The haunting ….

I use this quote in all my talks these days ….

“Conservationists see the conservation of living diversity as a moral necessity, something that is self-evidently right and just has to be done. In the language of conservation biology, conservation is a ‘mission’. Anything that detracts from that mission, or contextualises it as just one among other competing ideas or interests is therefore inherently suspicious.”

(Bill Adams, 2015, The political ecology of conservation conflicts)

Simon Phelps, a conservationist who works for Butterfly Conservation has just published this piece written in response to a talk I gave at the back end of last year where I quoted the above…..

Worth a look – you can read it here.

Thanks Simon – nice to get name checked and realise someone was paying attention!

 

Heather beetle damage on Dartmoor 2019

I have been very surprised how much Heather Beetle damage there is on Dartmoor this year. The Heather Beetle larvae hatch in June and then feed on the young leaves and shoots. As a result the affected parts of the heather plant turn orange brown.

Heather Beetle damage. It is very characteristic and eye catching.

Last week I walked from Rowtor on Okehampton Common up the military road to Observation Post 15 and then down to Ockerton Court. All the way along the track there are signs of extensive damage to the heather plants – I would estimate that over 90% of plants are affected.

Work carried out in the north of England and in Scotland suggest that the larvae are active until the end of August when they drop down into the litter and pupate into adult beetles. Despite three separate searches on Okehampton Common, the Forest of Dartmoor and Headland Warren Common I only managed to find three larvae and one adult beetle.

Here is a Heather Beetle larvae on Okehampton Common eating the few remaining green leaves of the plant.

I suspect that the absence of larvae and adults during my searches in the first week of August means that the larvae have already dropped into the litter and are beginning to pupate – as a result larvae and adults are not visible. However the very extensive areas of damaged heather indicates that they have been very active in June and July.

It is possible for the heather to recover from this attack and I will be monitoring it to see if it does. However parts or all of the heather plant can be killed. When this happens the shoots turn from orange brown to grey.

This is mature heather at Ockerton Court which has been killed by Heather Beetle

In this image the areas of dead heather (darker brown bits) are being over run by Purple Moor Grass (Molinia caerulea) – the bright green shoots of this year’s growth and the light brown leaves from last year. Molinia is unable to replace heather whilst the heather is alive but can and does do so when it is dead.

Heather Beetle is a seriously under-recorded species on Dartmoor – the National Biodiversity Network database has just one record and the is from Fingle Woods and not from the high moor!

There is clearly a need to gather more records ….

There is anecdotal evidence nationally that Heather Beetle attacks are getting worse and it has been suggested (based on research from the Netherlands) that the severity and frequency of Heather Beetle outbreaks is linked to the levels of atmospheric pollution – particularly nitrogen levels.

Dartmoor receives high levels of nitrogen deposition as a result of its high rainfall – Natural England have reported that Dartmoor receives 24kg / ha / annum of nitrogen (as NOx) which is damaging the blanket bog and mires. This high level of nitrogen deposition may also be responsible for the high levels of Heather Beetle damage.

Heather Beetles are a natural part of the moorland wildlife community and historically damage to heather was limited except in the ‘outbreak’ years. Last year when I was walking the Commons in July I also noticed extensive areas of affected heather – at this point in time heavy attacks appear to be frequent – maybe even annual.

There are implications for wildlife, conservation and hill-farming as a result of these serious Heather Beetle attacks.

1. The heather plants themselves are either killed or remain stunted
2. The species of wildlife which feed on heather shoots are also impacted – this includes moth species such as the Emperor Moth and the Fox Moth, whose hairy caterpillars are important prey items for one of Dartmoor’s iconic and successful birds – the cuckoo.
3. Heather has long been a conservation indicator for the condition of Dartmoor’s Commons and historically grazing levels were reduced significantly to reduce overgrazing pressures to conserve heather.
4. Heather is also a winter food for sheep on the Commons, if the amount of heather generally is significantly reduced as a result of Heather Beetle attacks it put pressure of the remaining plants that have survived.

Ironically it is thought that the severity and frequency of Heather Beetle attacks has increased because the nitrogen has made the young shoots and leaves more nutritious, it is also reported that sheep preferentially graze the new shoots too for the same reason.

There is a dearth of information on Heather Beetle issues on Dartmoor but from my own observations this year and last it is a potentially serious and widespread problem. However it would also appear that the problem is not universal across the moor. I searched for it in the heather stands around the Warren House Inn  and found Heather Beetle attacks to be minor – perhaps this level of damage is the natural level – whereas the levels seen on Okehampton Common, the north part of the Forest and on Headland Warren Common are the outbreak levels.

