ANALYSIS: The battle to protect 'irreplaceable' Askham Bog

EVEN on a cold, dreary day in January, Askham Bog has a stark, austere beauty all its own. It is hushed and quiet, apart from the occasional plinking of a bird. The dark, peaty water - rich in nutrients and life - that lies in deep pools and ditches is still and silent. Sedge and reed is withered: bare branches cut the skyline.

Whatever the time of year, this is a magical place. Regular visitors will know that the bog - the Yorkshire Wildlife Trust's first-ever nature reserve - changes throughout the seasons. In winter, there are often huge flocks of siskin and redpolls feeding on alder seeds, and it’s the best time to see mammals such as roe deer.

Spring brings frogspawn, the first butterflies of the year, early marsh orchids and marsh violets, and nesting birds such as buzzard, kestrel, whitethroat, tree creeper and reed bunting.

In summer, the fen meadows are a riot of colour, with meadowsweet, meadow rue, marsh and meadow thistles, yellow loosestrife, spotted orchids, marsh orchids and a spectacular display of water violets. Late summer and autumn, meanwhile, is when the rare royal fern for which the bog is famed (one of the biggest surviving European ferns) is at its best. Autumn also brings a wealth of fungi.

All of this (plus a well-maintained boardwalk which make it easily accessible) makes Askham Bog a wonderful place to visit - a tiny oasis of peace and seeming wilderness right on the edge of York.

Askham Bog in spring. Photo: Frank Dwyer

It is far more than just a lovely place for a walk, however. This is a uniquely diverse habitat for wild plants and animals that many - the great naturalist Sir David Attenborough among them - say is absolutely irreplaceable.

But what makes this small patch of land hemmed in by the York bypass and the railway line so special?

Time and ecology, that's what.

The bog formed on the site of an ancient lake left behind by a retreating glacier 15,000 years ago.

The lake was colonised by sphagnum mosses. Over thousands of years, layer upon layer of moss grew up, eventually forming a dome of peat up to 15 metres thick.

Once, there would have been a lot more peat than there is now. But the Romans began cutting the peat to burn, and by medieval times monks were also using it as fuel, reducing the dome of peat to its present level.

That practice of peat-cutting - which ended something like 300 years ago - actually added to the bog's richness and diversity. Some of the rarer plants to be found at the bog - the royal fern among them - may only be here because of the peat cutters, says Prof Alastair Fitter, a former head of the biology department at the University of York and a long-standing trustee of the Yorkshire Wildlife Trust. In about 1980, the Trust did some experimental peat-cutting, just to see what the effect would be. "And baby royal ferns sprang up all around the edges," he says.

Prof Alastair Fitter, left, showing Sir David Attenborough around Askham Bog in 2016

The result of all this - the action of the glaciers, the gradual growth over millennia of a dome of peat, and the centuries of man-made intervention in the form of peat-cutting - was the evolution over time of an extraordinary mosaic of habitats, including peat bog, ponds, fen meadow, woodland and the remains of drainage ditches, all in one small nature reserve.

More than 300 plant species are to be found there - not to mention a host of insects, birds, frogs and newts, and small mammals.

Nowhere in Yorkshire is there a greater diversity of plant and animals species than right here, says Prof Fitter.

The edges of the bog harbour the greatest diversity of plants and insects, including marsh orchids, marsh violet and meadow thistle. The colony of gingerbread sedge in Far Wood is the largest in England and some of the royal ferns are huge and probably very old - quite possibly more than 300 or 400 years old. "They may be the oldest living things in York," says Prof Fitter.

The bog is also home to rare species of water beetle and some vary rare moths. Birds are abundant, roe deer and foxes can be seen regularly, and the pond is a great place to watch water voles or spot dragonflies.

A Royal Fern at Askham Bog. Photo: Jo Richards

It is because the bog is so special that the Yorkshire Wildlife Trust is so determined to protect it.

And that means resisting plans by Barwood Land to build up to 516 new homes on farmland off Moor Lane, Acomb, which neighbours the bog.

Barwood has long wanted to build homes here. And now, even though the site is no longer allocated for housing in the draft York local plan, it has lodged a formal planning application.

The company says it has done extensive surveys and studies to look at the potential impact of new homes on the bog itself. And with the series of protective measures it says it would put in place (see panel), Barwood insists the development would pose no threat to Askham Bog.

The Yorkshire Wildlife Trust disagrees. Some of the protective measures proposed may work, some may not, says Prof Fitter. But such a large development so close to the bog would inevitably have an impact.

Yes, there is a need in York for new housing, Prof Fitter accepts. But this is not the place. There are other sites in and around the city that can be used to build the new homes we need. Asham Bog is simply too precious.

