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ContextAustralia has a high diversity of endemic vertebrate fauna. Yet, transnational human activities continue to increase the rate of transportation, introduction and establishment of new alien vertebrates in Australia, to the detriment of environmental and socioeconomic services. Eradication of invasive vertebrates is often costly and without guarantee of success; therefore, methods for detecting, intercepting and preventing the transport of alien species earlier in the invasion pathway provide substantial benefit. AimTo anticipate emergent threats to Australian biosecurity posed by the transport and introduction of new alien vertebrates over time. MethodsWe collated vertebrate interception data from various mainland Australian State, Territory and Commonwealth government reporting agencies, including data from a previously published study, at both pre-border and post-border stages from 1999 to 2016. Using generalised linear and generalised additive modelling, we predicted trends in interception frequency using predictors such as vertebrate taxa, detection category and alien status. Key resultsInterception frequency increased over time for all vertebrate classes, for pre-border stowaways and for post-border captive and at-large interceptions, with no saturation in the accumulation of new species over time. Five species were responsible for almost half of all incidents, of which red-eared sliders (Trachemys scripta elegans), boa constrictors (Boa constrictor) and corn snakes (Pantherophis guttatus) are prominent in Australia’s illegal alien pet trade. Rose-ringed parakeets (Psittacula krameri) are prominent in the legal alien cage-bird trade, which remains poorly regulated. Asian common toads (Duttaphrynus melanostictus) were frequently detected as stowaways, and most stowaway incidents originated from Southeast Asia, particularly Indonesia, via shipping. Data deficiency for pre-border incidents increased rapidly in 2015 and 2016. ConclusionsAustralia is subject to a persistent and increasing risk of alien vertebrate introductions and incursions over time, owing partly to emergent trends in the alien pet trade as well as increased global trade and tourism. ImplicationsThe future of Australia’s biosecurity remains dependent on stringent border security to prevent the arrival of novel species, but our findings also highlight the importance of ongoing management and control of high-risk species already present, often illegally, within Australia.

Many plant species with agronomic potential have been introduced for livestock forage and have subsequently become weeds of natural ecosystems, or ‘environmental weeds’. Stringent border quarantine procedures introduced by Australia in 1997 ensure few high weed risk species are now imported into the country; however, there are no protocols for assessing and managing weed risk in use on a national scale ‘post-border’ (i.e. once a plant species is in the country). Environmental weed risk management in forage improvement programs aims to minimise the risk that new species and cultivar introductions will be invasive in natural ecosystems. We describe an environmental weed risk assessment (EWRA) model specifically aimed at assessing the weed potential of exotic and native forage species. The EWRA model predicts and ranks species for weed risk by assessing invasiveness, impacts and potential distribution. Assessments are based on published evidence, experimental observations and intuitive responses from experienced pasture researchers, in collaboration with weed experts. This model specifically addresses the need for environmental weed risk management in forage improvement programs.

A range of risk assessment systems has been applied to the field of weed management globally to address the ever-growing problem of plant invasions. Here, we review the development of risk assessment and management systems across the spectrum of weed management, spanning pre-border (quarantine), post-border (generally aimed at eradication and containment) and the protection of environmental assets. These systems have been developed using broader risk management frameworks, enabling consistency with a range of other agreements and strategies (e.g. pre-border with international phytosanitary measures). While a weed risk assessment system (pre-border) has been developed and widely tested/adopted, post-border systems, especially for established weed species, have been more varied in their nature and application. For example, a triage system has been outlined only recently for managing the current risks of established or widespread weeds to native species. This review also highlights a range of other weed management areas in which risk assessment systems have been applied (e.g. invasion pathways) and where further progress is needed in the current systems to make them more robust. By assessing risk across the spectrum of weed management, we have demonstrated the role of each system and how they link together to address the majority of the spectrum. The application of risk assessment procedures has helped to create systems that aim to prevent, eradicate, contain and protect assets from the effects of weed invasions, the legacy of which will be long lasting, globally.

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Southern Australia’s annual-based agricultural system has come at a large cost to the landscape. Dryland salinity is a rapidly expanding environmental problem that is reducing the amount of land available for agriculture, and causing a significant ecological cost to remnant and riparian vegetation. There is an urgent need to increase the area of the landscape that is sown to deep-rooted herbaceous perennials to reduce the increase in dryland salinity, and for their successful adoption by landowners it is recognised that these perennials must be economically viable. Australian perennials are unlikely to provide such options in the short term and therefore there is a need to search for species overseas. Many agricultural weeds have arisen as a direct result of deliberately introduced species escaping cultivation and naturalising in the Australian environment. They cause a huge cost to agriculture in terms of both lost production and control. There is also a cost to natural ecosystems as a result of lost biodiversity and weed management. A conflict of interest thus arises. This paper follows on from a workshop held between the CRC for Plant-based Management of Dryland Salinity and the CRC for Australian Weed Management. It discusses 4 key areas where potential conflict exists between the maintenance of biodiversity in natural ecosystems and the development and introduction of new herbaceous perennials. Each of the issues within pre-entry weed risk assessment, post-entry weed risk assessment, weed risk of translocating native species and field assessments of new species is discussed in detail and suggestions are given on the means to resolve the conflicts. Actions to address the recommendations are urgently required if we are going to resolve the current conflicts of interest between the need for managing present and future environmental weeds and for mitigating dryland salinity.