Popular garden plants threaten biodiversity
IT APPEARS that there is an enormous amount of Japanese Spindle hedging being planted around the island at the moment (that one which at this time of year has shiny and perfect-looking lime-green leaves, called Euonymus japonicus). Without finding criticism, and having no idea why so many home-owners are planting this hedging, it is part of a quickening trend of the replacement of Guernsey's high biodiversity vegetation with increasingly very low biodiversity alternatives. It is an almost invariable rule of thumb that the less native a plant is, the fewer insects and other wildlife will grow on it.
As the island's hedging collectively constitutes a relatively large proportion of the island's habitats, the result of planting so much very poor biodiversity hedging will certainly be fewer insects, birds, bats, hedgehogs – less of everything.
Over only the past few decades the island's high biodiversity hedging types, such as hawthorn, spindle, privet and gorse, have been largely replaced, firstly with lowish biodiversity types such as Elaeagnus, latterly with very low biodiversity hedging from the other side of the planet, such as olearia, pittosporum, griselinia and Euonymus japonica.
We are increasingly seeing non-native invasive plants appearing on the island's cliffs and field borders (Japanese Spindle included), aided by increasingly mild and wet winters and the occasional person who deliberately spreads unused garden seeds.
Garden plants such as stinking onion are now effectively impossible to remove from the wild.
Others, such as montbretia (the one with orange flower spikes), are following. Hottentot fig, Japanese knotweed, German ivy and 15 others, are all well on their way to becoming unstoppable too.
These low-biodiversity non-natives retain their looks and favour with gardeners because nothing grows on them or eats them.
Wildlife suffers, but perhaps a more unfortunate side-effect is that, if these plants escape into the wild they will have an edge over their native competitors.
This can lead to a situation where rampant and uncontrollable very low-biodiversity plants crowd out vast swathes of native high-biodiversity plants, as with Hottentot fig and German ivy.
A 'garden' plant such as Japanese knotweed, which is kept under control in Japan because it is crawling with native invertebrates, becomes invasive when it grows in Guernsey; it has too much surplus vitality because nothing eats it.
It is understood that biodiversity might not be the only valid consideration for the selection of hedging, but it is hoped that this perspective might help inform those with an interest in wildlife.
ANDREW LEE,
Les Salines,
GY4 6DN.
