Understanding the influence of urbanization on the invasive species Carpobrotus edulis
Carpobrotus edulis (Aizoaceae: EPPO List of Invasive Alien Plants) is a succulent plant species native to South Africa. Within the EPPO region the species is invasive in Israel, France, Italy, Malta, Portugal, Spain and the United Kingdom. The species invades coastlines, in particular cliffs and dune systems, and is difficult to control due to the inaccessible areas it grows. The species has a number of negative impacts including modifying the nutrient dynamics, and outcompeting and reducing the fitness of native plant species. It was previously unknown however, if the impacts of C. edulis are greater in areas of human disturbance (for example beaches frequently used for recreation) compared to natural areas. To assess this, six dune sites all invaded with C. edulis were selected in Galicia (Spain): three sites were in urban areas and three were natural sites. At each site, soil characteristics (pH, conductivity, water content, nutrients and enzymatic activities) were measured, and the fitness of native plant species and C. edulis (expressed as germination and early growth) were measured under controlled conditions. At the urban sites, human disturbance had a negative impact on the soil characteristics and the presence of C. edulis increased the negative impact. These changes in soil characteristics allow for the establishment of the native ruderal Scolymus hispanicus, and C. edulis. These results suggest that human disturbed coastal areas might be more easily invaded than natural areas.
Sources
Lechuga-Lago Y, Novoa A, Le Roux JJ, González L (2017) Understanding the influence of urbanization on invisibility: Carpobrotus edulis as an exemplar. Biological Invasions, DOI: 10.1007/s10530-017-1593-z.