Summer temp journalists are here again. Today, Swedish Broadcasting’s radio news ran a really silly piece about invasive species. It made two main points: a new foreign species of plant or animal is discovered every month in Sweden, and some of them are poisonous. It’s basically a case of botanical xenophobia. The journalist also made the astonishing claim that these poisonous species pose a threat to the country’s biodiversity!
Poisonous plants and venomous animals are rare in Sweden, whose flora and fauna are quite poor because of the cold climate. On the other hand they are common in rich tropical biotopes. And the reason that biodiversity is plummeting in the Amazon certainly isn’t the presence of venomous frogs.
Invasive species of course increase an area’s biodiversity, at least in the short-term perspective. People are looking at ecology on the wrong scale level. Wait a thousand years before you decide whether a new arrival is good or bad. Almost all of Scandinavia was under two kilometres of ice until 10,000 years ago, which means that our ecosystem is a recent cobbling together of whatever species happened to be available when the ice melted. Nature’s way is continuous change. And to see a stable ecosystem re-established now, people would simply have to move out.