Impacts of Senecio inaequidens at a local and global level
Senecio inaequidens (Asteraceae: EPPO List of Invasive Alien Plants) is a perennial species native to South Africa. It is widespread in the EPPO region, in particular in western Europe where it occurs in a number of different habitats from dry pastures to woodland. It can have negative impacts on biodiversity and ecosystem services and it has been shown to reduce species richness in high-altitude pastures. A study was conducted in 2022 in Lombardia (northern Italy). Six habitat patches (30 x 30 m) were selected and within each, five pairs of 1 x 1 m invaded and uninvaded plots were randomly chosen. Soil samples were collected from each plot and the composition and cover of each plant species within the plot was estimated. The soil chemistry and bacteria diversity were measured for each soil sample. The results showed no difference in soil chemistry between invaded and uninvaded plots. Plant diversity and soil bacteria diversity marginally increased in invaded plots, whereas plant species richness increased significantly in low-productivity invaded plots. Overall, the field study showed only minor impacts, and in some cases positive impacts due to the presence of S. inaequidens. In addition to the field study, a global assessment of S, inaequidens was conducted using the Environmental Impact Classification for Alien Taxa (EICAT) framework. Twelve impact studies (including the current study) were used in the EICAT assessment with the outcome that S. inaequidens should be included in the moderate impact category, indicating negative effects on native taxa without causing local extinctions. Combining a local study with a global impact assessment highlights the need to consider context-dependency in invasion ecology.
Sources
Quaglini LA, Yannelli FA, Fasano F, Citterio S, Gentili R (2025) Assessing local and global ecological impacts of the alien plant Senecio inaequidens across different environmental conditions in Northern Italy and applying EICAT. Weed Research, 65, e70019. https://doi.org/10.1111/wre.70019