Animal production and livestock, Natural resources
Potential carrying capacities for land systems in the catchment of the Ashburton River were first estimated in 1983 as a result of a rangeland survey of the area undertaken during 1976, 1977 and 1978. Potential carrying capacity (termed capability capacity in the 1988 report) is a suggested sustainable level of use assuming that all pastures are in good range condition, the entire station is adequately watered for the effective management of livestock and seasonal conditions are average. The Ashburton Land Conservation District Committee had previously requested a re-assessment of carrying capacities for Ashburton stations following the widespread establishment of buffel grass (Cenchrus ciliaris) since the regional survey in the 1970s. In April 2001 and April 2002 the authors from the Department of Agriculture, Western Australia, and the Department of Land Administration re-inspected parts of the Ashburton survey area. Findings: Buffel grass (Cenchrus ciliaris) was dominant in some areas in the 1970s. The ground inspection in 2001 and 2002 verified that it and Birdwood grass (Cenchrus setigerus) had spread considerably since the original survey. Most pastoralists spoken to considered that buffel grass had really expanded since the huge Ashburton River flood in 1997 when silt and sand was deposited over extensive areas of alluvial plains. Carrying capacity implications: The carrying capacity of the introduced Cenchrus grasses is significantly higher than the capacity of the native vegetation. Thus buffel grass increases the potential carrying capacity of those systems on which it has expanded. The survey group reviewed the potential carrying capacities of the 21 land systems in the Ashburton survey area that were identified as supporting a buffel grass component. It also reviewed the potential carrying capacities of the other 61 land systems found in the area (see Table 4). Some of the carrying capacities allocated in the 1988 report are considered to be too conservative and were increased using pasture carrying capacity estimates developed in the adjacent Pilbara survey area (Van Vreeswyk et al. 2004) and reported in Payne and Mitchell 2002. Consequently, as well as the potential carrying capacities of land systems being increased in recognition of the spread of Cenchrus grasses, they were also increased by higher allocation to other pasture types. Station Reports: Reports for 26 stations falling within the catchment of the Ashburton River are presented in alphabetical order. Twenty-two stations fall wholly into the Ashburton catchment area. Four stations fall partly within the Ashburton River catchment and partly in the Gascoyne River catchment or the Pilbara survey area. Reports for the whole station are presented for these four stations.
Number of Pages
carrying capacity, land systems, rangeland, Ashburton, pasture, livestock, managment
Payne, A L, van Vreeswyk, A M, and Leighton, K A. (2004), Re-assessment of carrying capacities in the Ashburton River Catchment. Department of Agriculture and Food, Western Australia, Perth. Report 1447-4980.
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