It seems to me that there is a clear need to better understand the Heather Beetle situation on Dartmoor, this would be in the interests of Natural England, the Dartmoor National Park Authority and the Dartmoor Commoners Council. The time to survey for the impacts of Heather Beetle is July and August. Maybe a bit of ‘Citizen Science’ could come to the rescue?

I would also be interested to hear from people who have found the characteristic orange brown stands of heather this year on Dartmoor.

I’ve written before about Heather Beetles and this link takes you to my blog which contains further information and some references you can download.

Finally found the secret waterfall

Been on Holme Moor today doing a ‘reccy’ and finally found the secret waterfall below Venford Dam. Here are a few pictures. The waterfall is down from the dam but be careful it is a 300m plus walk down the river – the ‘path’ is tricky and there is no phone reception. Unlike me – go with a friend – you could easily end up in the river or twist your ankle or worse. Do as I say, not as I do …

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Cuckoos back on Dartmoor

Spent a couple of hours at Emsworthy Mire yesterday and eventually saw a couple of male cuckoos.

Made my day!

If you hear or see a cuckoo in Devon please log the details with Devon Birds – here.

Dartmoor is now one of the last strongholds for this declining species ……

Soil compaction on Dartmoor

I’ve now seen first hand some compacted soils on the moor. We spent some time looking at some soils which should have good drainage qualities opposed to the peat water logged soils higher up.

Richard Smith (Environment Agency), Sue Everett (Sustainable Soils Alliance), Mark July (former Natural England) and Tim Harrod (former Soil Survey of England and Wales) inspecting a compacted soil on Peter Tavy Common

The compaction means that the water cannot flow into the profile as there is a layer of compressed (gleyed) soil which is impermeable – as a result this soil has a perched water table. When it rains hard the water flows across the surface and down the hill side. The Environment Agency are interested in ameliorating this so that flooding incidents in Peter Tavy can be reduced.

Here is a soil from the Moor Gate series which is not compacted – the soil is friable to the touch and shows no signs of compression or gleying. Heavy rain on this soil will flow down through the profile and not across the surface.

The general theory is that the compaction at say, Peter Tavy Common happened between 1960-1990 and main suspects were cattle and ponies.

The question now is do these soils have the capacity to repair themselves or are they permanently damaged? These compacted soils are often very acidic and as a result possess very poor soil faunas which could potentially undo the damage.

I would be interested to know whether the last 60 years of atmospheric nitrogen pollution has lowered the pH of these soils and as a result reduced the soil fauna’s ability to repair the soil structure.

Unfortunately I cannot find anything in the literature to evidence a progressive lowering of pH in upland soils over the past 60 years – does anyone know of any evidence for this?

Soils are now very high on Defra’s agenda and it seems that answering questions like this and finding a remedy for such upland soil compaction is a high priority.

However there is a problem. The organisation that could have answered this question The Soil Survey of England and Wales has been disbanded (1987) and today soil science is a low profile academic discipline meaning that there are very few qualified professionals around to carry out such studies.

This has mean that the publication of ‘Soils in Devon IX Soil Survey Record No. 117 by Dr Tim Harrod has been undertaken pro bono by a retired soil scientist from the former Soil Survey of England and Wales. It is a majestic piece of scholarship which should have been funded by the State and not by crowd funding!

 

Defra undoubtedly needs to invest in soil science and soil scientists as otherwise solutions to problems will all too often be based on speculation (as above and here) and not science.

Michael Gove returns to the uplands

Michael Gove has just delivered his keynote speech to the NFU Conference in Birmingham – you can read the full speech here. I have selected the passages which refer to the uplands.

“Rural communities depend on profitable agricultural businesses to thrive. The landscapes which draw tourists, from the Lake District to Dartmoor, the Northumberland coast to Pembrokeshire, depend on farmers for their maintenance and upkeep.”

“As does the work of organisations like the Prince’s Countryside Fund which support smaller farms, especially those in more challenging areas. I firmly believe that supporting those farmers who help keep rural life, and economies, healthy is a public good.”

