From American racoons to Chinese mitten crabs,Germany is home to over 1300 non-native animals and over 600 non-native plants. Many are harmless,but some of these new arrivals can wreak havoc on the native wildlife.Take the American grey squirrel,which infected its red relation in Britain with a virus. Environmental organisations say that biological globalisation is a serious threat to biodiversity - and likely to increase on account of trade,tourism and climate change.