Hard spinifex plain pastures in the Kimberley

Page last updated: Thursday, 23 May 2019 - 9:39am

There are many different pasture types in the pastoral rangelands in the Kimberley region of Western Australia. We provide this pasture information to be used as a reference for assessing pasture condition, and as a guide for pastoral station staff and others interested in the productivity and maintenance of the pastoral rangelands.

Assessments can be used to monitor the success of management and to set goals for improving rangeland condition.

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 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.

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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.

Photograph of hard spinifex plain pasture in good condition
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.

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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).

Photograph of hard spinifex plain pasture in fair condition
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).

Photograph of hard spinifex plain pasture in poor condition
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.

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Associated plants

Plants associated with hard spinifex plain pastures in the Kimberley
Common name
(link to DPIRD species page)

Scientific name

(link to FloraBase)

Life form
Desirable species    

Hard spinifexes

Triodia intermedia, Triodia wiseana and other hard Triodia spp.

perennial

Soft spinifex

Triodia pungens

perennial

Ribbon grass

Chrysopogon fallax

perennial

Silky browntop

Eulalia aurea

perennial

White grass

Sehima nervosum

perennial

Intermediate species    

Citronella grass

Cymbopogon bombycinus

perennial

Black speargrass

Heteropogon contortus

perennial

Limestone grass

Enneapogon polyphyllus

annual or short-lived perennial

Wire grass, Northern Wanderrie grass

Eriachne obtusa

perennial

Slender Wanderrie grass

Eriachne ciliata

annual

Rice grass

Xerochloa laniflora

annual or short-lived perennial

Undesirable species    

Threeawn grasses

Aristida spp.

annual or perennial

Contact information

Kath Ryan
+61 (0)8 9166 4015
Matthew Fletcher
+61 (0)8 9166 4019