“I am acutely conscious that the changes which are coming to farming leave some sectors more worried than others. And I am particularly aware that many smaller farmers, such as dairy farmers in areas like Devon or upland sheep farmers in Cumbria and Northumberland, fear that the future is particularly challenging for them. Margins are tight. Milk and lamb prices are far from generous. The risks to profitability of Bovine TB or other forces beyond the farmers’ control add to stress. And the prospect of public support diminishing or disappearing makes many wonder how they can go on. I believe we have to ensure future methods of agricultural support recognise how critical it is to value the culture in agriculture – Devon and Somerset would not be as they are – with the countryside as beautiful as it is and communities as resilient as they are – without dairy farmers. Cumbria and Northumberland, Yorkshire’s Dales and Pennine Lancashire would not be as they are – both as breathtakingly beautiful and as resilient – without upland farmers.”

“And yes, I am romantic about it. You cannot read James Rebanks’ A Shepherd’s Life, with its descriptions of life sheep farming in the Lake District, without realising how precious and valuable a link with all our pasts the continuation of farming in communities such as James’ provides. Men and women are hefted in those hills just as much as the sheep they care for. And preserving profitable farm businesses in those communities is just as much a public good as investment in anything I know.”

The specific mention of uplands and hill-farmers as ‘public goods’ therefore entitled to ‘public money’ will be seen as a big relief to many as the 25 year Environment Plan made no mention of the uplands at all and led to consternation in some quarters. e.g.

Gove did mention the uplands in his Age of Acceleration speech at the Oxford Farming Conference in January:-

On hill-farmers
So that does mean …. asking how we can support those farmers, for example upland sheep farmers, whose profit margins are more likely to be small but whose contribution to rural life and the maintenance of iconic landscapes is immense.

Rural resilience as a public good
Finally there is rural resilience. There are any number of smaller farm and rural businesses which help keep communities coherent and ensure the culture in agriculture is kept healthy. Whether it’s upland farmers in Wales or Cumbria, crofters in Scotland or small livestock farmers in Northern Ireland, we need to ensure support is there for those who keep rural life vital. The work of the Prince’s Countryside Fund has been invaluable here and the kind of enterprises that it supports are, I believe, worthy of public support.

but it was curious to say the least that they didn’t get a mention in the 25 year Environment Plan.

So Michael Gove has responded to the ‘feedback’ he has received and made specific mention. The Devil though is still in the detail which we have yet to see. This should begin to emerge once the Consultation Paper on the future of agriculture is published in a month or so.

The key questions to answer in the Consultation Paper with regards to the uplands are

will sufficient public money be made available for the uplands
and
will hill-farmers be prepared to earn it by the providing the public goods?

Landscape conservation and nature conservation: uneasy bedfellows?

Two perspectives – one from Europe and the other from Dartmoor.
On the face, of it you would think that all those who want to protect the environment get along with each other working towards a common goal. This can happen especially if the nature conservation of species is dependent on traditional farming practices in culturally developed and ancient landscapes, but when conservation relies on process driven rewilding there are huge consequences for landscapes and the traditional cultures that sustain them.

I recently came across a couple of essays, an editorial and opinion piece about this very topic from a mainland southern European perspective. You can download the four pieces here. I was struck how the perspective essay by Mauro Agnoletti ‘Rural landscape, nature conservation and culture: some notes on research trends and management approaches from a (southern) European perspective’ shared many of the same concerns as those held by Tom Greeves who has written on the subject from a Dartmoor perspective. You can download Tom Greeves’ paper ‘Dartmoor and the displacement of culture: analysis and remedy’ here.

This blog reviews the assertions of Agnoletti and Greeves and discusses the future for landscapes and local cultures in the face of the globally driven economic, social and environmental pressures and changes.

Rural landscape, nature conservation and culture: some notes on research trends and management approaches from a (southern) European perspective
Agnoletti says that landscapes are largely a cultural construct i.e. they have been created over time by the people who have inhabited and farmed the land. A cultural landscape is fashioned from a natural landscape by a cultural group: culture is the agent, the natural area the medium and the cultural landscape is the result.

He argues that whilst the importance of landscapes is acknowledged at an international and European scale the policies required to conserve them are largely lacking. He suggests that if a landscape scale approach was adopted across Europe a new paradigm for a development model could harmoniously integrate social, economic and environmental factors in time and space.

But as the globalisation of agriculture has occurred during the 20^th century traditional farming practices have collapsed leading to cultivatable land being industrially intensified whilst the pastoral landscapes which are on poorer land, and therefore unimprovable from an agricultural perspective, are being abandoned.

