No saturation in the accumulation of alien species worldwide
The movement of species beyond their native ranges has increased significantly over the last centuries with prominent factors leading to the accumulation of certain taxa. For example, in the ninetieth century plant hunters increased the number of plant species brought into Europe and the trade in exotic bird species in South East Asia has led to established populations. Invasive insects have been introduced in more recent times through increased trade and travel pathways. Using a dataset of 45 813 first records of 16 926 established alien species from a wide range of taxonomic groups and non-overlapping geographical regions from all continents, the development of alien species accumulation was assessed. One key prediction, which was tested with this large dataset was that the rates of introductions of species often intentionally introduced, for example mammals, birds and vascular plants, would have declined in recent years due to increased awareness. This was however, not the case. 37 % of all recorded alien species have been introduced between 1970 – 2014 even though there has been an increase in national legislation and international agreements over the last 100 years. There are exceptions to this trend, where the authors highlight a decrease in the number of first records of vascular plant species in New Zealand in the 1990s corresponding to the implementation of the Biosecurity Act (1993) which is based on a white list of permitted species compared to a black list of unwanted species. In New Zealand, any non-listed species would need to be risk assessed before entry is allowed. The authors highlight that pathways of introduction for invasive species into new regions are changing because of increased anthropogenic pressures and climate change and there is a need to implement more effective prevention policies at all scales.
Sources
Seebens H, Blackburn TM, Dyer EE, Genovesi P, Hulme PE, Jeschke JM, Pagad S, Pyšek P, Winter M, Arianoutsou M, Bacher S, Blasius B, Brundu G, Capinha C, Celesti-Grapow L, Dawson W, Dullinger S, Fuentes N, Jäger H, Kartesz J, Kenis M, Kreft H, Kühn I, Lenzner B, Liebhold A, Mosena A, Moser D, Nishino M, Pearman D, Pergl J, Rabitsch W, Rojas-Sandoval J, Roques A, Rorke S, Rossinelli S, Roy HE, Scalera R, Schindler S, Štajerová K, Tokarska-Guzik B, van Kleunen M, Walker K, Weigelt P, Yamanaka T, Essl F (2017) No saturation in the accumulation of alien species worldwide. Nature Communications. DOI: 10.1038/ncomms14435