Meggin Leigh:
You're an expert on plant species. Is it really the case that foreign species completely wipe out domestic ones?
Ingolf Kühn:
It really depends where you are. In Central Europe it's less of a problem because there is just a small proportion of alien plant species that really cause economic or ecological problems in native ecosystems. But if you go to the United States, Australia or New Zealand, substantial parts of the landscape are covered by alien species, completely eradicating - locally, at least - native species.
Having said that, what are then the concrete dangers of invading species?
There are several. For example, there are parts in Australia and New Zealand which are completely covered by European broom. There is gorse covering large parts of Oregon threatening native species. But also there are health problems, for example, by alien ragweed or giant hogweed.
What are the health problems?
Giant hogweed for example can cause severe skin irritation, whereas ragweed is one of the most allergenic plant species. And additionally it's not only allergenic, but it also flowers in September, November, so when usually the allergy season is over in Central Europe.
Well it can't all be bad, there must be some positive examples.
I'm not sure whether there are really positive examples, but there are cases in which alien species are - let's say - necessary for example to restore ecosystems in opencast mining systems. Here environmental conditions are so harsh that there is hardly any native plant species that could cope with these environmental conditions.
But surely this adds to biodiversity, these foreign species.
It adds to local biodiversity, but the problem is that it also homogenizes global biodiversity. Then it might happen that you go all over the globe and see the same species everywhere.
On a political level, what kinds of measures are being taken to prevent invasions by non-native species?
Currently there is a European Union regulation on invasive alien species. There's just the problem that the current suggestion restricts the number of species that needs to be taken care of to 50 - and this is just a political measure, because having more species on there would be too costly. But in fact it could be more than a hundred where European action might be necessary.
What role does climate change play in preventing invasions of foreign species?
Climate change probably would facilitate biological invasions because most of the plant species are from warmer climates. Nevertheless under climate change we are probably also going to lose some of the native species, so there might be the need for alien species of neighboring countries to enter the country to replace ecosystem functioning of native species.
Briefly, what does the future of invasions look like?
It's likely to increase due to mounting traffic and to climate change.
(Interview by Meggin Leigh)