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There's a particular kind of knowledge that comes from walking the same path repeatedly, isn't there? You remember where the bank gets muddy after rain. You recognise the tree bent across the beck, the patch of wild garlic beneath the wall and the place where the curlew can usually be heard before it is seen.
Then, one day, something appears that wasn't there before.
Perhaps it's a stand of tall pink flowers gathering beside a watercourse. Perhaps an unfamiliar plant has taken hold at the edge of a field or woodland. Perhaps something moving beneath the water doesn't resemble the native wildlife that you know should inhabit it.
It's this everyday familiarity with place that Nidderdale National Landscape hopes to mobilise as it asks farmers, landowners, anglers, walkers and local communities to record sightings of invasive non-native species across the dale.
The appeal, made during Invasive Species Week, is intended to help build a clearer map of what's already established in Nidderdale, what might be spreading and where practical intervention could be most effective.
People are being encouraged to submit sightings through INNS Mapper, a free national app and website used to record invasive plants and animals.
The task sounds modest: notice something, photograph it if safe to do so, record its location and submit the information. Collectively, however, those individual observations could become an important body of local evidence. That'sCitizen Science!
“Good records are one of the most useful tools we have when it comes to understanding invasive species,” explains our NL chum Matt Trevelyan, Farming in Protected Landscapes officer for Nidderdale National Landscape.
“They show us where the problem is, where it may be spreading and where there are gaps in local information.”
Conservation is often presented as something done by specialists: ecologists conducting surveys, organisations developing management plans and trained teams carrying out work on the ground. All of that expertise is essential of course.
But people who spend their lives within a landscape possess another form of knowledge. A farmer knows the boundaries, wet corners and changes within their land. An angler observes the condition of a river over months and years. A regular walker notices when a plant begins crowding a path or spreading along a bank. And that knowledge might be informal, but it is not insignificant. (Just ask Michael Pattinson.)
“People who live, work or spend time in the landscape are often the first to notice when something appears in a new place or starts spreading along a riverbank, path, field edge or woodland,” says Matt.
“By taking a few minutes to record a sighting through INNS Mapper, people can help build a much clearer picture of what is happening across Nidderdale.”
This doesn't mean asking the public to become amateur enforcement officers or to begin uprooting plants they can't confidently identify.
It means recognising that thousands of ordinary journeys through the dale produce observations which, if recorded consistently, could help the National Landscape team and its partners understand where attention is most urgently needed.
A map created in this way isn't merely a collection of coloured dots. It can reveal patterns: a plant progressing along a watercourse, a previously unrecorded population or a gap between known areas of infestation.
It can also provide the evidence needed to begin conversations with landowners, farmers, community organisations and conservation bodies about coordinated action.
Perhaps the most recognisable of Nidderdale’s invasive plants is Himalayan balsam.
With its tall stems, pink helmet-shaped flowers and seed pods that burst when touched, it might appear attractive. Its rapid spread along riverbanks, however, creates serious problems for native vegetation and the physical stability of the banks themselves.
Himalayan balsam forms dense stands which can crowd out smaller native plants. When it dies back during winter, it leaves areas of bare earth with fewer roots to hold the soil together. On the edge of a watercourse, that can make a bank more vulnerable to erosion.
Its ability to disperse seeds explosively gives the plant an additional advantage. Water then provides an efficient transport system, carrying those seeds downstream and allowing one infestation to contribute to another.
This is why isolated attempts to remove it can have limited effect if substantial growth remains farther upstream. Successful control requires persistence, good timing and coordination across neighbouring stretches of land. There's no dramatic one-day solution. Instead, there may be repeated seasons of hand-pulling, careful monitoring and returning to locations where seeds left in the soil can produce further growth.
For eligible farmers, landowners and land managers, support may be available through the Farming in Protected Landscapes programme for practical Himalayan balsam control, including properly planned hand-pulling projects.
“There is no single solution to invasive species,” Matt explains.
“Some are already well established and need long-term, coordinated work, while others can be tackled more effectively if they are picked up early.
“For Himalayan balsam, practical action such as hand-pulling can still be one of the most effective approaches where it is well planned and carried out at the right time.”
And it's Matt's phrase - well planned - that's especially important.
Removing balsam from one section of riverbank while leaving a large source population immediately upstream is unlikely to deliver a lasting result. Neither is pulling it after the plant has released its seeds.
Effective control requires an understanding of the wider watercourse rather than treating each patch as an entirely separate problem.
That's precisely where better records can help.
