Format: ORAL

Thomas de Solan1, Aurlien Caillon1, Guillaume Fried2, Yohann Soubeyran3, Arnaud Albert4

1 Conservatoire Botanique National Sud Atlantique, Audenge, France 2 Anses, Laboratoire de la Santé des Végétaux, Unité entomologie et botanique, Montferrier-sur-Lez, France 3 French committee of the International Union for Conservation of Nature, Montpellier, UMR AMAP (Univ Montpellier, CIRAD, CNRS, INRAE, IRD), France 4 French Biodiversity Agency, Research and Scientific Support Department, Nantes, France

The creation of prioritized checklists ranking alien taxa depending on their risk for biodiversity is an essential step for an effective management of invasive alien species (IAS). In France, such lists for alien plants are drawn up by different structures at regional and national scales using various risk assessment methods. This lack of homogenization in assessment methods limits the implementation of the French national strategy on IAS. To address this problem, we investigated if two recent frameworks, EICAT and EICAT+, have the potential to become standards for assessing the ecological impacts of alien plants in France. We first identified the needs and constraints associated with the use of these two protocols, and proposed several modifications. We then assessed with the modified EICAT/EICAT+ (i) the regional impacts of 100 alien plants naturalized in a French region, and (ii) the national impacts of the 230 plants identified as invasive in France. Modifying EICAT and EICAT+ is tricky, as too many changes would compromise the standardization feature of these methods and limit comparison with assessments from other regions. Firstly, we propose criteria to better define some concepts (e.g. local population), which were difficult to handle with plants in a continental context. Sourced impact data are required in both methods, but are either non-existent or fragmentary for most species at a regional scale, leading to a high number of data deficient species. Therefore, we include local knowledge from botanists and wildlife specialists, in addition to literature review. Finally, we propose a key for translating field observations into impact levels, because local knowledge is usually related to species behaviour and often cannot be translated into EICAT(+) impact. This work provides the most comprehensive assessment to date of the current ecological impacts in France of 280 alien plants on a local and/or national scale.