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Alien species on the rise worldwide
Frankfurt, Germany, 02/15/2017. The increase in numbers of alien species does not show any sign of saturation at a global level, an international team of 45 researchers led by scientists from Senckenberg, Germany, and University of Vienna, Austria, has discovered. They found that during the last centuries the number of new introductions has continuously increased worldwide, with more than a third of all first introductions recorded between 1970 and 2014. Although individual trends differ among taxonomic groups, the ongoing increase in alien species numbers is still visible for all groups of organisms. The study is published in Nature Communications.
Although it was known that the number of alien species increased during the last decades, it remained unclear whether or not the accumulation of alien species has already reached a point of slow-down. Dr Hanno Seebens from Senckenberg, Germany, first author a new study on the topic has an answer now: “For all groups of organisms on all continents, the number of alien species has increased continuously during the last 200 years. For most groups, even the rate of introduction is highest recently. Barring mammals and fishes, there are no signs of a slow-down and we have to expect more new invasions in the near future.”
His outlook comes at the end of a large collaborative effort in which 45 scientists from all over the world established a database of the date an alien species was first detected in a region outside the species’ native range. Using more than 45.000 of these first records of more than 16.000 alien species, they analysed the development of alien species accumulation during the last centuries.
They found that 37% of all recorded alien species have been introduced between 1970-2014 and thus recently. At its peak 585 new species were recorded within one year. This corresponds to more than 1.5 new alien species per day globally. “As the date of first record is not available for most alien species, these numbers are clearly underestimating the full extent of alien species introductions”, says Dr. Franz Essl from the University of Vienna, Austria, senior author of the study.
The trends of increase vary among taxonomic groups, which can be attributed to human activities. “We observe a distinct increase in first record rates of vascular plants in the 19th century, probably as a result of the intensification of horticulture. The rates of new introductions of other organisms such as algae, molluscs or insects increased steeply after 1950. This is most likely a consequence of the ongoing globalisation of trade,” explains Seebens.
The unprecedented increase in alien species numbers can lead to an increase in regional species richness. However, these come at the cost of a variety of negative impacts on native ecosystems, the global homogenisation of floras and faunas, and the global extinction of native biota. Therefore various legislations are currently in force globally attempting to mitigate the introduction of new alien species. “However our results show that the past efforts have not been effective enough to keep up with ongoing globalisation. There is an urgent need to implement more effective prevention policies at all scales”, concludes Essl.
The rose-ringed parakeet is native to parts of Africa and Asia. It was introduced as an ornamental species and has established populations at various sites in Europe, North America and Australia. Photo: Tim M. Blackburn, University College London
The eastern grey squirrel, originally from North America, was introduced to various locations worldwide including the UK, where it has largelydisplaced the native red squirrel. Photo: Tim M. Blackburn, University
Garden lupine (Lupinus polyphyllus) in extensively used mountain hay meadows in the The Katzbach Mountains in Poland. In Europe this species has been planted as a fodder crop and as an ornamental, and is now widely naturalized. Photo: Barbara Tokarska-Guzik, University of Silesia in Katowice
A large population of American pokeweed (Phytolacca americana) in Hungary. This toxic plant is native to North America and was grown for ornamental and medicinal purpose in Europe. Photo: Petr Pyšek, The Czech
Dr. Hanno Seebens
Seebens, H. et al. (2017): No saturation in the accumulation of alien species worldwide, Nature Communications, doi:10.1038/ncomms14435
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To study and understand nature with its limitless diversity of living creatures and to preserve and manage it in a sustainable fashion as the basis of life for future generations – this has been the goal of the Senckenberg Gesellschaft für Naturforschung (Senckenberg Nature Research Society) for 200 years. This integrative “geobiodiversity research” and the dissemination of research and science are among Senckenberg’s main tasks. Three nature museums in Frankfurt, Görlitz and Dresden display the diversity of life and the earth’s development over millions of years. The Senckenberg Nature Research Society is a member of the Leibniz Association. The Senckenberg Nature Museum in Frankfurt am Main is supported by the City of Frankfurt am Main as well as numerous other partners. Additional information can be found at www.senckenberg.de.
200 years of Senckenberg! 2017 marks Senckenberg’s anniversary year. For 200 years, the society, which was founded in 1817, has dedicated itself to nature research with curiosity, passion and involvement. Senckenberg will celebrate its 200-year success story with a colorful program consisting of numerous events, specially designed exhibitions and a grand museum party in the fall. Of course, the program also involves the presentation of current research and future projects. Additional information can be found at: www.200jahresenckenberg.