By FWJ van Rooijen (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia CommonsPlease could Northumberland National Park name, or at least give a reference, for the 20% of Britain’s spiders that will disappear if upland heather burning were to cease. I’m pretty sure that the one above isn’t one of them.
But I was wondering, surely the lowlands are the place for spiders anyway – like they are the place for trees to grow!
14 Replies to “Please could Northumberland National Park…”
Can you answer my questions on your Facebook page?
Andy – not right now, no.
Mark…. we are regularly told that we need to burn Heather to “keep the hills purple”. I have searched and searched but I can’t find anything that tells me at what age Heather stops flowering. In my experience, Heather in the 30-40 year bracket flowers just as prolifically as 6 year old.
I suspect that this is another statement which has no basis in fact. Grouse moor owners like that sort statement. Let no myth remain unchallenged.
Good point.
These lowland Calluna heaths always flower well (plus both Ericas) and they are never burnt except for the occasional wildfire. There’s an overgrown few acres here on my local common which has not had a fire for well over 40 years and it produces a fine display of purple every year.
A very basic point really, but since I’ve never heard it being expressed anywhere so here goes…Given that flowering heather will only be accessible for a certain number of pollinator species and that its flowering period is comparatively short the fact that hills turn purple with it means there isn’t much of anything else to sustain non heather feeding insects, and the ones that do visit it have effectively sod all to sustain them outside its flowering period – a glut then famine. Ironically purple hills could be a sign that our grossly ‘managed’ uplands are really crap for pollinating insects. I’m not an entomologist so would be happy to be corrected, but the purpose of having a nectar bar in a wildlife garden is so many different pollinators have food throughout the growing season, heather near monocultures don’t do that surely?
You need to contact the British Arachnological Society for an expert opinion. In my spider survey experience the diversity of spiders in heather goes up markedly when heather is left to grow tall even on upland heather stands.
The claim looks unlikely.
It’s not clear if it’s numbers or species that would loose 20%. Given the small area of the UK covered by heather and its comparatively low productivity it is extremely unlikely that that proportion of spiders could be found on moors. The basic ecological work to make the assessment doesn’t exist.
In terms of species there is more hope and some data does exist. 20% of UK species would be about 150 species. It could be that this number of species have been listed as associated with heather or found in one of several surveys of moorland in the UK. But this does not mean they dependent on moorland or would be lost if moorland were removed completely. The role of burning in the survival of these species will be marginal.
If the data exists in any form I’d love to see it. Heathland, especially in the south, has a diverse spider community and some very rare species. It may be that Dorset Heath is being used as the basis for the claim, but burning and grouse are not important there to the best of my knowledge.
It might even have been you that commented about the role that Juniper should play…..jings crivens help ma bob!
Spiders live in a 3D matrix and they depend on the vegetation creating the correct “space pattern” to suit their particular web building needs/limitations. The greater the spatial diversity, the greater the variety of web types and sizes that it can accommodate. Muirburn is all about simplifying the structure.
I can remember reading somewhere (probably back in the 80’s!) that many of our moorland spider species space requirements are better served by juniper…. a species which has been burnt off the moors.
PS… I don’t ever remember reading about fire resistant spiders, some might survive in the litter if its not burnt but above ground?
“for the 20% of Britain’s spiders that will disappear if upland heather burning were to cease.”
They never said that though
What they actually said:
“For instance, e’ve got 20% of all the spider species in the UK are actually only in Heather Moorland, if we lost the heather moorland, we’d lose all of them”
Not the same is it? you little billy liar you…
In the meantime, you might like to watch this video from the New Forest, where theres no Grouse
Kie – why don’t you stop burning and let it revert to woodland was the bit that came before that. You know.
Would you apply the same argument to lowland heaths?
Why not let them revert to woodland? Who cares about nightjar and dartford warbler.
Thanks for the clarification, Kie. It makes it easier to assess the statement.
670 species of spider have been recorded in the UK.
The Spider Recording Scheme contains broad habitat information. For example it lists 500 species recorded from Heath/moor, heather and 452 species from Heath/moor other. Grassland has 495 species and woodland 458. There is clearly a lot of overlap in these lists. Most spiders show wide habitat preferences.
I have looked a a few species I associate with heather on SRS and in all cases they have a range of other broad habitats listed, eg woodland or grassland. The Ladybid spider, restricted to heathland in Dorset, was one exception. If someone has time they could check all 670 records and see if they can find 134 recorded only from heather, but I don’t think they will.
If the 20% claim is based on anything it would be good to hear what it is. Until then I’m very doubtful about the statement.
As Alastair says, the figure of 130-150 species seems incredibly unlikely. I have put this question to the British Spiders Identification (Facebook) Group (as it has many knowledgeable members), and so far, there is consensus that the figure looks most dubious. N.B. The figure has also been discussed (and questioned) at BugLife’s offices, albeit only informally.
Put simply then, as we all know(!), if you are going to see high numbers of any and all metazoan species in any one place in the UK (as opposed to ecosystem specialists), then you are going to also need a variety of habitats to accommodate them. And, still assuming the 20% figure is correct, a good percentage of these numerous species of spider would then need the very things (additional woodland, scrub, bog, etc.) that a regular burning programme inhibits.
So, to suggest that “controlled” fire maintains high (spider) species diversity is completely wrong. It certainly might aid a few specialists that could be in danger if the (mono)culture were to change, but that was not Andrew Miller’s point. Maybe he should have said that instead to be safe?
Moreover, it also seems unlikely that (upland) heathland accommodates 20% of the UKBAP listed spiders either (http://srs.britishspiders.org.uk/portal/p/UKBAP+spiders), let alone 20% of the overall species! I’m not even sure you could claim the UKBAP listed figure for upland and lowland heath combined as well… but there we go!
