Cortaderia selloana in southern France
Cortaderia selloana (Poaceae: EPPO List of Invasive Alien Plants) is a South American native species and a popular garden ornamental which has also been utilised as a windbreak and a sand bank stabiliser species. The species has been commonly planted along roadsides in the Mediterranean region. In the current study, the authors set out to evaluate if urban areas are a source of C. selloana propagules which then spread into natural habitats. The study was conducted in Camargue in southern France in a 600 km2 area of the delta of the Rhone river. Between 2002 and 2013 (September to November each year) C. selloana was surveyed using distance sampling techniques (a method to estimate the density of biological populations using measured distances to individuals in the population). A total of 1 285 points were sampled, and from each point the recorder searched for C. selloana stands using binoculars. In 2002, 216 planted stands were recorded growing in home gardens, parks and roundabouts along with 853 naturalised stands which were closely associated with anthropogenic habitats around urban areas. In 2013, the distribution of planted stands was similar to 2002, with 241 planted stands observed and 1074 naturalised stands (with over 85 % of these associated with anthropogenic habitats around urban areas). Therefore, in 2002 and 2013, less than 15 % of the naturalised individuals occurred in natural habitats. This highlights that in this study, spread of C. selloana from urban areas to natural habitats is low and remains closely associated with anthropogenic habitats.
Sources
Charpentier A, Kreder M, Besnard A, Gauthier P, Bouffet C (2020) How Cortaderia selloana, an ornamental plant considered highly invasive, fails to spread from urban to natural habitats in Southern France. Urban Ecosystems. https://doi.org/10.1007/s11252-020-01003-4