Weed risk assessment and control Peter Williams, Mark Lewis, Alan Hastings, Rua Murray, Miranda...
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Transcript of Weed risk assessment and control Peter Williams, Mark Lewis, Alan Hastings, Rua Murray, Miranda...
Weed risk assessment and control
Peter Williams, Mark Lewis, Alan Hastings, Rua Murray, Miranda Bennett, Jeff Diez, Ian Westbrooke, Rohan, Tanya Soboleva, Kyoko Fukuda, Ben Perdriau
Risk assessment
• Legally introduced species are assessed for “weediness” before being allowed into NZ
• Some accidentally/illegally introduced• Many already present• Would like a method for quick assessment
of weeds already introduced• Need info on cases of good plants turned
bad
Control
• Control effort focussed on relatively small number of invasive species
• RCs reluctant to add new species to strategy
• But what about currently introduced (30000) and naturalised (3000) species that may be future pests?
Introduced
30000
Wild
3000
Pest
300
• 3 categories of exotic species
• Transition between categories
• Limited control effort
• Optimisation problem for allocation of control effort
• Minimise present cost over finite time horizon
• Linear -> “All eggs in one basket”
• Nonlinear??
Pests can be divided into further categories
• Different species (or class of species)
• Different regions
• RC categories: total control (eradication), surveillance (banned from sale), containment.
Still to do…
• Data on cost/damage of having species in each category
• Include amount of spead?
• Risk of transition between classes?
• Maximum (and minimum?) effort for each class (or more realistic nonlinear control efficacy)?
• Solve it!