Doria Gordon
Wednesday, October 15, 2008 - 9:00-9:30
The Australian Weed Risk Assessment system (WRA) has now been tested in temperate and tropical, island and continental geographies. On average across these tests, the WRA correctly rejected major plant invaders 90%, and correctly accepted non-invaders 70% of the time. Use of a secondary screening tool on species requiring further evaluation reduced the proportion in that outcome from 27% to 10%. However, these results do not indicate the potential impact to importers of new plant species if such a screening system were implemented in the U.S. Results from Australia (not using the secondary tool) suggest that over 70% of novel species will be accepted or require further evaluation, with fewer than 30% of the species rejected as having high probability of becoming invasive. We tested the hypothesis that similar results would be found for 100 plant species introduced to the U.S. since 1995. These species are unlikely to have already expressed any invasive potential, so should be a good reflection of the potential impact of a screening regulation on plant importers. Data used to address the WRA questions were from occurrences outside of the continental United States. Results indicate that over 70% of these species would be accepted for import, 20% require further evaluation, and fewer than 10% would be rejected as likely to become invasive in the U.S. More species than hypothesized would be accepted for import if this system were implemented.
Keywords: INVASIVE NON-NATIVE PLANTS, PREDICTIVE SCREENING, WEED RISK ASSESSMENT