Delta Life 9

18 DELTARES, APRIL 2018 4 3 2 1 Exotic plants: they look great in the garden but they can overwhelm native species in the wild and even cause flooding when there are too many. What next?  BY ANDREA FORZONI / IMAGE ISTOCKPHOTO FLOODED BY EXOTICS People do not always deliberately contribute to the spread of plants: ships can transport roots and soil containing seeds by accident. Rivers are busy avenues for the spread of exotics. The Japanese Knotweed came to Europemore than a century and a half ago as an ornamental plant. It escaped from the garden and is now found everywhere. Exotics are animals and plants that, as a result of human activities, end up in areas where they don't belong. Some exotic species can damage the local ecosystem, health or safety. Particularly where rivers deposit new sand and silt, pioneer species spread like lightning. Parts of stems and roots grow into new plants. Some species have a real talent in this area. When they also create problems, we describe themas 'invasive species'.