My last post was a gentle introduction to the topic of INNS (invasive non-native species) and the problems which they can have on vulnerable ecosystems. INNS affect us all and in Britain cost in the region of £1.7 billion each year. The impact of INNS on biodiversity, our environment and infrastructure are severe and growing. Once a species has been introduced the problems persist and escalates as it spreads. Control and eradication are often difficult and expensive, but there are steps that we can take to limit their spread.
Fortunately geography is on our side and the islands of the Outer Hebrides have only been affected by a limited number of INNS. Our problems are not as serious as in other parts of Scotland and so far we have not been invaded by giant hogweed although both Himalayan balsam and Japanese knotweed have now arrived. Our major thugs are Rhododendron ponticum and Gunnera and my particular bête noire Crocosmia.
Rhododendrons were originally planted in the last century as cover for game, whilst Gunnera and Crocosmia, along with Cortaderia (pampas grass) are all garden escapes, albeit with a little help over the garden fence in some cases.
Identifying the big thugs is easy, but some like Canadian Waterweed Elodea canadensis and Nuttall’s Waterweed Elodea nuttallii are more insidious and difficult to identify. So before we (the amateur naturalists of Outer Hebrides Biological Recording) could add these species to our monitoring blacklist we had to learn how to identify them.
Now on with the wellies and into the loch