More zombie ideas in ecology
ADDENDUM - February 2019
It is uncommon to see a colloquialism published in a scientific journal – a certain descriptive rigor is usually required of authors. However, I stumbled across a rather intriguing one when I read a recent paper that called into question the commonly held view that habitat fragmentation had negative consequences for native ecology. Prof. Lenore Fahrig of Carleton University in Canada reviewed empirical studies that showed a significant response to habitat fragmentation (1). Her finding that 76% of the studies showed a positive rather than a negative response was what led her to challenge the assumption that habitat fragmentation is a major cause of the erosion of biodiversity. I looked at the impact of habitat fragmentation a few years ago, taking the approach of looking through the eyes of other, smaller mammal species. It seemed to me that responses to habitat fragmentation depended on the habitat selection and dispersal ability of individual species (2). The effects of fragmentation will depend on the extent of specialisation of the species, and what variety of landscape niches that are utilised. Thus the reduction in population for a species that relies on a continuous natural habitat begins to bite when the distance between fragments becomes daunting to the point where it prevents dispersal, and so connectivity breaks down. Those species which utilise edge habitats could at first benefit from fragmentation as the extent of edge habitat increases, but increasing fragmentation again leads to a breakdown in connectivity and population decline. However species that utilise a number of niches could show an increase in population with fragmentation, as the mosaic of niches becomes more mixed. There comes a point though when habitat loss supersedes habitat fragmentation, breaking down any connectivity and leading to population decline.
Ideas that should be dead but are not
I noted before that this increasing anthropogenic fragmentation leads to an artefactual landscape. Fahrig evidently seems to embrace this artefactualism, since she avers that her results suggest that “generally speaking, land-sharing policies will provide higher ecological value than land-sparing policies”. This is an argument that condemns wild nature to a continuing, enforced co-existence within our modified landscape rather than be given its own space. Even then, “land sharing” is a misnomer when you consider how much of wild nature has been purposively removed in the past as being inconvenient, and is still being removed today in the ever downward spiral of trophic degrading (3). Given her stance, I became more critical of her findings. Fahrig does acknowledge some of the issues I outline above, but also acknowledges her dependence on analysing studies that used species richness, an unrevealing, bean-counting metric, as well as almost exclusively single-species responses in the studies on birds. The limitations of species richness in relation to landscape transformation have been addressed recently (4) as has the issue of studies that used small plots and over short time periods, and which will not fully represent the reality of landscapes that are fragmented, dynamic, and continuously influenced by countless human activities on different scales in time and space – shades of artefacts again (5). Fahrig is also weak in incorporating aspects of dispersal, an overridingly important aspect of fragmentation, but which have also been covered by a more recent paper (6). Irrespective of these reservations, I do acknowledge Fahrig for introducing me to the expression “zombie ideas”, these being “ideas that should be dead but are not”. Thus it is her contention that negative consequences arising from habitat fragmentation is a zombie idea, and that the “fact that this zombie has persisted for more than 45 years is a testament to its intuitive appeal”. Well, another word for intuition is instinct, and instinct in wild animals is a pattern of behaviour in response to stimuli, and thus is based on survival experience.
Fahrig references the phrase zombie ideas to a blog by Prof. Jeremy Fox, an ecologist at the University of Calgary (7,8). Fox in turn attributes the phrase to Prof. John Quiggin, an economist at the University of Queensland, whose early use was in a demolition of neo-liberal market ideas that resurfaced after the financial crash of 2008, but which the crash had refuted (9,10). Quiggin, however, associated the phrase with Paul Krugman (11) a columnist for the New York Times, who wrote that he originally saw it in the context of myths about Canadian health care (12). He explained that “Zombie ideas…are policy ideas that keep being killed by evidence, but nonetheless shamble relentlessly forward, essentially because they suit a political agenda”. Economics aside, but an interesting diversion, Fox made a compelling case in his blog for the existence of zombie ideas in ecology, and his prose stuck within the milieu – “Ecology (and probably every field) has its own zombie ideas. In some cases they’ve survived decades of attacks from the theoretical and experimental equivalents of chainsaws and shotguns, only to return to feed on the brains of new generations of students” (8). His focus in the blog was the intermediate disturbance hypothesis, and while it is not entirely the same, it has some similarities for me with the unimodal, hump-backed or bell-shaped relationship between species richness and the level of disturbance (see Fig. 1a in (13)).
