Environmental Engineering Reference
In-Depth Information
5.3.10 Exploit times when invasive species' populations are low
In the annual life cycle or history of an invasive species, some occasions may pre-
sent particular opportunities for more effi cient or more effective control. These
may relate to stages of the life cycle that are more prone to particular treatments
or to weaknesses imposed by episodic climatic or other circumstances. Applying
control measures prior to major reproductive episodes may reduce rates of spread
and/or the time during which follow-up treatments may be required. This applies,
for example, to invasive plant species that build long-lived soil seed-banks and is
especially important in the case of new infestations where seed-banks have not yet
accumulated. When rabbit calicivirus was introduced to Australia in 1995, the
disease spread rapidly and killed up to 95% of feral rabbits ( Oryctolagus cuniculus )
in some areas. Land managers were encouraged to reinforce the effects of the dis-
ease by mechanical treatment of rabbit warrens even though rabbits were in very
low numbers.
5.3.11 Acquire continuing commitment
Containment and control programmes should be developed as long-term strat-
egies because there is generally a low likelihood that a particular programme will
achieve an end-point where no further action is required. An important implica-
tion of this is that there will be a continuing need for resources. Careful consider-
ation should be given to how these resources will be obtained.
Important decisions in the development of containment or control programmes
relate to how responsibility for the programme will be attributed to the various
stakeholders. h is must cover the relative contributions of public and private
sectors. Socio-economic factors are crucial here. Decisions about responsibility
will be aff ected by the various stakeholders' perceptions about who is to blame.
In Australia, many invasive plant species were originally promoted to the pri-
vate sector (particularly grazing industries) as benefi cial species, only to subse-
quently be recognized as problematic. Two examples are Kochia scoparia , which
was introduced as a pasture species for saline soils in Western Australia (Dodd
and Moore 1993), and prickly acacia ( Acacia nilotica ), which was promoted as
a shade and fodder tree for use in naturally treeless Astrebla spp. grasslands in
western Queensland (Mackey 1998). h e former was subsequently targeted by a
largely publicly-resourced eradication campaign (Dodd 2004) while the latter, was
declared a Weed of National Signifi cance (h orp and Lynch 2000) and became the
focus of a national management plan that continues to receive substantial funding
from Commonwealth and State governments (QNRME 2004a).
h ere are several other factors that may encourage substantial inputs from the
public sector into containment and control programmes. One is a need for very
rapid responses in cases where new, high-risk incursions are discovered in the very
early stages of invasion. A publicly funded and coordinated programme may facili-
tate a timely response to such incursions and also help resolve confl icting interests
if these arise. Part of this support could be in the form of incentives to those who
 
 
 
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