These trends are therefore leading to a cultural globalisation (i.e. homogenisation). The idea of nature has been overlapped with landscape and this is leading to re-naturalisation (what in the UK we would call rewilding) and increasing forest cover which overlays the ancient landscapes patterns along with their associated long and rich cultural history that led to their creation.

Agnoletti argues that there is a growing tendency to see a scientific approach to the study of landscape as a natural resource opposed to a cultural phenomenon. The workstreams that flow from this are ecological in nature with little cultural focus. Academic journals see landscape as an ecological issue largely in the context of nature conservation and he suggests that scientific publications have a higher academic credibility than chapters and books in the Humanities which therefore establishes an ecological bias.

Agnoletti states that such an approach causes three problems:

a) Degradation of the rural landscape
Farming per se is considered damaging to nature: 20^th and 21^st century approaches to traditional pastoral farming methods are lumped in together with modern intensive agricultural methods. Pastoral landscapes do not receive the financial support they require to remain sustainable and are abandoned either to be re-naturalised or afforested. Cultivated land is intensified agriculturally – both phenomena lead to a loss of local knowledge, cultural landscapes and the rural population.

b) Abandonment and reforestation
The abandonment of European landscapes has also been encouraged by European Union set-aside policies. As a result of this and globalization it is estimated that 400-500k ha of forest advance occurs per annum – partly through abandonment and partly through active re-afforestation.

The dominant narrative of European ecologists is that the environment needs to be returned to the natural state, partly because Man has destroyed nature and partly because the EU Habitats Directive has an emphasis on natural habitats.

How can it be logical to want to return to the natural state in landscapes that haven’t been natural for 8000 years? Nevertheless, re-naturalisation has been aligned in Europe with nature policies and the promotion of rewilding and afforestation in the fight against climate change through increased carbon sequestration.

c) Rural landscapes, history and biodiversity
Whilst the re-naturalisation of closed forest landscapes provides new habitats for some wildlife this is at the expense of the wildlife which already lives in the historical and largely open landscapes. A greater diversity of wildlife will be conserved if many cultural landscapes are protected.

Agnoletti summarises his argument as follows:-

• Landscapes need to be viewed for they are i.e. their cultural origins
• Europe needs an adequate characterization of rural landscapes
• Support for traditional agriculture is required to halt further losses
• Nature narratives need to be combined with cultural ones to create biocultural diversity
• Natural habitats need to be prevented in unnatural places
• Achieving these things will help maintain rural communities

This is an interesting and informative perspective from Southern Europe however it contrasts markedly with the situation found in the UK for the following reasons:-

1. The UK values its Cultural Landscapes and has categorized them in great detail under the Natural Area Profile assessment (see here).
2. The abandonment of land seen on marginal land in Europe simply hasn’t happened on anything other than a minor scale in the UK
3. Marginal land particularly those in protected areas have received considerable sums of subsidy through the agri-envionment schemes to ensure that traditional management practices are encouraged and continued so that the landscapes, the cultural groups that produced them and the biodiversity are protected.

On the face of it then, it would appear that in the UK, the conservation of landscapes and local farmers was working in harmony with the objectives of nature conservation. However, this is not the case in the uplands of Britain where their special landscapes are deeply contested today by various groups of interested parties. Tom Greeves, argues very strongly that culture and landscape on Dartmoor have been detrimentally out manoeuvred by advocates of the natural environment.

Dartmoor and the displacement of culture: analysis and remedy – conservation imbalance
Greeves points out that the post-war conservation movement has been dominated by the natural environment and is heavily skewed towards nature. He argues that nature and culture should be given equal balance. He says that even the name Natural England reinforces the belief that the environment is natural. The 25k ha of Sites of Special Scientific Interest on Dartmoor are all about animals and plants and no mention is made about culture.

In 2006 when the Dartmoor Vision was published, areas called ‘Premier Archaeological Landscapes’ were introduced – these were areas where the historic landscape would be given primacy over wildlife. Greeves dismisses this concession as he argues that no part of the moor is without cultural value. He goes on to argue that the era of ‘overgrazing’ (i.e. circa 1950-1980) was actually revolutionary for the historic environment as it revealed many archaeological features and sites which had become lost in the vegetation. Once the agri-environment schemes were introduced and the numbers of grazing animals were reduced gorse and unpalatable grasses took over in many areas and hid and in some cases damaged the cultural landscape. Greeves argues that Natural England have ‘clung on to the concept of overgrazing’ and as a result ‘awareness of the cultural riches of Dartmoor has not yet impinged on Establishment thinking.

