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Alien invaders threaten Norfolk Broads

PUBLISHED: 09:33 26 June 2009 | UPDATED: 10:25 06 July 2010

A volunteer removes floating pennywort from the Broads

A volunteer removes floating pennywort from the Broads

They might look a picture in your pond but they have the potential to cause havoc across the Broads.Many are freely available in garden centres and their exotic names, like parrot's feather and Australian swamp stonewort, carry not a hint of danger.

They might look a picture in your pond but they have the potential to cause havoc across the Broads.

Many are freely available in garden centres and their exotic names, like parrot's feather and Australian swamp stonewort, carry not a hint of danger.

However, when allowed to grow unchecked, such alien species can easily clog up waterways, rendering fishing and navigation by boats impossible, and the choking of drainage channels can even increase the risk of flooding.

A new report highlighting the threat of non-native plant species to the Broads landscape warns that dealing with it is already costing the Broads Authority tens of thousands of pounds a year.

Its author, Mike Sutton-Croft, who has been employed by Natural England to manage the Norfolk Non-Native Species Initiative (NNNSI), a three-year action plan to meet the threat, said: “The public has a key role to play in this as most of the plants causing the problems start out in garden ponds.

“Because they are non-native species there is nothing to impede their growth and they can quickly take over ponds. People then think that because they are pretty plants they will dump them somewhere rather than composting them in their garden, which is what we would ask them to do.”

Andrea Kelly, the Broads Authority's head of conservation, said: “We would also like to work with garden centres and introduce an accreditation scheme for ones that don't stock invasive plants.”

She warned that the risk of such plants taking hold quickly was heightened by the fact that water quality in the Broads was returning to a level not known for many years.

In a report to today's meeting of the Broads Authority, Mr Sutton-Croft highlights five species - floating pennywort, giant hogweed, Himalayan balsam and Japanese knotweed as well as Australian swamp stonecrop and parrot's feather - that pose the biggest threat.

He warns that the Broads is experiencing an unprecedented increase in invasive non-native species that are “rapidly dominating areas of our waterways” - pennywort, which originated from North America, can grow up to 20cm a day,

The potential economic impact of invaders is highlighted by the Olympic site at Stratford, in London, where the cost of clearing Japanese knotweed has exceeded £70m.

Mr Sutton-Croft said it was only by swift Broads Authority action, using Defra funding, that the threat of pennywort had been contained on the River Waveney.

He said: “It is critical that the Broads Authority is involved in the removal of this species at an early stage as control in the lower reaches of our waterways may be impossible and the consequences of not acting early or in partnership will be severe.”

The NNNSI is holding a countywide day of action on July 5 and the Broads Authority has organised an event for volunteers to go and help clear rhododrendon from Fritton Lakes country park. For details, log on to Mr Sutton-Croft's website, www.norfolkbiodiversity.org

Anyone spotting invading species on the Broads is asked to email him at michael.sutton-croft@norfolk. gov.uk

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