A Thorny Problem for Biodiversity

Why native plant species can pose a threat to biodiversity.

Thistles, nettles, brambles. They’re such a familiar feature of the UK countryside, it’s easy to overlook them. Yet the evidence shows they’re spreading – with potentially serious implications.

“Our research has revealed that these native plant species currently pose much more of a threat to biodiversity than non-native invasive species,” says Dr Lindsay Maskell, who works on the LWEC-accredited Biodiversity Programme at the Centre for Ecology & Hydrology. “They’re particularly good at extending their influence in places where countryside management is inadequate or nutrient run-off from farmland has increased.”

Underpinning this conclusion are findings from the Countryside Survey, a unique audit of the UK countryside’s natural resources carried out regularly since 1978. The latest survey in 2007 revealed that, while non-native plants like Himalayan balsam are a problem in some localised areas, the main danger is posed by less exotic plants (such as the humble thistle) getting out of control and suppressing other species.

“They’re putting particular pressure on small areas of habitat that can provide a vital refuge for different animals and plants,” Dr Maskell explains. “Safeguarding these areas is crucial because they can act as a ‘pool’ from which damage to biodiversity can be reversed.”

A key part of the solution is to raise awareness of the threat among farmers and other land managers and so encourage initiatives to keep the problem in check.

Dr John Hopkins, Principal Advisor at Natural England, says: “The spread of these invasive native species at the expense of other wildlife reinforces the need for us to improve the management of wildlife habitats and reduce the impact of fertilisers and other pollutants”.