Policies of Natural England and the destruction of neighbourliness
Not only does Greeves loathe the agri-environment schemes for their stocking reductions he also blames them for creating divisiveness amongst the hill-farming Commoners. The subsidy money was handed over to the local Common Associations who then had to decide how to allocate sums to individuals, this practice lead to arguments and squabbles where none had existed before. Without doubt Natural England’s policies in the latter parts of the last century and earlier parts of this one created great resentment as Commoners considered they were ‘fighting for their rights’ against the Natural England ‘dictatorship’.

The Mires Project
The Dartmoor Mires restoration project, a £1.1 million scheme which ran between 2010 and 2015 also comes in more considerable criticism from Greeves. He states that no evidence was ever presented to suggest that the moor was in fact actually damaged and therefore needed restoration. He was particularly incensed that large tracked machines were taken into the ‘wildest parts of the moor’ to carry out various works to impound water and rewet the peat. He calls it ‘one of the least prepared and worst pseudo-scientific projects’ that Dartmoor has ever seen.

Rewilding
With regards to calls to rewild Dartmoor as a result of ‘sheepwrecking’ he dismisses these ideas as they take no account of ‘the significance of the cultural landscape of Dartmoor and what it means in terms of the human story over the last eight millennia or so’.

Remedy
Greeves suggests that radical reform is needed underpinned by research. The stranglehold of Natural England must be challenged and removed as they have no right to upset the age old social fabric of hill-farming and they have no right to obscure the archaeology of the moor. With regard to how the moor should be managed he urges that Commoners be asked for their views and then allowed to enact them. He urges that culture, flora and fauna are respected in equal measure and that the existing designations such as SSSIs and Scheduled Ancients Monuments are replaced with a new overarching protective mechanism and that Dartmoor is viewed in the future as an ecocultural zone. Finally he recommends that the National Park Authority is replaced by a Dartmoor Assembly which consists of elected local people.

There is much passion throughout much of Tom Greeves paper and it is fair to say that it has not been well received in a number of places! But rather like the Agnoletti paper it does raise a number of important points. Amongst the displeasure of the status quo raised in both papers there is a plea that cultural landscapes are given equal consideration to biological landscapes.

This of course sounds entirely reasonable but in practice achieving this has historically proven to be extremely difficult. A heavily grazing and swaled Dartmoor landscape (the over grazing over burning narrative) is good for the cultural landscape but bad for the biological one and of course was the exact scenario that led to the introduction of the agri-environment schemes.

Conversely a less grazed and less burnt Dartmoor landscape, even one which contains Premier Archaeological Landscapes, currently pleases no one completely as the effects of climate change and atmospheric pollution are reconfiguring the moors in ways that satisfy very few. However, the search for a better consensus must continue in the brave new world of Brexit and the ‘public money for public goods debate’, for most agree (with the exception of the rewilders) that a world without hill-farmers will create a new Dartmoor landscape that the majority don’t want.

The mystery of Vancouver’s sheep figures on Dartmoor in 1808

Charles Vancouver’s General View of the Agriculture of the County of Devon [1] written in 1808 is a widely cited source with regards to grazing and potential agricultural improvements on the Dartmoor Commons.

Vancouver’s book is an amazing treatise on the state of agriculture across Devon in the early 19^th century and while much of its focus was on agricultural improvement it contains several sections about the grazing potential of the Dartmoor Commons.

Vancouver described Dartmoor as follows

The whole surface of Dartmoor, including the rocks, consists of two characters, the one a wet peaty moor, or vegetable mould, but affording good sheep and bullock pasture, during the summer season. The other an inveterate swamp, absolutely inaccessible to the lightest and most active quadruped that may traverse the sounder parts of the forest. P281

He then goes on to recommend that the ‘inveterate swamp’ is drained and improved but defends the ‘wet peaty moor’ as follows:

The depasturable parts of the forest, consist of a black moory soil, from eighteen inches to two feet in thickness, generally forming peat below, always highly charged with moisture, and ultimately resting upon a reddish-coloured argillaceous loam, called fox-mould, and which is also retentive of water in a very high degree. The spontaneous vegetation of this part of the forest, among many other herbs and grasses, consisted of purple melic grass, mat grass, downy oat grass, bristle-leaved bent, eye-bright, bulbous rooted rush, common termentel, smooth heath-bed straw, common bone binder, cross-leaved heath, common heath or ling (dwarf), milk-wort, dwarf dock and agrostis vulgaris in very large quantities. The disturbing of this herbage, however inferior it may appear in the eye of the refined agriculturalist, is on no account whatever to be recommended to permitted.

