Heather burning – GWCT responds to criticisms

By Andrew Gilruth, GWCT Communications Director

It has come to our attention that an RSPB presentation, delivered to raptor study groups last November, accused the GWCT of “distorting and discrediting the science” around heather burninga. We reject this.

Muirburn www.lauriecampbell.com

We feel we have accurately and openly reported the breadth of evidence available. The fact we have not reached the same conclusion as the RSPB does not amount to distortion. Disagreement and challenge is a normal part of the scientific process.

What has the GWCT said about heather burning?

A month before the presentation in this video the GWCT had stated the following in our submission to the Petitions Committee inquiry into grouse shooting:

“There remains contradictory evidence about the actual positive or negative impact of burning when longer time-scales are taken into account1. More research is needed.” 

What did the RSPB say to the inquiry?

Their submission is here and, during the oral evidence session, Rishi Sunak MP asked the RSPB witness: “Where have you seen examples that there are conservation benefits from selective vegetation burning?”

Rather than answer the question, the RSPB said that they see heather burning as an “an environmental ill” and “a net negative [environmental] impact”.

This may be their view, but the scientific literature is conflicting and there is not yet a consensus to back such a generalisation. As with most management practices, if it is done incorrectly it can be damaging; however, used appropriately it can be an effective management tool with conservation benefits.

How did the GWCT respond at the time?

Since the GWCT felt that comments made in the oral evidence were not supported by the evidence base, we submitted supplementary information including the followingb:

“The evidence on burning is highly contested; this is demonstrated by the high level of debate amongst 16 scientists from six nations in recent exchanges in the journal of the Royal Society, the world's longest-standing scientific society. They agree that more research is needed here. Examples of the wider debate include: 

1)  Peat formation – as well as negative impact there is also evidence that burning heather has a positive impact on the Sphagnum mosses that are important in peat formation2. The authors “found no evidence to suggest that prescribed burning was deleterious to the abundance of peat-forming species; indeed, it was found to favour them”.

2) Dissolved Organic Carbons (DOC) – There is also some evidence that DOC levels are unaffected or decline where burning has taken place3,4.

3) Water table – the EMBER study suggests heather burning lowers the water table, others suggest it does the opposite3,5,6.

4) Scale of burning – some authors express concern that more burning, rather than less, should be occurring, to reduce potential fuel build-up and wildfire risk7. Recent evidence from the Peak District shows that burning is generally carried out in accordance with guidelines, with appropriately sized burns and only 0.9% area being burnt per year, well below the recommended 10%. 

5) Carbon budgets – a Natural England evidence review assessed that the evidence for overall carbon budgets is limited and contradictory8

6) Flooding – a Government committee report does not implicate increased burning in increased flood risk9.

There is contradictory evidence. For instance, the EMBER study also suggests overland flow is less common on burnt peat than unburnt peat. For the lowest 80% of rainfall events, the lag period is greater on burnt areas, and there is no difference for the top 20% (heaviest storms). For the top 20% of storms, the hydrograph intensity is higher for burnt areas but the lag time is not affected. This means that the peak discharge (amount of water in the stream), is higher for these heavy storms, but it does not happen faster10.  

This is precisely why the GWCT feels more research is required, before advocating wholesale changes to a land management tool that may be supporting the very biodiversity that we are all striving to protect.

A wider GWCT summary of the available evidence on a wide range of moorland management issues, including heather burning, can be downloaded here.

If you would like to read a copy of our submissions to the 2016 Westminster grouse inquiry, it can be found here

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1. Clay, G. D., Worrall, F. & Aebischer, N. J. Carbon stocks and carbon fluxes from a 10-year prescribed burning chronosequence on a UK blanket peat. Soil Use Manag.31, 39–51 (2015).

2. Lee, H., Alday, J. G., Rose, R. J., O’Reilly, J. & Marrs, R. H. Long-term effects of rotational prescribed burning and low-intensity sheep grazing on blanket-bog plant communities. J. Appl. Ecol.50, 625–635 (2013).

3. Worrall, F., Armstrong, A. & Adamson, J. K. The effects of burning and sheep-grazing on water table depth and soil water quality in a upland peat. J. Hydrol.339, 1–14 (2007).

4. Clay, G. D., Worrall, F. & Fraser, E. D. G. Effects of managed burning upon dissolved organic carbon (DOC) in soil water and runoff water following a managed burn of a UK blanket bog. J. Hydrol.367, 41–51 (2009).

5. Clay, G. D., Worrall, F. & Aebischer, N. J. Does prescribed burning on peat soils influence DOC concentrations in soil and runoff waters? Results from a 10year chronosequence. J. Hydrol.448–449, 139–148 (2012).

6. Clay, G. D., Worrall, F., Clark, E. & Fraser, E. D. G. Hydrological responses to managed burning and grazing in an upland blanket bog. J. Hydrol.376, 486–495 (2009).

