Hard spinifex plain pastures in the Kimberley, Western Australia

Hard spinifex plain pastures

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

Pastoral value

Hard spinifex plain pastures have a very low pastoral value. Hard spinifex is unpalatable at most stages of growth, although cattle may sometimes graze spinifex plants regenerating after fire. Frequent burning of small areas off tracks can lead to a concentration of livestock on the regenerating pasture and a decline in condition.

Grazing pressure needs to be managed to prevent the few palatable species present being grazed out. Despite its low palatability, hard spinifex is considered a desirable species in this pasture type because it is a perennial and helps control erosion.

Occurrence

Hard spinifex plain pastures occur on level to undulating plains in drier areas of the Kimberley. They are found on loamy and sandy soils which are generally shallow or stony. They occur as hummock grasslands, with occasional trees or shrubs.

Back to top

Pasture condition

Good: In good pasture condition, there is an even coverage of hard spinifex plants. A few desirable perennial grasses, such as silky browntop, ribbon grass and soft spinifex, may occur in low numbers between spinifex hummocks but they will tend to be concentrated along the drainage lines or under trees (Figure 1).

A variable cover of palatable intermediate annual grasses, such as limestone grass, may also be found for a short time following a good wet season.

Figure 1 Hard spinifex plain pasture in good condition in the Kimberley (photograph taken May 2008).  A There is an even coverage of hard spinifex, a desirable species, with only small spaces between hummocks.  B The palatable perennial silky browntop is present and appears vigorous.

Back to top

Fair: Hard spinifex is generally ignored by livestock, so it is mainly the species growing between spinifex plants that cattle will graze when on these pastures. For this reason, a decline from good to fair condition is usually accompanied by reduced frequency and vigour of the palatable species.

The coverage of spinifex plants may appear patchy or uneven, with the areas in-between supporting a sparse cover of annual and undesirable perennial grasses, such as threeawns. Poor post-fire grazing management leading to overgrazing can cause an uneven appearance in this pasture type (Figure 2).

Figure 2 Hard spinifex plain pasture in fair condition in the Kimberley (photograph taken May 2008).  A There is an uneven coverage of hard spinifex.  B There are increased spaces between spinifex plants with only annual species present, in this case, an undesirable annual threeawn; there is a lack of desirable species growing between spinifex hummocks.

Poor: In poor condition, larger bare patches occur among the spinifex. Desirable grasses lack vigour or are absent. Any non-spinifex species present tend to be undesirable perennial grasses, or annuals with low fodder value. The abundance of annual grasses depends on the season (Figure 3).

Figure 3 Hard spinifex plain pasture in poor condition in the Kimberley (photograph taken May 2008).  A There is a low coverage of hard spinifex.  B Other plants are undesirable species with low fodder value.  C There are large areas of bare ground.  D Some areas of the soil surface are actively eroding.

Back to top

Associated plants