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![By FWJ van Rooijen (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons](https://markavery.info/wp-content/uploads/2016/04/800px-European_Garden_Spider_Kruisspin.jpg)
Can you answer my questions on your Facebook page?
Andy – not right now, no.
Mark…. we are regularly told that we need to burn Heather to “keep the hills purple”. I have searched and searched but I can’t find anything that tells me at what age Heather stops flowering. In my experience, Heather in the 30-40 year bracket flowers just as prolifically as 6 year old.
I suspect that this is another statement which has no basis in fact. Grouse moor owners like that sort statement. Let no myth remain unchallenged.
Good point.
These lowland Calluna heaths always flower well (plus both Ericas) and they are never burnt except for the occasional wildfire. There’s an overgrown few acres here on my local common which has not had a fire for well over 40 years and it produces a fine display of purple every year.
A very basic point really, but since I’ve never heard it being expressed anywhere so here goes…Given that flowering heather will only be accessible for a certain number of pollinator species and that its flowering period is comparatively short the fact that hills turn purple with it means there isn’t much of anything else to sustain non heather feeding insects, and the ones that do visit it have effectively sod all to sustain them outside its flowering period – a glut then famine. Ironically purple hills could be a sign that our grossly ‘managed’ uplands are really crap for pollinating insects. I’m not an entomologist so would be happy to be corrected, but the purpose of having a nectar bar in a wildlife garden is so many different pollinators have food throughout the growing season, heather near monocultures don’t do that surely?
You need to contact the British Arachnological Society for an expert opinion. In my spider survey experience the diversity of spiders in heather goes up markedly when heather is left to grow tall even on upland heather stands.
The claim looks unlikely.
It’s not clear if it’s numbers or species that would loose 20%. Given the small area of the UK covered by heather and its comparatively low productivity it is extremely unlikely that that proportion of spiders could be found on moors. The basic ecological work to make the assessment doesn’t exist.
In terms of species there is more hope and some data does exist. 20% of UK species would be about 150 species. It could be that this number of species have been listed as associated with heather or found in one of several surveys of moorland in the UK. But this does not mean they dependent on moorland or would be lost if moorland were removed completely. The role of burning in the survival of these species will be marginal.
If the data exists in any form I’d love to see it. Heathland, especially in the south, has a diverse spider community and some very rare species. It may be that Dorset Heath is being used as the basis for the claim, but burning and grouse are not important there to the best of my knowledge.
It might even have been you that commented about the role that Juniper should play…..jings crivens help ma bob!
Spiders live in a 3D matrix and they depend on the vegetation creating the correct “space pattern” to suit their particular web building needs/limitations. The greater the spatial diversity, the greater the variety of web types and sizes that it can accommodate. Muirburn is all about simplifying the structure.
I can remember reading somewhere (probably back in the 80’s!) that many of our moorland spider species space requirements are better served by juniper…. a species which has been burnt off the moors.
PS… I don’t ever remember reading about fire resistant spiders, some might survive in the litter if its not burnt but above ground?
“for the 20% of Britain’s spiders that will disappear if upland heather burning were to cease.”
They never said that though
What they actually said:
“For instance, e’ve got 20% of all the spider species in the UK are actually only in Heather Moorland, if we lost the heather moorland, we’d lose all of them”
Not the same is it? you little billy liar you…
In the meantime, you might like to watch this video from the New Forest, where theres no Grouse
https://www.youtube.com/watch?v=EFUSUOJO2Ac
Kie – why don’t you stop burning and let it revert to woodland was the bit that came before that. You know.
Would you apply the same argument to lowland heaths?
Why not let them revert to woodland? Who cares about nightjar and dartford warbler.
Thanks for the clarification, Kie. It makes it easier to assess the statement.
670 species of spider have been recorded in the UK.
The Spider Recording Scheme contains broad habitat information. For example it lists 500 species recorded from Heath/moor, heather and 452 species from Heath/moor other. Grassland has 495 species and woodland 458. There is clearly a lot of overlap in these lists. Most spiders show wide habitat preferences.
I have looked a a few species I associate with heather on SRS and in all cases they have a range of other broad habitats listed, eg woodland or grassland. The Ladybid spider, restricted to heathland in Dorset, was one exception. If someone has time they could check all 670 records and see if they can find 134 recorded only from heather, but I don’t think they will.
If the 20% claim is based on anything it would be good to hear what it is. Until then I’m very doubtful about the statement.
As Alastair says, the figure of 130-150 species seems incredibly unlikely. I have put this question to the British Spiders Identification (Facebook) Group (as it has many knowledgeable members), and so far, there is consensus that the figure looks most dubious. N.B. The figure has also been discussed (and questioned) at BugLife’s offices, albeit only informally.
Put simply then, as we all know(!), if you are going to see high numbers of any and all metazoan species in any one place in the UK (as opposed to ecosystem specialists), then you are going to also need a variety of habitats to accommodate them. And, still assuming the 20% figure is correct, a good percentage of these numerous species of spider would then need the very things (additional woodland, scrub, bog, etc.) that a regular burning programme inhibits.
So, to suggest that “controlled” fire maintains high (spider) species diversity is completely wrong. It certainly might aid a few specialists that could be in danger if the (mono)culture were to change, but that was not Andrew Miller’s point. Maybe he should have said that instead to be safe?
Moreover, it also seems unlikely that (upland) heathland accommodates 20% of the UKBAP listed spiders either (http://srs.britishspiders.org.uk/portal/p/UKBAP+spiders), let alone 20% of the overall species! I’m not even sure you could claim the UKBAP listed figure for upland and lowland heath combined as well… but there we go!