Impact reduction and asset protection.
Management of weed impacts occurs across a spectrum of activities from: quarantine, to exclude species entirely; eradication or containment, where feasible; and asset protection strategies to reduce the impact of established weed species. The transition between containment and asset protection strategies occurs after containment of a weed species is no longer economically rational. Weed management efforts are then directed at reducing or maintaining a weed's rate of spread and/or its population below a notional threshold level. Management activities aligned with a putative weed invasion curve have 'containment' followed by 'asset protection'. We propose that the weed management activities previously commonly termed 'asset protection' be split into at least two categories: 'impact reduction' and a new 'asset protection' category. The transition between the two proposed categories occurs when management activities are no longer directed at the management of a weed species, that is species-led. 'Impact reduction' would involve species-led management activities, generally aimed at managing the recovery of some asset/s. The long-term program to manage the recovery of threatened species populations and ecological communities from bitou bush (Chrysanthemoides monilifera (L.) Norlindh subsp. rotundata (DC.) Norl.) in eastern Australia is an excellent example. In contrast, the new more restricted 'asset protection' category occurs after this point, when a decision to protect areas/assets from multiple species weed invasions is made. The New South Wales state framework evaluating and prioritising biodiversity priorities from widespread weeds is an example of this. Both new categories will help better tailor weed investment, and management activity parameters.