07.05.2014 | Media Release

How to quantify the impact of alien species

Non-native species cause changes in our ecosystems to which they are introduced. But there is a large gap in the understanding of these changes to biodiversity and ecosystems because the impacts are often not clearly defined. As the very first outcome, the Synthesis Centre of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig submits two publications how to define and classify the impacts of non-native species.

One of the major transformations of the planet from human activities is the wholesale redistribution of species, through the deliberate or accidental translocation of their populations to areas outside their native range. Some of these so called “alien species” cause substantial deleterious impacts to the environment – e.g. extinctions of native populations and species or the disruption of soil nutrient and water cycling.

For instance, between 600,000 and 800,000 North American Raccoons (Procyon lotor) live in Germany. They are omnivorous, they eat almost everything, they are very widespread, can carry animal diseases and they use almost all different kinds of resting places, like caves, burrows, fox dens or even buildings. But how large is their impact on other species and the ecosystem as a whole? How to assess and evaluate the impact of introduced species in general? A timely and important question for policy and the public, given the huge amount of introduced species everywhere in the world in the era of the Anthropocene.

As the very first outcome of the Synthesis Centre for Biodiversity Sciences (sDiv), the international sDiv workshop sImpact produced two publications in leading ecological journals, PLoS Biology and Conservation Biology. In these publications, common frameworks how to classify (1) and to define (2) the impacts of alien species are proposed.

The international team of leading experts from four continents proposes a pragmatic solution to this problem. They define scenarios describing increasing levels of impact on native species by different mechanisms. Scenarios are designed so that successively higher categories reflect an increase in the order of magnitude of the particular impact mechanism (impacts on native individuals, populations, communities), so that the magnitudes of impacts caused by different mechanisms are directly comparable. A species assigned to a higher impact category is considered to have had a greater deleterious impact on some aspect of an environment in which it is alien than a species in a lower impact category.

This work is funded by sDiv, the Synthesis Centre for Biodiversity Sciences, which is a subunit of the newly established German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by the German Science Foundation and coordinated by Dr. Marten Winter. Embedded in the active research environment of iDiv, sDiv offers international workshops, PostDoc positions and a sabbatical program to catalyze theoretical and synthetic thinking about biodiversity. As an additional "think tank", it brings together researchers from different projects and disciplines, and creates conditions that promote a creative process. The centre is open to everyone and supports national as well as international working groups focusing on theory-driven synthesis projects. These working groups can be supported by PostDocs and integrate leading scientists in a sabbatical program. Since its start, sDiv already welcomed 422 workshop participants from 33 countries, while supporting 16 workshops, 10 PostDocs and two sabbatical professors.

Blackburn, T.M.; Essl, F.; Evans, T.; Hulme, P.E.; Jeschke, J.M.; Kühn, I.; Kumschick, S.; Marková, Z.; Mrugała, A.; Nentwig, W.; Pergl, J.; Pyšek, P.; Rabitsch, W.; Ricciardi, A.; Richardson, D.M.; Sendek, A.; Vilà, M.; Wilson, J.R.U.; Winter, M.; Genovesi, P.; Bacher, S.: A Unified Classification of Alien Species Based on the Magnitude of their Environmental Impacts. PLoS Biology.

Jeschke, J.M.; Bacher, S.; Blackburn, T.M.; Dick, J.T.A.; Essl, F.; Evans, T.; Gaertner, M.; Hulme, P.E.; Kühn, I.; Mrugała, A.; Pergl, J.; Pyšek, P.; Rabitsch, W.; Ricciardi, A.; Richardson, D.M.; Sendek, A.; Vilà, M.; Winter, M.; Kumschick, S.: Defining the Impact of Non-Native Species. Conservation Biology.

Contact for queries:
Dr. Marten Winter
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
Email: marten.winter@idiv.de
Phone: +49 341 9733129

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