I have seen this hump-backed relationship of Grime (14) pressed into a justification by proponents for High Nature Value (HNV) farming, the concept of HNV characterised by low-intensity pastoral systems with semi-natural vegetation, often in marginal farming areas (15,16). The explanation is that the low to medium levels of disturbance associated in extensive pastoral systems introduces a greater variety of niches and provides greater colonisation opportunities for a wider range of species i.e. mobile, opportunistic, stress tolerant or disturbance tolerant species. It’s the CSR strategy for plant distribution based on levels of disturbance and stress – Competitor – Stress tolerators – Ruderals (17). Beware though that the diversity of niches in HNV doesn’t necessarily always have to be of a natural origin arising from semi-natural vegetation, since it can also include stone walls and hedges that can add to the density of features providing ecological niches. At an intuitive, or instinctive level, I refute that a little bit of farming is good for wild nature. What is ludicrous about this is the implication that a lower value of species richness as it descends on the left-hand side of the bell curve is a failure of undisturbed wild nature! Not everyone accepts the Grime model, and various authors have fought it out in the journals (e.g. 18,19). On first observation, it seemed mostly to be characteristic of grassland systems, thus questioning whether the hump-back relationship is an artefact of human modification, and not the result of a natural disturbance, because it certainly didn’t apply to woodland (20). It has become clearer though, that the unimodal relationship of species richness is conditional upon what organism is being studied and in which environment (13).
The hump curve is amongst some of the other
zombie ideas in ecology that Fox identifies and refutes (21,22). However,
before I move on to consider where the modern-day zombie ideas in ecology are
coming from, I want to give you one of Fox’s “zombie-fighting lessons”
which he says can be used to protect you against any other zombies which might
try to eat your brain – “Just because a famous ecologist, or lots of
ecologists, or a textbook, says something doesn’t make it true”. This would
certainly be the case for John Lawton, the “eminent British ecologist”,
Chair of Yorkshire Wildlife Trust, and who led the review of the resilience
and adequacy of England’s wildlife sites (23). While
walking around Ennerdale during the 10th anniversary meeting in 2013, Steve
Carver and I challenged Lawton, a keynote speaker, to explain his support for
the fake farming there (24-26). He said that it was
all about the hump-backed curve. Steve and I were astonished at this response,
Steve subsequently following it up by email with Lawton in which he described
the evidence from the matched contrasts of the ungrazed and grazed Scar Close/Southerscales
and South House Moor/ Park Fell and Borrins. Steve thought that this evidence
told him that the relationship between grazing and biodiversity and associated
indices of fragmentation, dominance, biomass, together with successional
trajectories, isn't a simple one:
Steve finished by asking Lawton what his thoughts were, but twice Lawton refused to engage. Perhaps he suddenly remembered his paper from 1999 on deciding whether there were general laws of ecology, and in which he asserts that the unimodal species richness-relationships may be considered a contingent rule in that it depends on the organism and environment, as well as considerations of scale (27). So why was Lawton so ready to apply the hump curve at Ennerdale? Perhaps it was, as Paul Krugman would say, essentially because it suited a political agenda (see above).
Other realities exist
Stewart Brand, inveterate founder of organisations and an ecopragmatist, was quick to respond to Fahrig’s paper and its message. He tweeted - “Habitat fragmentation is generally GOOD rather than bad for wildlife--reversing a major premise of conservation” (28). Brand labelled this a “major narrative violation” - and which led him to assert that we should “protect and restore wildlands at *every* scale”. Brand has previous form on challenging environmental doctrine in the sense that he has written about the four environmental heresies that his ecopragmatism tells him will become increasingly acceptable, such as technological means to mitigate climate change, and urbanisation as a form of population control (29). In this case, however, on habitat fragmentation, is he missing the point or is he just applying a sticking plaster? My reaction to the slavish dogma of the mainstream conservation industry is that “other realities exist”, it being very apparent to me that there is a very discernible biophysical reality when wild nature is in control, and which is destroyed by the conservation industry’s managerialism – this would be the degraded bits in between the habitat fragments. I have come across so much that refutes managerialism since I began my advocacy of self-willed land that I think I should now be able to attribute the slavish dogma to being a zombie idea, and use the phrase as a riposte to what I see. It is so blindingly obvious to anyone with freedom of thought, that it is a “major narrative violation” to see it any other way.