7. Allen, K. A., Denelle, P., Ruiz, F. M. S., Santana, V. M. & Marrs, R. H. Prescribed moorland burning meets good practice guidelines: A monitoring case study using aerial photography in the Peak District, UK. Ecol. Indic.62, 79–85 (2016).

8. Glaves, D. et al.Natural England Review of Upland Evidence 2012 - The effects of managed burning on upland peatland biodiversity, carbon and water. (2013).

9. Committee on Climate Change. Written evidence to the Inquiry on Soil Health. (2016). Available here. (Accessed: 28th October 2016)

10. Holden, J. et al. Impact of prescribed burning on blanket peat hydrology. Water Resour. Res.51, 6472–6484 (2015).

a The 2016 Northern England Raptor Forum (NERF) conference was held on 19th November.

b For brevity, some of these points have been condensed. The full submission can be read here


RE THE RSPB report

at 15:19 on 31/01/2017 by Howard Siviter

Looks like pretty good evidence of criminal activity by gamekeepers on Grouse Moors to me. What a shame the law doesn't allow for those who employ the keepers breaking the law to be imprisoned.

heather burning

at 17:57 on 30/01/2017 by C Batchelor

Frank Stevens' question is simplistic. Constant burning has destroyed the native flora, turning the moors into a monoculture which only supports fauna which find heather beneficial. So of course the existing "fauna that inhabit that heath" find the situation beneficial - but we should also be concerned with the fauna which did inhabit, and could again with proper management.

heather burning

at 23:33 on 19/01/2017 by frank stevens

The question must be: does heather burning promote an increase in the proportion of young to old heather (on a heath) and is this beneficial to all the fauna that inhabit that heath? If the answer to part (b) is "yes" then heather burning is a beneficial tool. Ecology does not recognise words such as 'cruel' which do not allow for the diversity of means of death that occur in Nature. Is a dog or fox cruel when it kills a rabbit? But an eagle not cruel when it kills a hare? If a human takes a bird or beast and eats it is he/she more cruel than a fox or tiger?

Muirburn & Biodiversity

at 11:26 on 18/01/2017 by J. Robertson

Thanks to Iain Gibson for his "unbiased" comments!!

Effects of heather burning

at 22:30 on 17/01/2017 by A.Branthwaite

Has nobody yet cottoned on to the fact that the massive drainage of coniferous forests cause more flooding than anything, due to the quick runoff of water rather than a more gentle absorption into the ground and therefor a more gradual introduction into the streams and rivers. Far more impact on the environment than heather burning ever had. Surely not rocket science to realise that .

Muirburn and Biodiversity

at 21:47 on 17/01/2017 by Iain Gibson

As a naturalist who has been immersed in the study of peatland ecology for many years, I am not content that the scientific research you quote is completely unbiased. Obviously it is very difficult to prove the following opinion, but it appears to me that certain scientists who "support" grouse shooting and cruel sports in particular are deliberately amending or misinterpreting data to suit your agenda. Of course the predictable response to such a suggestion is that I'm nothing more than a conspiracy theorist. However all I can say is that anyone who believes most of the evidence you present in this article must surely be unfamiliar with the terrain of a grouse moor, or else remarkably unobservant. The visual and ecological signs of damage through desiccation are all too plain. I would particularly take issue with your contention that "...the GWCT feels more research is required, before advocating wholesale changes to a land management tool that may be supporting the very biodiversity that we are all striving to protect." First of all, I just don't believe you are devoted to the conservation of biodiversity. If you are, you have an inordinately strange way of showing it! More importantly, if your scientific advisers claim to have demonstrated that heather burning is "good" for biodiversity, you should be sacking them for misleading yourselves and the public. I have carefully studied four grouse moors over a period of forty-odd years, and the impact of strip burning on biodiversity has been absolutely catastrophic. It would take an ecologist with very little natural history knowledge (yes they do exist) not to notice this effect. Repeated burning over decades or centuries leads to a great loss of native plant life; after such time very little regenerates except heather. As this is presumably the desired effect to swell grouse numbers, you must know this, suggesting that your concern for biodiversity is a sham. It implies that the data is almost certainly manipulated, however I also notice that as evidence of enhancement of biodiversity, it is still very poor. Not only plants are affected, but invertebrates which rely on these plants for hosts, and soil invertebrates which are simply burned to death. Small mammals suffer in turn, with fires killing literally many thousands of field voles, creating artificial suppression of their populations - hardly surprising that harriers under such stressed circumstances are forced to resort to grouse for food. The 'keepers solution to this self-inflicted "problem" appears to be to kill the hen harriers (and other raptors like Buzzards which also rely heavily on voles), hence the main public reaction to the pseudo-sport of grouse shooting. It is my belief, and that of many others, that organisations like GWCT resort to post-truth solutions in attempt to turn the tide in their favour. However you can't fool everyone. I will give you some credit for being willing to publish counter-arguments.

heather burning

at 17:54 on 17/01/2017 by harrier lover

It is not worthy of time spent on writing . More junk spewed from the bird charity . Sick to death of hearing the same ill founded rubbish. GWCT ....keep up the excellent work.

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