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Himalayan balsam might already be widespread, but Nidderdale’s invasive species problem isn't confined to one highly visible plant.
Japanese knotweed and Himalayan knotweed have both been confirmed within the National Landscape. Their capacity for vigorous growth and regeneration means treatment needs to be undertaken carefully and with proper advice.
Giant hogweed is also present, although it's not currently thought to be widespread across Nidderdale. And that's what makes early reporting particularly valuable. It also makes caution essential.
Giant hogweed shouldn't be touched. Its sap can make skin acutely sensitive to sunlight, causing severe blistering and burns. Contact with the eyes can result in serious injury.
Anyone who believes they've found giant hogweed should keep a safe distance, record its location without disturbing it and seek appropriate advice rather than attempting to remove it.
This isn't a call for enthusiastic plant pulling conducted on the basis of a hurried internet search.
Several native members of the carrot family can look superficially similar to invasive hogweed species. Records can be checked and verified; a severe burn can't be undone so easily. The safest and most useful action is often simply to observe, record and leave the plant alone.
Not every invasive species in Nidderdale announces itself with towering stems or brightly coloured flowers. Signal crayfish have also been confirmed within local watercourses.
Introduced to Britain from North America, signal crayfish are larger and more aggressive than our native white-clawed crayfish. They compete for food and habitat, damage banks through burrowing and can carry crayfish plague.
The invasive crayfish can survive while carrying the disease. Native white-clawed crayfish can't. Once introduced into a vulnerable population, the plague can have devastating consequences.
The white-clawed crayfish is Britain’s only native freshwater crayfish. Once far more widespread across Yorkshire, it's suffered greatly as signal crayfish and the disease associated with them have expanded through river systems.
Its decline is an illustration of how quickly the ecological character of a watercourse can change.
An invasive species doesn't need malicious intent. It needs only the ability to reproduce, spread or compete more effectively than the species already present - often in an environment altered by human activity.
Our rivers and becks are particularly vulnerable because they are connected systems. Water carries seeds, fragments, organisms and disease. Boots, fishing equipment, nets, machinery, dogs and vehicles can also transfer biological material between sites.
Protecting one stretch therefore depends partly upon what happens elsewhere. A beck doesn't recognise a farm boundary, a parish line or the edge of a protected landscape.
Nidderdale National Landscape covers 233 square miles of North Yorkshire. Within it are rivers, becks, farmland, woodland, moorland, villages and the countless smaller habitats connecting one to another.
No single team can observe every change taking place across that area, even if they have a giant curlew on the team.
The people already moving through it become an essential network of eyes and ears.
That doesn't transfer responsibility for invasive species control from public bodies to the public. Nor should recording become a substitute for properly funded, strategic environmental work. But good environmental decisions depend upon good information.
The earlier an emerging problem is recognised, the greater the possibility that it can be contained before it becomes established. Where a species is already widespread, accurate records can help direct limited resources towards work with a realistic prospect of success.
The National Landscape team’s appeal is therefore about more than downloading an app. It is an invitation to pay closer attention.
To notice not only the beauty of a riverside in summer, but which plants are dominating it. To look beneath the surface of a beck (safely) and understand that the presence of one species might indicate the disappearance of another. To recognise that familiarity with a place can itself become a valuable kind of environmental stewardship.
There's sometimes a tendency to imagine protected landscapes as finished pictures: scenes whose beauty has been recognised, designated and therefore secured.
They're nothing of the sort. They're living systems, continually changing under pressure from climate, land use, pollution, disease and the movement of species. Their protection is an active process, not a title bestowed once and left to do the work.
In Nidderdale, some of the most useful conservation work this summer might just begin with a person pausing beside a riverbank and thinking: 'I don’t remember seeing that here before'. Then taking the few minutes required to tell somebody.
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Sightings of Himalayan balsam, Japanese knotweed, Himalayan knotweed, giant hogweed, signal crayfish and other invasive non-native species can be submitted through the free INNS Mapper app or its website.
Only make a record where it is safe to do so. Do not touch, disturb or attempt to remove any plant or animal that you cannot confidently identify.
Never touch giant hogweed. Record its position from a safe distance and seek expert advice.
Farmers, landowners and land managers who would like to discuss possible Farming in Protected Landscapes support for Himalayan balsam control can contact Matt Trevelyan:
Email: matthew.trevelyan@northyorks.gov.uk
Telephone: 07745 544 872
Header image: Himalayan Balsam near the River Nidd (Elizabeth Bishop)