Vancouver goes on to describe the importance of the ‘wet peaty moors’ for grazing by sheep and cattle.

“The importance of the first description of these wastes (referring to his earlier writing on the boggy character of Dartmoor), can in no way be so fully shewn as by stating the stock feeding upon them. The Commons belonging to the parish of Widdecombe [and Buckland in the Moor] will furnish a sufficient example, when in the month of October last, there were estimated by gentlemen residing in the neighbourhood, to be no less than 14,000 sheep, besides the usual proportion of horned cattle.” p228

 

Mercer (2009) comments on these high sheep numbers suggesting that the Commons of Widecombe and Buckland today amount to 1032 ha. and therefore in 1808 were subject to a grazing pressure of over 2 sheep per ha. My own research concludes that the two Commons amount to 1940ha., nearly twice the area Mercer states. With regard to the cattle we are left unclear on their stocking density but Mercer (p292) states that Vancouver described them as standing ‘shoulder to shoulder’. These two Commons account for around 5% of Dartmoor’s Commons, so if we take an estimate that there were 10,000 cattle on the Commons of Dartmoor in the early 19^th century we could speculate that there were 500 (5%) on these two Commons.

By doing this we are then able to construct some grazing pressures, measured in Livestock Unit (LSU) where 0.15 sheep equates to 1 bovine, which we can then compare to those seen in the modern era.

14,000 sheep May to Oct       =          2100 LSU

500 cattle May – Oct              =          500 LSU

Total                                                       2600 LSU

over 1940 ha of Common       =          1.34 LSU / ha / year.

Many studies have been published which seek to recommend appropriate grazing levels on upland grasslands and heaths. The majority of these have been carried out either in Scotland, the Peak District and the Pennines.

In north-east Scotland a grazing pressure of 0.2 cattle and 2.7 sheep / ha (this equates to 0.605 LSU / ha [2]) caused damage to heather communities. Additionally, with cattle at 1.2 / ha (1.2 LSU / ha) there was a 32% decline in 4 years and a decline from 80% to 5% heather cover in 10 years. With 5 sheep / ha (0.75 LSU / ha) there was a 9% decline in heather cover over 4 years (Welch 1984).

A grazing pressure of 2 sheep / ha (0.3 LSU / ha) on heather moorland and 0.37 sheep / ha (0.055 LSU / ha) on blanket bog was considered to be compatible with nature conservation objectives. Whilst 0.5 sheep / ha (0.075 LSU / ha) on heather moorland and 0.1 sheep / ha (0.015 LSU / ha) on blanket bog was required for heather to regenerate (Evans & Felton 1987).

On the face of it the grazing pressure reported by Vancouver is in excess of that which modern research found that habitat damage would occur. However Vancouver reported both cross-leaved heather and ling as being notable in these pastures.

The situation is further complicated as Vancouver also reports the following.

“From the number of sheep annually summered upon Dartmoor and Exmoor forests, the ewes and lambs of which are always brought down into the country on the approach of winter, it will be readily supposed, that a large proportion of sheep stock is always found to occupy the surrounding districts during the winter season. The greater part of these flocks, however being wethers (castrated rams), and chiefly preserved for their wool are left upon the forests during winter.” P345

The sheep in question here are White-faced Dartmoors, these sheep were being raised to produce wool and mutton. The wethers were the principle producer of wool fleeces and may have been kept for up to 6 years. The key factor in the above text is that they were being overwintered on the moor. It is widely assumed that all-year round grazing on Dartmoor did not occur until the late 19^th century and the early 20^th century when Scotch Black-faced sheep and the Galloway cattle arrived. It would appear that the practices of transhumance (summer grazing and winter resting) along with levancy and couchancy – the rule that determined the number of grazing stock that could be summered on the Common by reference to the capacity of the land to which the rights were associated to feed stock over the winter months, i.e. all stock on the Common in the summer had to be accommodated and fed on the farm in the winter months were already breaking down.

If we assume that that the wethers accounted for 8000 of the 14,000 sheep (‘the greater part’) then we need to add an additional 1200 LSUs in to the calculation.

14,000 sheep May to Oct       =          2100 LSU

8000 wethers Nov to Apr       =          1200 LSU

500 cattle May – Oct              =          500 LSU

Total                                                        3800 LSU

over 1940 ha of Common       =          1.96 LSU / ha / year.

