Nature reserve bosses fear there could be “devastating consequences” for their site if neighbouring lands fall into private hands.
Officials at the Sculthorpe Moor reserve, near Fakenham have outlined their vision for the area after launching an appeal to raise £850,000 to buy two adjacent sites.
The Hawk and Owl Trust, which runs the reserve, has been given a two year window by the landowners to complete a purchase.
Officials say it is a “once in a lifetime” opportunity and admit they are concerned about what could happen if they can’t raise the money they need.
Reserve manager Nigel Middleton said: “Sculthorpe Moor is a hidden gem.
“Its value for wildlife is immense but, more than that, it is a place of peace, a place to immerse yourself in the quiet and the amazing richness of the habitats.
“The Moor is surrounded by a large area of rough farmland, fen and plantation. We have been lucky enough to be offered the chance to buy that land.
“If it is sold on the open market it would have devastating consequences for the existing reserve, in terms of land use, access issues and even our ability to manage our own reserve, as we can’t do that without coming across the neighbouring land.”
The appeal relates to two areas of Sculthorpe Fen which surround the site of the existing reserve.
A successful campaign would more than treble the size of the protected area in the trust’s care.
Although the trust has provided agricultural stewardship of those areas for the past 10 years, the current arrangement expires later this year.
The trust says the chance to buy the sites has been offered as a consequence of that and would enable them to open the lands up to the public.
Mr Middleton said purchasing the land would also help to avoid the uncertainties they fear could be created around environmental protection regulations as Britain leaves the European Union.
He said: “After 2020, we don’t know what’s going to happen.”
A total of £1.7 million is needed to purchase the land, of which the trust hopes to raise half through fundraising.
The other half is due to be the subject of a grant application to the Heritage Lottery Fund, which is due to be submitted this summer. If the bid is successful, the trust hopes to be able to secure a grant in late 2018 or early 2019.
As part of its bid, the group plans to build a new footpath from the visitors’ centre to the reserve, which the trust has managed since 2001, and is fully accessible with wheelchair-friendly pathways.
The trust also plans to build a new, classroom-sized hide for use by school groups.
And officials are keen to emphasise the heritage of the fen land, which includes the earthworks of a medieval motte and bailey castle.
Parts of the land have been used for peat cutting, gravel extraction, gunpowder making, charcoal making and as a shooting range during its history, while water mills were also sited there.
Promotional literature released this week for the appeal said: “Our vision for Sculthorpe Fen is about much more than its amazing wildlife.
“We see a future where the rich eco-system co-exists with the local community with access for all, rural history, rural crafts and traditional sustainable management which benefits the landscape, people and wildlife.
“If the landscape is right, the wildlife will thrive.”
Trust spokesman Su Gough said: “Buying the land is just the first step. We need the public’s help to bring the vision to life.
“Being able to join the existing reserve with Sculthorpe Fen will result in a unique, diverse area for all to explore, where education, scientific research and quiet enjoyment exist side-by-side now and into the future.”
Around 17,500 people are expected to visit the reserve this year, and the trust hopes to increase that figure to 25,000 by 2020.