There’s a lot of nonsense talked about invasives so it’s refreshing to see one of Britain’s most respected botanists talking some real sense. David Pearman is a former President of the Botanical Society of the British Isles and a leading light in the development and publication of one of the most vital British plant publications of our times, the New Atlas of the British and Irish Flora.

In a piece entitled The Alien Invasion Myth which appears in the current issue of The Garden, the membership magazine of the Royal Horticultural Society, he writes: “For the last 20 years I have coordinated our Society’s largest network of botanical recorders (from the Botanical Society of the British Isles): together we have accumulated about 18 million records, covering the entire area and 4,000 species. In simple terms, the data shows that most aliens are rare; that they occur overwhelmingly in and around towns and transport networks; and they are generally uncommon in the semi-natural habitats that we most want to preserve. Recording alien plants is, broadly, a recent phenomenon, and all extrapolations are to be taken with a pinch of salt.”

He goes on: “But the real, inescapable line is that our countryside and flora is changing like never before, mainly from abandonment of traditional management practices and pollution. It is largely ‘native’ plants that are to blame – look at the chalk downlands of southern England (choked with gorse on the dip slopes) or our rivers (a vast increase in reeds, due to higher nutrients).”

Of course the situation is slightly different in North America where there’s more genuinely natural habitat; in Britain almost all habitats are, as he puts it, “semi-natural” – most woodlands, meadows, mountains and aquatic habitats show the hand of man in some form. But in North America there’s also a tendency to rip out any non-native plant that turns up before anyone has had the chance to record its distribution or study its tendency to spread – or, perhaps, its tendency simply to fade away.

Changes in management, and pollution, are the drivers of change in Britain’s natural habitats, says David Pearman. We can hardly blame plants for what happens as a result.

Himalayan balsam image by ArtMechanic used under the Creative Commons Attribution-Share Alike 3.0 Unported license. Thank you.