"The bottom line is, why take the risk?" he says. "If development affects the water table and the bog dries out, all you'd be left with is an uninteresting piece of dry woodland. 20,000 years of history would be down the tube. Why take that risk?"

ANALYSIS: Is Askham Bog at risk?

The view from Moor Lane to Askham Bog across the farmland on which Barwood wants to build up to 516 homes

The Yorkshire Wildlife Trust fears the proposed Barwood development at Moor Lane could damage Askham Bog in three ways:

• by causing an increased risk of predation from domestic cats and dogs, plus other problems such as increased litter etc
• by cutting off Askham Bog, which is already hemmed in by a railway and ring roads, from open country, meaning it would become an isolated 'island' reserve
• by affecting the water levels, leading to a risk the bog could dry out. This is the main concern.

Barwood says it has spent years studying the bog and developing mitigation measures that would negate any threat.

Cats and dogs

Barwood says its mitigation measures would include a 570-foot wide 'buffer' to separate the development from the bog. This buffer area would contain a 410-foot wide 'ecological protection zone' (EPEZ), which would include a thorny hedge and deer fence to the north; a long, narrow open water lake and marsh; a long earth 'bund' capped by thorny scrub south of this; and a 10-foot-tall security fence running the length of the southern edge of the EPEZ. This would act as an 'impenetrable barrier' that would prevent domestic pets accessing the bog from the north.

Not so, the wildlife trust says. There would need to be routes through the EPEZ (admittedly protected by gates) to allow drainage board inspectors to get through, and also to allow the trust itself to bring grazing animals such as cattle into the bog (a vital part of its management). And in any case, the Trust says, there would be nothing to stop domestic animals simply going around the edges of the so-called 'impenetrable barrier'.

An 'illustrated masterplan' of the proposed development at Moor Lane, showing Woodthorpe homes at the top, Moor Mane itself, the proposed new homes, the proposed Ecological Protection Zone (bright green, centre) and Askham Bog (dark green, bottom). Image: Barwood Land

Isolating the bog

The wild animals which live in nature reserves need to have corridors along which they can move in and out of a reserve, otherwise they become cut off from the countryside around. When that happens, the wildlife that lives there is much more vulnerable to disease, the effects of climate change, and the dangers of in-breeding.

Askham Bog is already hemmed in by the railway, the A64 and the A1237. Ironically, the 'impenetrable barrier' designed to protect the bog from domestic pets would only increase its isolation, the wildlife trust says. Barwood disagrees. The proposed ecological protection zone would see farmland replaced by wetland, grassland and scrub, and make it easier for wildlife to move in and out of the reserve, Barwood says.

Water levels

Barwood insists that the water table of the land where the homes would be built is not connected to Askham Bog under 'normal conditions'. "Over the past 3-4 years we have carried out extensive research to establish the hydrological connectivity between the site and the SSSI (Askham Bog)," says Barwood MD Jamie Gibbins. "These also include observations, topographical and channel surveys, geotechnical investigations, groundwater studies (including 15 months in which we monitored the ground water levels across the site) and surface water monitoring." The research shows that Askham Bog is mainly fed by rain and not by groundwater from development site, he says. There is, therefore, no risk of the bog drying out as a result of building homes at Moor Lane.

The Yorkshire Wildlife Trust does not accept this. The issue isn’t so much where the water which keeps the bog wet comes from, as how the bog loses water, says Prof Fitter. "We (the wildlife trust) have water table data going back to the 1970s. They show very clearly that in winter the bog recharges from groundwater and rainfall and in summer it loses water to evapotranspiration and seepage out to Holgate Beck.

"When the level in Holgate Beck falls, there is a drawdown that extends into the bog. The critical feature, therefore, given that we are going to experience drier summers, is that the beck level is maintained. Their plans appear to show drainage into the beck being diverted to fill their water feature. Clearly if they create a new lake there, it must receive water from somewhere and equally inevitably it will lose water by evaporation, so there must overall be less water available."

Barwood stands by its research. It says York badly needs new homes. The company's planning application includes a lengthy chapter on ecology and nature conservation, together with numerous appendices, which between them go into great detail about the claimed risks to the bog and the mitigation measures Barwood proposes.

Ultimately, Barwood MD Jamie Gibbins says, it will be up to planners or planning inspectors to evaluate that evidence for themselves.

Planning inspectors? Does that mean that, if City of York Council throws out the application, Barwood would appeal?

"If necessary, we will go to appeal," Mr Gibbins confirmed.

HAVE YOUR SAY

You have until February 8 to have your say on the proposal to build homes at Moor Lane. Visit www.york.gov.uk/PlanningAndBuilding