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Fire is an effective tool on P. pallida, which is
relatively fire-sensitive, especially in wetter regions where
fuel isn't limiting. P. pallida is also a tree-form
and mechanical control techniques such as chaining can result
in quite high mortalities.
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Mesquite hot fire
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However, some of the most serious mesquite infestations in
Australia are of shrub-form mesquite that is relatively fire-resistant.
They also frequently grow in more arid conditions where fuel
can be patchy in both time and space and the conditions necessary
to generate a sufficiently hot fire relatively rare. For these
taxa the only currently available methods for managing broad-scale
mesquite infestations are very expensive, especially when
follow up costs are considered. These costs can be much greater
if follow-up control is not done in time.
Preliminary data from hot-fires in the Pilbara
region has resulted in close to 100 % mortalities in dense
mesquite, although they fires fail to cross fuel gaps only
10's of metres wide. It does, however, suggest that the use
of fire could be a promising tool under some circumstances,
even for fire-tolerant mesquite.
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Pre-treatment of Mesquite
with dozers
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In 2001 CSIRO and the PMMC initiated a large-scale (144 ha)
replicated integrated control trial to determine:
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size-related mortalities caused by dozing and chaining
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whether pre-treatment of mesquite with either dozers
or chains will help provide a more homogeneous fuel
layer and thereby allow fires to carry over a larger
area
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what fuel and weather conditions are required to initiate
sufficiently hot fires
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what impact hot fires will have on immediate mesquite
plant and seed bank survival, and subsequent regrowth
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how the herbaceous and grass flora will respond to
hot fires
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Mechanical treatments were applied in late 2002. However,
ongoing drought has prevented sufficient fuel build-up
to allow lighting of the first of three replicated fire
treatments.
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It is intended that data from the integrated trial will
be used to predict conditions in other years, regions
and countries when hot-fires could be used to manage fire-tolerant
mesquite.
References
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Osmond, R., van Klinken, R.D., March, N., Cobon, R.,
and Campbell, S. (2003). The mesquite tool box. In Mesquite
Best Practice Manual.
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