Testing the Australian Post-Border Weed Risk Management (WRM) system for invasive plants in Iran

Given the global threat from invasive plant species, management systems are needed to determine the risk posed. Whilst pre-border weed risk assessment systems have been tested and applied broadly, risk assessment systems for species post-border (or weed risk management) are yet to be subjected to such levels of scrutiny. Here we adapted the Australian Weed Risk Management (AWRM) approach to the geographic, climatic and weed management context of Iran. Then we evaluated and tested the performance of the adapted WRM system using 38 candidate species, comprising both native and non-native invasive plant species present in Iran. Additionally we modified the post-border WRM approach by specifically focusing on the feasibility of containment, rather than control per se, given that eradication of native species is not appropriate; even when considered to be invasive. We also subsequently modified the management emphasis associated with each cell of the WRM matrix of weed risk and feasibility of containment levels, to account for the changes outlined above. We examined the effectiveness of the system using receiver operating characteristic (ROC) curves for the 38 candidate species, which showed that our results were similar to those observed during testing and evaluations of the WRM systems developed in Australia. Examination of the outcomes revealed that the current management and research for five of the highest priority species did not match or align with the level of risk derived from the WRM assessment. Additionally at least seven invasive plants species currently not on the lists examined should be included on the Noxious Weed lists of Iran based on our assessment of the risk posed. The two highest priority species (Ambrosia psilostachya and Imperata cylindrica) are both alien species and should be priorities for containment. Despite successfully modifying the AWRM for Iran, additional studies are required to further examine and test the best cut-off values for each risk level in the WRM matrix using larger numbers of plant species. Our results show that the AWRM can be modified for use in other countries, which could see broader adoption of post-border WRM systems for managing established alien plant species.