The invasion history of Elodea canadensis and E. nuttallii (Hydrocharitaceae) in Italy from herbarium accessions, field records and historical literature

We analysed the invasion history of two North American macrophytes (Elodea canadensis and E. nuttallii) in Italy, through an accurate census of all available herbarium and field records, dating between 1850 and 2019, and a rich literature col- lection describing the initial introduction and natu- ralisation phase that supports the results obtained by the occurrence records. Elodea canadensis arrived in Italy before 1866 and had two invasion phases, between the 1890s and 1920s and between the 1990s and 2000s; E. nuttallii, probably arrived in the 1970s, started invading in 2000 and the invasion is still ongoing. Botanical gardens and fish farming played a crucial role in dispersal and naturalisation of both species. The current invasion range of both species is centred in northern Italy, with scattered occurrences of E. canadensis in central and southern regions. River Po represents a dispersal barrier to the Medi- terranean region and a strategic monitoring site to prevent the invasion in the peninsula. The study detects differences in the niches of the two species during the introduction and naturalisation phase and a habitat switch occurred after 1980 in E. canadensis and after 2000 in E. nuttallii, during their expansion phases. For E. canadensis the switch corresponds to the second invasion round. Further research can clarify whether the second invasion round is due to confusion of the recently introduced E. nuttallii with E. canadensis, to a cryptic introduction of a new genotype, to post-introduction evolution, or just to an increased scientific interest in biological invasions

La dimensione storica delle invasioni nelle acque dolci italiane

none51noneCarla Lambertini, Fabrizio Buldrini, Martina Barbero, Alessandro Chiarucci, Juri Nascimbene, Alessandro Alessandrini, Lucia Amadei, Sebastiano Andreatta, Nicola Maria Giuseppe Ardenghi, Stefano Armiraglio, Simonetta Bagella, Rossano Bolpagni, Ilaria Bonini, Daniela Bouvet, Lisa Brancaleoni, Giuseppe Brundu, Massimo Buccheri, Gabriella Buffa, Simona Ceschin, Annalena Cogoni, Gianniantonio Domina, Luigi Forte, Riccardo Guarino, Leonardo Gubellini, Laura Guglielmone, Nicole Hofmann, Mauro Iberite, Lorenzo Lastrucci, Fernando Lucchese, Rossella Marcucci, Giacomo Mei, Umberto Mossetti, Nicodemo Giuseppe Passalacqua, Simonetta Peccenini, Filippo Prosser, Gianni Repetto, Gabriele Rinaldi, Enrico Romani, Leonardo Rosati, Annalisa Santangelo, Anna Scoppola, Giovanni Spampinato, Adriano Stinca, Maria Tavano, Caruso Fulvio Tomsich, Roberta Vangelisti, Roberto Venanzoni, Marisa Vidali, Thomas Wilhalm, Francesco Zonca, Giovanna PezziLambertini, Carla; Buldrini, Fabrizio; Barbero, Martina; Chiarucci, Alessandro; Nascimbene, Juri; Alessandrini, Alessandro; Amadei, Lucia; Andreatta, Sebastiano; Maria Giuseppe Ardenghi, Nicola; Armiraglio, Stefano; Bagella, Simonetta; Bolpagni, Rossano; Bonini, Ilaria; Bouvet, Daniela; Brancaleoni, Lisa; Brundu, Giuseppe; Buccheri, Massimo; Buffa, Gabriella; Ceschin, Simona; Cogoni, Annalena; Domina, Gianniantonio; Forte, Luigi; Guarino, Riccardo; Gubellini, Leonardo; Guglielmone, Laura; Hofmann, Nicole; Iberite, Mauro; Lastrucci, Lorenzo; Lucchese, Fernando; Marcucci, Rossella; Mei, Giacomo; Mossetti, Umberto; Giuseppe Passalacqua, Nicodemo; Peccenini, Simonetta; Prosser, Filippo; Repetto, Gianni; Rinaldi, Gabriele; Romani, Enrico; Rosati, Leonardo; Santangelo, Annalisa; Scoppola, Anna; Spampinato, Giovanni; Stinca, Adriano; Tavano, Maria; Fulvio Tomsich, Caruso; Vangelisti, Roberta; Venanzoni, Roberto; Vidali, Marisa; Wilhalm, Thomas; Zonca, Francesco; Pezzi, Giovann

Invasion trends of aquatic Ludwigia hexapetala and L. peploides subsp. montevidensis (Onagraceae) in Italy based on herbarium records and global datasets

Identifying areas susceptible to invasion by an alien species is a strategy of prevention. We used national herbaria and global databases to assess the invasion trends of the two aquatic invasive species Ludwigia hexapetala and Ludwigia peploides subsp. montevidensis in Italy. We defined the invasion status with invasion curves and predicted potentially suitable areas with Species Distribution Models based on WorldClim variables and the human footprint index. Low seasonal variation in temperature and precipitation, temperature ≥ 20 °C in the driest period of the year and low precipitation in the coldest period are the bioclimatic factors that most account for the potential distribution of the two species. The human footprint has a lower relative importance than bioclimatic variables. All Italian peninsula appears as a suitable bioclimatic environment for the invasion of the two Ludwigia species, with over 90% of areas with high suitability lying below 600 m altitude. Only mountain regions and the islands appear less suitable. The agricultural land at the foothill of the Appennine in the Mediterranean region is the most vulnerable to the invasion. Considering the trend of the invasion curves, which have been sharply rising for the latest decades, there are reasons to expect that the alien Ludwigia species will continue their expansion, if no timely and effective actions are taken. Informative campaigns, accurate monitoring and prompt management are fundamental preventive tools in areas predicted as vulnerable to invasion by this study