The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) has launched its new assessment on invasive alien species on 4 September 2023. Biodiversa+ proposes to highlight concrete examples and pathways at pan-European level to better understand this main driver of biodiversity loss worldwide.
Invasive alien species are one of the five major direct drivers of biodiversity loss globally, alongside land-and sea-use change, direct exploitation of organisms, climate change, and pollution[1]. Target 6 of the recently adopted Kunming-Montreal Global Biodiversity Framework is to “eliminate, minimize, reduce and or mitigate the impacts of invasive alien species on biodiversity and ecosystem services”. The IPBES Invasive Alien Species Assessment responds to the need to support decision-makers in understanding the current status and trends of invasive alien species, their impacts, their drivers, management, and options for policy that effectively deal with the challenges they pose.
The European Biodiversity Partnership Biodiversa+ had identified early on the need to characterise the impacts of biological invaders and identify levers for mitigating and/or reversing their impacts, and 9 projects were selected in 2013 under the call “BiodivInvasives” for 8.9 M€. 25 scientific and peer-reviewed publications resulting from the BiodivInvasives projects were used in the assessment, demonstrating their relevance and quality for the comprehensive work undertaken by IPBES. Moreover, experts involved in those projects were also chosen to be authors in the assessment.
For instance, the project WhoIsNext investigated the potential establishment and invasiveness of various ornamental plant species under climate change, and which regions of Europe will most likely be affected by invasions. They analysed thousands of alien species in the European garden flora and showed that the success of these species naturalising (transitioning from cultivation into native ecosystems) are mainly determined by climate suitability and nursery availability. With climate projections for 2050 the researchers could forecast future naturalisation risks for 1,583 ornamental alien species not yet naturalised in Europe.[2] They also analysed the effectiveness of policy instruments that tackle invasions along the horticulture supply chain. They found that (i) effective pre-border interventions rely on rigorous risk assessment and high industry compliance, (ii) post-border sales bans gradually lose effectiveness when alien species become widespread in a region and that (iii) a lack of independent performance evaluation and of public disclosure limits the uptake and effectiveness of voluntary codes of conduct and discourages shifts in consumer preference away from invasive alien species.[3]
The lead-principal investigator of the WhoIsNext project, Prof. Mark van Kleunen of the University of Konstanz, points out that in the case of plants, many of the potential future invaders are already growing in our gardens. This means that when the climate becomes more suitable, these species only need to jump the garden fence. Therefore, prevention of new plant invasions should not only focus on new introductions but also requires the help of gardeners and the ornamental horticulture to prevent garden escapees.
Other interesting examples come from the project FFII, Forecasting Future Invasions and their Impacts, which paid a particular attention to patterns, processes and the impacts of biological invasions globally. They identified three essential variables for monitoring biological invasions: alien species occurrence, species’ alien status and alien species impact[4]. They proposed a standardised method for classifying alien taxa in terms of the magnitude of their impacts on human well-being, using changes in peoples’ activities as a common metric for evaluating impacts on well-being[5]. They classified the impacts of amphibians globally with this method and found that the cane toad (Rhinella marina) scored “major impacts” (fourth level on the scale from “minimal concern” to “massive impact”).
In a more recent call by Biodiversa+ and the Belmont Forum for research on scenarios, the project AlienScenarios evaluated the range of plausible futures of biological invasions and warned that improved international cooperation is crucial to reduce the impacts of invasive alien species on biodiversity, ecosystem services, and human livelihoods[6]. Indeed, invasive alien species can affect the composition and abundance of native species, increase the risk of native species extinction, affect the genetic makeup of native populations, change native animal behaviour, alter phylogenetic diversity across communities, and modify trophic networks. Many invasive alien species can reshape ecosystem operations and the provisioning of ecosystem services by altering nutrient and contaminant cycling, hydrology, habitat structure, and disturbance regimes. These impacts on biodiversity and ecosystems are accelerating and are projected to intensify in the coming years. They point out that countries can strengthen their biosecurity regulations to implement and enforce more effective management strategies that should also address other global changes that interact with invasions.
Franck Courchamp, principal investigator of FFII, member of AlienScenarios and researcher at CNRS, points out the need for funding allowing international collaboration “We were able to collaborate at the European level to predict which species were likely to become future invaders and where, something that individual teams alone would have struggled to achieve.”
Curious about the AlienScenarios project? Discover the short animated video about the project below, and find out about its 4 possible scenarios for the future of biological invasions!
[1] As identified in the 2019 IPBES Global Assessment Report
[2] Haeuser, E., Dawson, W., Thuiller, W., Dullinger, S., Block, S., Bossdorf, O., … & van Kleunen, M. (2018). European ornamental garden flora as an invasion debt under climate change. Journal of Applied Ecology, 55(5), 2386-2395. https://doi.org/10.1111/1365-2664.13197
[3] Hulme, P. E., Brundu, G., Carboni, M., Dehnen‐Schmutz, K., Dullinger, S., Early, R., … & Verbrugge, L. N. (2018). Integrating invasive species policies across ornamental horticulture supply chains to prevent plant invasions. Journal of applied ecology, 55(1), 92-98. https://doi.org/10.1111/1365-2664.12953
[4] Latombe, G., Pyšek, P., Jeschke, J. M., Blackburn, T. M., Bacher, S., Capinha, C., … & McGeoch, M. A. (2017). A vision for global monitoring of biological invasions. Biological Conservation, 213, 295-308. https://doi.org/10.1016/j.biocon.2016.06.013
[5] Bacher, S., Blackburn, T. M., Essl, F., Genovesi, P., Heikkilä, J., Jeschke, J. M., … & Kumschick, S. (2018). Socio‐economic impact classification of alien taxa (SEICAT). Methods in Ecology and Evolution, 9(1), 159-168. https://doi.org/10.1111/2041-210X.12844
[6] Pyšek, P., Hulme, P. E., Simberloff, D., Bacher, S., Blackburn, T. M., Carlton, J. T., … & Richardson, D. M. (2020). Scientists’ warning on invasive alien species. Biological Reviews, 95(6), 1511-1534. https://doi.org/10.1111/brv.12627
