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Plant Invasive Alien Species

Invasive alien species represent one of the greatest threats to biodiversity as they compete with native species and their rapid spread often changes the floristic composition and vegetation of even very large areas in an incontrovertible way. Action C5 aims at the eradication of Baccharis halimifolia and the reduction of Robinia pseudoacacia.

Baccharis halimifolia is a shrub belonging to the Asteraceae family, originating from the eastern coasts of North America that is spreading rapidly in the Venice lagoon thanks to its resistance to salinity. Another adaptation that facilitates its spread is the high production of seeds with pappus, which are dispersed by the wind even over large distances. B. halimifolia is included in the 2016/1141 European Commission Regulation which adopts a list of invasive alien species of EU significance. For Baccharis halimifolia the total manual eradication of the subjects is recommended.

Baccharis halimifolia
Specimen of Baccharis halimifolia, species subject to eradication activities related to action C5. Several years old specimen with shrubby habit (left); detail of the flower buds (right) (WWF Oasis of Valle Averto)


Eradicazione Baccharis
Eradication sequence of a medium to large specimen. Identification of the species (A) isolation of the root ball (B) and removal (C).

Robinia pseudoacacia is an arboreal species belonging to the Fabaceae family. In the Po Valley it is widespread and impossible to completely eradicate. The greatest difficulty in containing this species may lie in its ability to generate new suckers after killing. Unlike Baccharis halimifolia, the intervention involved an initial killing activity followed by a periodic check for the removal of new suckers. The planting of native species (trees and shrubs) was also carried out in all abatement areas to limit the growth of black locust suckers through shading.

Robinia pseudoacacia
Cutting of a specimen of Robinia pseudoacacia of medium size.


Published news about C5 action