Biological invasions to play havoc with future generations
What drives biological invasions? New EU-funded research shows that while globalisation and economic growth fuel these invasions, the older arrivals of alien (non-native) species rather than recent arrivals are responsible for the problems. So there's a stronger link between patterns of established alien species richness and historical, not contemporary, levels of socioeconomic drivers. The study, presented in the journal Proceedings of the National Academy of Sciences (PNAS), has found that the consequences of current high levels of socioeconomic activity on the extent of biological invasions will only be realised in the future, not now. The research is part of the DAISIE ('Delivering alien invasive species inventories for Europe') project, which is supported under the 'Sustainable development, global change and ecosystems' Thematic area of the EU's Sixth Framework Programme (FP6) to the tune of EUR 2.4 million. It is also received support from the ECOCHANGE ('Challenges in assessing and forecasting biodiversity and ecosystem changes in Europe') project, which has clinched EUR 7 million under FP6. Past studies have shown that human economic activities significantly influence the level of biological invasions. That is why much talk has arisen to determine ways to limit such introductions including regulations on trade. However, hold-ups between the initial introduction of a species in a new territory and its establishment and spread indicate that invasions resulting from current economic behaviour may take more time than expected, triggering an 'invasion debt', experts say. For the purposes of this study, the 16-strong research team chose three predictors of socioeconomic activity related to invasions, namely per capita GDP (gross domestic product); human population density; and share of exports in GDP. The biological invasions were examined based on extensive data of alien species from 10 taxonomic groups and 28 European countries, showing patterns of established non-native species. According to the experts, socioeconomic data from 1900, rather than from 2000, can be used to elucidate current alien species richness. The intensity of the historical signal varies between different taxonomic groups, with those possessing good capabilities for dispersal, such as insects and birds, more strongly linked to recent socioeconomic driver levels, the researchers suggest. But their findings point to a significant historical legacy for most species under review. 'The broad taxonomic and geographic coverage indicates that such an "invasion debt" is a widespread phenomenon,' explains Franz Essl from the Austrian Environment Agency, the lead author of the study. For his part, Stefan Dullinger from the University of Vienna, says: 'This inertia is worrying as it implies that current, increased levels of socioeconomic activity will probably lead to continuously rising levels of invasion during the upcoming decades, even if new introductions could be successfully reduced.' In the paper, the scientists write: 'Our data demonstrate that socioeconomic legacies on alien-species richness are important across a broad array of taxonomic groups and might extend back at least one century.' 'This inertia implies that the consequences of the current socioeconomic activity on the extent of biological invasions will not be completely realised until several decades into the future. This finding should not discourage ongoing European and global initiatives to tackle invasions. 'In the long term, a more precise identification and a better control of taxon-specific high-risk introduction pathways and a general reduction of propagule pressure will certainly be key to managing the problems arising from biological invasions. However, our results highlight that even if further unintended introductions could be successfully reduced by these ongoing initiatives, the mid-term impacts of alien species on biodiversity and the economy might even be higher than currently expected.' Scientists from Austria, the Czech Republic, France, Germany, Italy, New Zealand, Spain and Switzerland made strong contributions to the study.
Countries
Austria, Switzerland, Germany, Spain, France, Italy, New Zealand