The potentially invasive alien flora of Algeria: first description of potentially invasive species cultivated in nurseries and gardens

Description of the subject. The potentially invasive alien flora cultivated in the wilaya of Skikda has never previously been the subject of research. In view of the adverse effects this flora has on ecosystems if it becomes invasive, a study was carried out in 60 horticultural localities, spread over 4 nurseries, 54 private gardens and 2 gardens of Skikda University. Objectives. This study aimed to determine the potentially invasive species cultivated in these localities, to study their characteristics, and to estimate their degree of naturalization. Method. A list of potentially invasive species was elaborated on the basis of the international lists appearing in various existing studies. The floristic records specify the biological type and the possible fruiting and regeneration of the seedlings followed in situ. The degree of naturalization of the species was determined by conducting surveys in three municipalities. Results. Fifty species and 43 genera, belonging to 29 botanical families, were identified. The best represented families were Fabaceae, Cactaceae, Myrtaceae and Poaceae. Species of American origin were largely dominant (46%), followed by Asian (26%) and Australian (20%) species, and finally, by those of southern African (8%) origin. All biological types were recorded, with a dominance shown by woody species (66%). Fruiting was observed in 40 species, only 13 of which managed to produce seedlings in the vicinity of the mother plants. Eleven species were naturalized in the sites prospected, 2 were in the process of naturalization, and 37 were non-naturalized species. Conclusions. For the first tune in the region, a preliminary list of potentially invasive species cultivated has been established. This should allow the implementation of an action plan to monitor the cultivation and commercialization of these species.