Grazing pressures at these levels, according to the recent research would cause serious problems of overgrazing and habitat degradation. However this would appear not to be the case in 1808 as Vancouver goes on to report:

“The number of sheep thus summered and kept the year round upon the forest of Dartmoor, the depasturable parts of which, in a dry summer, is one of the best sheep-walks in the kingdom, is not easy to ascertain; but if any inference can be drawn from the returns made from Widdicombe and Buckland in the Moor, their numbers must necessarily be very considerable indeed. A dry summer (as just observed), is always the most favourable for these sheep walk. These afforded in the months of August and September last, flocks were more numerous, and in much higher condition, than has ever been observed by the surveyor in any other part of England, when such have not been aided by access to the enclosures or artificial food. Yet the grass of the sheep-walks upon the forest of Dartmoor, in the beginning of November was scarcely half consumed.” P346-347

Additionally Mercer (p303) quotes Vancouver who reported seeing ‘knee high grass’ on the Widecombe Commons in May. Ample grazing at the beginning of the growing season and scarcely half consumed in November.

Vancouver’s 1808 account of sheep on Dartmoor contrasts markedly with that of Robert Frazer who in 1794 published a ‘General View of the county of Devon with observations on the means of its improvement’[3]. On page 53 he states

The south and east quarter are the driest and best for sheep, and from the most accurate information I could obtain, there are not five thousand sheep kept on both these quarters. Certainly not so many on the north and west. So that if we say 10,000 sheep for the whole of Dartmore, we shall be beyond the mark. I think there are not 8,000 in the whole forest in any summer.

However, Fogwill (1954) in his essay on Pastoralism on Dartmoor stated that in Annals of Agriculture there is a footnote stating that ‘this a great error’.

It is difficult to unravel this mystery and we may never be able to do so: perhaps the gentlemen of the parish miscalculated the number of sheep; perhaps the 14,000 sheep were not solely on the Commons or perhaps the breeds of animals involved i.e. the White-faced Dartmoor sheep and the Ruby Red Devon cattle impacted less severely on the vegetation than Scotch Blackfaces and Galloways.

Or maybe, just maybe, in the time before the Industrial Revolution began, before the era of atmospheric pollution and climate change, the hill-farmers of Dartmoor had perfected a system of pastoralism which allowed them to graze the Commons with great numbers of animals without damaging the vegetation.

A mystery indeed.

[1] The entire manuscript can be downloaded here free of charge https://books.google.co.uk/books/about/General_View_of_the_Agriculture_of_the_C.html?id=BwhLAAAAYAAJ&redir_esc=y

[2] LSU is known as a livestock unit Cattle = 1LSU, Ponies = 1 LSU & Sheep = 0.15 LSU

[3] Download free of charge here https://books.google.co.uk/books/about/General_View_of_the_County_of_Devon.html?id=-H5bAAAAQAAJ

Evans S. & Felton M. (1987) Hill livestock compensatory allowances and upland management. In Bell and Bunce (1987) pp66-72.

Fogwill E. (1954) Pastoralism on Dartmoor. Transactions of the Devonshire Association 86: 89-114.

Mercer I. (2009) Dartmoor: a statement of its time. Collins. HarperCollins. London.

Welch D. (1984) Studies in the grazing of heather moorland in North-East Scotland. II. Response of heather. Journal of Ecology 21: 197-207.

Marsh and Small Pearl- bordered Fritillaries on Dartmoor

It was a sunny morning when I left Exeter yesterday to go to Dartmoor but as the afternoon progressed it clouded over and eventually broke into heavy rain. I was therefore quite lucky to find what I went to Dartmoor to see.

A Marsh Fritillary sunning itself as the sun broke through the clouds momentarily

In total I saw 6 Marsh Fritillaries in the rhos pastures at Challacombe

If you look carefully individual butterflies are all subtly different in their markings

Marsh Fritillaries are now a very rare species but do flourish in a few selected locations on Dartmoor (and elsewhere)

I also found a couple of Small Pearl-bordered Fritillaries – another rare and declining species for which Dartmoor is another stronghold

Just before the heavy rain arrived I found this individual

Amazing details and colours in the wings

Here is a shot of a Pearl-bordered Fritillary I photographed a few years ago at Hembury Woods

 

The problem with Heather Beetles

The Heather Beetle (Lochmaea suturalis) is a native Chrysomelid leaf beetle which feeds almost exclusively on heather (Calluna vulgaris). It is common in areas whether heather grows from the south of England to Orkney in the north (Duff 2016).

