Western Australian Department of Agriculture, Technical Report 124. Payne, A.L. and Tille, P.J. (1992). An inventory and condition

survey of the Roebourne Plains and surrounds, Western Australia. Western Australian Department of Agriculture, Technical Bulletin No. 83.

Raupach, M., and Tucker, B.M. (1959). The field determination of soil reaction. Journal of the Australian Institute of Agricultural

Science 25: 129-33.

Schoknecht, N. (2002). Soil Groups of Western Australia - A simple guide to the main soils of Western Australia. Resource

Management Technical Report 246, third edition. Agriculture Western Australia.

Scholz, G. (1995). A practical guide to rangeland revegetation in Western New South Wales using native grasses. NSW Department of Land and Water Conservation, Technical Report No. 33.

Teakle, J.H. (1936). The red and brown hardpan soil of the Acacia semi-desert scrub of Western Australia. Journal of Agriculture,

Western Australia 13: 480-99.

Tongway, D. (1994). Rangeland soil assessment manual. CSIRO Division of Wildlife and Technology, Canberra, Australia. Ward, B.H. (1990). The role of seed placement and gypsum in

improving the establishment of spiny bluebush on scalded duplex soils in north-western Australia. Proceedings of the Fifth Australian Agronomy Conference, Perth, February 1990, p. 607. Wells, M.R. and King, P.D. (1989). Land capability assessment

methodology for rural-residential development and associated agricultural uses. Western Australian Department of Agriculture, Land Resources Series No. 1.

Williams, A.R. and Shepherd, R. (1991). Regenerating the rangelands. Journal of Agriculture Western Australia 32: 69-74.

Vegetation

A.M.E. Van Vreeswyk

This chapter describes aspects of the vegetation in the survey area. The first section provides a review of previous work undertaken by Beard (1975), then the findings from the current survey are presented. A summary listing of major plant families and genera provides the taxonomic context for subsequent description of the vegetation, first according to plant forms and second according to vegetation formations. Regional vegetation patterns across the survey area are then considered. Flora conservation is the final topic addressed.

This chapter focuses on describing the plants and the communities they comprise. The Site type ecology chapter looks in more detail at plant community ecology including aspects of land use impacts and conservation. Site types at plant community/landform/soil type scale are described.