Curly spinifex/annual sorghum hill pastures in the Kimberley, Western Australia

Curly spinifex/annual sorghum hill pastures

These pastures are part of the Kimberley red soil group - spinifex pastures, and curly spinifex and annual sorghum are the identifier grasses. Use the interactive key to pasture condition to help identify pasture type.

Pastoral value

This pasture type is of low forage value and a decline in condition reduces the value even further. However, the relative inaccessibility of this pasture type means that it is unlikely to be heavily grazed under most circumstances. Excessive pressure on these pastures, due to frequent fire or hot fire in conjunction with grazing, reduces the frequency of curly spinifex plants. The amount of annual sorghum varies in response to rainfall and fire history, and its height varies in response to rainfall. Annual sorghum usually grows much taller in the higher rainfall areas in the north than it does further south.

Occurrence

These pastures are a mixture of curly spinifex and annual sorghum, occurring with a tree layer of eucalypts and small terminalias. They are found in various locations north of Halls Creek, and are most common on stony hillslopes with shallow soils.

Back to top

Pasture condition

Good: In good pasture condition, these pastures are dominated by curly spinifex and annual sorghum. Curly spinifex is quite obvious among the taller sorghum plants, and a small amount of other perennial grasses may be present (Figure 1).

Figure 1 Curly spinifex/annual sorghum hill pasture in good condition in the Kimberley (photograph taken May 2008).  A Curly spinifex, a desirable species, is dominant.  B Annual sorghum, an intermediate species, is growing among the curly spinifex.  C Only a few other perennial grasses, in this case black speargrass, are present; groundcover is optimal for the site, considering the poor soil and slope.

Back to top

Fair: Condition decline in this pasture type is marked by a reduction in frequency of curly spinifex plants, with annual sorghum becoming far more obvious in fair condition as a result. Other perennial grasses, such as white grass and black speargrass, may also become more apparent in fair condition (Figure 2).

Figure 2 Curly spinifex/annual sorghum hill pasture in fair condition in the Kimberley (photograph taken March 2009).  A Annual sorghum, an intermediate species, dominates.  B The desirable curly spinifex remains scattered among the annual sorghum.

Poor: In poor condition, there are few curly spinifex plants left. Annual sorghum, an intermediate species, and undesirable species such as hard spinifex or threeawns, make up the bulk of the stand (Figure 3).

Figure 3 Curly spinifex/annual sorghum hill pasture in poor condition in the Kimberley (photograph taken March 2009). Intermediate and undesirable grasses dominate at this site. The desirable curly spinifex is present only as isolated plants.  A Annual sorghum, an intermediate species, is prominent.  B Hard spinifex, an undesirable species, makes up a high proportion  of the stand.

Back to top

Associated plants