A volunteer army is being sought to help tackle the problems posed by invasive plant species in Chorley.

A year-long project is poised to get under way in the coming weeks – beginning with a mammoth effort to map all of the non-native menaces that have taken root along the banks of some of the borough’s riversides.

The scheme, which is being led by the Lancashire Wildlife Trust (LWT), will involve searching for the likes of Japanese knotweed, Himalayan balsam and giant hogweed in the River Douglas catchment area.  

As well as the Douglas itself, that includes tributaries such as the River Yarrow and River Chor.

The mapping process is expected to take up to four months and LWT’s Wigan Projects Manager Mark Champion is calling for “a collaboration” between all interested parties in order to ensure that the work is a success.

He is inviting councillors, landowners and anybody else with knowledge of where there may be growth of problem weeds – within around 50 metres of the banks of the Douglas or its offshoots – to feed in to the exercise.

Chorley Council estimates that there are around 70 knotweed sites in the borough.

Volunteers will be recruited to help accurately plot these, along with any other, unknown riverside spots where invasive plants can be found.   Mark says that methodical mapping is crucial, because of the ease with which the species in question can spread.

“We need that intelligence of where the hotspots are and where the enemy is.

“You have to work with the flow of the river.   You can’t say: ‘Wow, there is a really big patch of knotweed ay Croston, we will treat that’ – because all that happens is the next piece of broken off stem floating down the river will neatly land back on the bank at Croston.

“And then you will have used tonnes of money getting rid of it, only to have it reseeded – in the broadest sense of the term – from upstream.

“That is why it is important to map it, because if you miss a dirty great patch of it, all your time and energy is wasted,” Mark explains.

It is for that reason that both the mapping and treatment phases of the work have to start at the source of the Douglas, close to Winter Hill, and proceed down through Rivington and the rest of the catchment area.

As a result, it is the upper sections of the Douglas, the Yarrow and the Chor that are likely to benefit first, while areas further downstream might not be reached during the course of the 12-month funded scheme.

That might disappoint those concerned about Japanese knotweed in Croston – not an example Mark chose at random – where there has long been a problem with the species around that part of the Yarrow that flows through the village, prompting fears that it could damage the river’s retaining walls and cause flooding.

However, Mark’s hope is that the systematic approach will pay dividends by demonstrating to those who make funding decisions that it is an effective way of working – and so attract more cash to complete the job across the whole catchment area in future years.

He also believes that it will persuade landowners to support the project by reassuring them that they will not be “wasting their money” on haphazard treatment work that sees the same problem spring up again a few months down the line.

The 2022 project has received cash from the government’s Green Recovery Fund, which has provided approximately £30,000 for LWT to recruit someone to lead the work on behalf of the River Douglas Catchment Partnership.

If all goes to plan, the project should also benefit those creatures that are disadvantaged by the rampant growth of non-native species, as a result of their capacity to crowd out their native counterparts.

“Pollinators are all designed to use native plants – their tongues are the right length to go into native species.

“So when the land gets covered in these things, you lose biodiversity,” Mark adds.

Details of how volunteers can offer their services and interested parties get involved in the project will be published in mid-January.