Section 1: Prickly acacia—ecology and threat - Weeds Australia

Impact on primary industry
While prickly acacia at low densities can
increase stock productivity by providing shade
and fodder, most landholders view it as
undesirable because of its invasive potential
and its effect on primary production. Dense
infestations reduce pasture production,
increase soil erosion, increase mustering costs,
impede stock movement, restrict access of
stock to water, increase the cost of maintaining
bore drains and damage vehicle tyres.
Of these impacts, two of the most significant
are the loss of pasture and increased mustering
difficulty. Under normal grazing pressure a
25–30% canopy cover (the proportion of
ground covered by the canopy of trees) of
prickly acacia reduces pasture production by
Suitabilitiy rating
Unsuitable
Marginal
Suitable
Highly suitable
Figure 3: Predictive distribution of prickly acacia
(Calvert & March, 2004)
50% compared with acacia-free pasture (Carter
1994) and pasture growth is virtually prevented
by a 50% canopy cover (Carter pers. comm.,
1995 in Mackey 1998). This loss of pastures
will directly affect the potential carrying
capacity of affected properties.
Mustering becomes increasingly difficult as
prickly acacia increases in density and the
associated costs may increase by up to ten-fold
(Mackey, 1996). The failure to conduct clean
musters also has implications for stock hygiene
as the remaining stock may harbour diseases
and parasites. Additional expenses also include
the cost of clearing droving lanes and erecting
new fences so that stock handling and
mustering can be better managed.
‘Mustering
becomes
increasingly
difficult as
prickly
acacia
increases
in density
and the
associated
costs may
increase by
up to
ten-fold.’
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