WRASP: A spatial strategic weed risk analysis tool reveals important subnational variations in weed risks

Abstract

Summary The number and diversity of introduced invasive plants, coupled with limited weed management budgets, require biosecurity managers to employ systems to prioritise weeds for management attention. To assist this process, an analytical protocol and spreadsheet tool were previously developed for post‐border weed risk management (PBWRM). The popular PBWRM tool utilises a framework that ignores any spatial variation in risk factors within the geographical area of risk concern. However, invasive plants vary in risk factors such as invasiveness, potential impacts and feasibility of control as a function of spatially variable factors. Logically, the assessment of weed risks should also be spatially explicit, in order to best understand them and to target management appropriately. To address these concerns, we took the PBRWM logic and spatialised it, to allow weed managers to assess weed risks and management across geographical space. We illustrate this new spatial system using a case study of Senecio glastifolius in New Zealand, comparing the results of a spatial and an aspatial analysis of the risks it poses and the logical management options. The spatial view of risks revealed locations of higher and lower risk and suitability for management attention that were hidden by blanket, aspatial weed risk scores of the current PBWRM system. The national level risk was also significantly higher when considered in the light of the results from the spatial tool. The spatial tool, WRASP, takes its name from Weed Risk Assessment SPatial.

Outbreak of a new alien invasive plant Salvia reflexa in north‐east China

“…This early detection affords the possibility of regulating alien plants prior to their introduction to new regions (Sakai et al ., ). Meanwhile, predicting the invasiveness potential of introduced plants has been a long‐standing target of ecologists, and this knowledge could translate into risk assessment systems that attempt to evaluate the behaviour of alien plants in introduced regions (Daehler & Carino, ; Kriticos et al ., ). There were mainly three approaches to adopt in WRA, including quantitative statistical models, semi‐quantitative scoring and qualitative expert assessment.…”

A preliminary assessment of the presence and distribution of invasive and potentially invasive alien plant species in Laikipia County, Kenya, a biodiversity hotspot

“…Another approach may be to replace alien species with native species, facilitated through the establishment of nurseries focussing on indigenous plantings. Actions can also be supported by undertaking Weed Risk Assessments, or similar, which should ideally include eco-climatic maps to determine the climatic suitability of Laikipia to invasions by selected species (Kriticos, Beautrais & Dodd 2018). Cost-benefit analyses (CBAs) should ideally also be undertaken to consider issues around those species that have benefits but are also known to be invasive -the so-called conflict species such as Prosopis juliflora (Wise, Van Wilgen & Le Maitre 2012).…”