How are ‘priority habitats’ assessed in the Yorkshire Dales National Park?

From where I’m sitting at a desk in Bainbridge, gazing out of the window (hard life), the Yorkshire Dales National Park is looking mighty fine.  But is it as lovely as it looks?  Just what is the state of nature in the Park?  Do we even know?

It was these questions which prompted me to take a look at a piece of work our wildlife conservation team has been conducting since the start of the decade.

Every year since 2010, the Authority has commissioned ecologists to assess the condition of the most important habitats in the National Park outside of Sites of Special Scientific Interest.  By 2020, all such so-called ‘priority habitats’ in the Park – which include upland hay meadow, limestone grassland and blanket bog – will have been surveyed where landowner permission has been granted.

It means a significant body of data is being assembled on the state of nature in the National Park.  The data so far suggests there is room for improvement, as illustrated by last year’s survey results from Swaledale.

I thought it would be helpful to cast light on how the surveys are conducted, so one hot morning in late June I went to meet ecologists Robyn Guppy and Steve Heaton from the Otley-based firm, Haycock & Jay Associates, at Holme Open Farm near Sedbergh.

Steve and Robyn, with Hodgehill wood in the background
Steve and Robyn, with Hodgehill wood in the background

The landowners had kindly granted permission for the ecologists to assess the condition of Hodgehill Wood, a bank of trees a short distance from the farmhouse.  A digital mapping exercise carried out by my colleagues had identified the wood as being potentially ‘ancient semi-natural woodland’ – a priority habitat.

As we went into the wood, Robyn explained that her technique was first to walk through the woodland to get the measure of it.  Then she would re-trace her steps, stopping ten times at equal distances apart to record the species around her, as well as other information.

Straight away there was good news and bad news.  The good news was that there was abundant ash regeneration (which was still free of ash dieback disease).  The bad news was that some of the young ash saplings had been munched by sheep.

Wool caught on ash saplings - a tell tale sign that sheep have got into the wood and had a munch on the saplings
Wool caught on ash saplings – a tell tale sign that sheep have got into the wood

At first it was something of a mystery.  How could sheep have gotten in?  A stock-proof perimeter fence has been installed around the woodland to protect it.

“It looks like the sheep have broken in quite recently,” said Steve.  “The extent of browsing is quite low.  Regeneration has been able to happen.  But a few rogue sheep have managed to get in.”

It was then that Robyn declared that this was a very “badgery” wood.  She pointed up the bank where there was evidence of a badger sett – an exciting and welcome discovery.  I couldn’t at first see the connection between the sheep and the badgers, but soon it became obvious.

This is where the sheep got in. The hole beneath the fence was probably dug out by badgers
The mystery of the “rogue” sheep solved

The badgers – as Robyn had guessed – had decided to ignore the wood flaps that had been installed in the fence for them.  Instead, they had dug out a section underneath the fence, which happened to be big enough for a sheep.

Robyn notes the presence of badgers
Robyn notes the presence of badgers

As we walked through the wood, we looked down as well as up above.  This was partly to keep our balance (“a lot of woodlands in the Dales are on really steep ground – that’s why they are still here,” said Steve), but mainly to see the ground flora.

Robyn observed that the ground flora did not appear to be particularly diverse.  Part of the reason for that was the presence of quite a number of sycamores, as well as mature beeches which had been planted along one edge of the wood.

One of the beech trees in Hodgehill Wood
One of the beech trees in Hodgehill Wood

Who knew that beeches were not native to the Yorkshire Dales? The great spread of a beech, and the thick layer of leaves it deposits in the autumn, inhibits native ground flora.  The presence of ash, being the dominant native tree, is looked upon far more favourably.

An ancient ash in Hodgehill Wood
An ancient ash in Hodgehill Wood

Beneath the ash and some of the other native trees such as hazel, native ground flora appeared to be doing well.  There was barren strawberry, wood avens, wood speedwell, yellow pimpernel – and enchanter’s nightshade in abundance.

Enchanter's Nightshade, a pretty and common native woodland plant
Enchanter’s Nightshade, a pretty and common native woodland plant

After about half an hour, Robyn began the survey proper.

“I think this can be plot one,” she said, as she got a handful of gadgets going.  “This year we’ve got hand held tablets to record the information.  Each plot is 20 metres square and this first plot is fairly open with about 60 per cent canopy cover.”

Robyn uses a tablet to enter the data
Robyn uses a tablet to enter the data

Robyn recorded the species she could find at ground level (which included barren strawberry and primrose), at shrub level (holly, wych elm and hawthorn), and canopy layer (ash and sycamore).  Unfortunately, she also had to record the presence of Himalayan Balsam, a non-native invasive species which has taken hold in many places in the National Park, mainly near rivers.  Robyn’s guess was that seed had blown up bank from the nearby River Rawthey.

A bad sign - Himalayan Balsam, a non-native invasive species
A bad sign – Himalayan Balsam, a non-native invasive species

This surveying process was carried out at a further nine stops during the wood – and all the data inputted into the tablet computer.  A willow warbler was singing.  Steve pointed out bluebells that had gone to seed.  At another stop, he identified wood sorrel, another slow-spreading species suggesting the wood was at least several hundred years old.

Wood sorrel, a key indicator of an ancient woodland
Wood sorrel, a key indicator of an ancient woodland

So, at the end of two hours, could an overall assessment be made of the condition of Hodgehill Wood?  Was it in condition A (good), B, or C?  Robyn said the data needed to be analysed thoroughly, but in her judgement Hodgehill would likely be assessed as a ‘B’.

“It wouldn’t be in condition A because of the stock intrusion and the invasive species,” she said. “A way to get this particular woodland in good condition would be to remove some sycamore and make sure sheep can’t get in.”

All the data will be made available free to the landowner on request, and can be used to support agri-environment scheme applications.

The current 2018 YDNPA priority habitat survey – of which the Hodgehill Wood assessment was but one small part – will be completed by the end of September.  The survey is taking place in areas which became part of the Yorkshire Dales National Park when its boundaries were extended in 2016.  For more details, see this news release.

It had been an enjoyable experience for me.  As Robyn said, “Doing these surveys is good because you have to stop and look – it’s amazing.”

Steve and Robyn before an ancient ash
Steve and Robyn observing an ancient ash tree

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