Prioritizing management actions for emergent invasive non-native plants through expert-based knowledge and Species Distribution Models

Given the high number of alien plants introduced in Italy and time required to process a formal pest
risk analysis, a prioritization process is necessary as an earliest action. We propose a rapid and simple
methodology to prioritize the management towards the eradication, control and monitoring of emergent
invasive plants, combining expert knowledge, current and future climatic suitability estimated by species
distribution models (SDMs), clustering and ordination techniques, and integrating the spatial patterns into
the three biogeographical regions of Italy (Alpine, Continental, and Mediterranean). Three categories of
management actions were identified: Eradication, Control and containment, and Monitoring. Two priority
classes were proposed for the management actions: high and low. A total of 36 alien plants have been identified.
SDMs highlighted a high suitability for Continental and Mediterranean bioregions for the majority
of invasive plants. Cluster analysis revealed three distinct clusters (C) with varying levels of suitability for
the Italian bioregions. C1 exhibited a higher suitability across all Italian bioregions, whereas alien plants
grouped in C2 predominantly featured high suitability in Mediterranean areas. Finally, C3 showed the lowest
suitability values. Ordination analysis highlighted the variability in bioclimatic suitability for each alien
plant within each cluster, as well as their current spatial pressure on each Italian bioregion. Lastly, a third
ordination, integrating bioclimatic suitability and spatial patterns, has allowed the differentiation of management
actions for each alien plant at both national and bioregional scales. Specifically, seven alien plants
were earmarked for Eradication, six for Monitoring, while the remaining species were deemed suitable for
Control and containment.
Our results and the methodology proposed coincide with the demand for new early warning tools, that is,
to predict the location of new outbreaks, to establish priorities for eradication, control and containment,
and monitoring of emerging invasive species.