Heather beetle populations are well known to fluctuate greatly from low numbers which have little over impact on heather plants to very high numbers which can lead to the widespread defoliation of heather and can cause its death.

Heather Beetle damage on Ryders Hill March 2016

Heather beetle outbreaks have historically been problematic for grouse moor owners and the issue of heather beetle and its control has been championed by the Heather Trust who have produced a short document on the species (Heather Trust undated).

In addition the Heather Trust commissioned a literature review of the species (Rosenburgh & Marrs 2010) which summarises the ecology of the beetle, its impact as a pest and strategies for control. This work has been updated (Gillingham et al 2015a and 2015b) and published as Natural England Evidence Reviews on its ecology and its management.

These reviews state the following regarding heather beetle outbreaks:-

• ‘Considerable damage to heather can occur with complete death in the worst cases’.
• ‘Large scale vegetation change can follow’ (heather outcompeted by invasive grass species).
• ‘The occurrence and severity of heather beetle attacks appears to be made worse by increased levels of nitrogen in the soil and plant tissues, which has been blamed on high nitrogen pollutant inputs from the atmosphere in recent years’.
• ‘The high nitrogen in the leaves provides the beetles with more high quality food to consume’
• ‘Climate change is expected to lead to increased winter survival of heather beetles’

On Exmoor heather beetle is considered a major problem, and the National Park Authority report that outbreaks are common and are spreading from the south to the north of Park. They also suggest that in areas where Purple Moor Grass (Molinia caerulea) is absent the heather plants recover fully and rapidly but where Molinia is present this quickly swamps the heather and replaces it (ENPA 2015).

I have written before about the loss of heather that had occurred on the National Trust’s land in the Upper Plym valley on Dartmoor (see here). In 1995 there was a serious outbreak of heather beetle which killed off the heather in the area known as Hen Tor Fields. At the time it was assumed that overgrazing was the cause although no increase in stocking levels had taken place for a number of years.  In this specific instance the heathland communities (H12 Calluna vulgaris-Vaccinium myrtillus) were replaced by upland grass communities (U4 Festuca ovina-Agrostis capillaris-Galium saxatile) which do not naturally contain Molinia. On the wet heaths of the Upper Plym Estate there were numerous other outbreaks on heather beetle during the 1990s and 2000s (Helen Radmore NT tenant pers comm) and in these habitats Molinia now dominates (my observations).

There has been no systematic survey of heather beetle on Dartmoor and Goodfellow et al (1997) only briefly mention it “Outbreaks of heather beetle cause local declines in heather”, however my recent observations on the moor suggest that heather beetle damage is very widespread and extensive.

Heather Beetle damage on Ryders Hill – March 2016

I would be very interested to hear from anyone with information about heather beetles on Dartmoor in recent years – it is an issue which is begging for more research.

References
Duff A.G. (2016) Beetles of Britain and Ireland. Volume 4 Cerambycidae to Curculionidae. A.G. Duff (Publishing) West Runton.
ENPA (2015) Exmoor Swaling Review 2014/15. Seminar Notes ENPA. Dulverton. http://www.exmoor-nationalpark.gov.uk/__data/assets/pdf_file/0011/583454/Exmoor-Swaling-Review-2014-15.pdf
Gillingham P., Diaz A., Stillman R. & Pinder A.C. (2015a) A desk review of the ecology of the heather beetle. Natural England Evidence Review, Number 008. http://publications.naturalengland.org.uk/publication/6386866406293504
Gillingham P., Diaz A., Stillman R. & Pinder A.C. (2015b) Desk review of burning and other management options for the control for heather beetle. Natural England Evidence Review, Number 009. http://publications.naturalengland.org.uk/publication/4817807814426624
Goodfellow S., Wolton R. & Baldock N. (1997) The Nature of Dartmoor: a biodiversity profile. English Nature / Dartmoor National Park Authority publication. http://www.dartmoor.gov.uk/__data/assets/pdf_file/0014/42701/au-natureodp2.pdf
Heather Trust (undated) Heather Beetle. Download from Heather Trust Website http://media.wix.com/ugd/fdc287_2b9ec8fa073d4ca38baf4a754d7a77f4.pdf
Rosenburgh A. & Marrs R. (2010) The Heather Beetle: a review. Report to the Heather Trust. http://media.wix.com/ugd/111722_4370d9fb976442b2af6e678aa83c3663.pdf