A new project has been launched to rid the River Wensum of Himalayan balsam - an invasive plant which threatens to choke this delicate ecosystem.
Norfolk Rivers Trust (NRT) and the Norfolk Non-Native Species Initiative (NNNSI) have joined forces to remove and, where possible, eradicate Himalayan balsam from the river catchment.
The project, funded by Anglian Water and launched to coincide with Invasive Species Week, will run until 2025 - aiming to bring together organisations, businesses and community and recreational groups across the Wensum area.
As one of only 200 chalk streams worldwide, the River Wensum is recognised as a globally-important ecosystem, with the mineral-rich water supporting an array of wildlife including water voles, brown trout and white-clawed crayfish.
But balsam threatens the river's ecological balance, growing up to two metres tall in dense stands, with the ability to steal light, space and nutrients from native plants.
The plant can colonise new areas rapidly, using "explosive" seed pods which fling seeds up to seven metres away – releasing as many as 800 seeds per plant. The seeds can also be carried downstream by water, where they will colonise any damp area.
The NNNSI has already been working on balsam hotspots found near Taverham, Lenwade and Lyng.
Martin Horlock, environment manager from Norfolk County Council, said: "We’ve already been controlling balsam in some areas, but since balsam seeds can remain viable in the soil for several years, ongoing removal is critical.
"Co-ordinated control at a catchment-scale is essential for full eradication, and this project enables us to expand efforts to cover the full Wensum area over a number of years.”
The partnership has developed web and mobile apps to encourage the public to report balsam sightings, along with any control work already taking place.
Georgia Waye-Barker, evidence and engagement coordinator for Norfolk Rivers Trust, said volunteer involvement will be a crucial element of the project.
“We’ll be hosting various ‘balsam bash’ events and coordinating work parties in line with Covid-19 guidelines," she said. "Since balsam can be easily identified and uprooted, we’ll also be encouraging landowners and volunteers to take their own action, following a best practice guide that we’ve produced.
"Fortunately, giant leaps in progress can be made over a short period of time, so control work is really quite satisfying."
- For more information, see norfolkriverstrust.org/project/balsam_project
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