In terms though of a more focussed riposte, I
deem nature development as exemplified by the ecological disaster that
is the Oostvaardersplassen as being a true zombie idea. Nature development is
a peculiarly Dutch concept about creating new nature (30). The concept may have had its
origins in the early 1970’s, when grazing was increasingly practised in nature
reserves (31). Like conservation grazing in Britain, the main emphasis was
botanical management with herbivores acting as lawn mowers. A new emphasis
evolved from the mid-70s to the early 1980’s when nature conservationists in
the Netherlands saw the opportunity to create what they alleged would be more
diverse woodlands, through experiments on forest grazing of stands of Scots
pine by Scottish Highland cattle in a complex of nature reserves at the
southern fringe of the Veluwe, a forest-rich ridge of hills. The thinking was
that the large herbivores would play a significant role as a tool in the
management of the area, but were increasingly being touted instead as part of
the ecosystem (32). It appears that Dutch ecologist Harm van de Veen was
instrumental in pushing this, based on his experiences in N. America (33, 34).
van de Veen gives one of the clearer explanations for the use of a nature
development approach when he wrote a critique in 1989 of the nascent
He didn’t think that the Oostvaardersplassen, famed after its reclamation from the sea for its greylag goose population (36) then later for the cattle and horses introduced there, was much of a demonstration of nature development. He concluded that since the Management Committee had opted solely for water management, instead of setting goals within which there was room for fundamental natural processes, then it was hardly surprising that the Oostvaardersplassen Development Vision was actually a "bird conservation vision". The issue for him was that it is was not indicated which species would and which species would not belong there, when he could foresee that a habitat like the Oostvaardersplassen had many missing mammals, such as wild boar, otter, badger and the other, smaller carnivorous mustelids (such as weasel, polecat, pine marten, stone marten). He also believed that the lynx and wolf should be there, but he noted that while the spontaneous migration in and establishment of otter, pine and stone marten, and badger were likely, the other missing mammals had been “reasonably ruled out for many decades”. It is likely that he was particularly referring to the large carnivores, since he had been rebuffed before about reinstatement of wolves in his experimental areas, and it had always been his aim for self-regulation within the fauna community, as well as a dynamic interaction between fauna and vegetation (34,35). In this, van de Veen obviously realised the importance of building trophic occupancy and structure at all levels.
Don’t trust your intuitions without doing the math
It is a sad misfortune that Harm van de Veen
died in 1991 at the age of 45 (33). He would likely have been a strong
advocate in keeping nature development away from its disastrous course of
trophic imbalance through solely dumping herbivores into fenced landscapes, a
policy that is of course wedded to the one-eyed fanaticism of Frans Vera as
the architect of the approach at the Oostvaardersplassen (37). The
Oostvaardersplassen thus became increasingly the emblematic area of Dutch
nature development (38) with Vera advocating that it be turned into a national
policy (39). In unravelling the cant at the Oostvaardersplassen, I
inadvertently followed another of Fox’s “zombie-fighting lessons”, this
one being “Don’t trust your intuitions without doing the math” (8). My
intuition told me, on seeing evidence of the overgrazed and degraded
landscape, and the many emaciated corpses of horses, deer and cattle, that
something was very wrong at the Oostvaardersplassen (40,41). I initially
calculated mortality from the difference between yearly counts of births of
the herbivores, set against a mostly unchanging total population density, and
found that the total deaths from starvation between 2005-2013 was around
8,000, or twice the total population (23, 40). I recalculated from a later
graph of winter animal deaths, finding a similar number of 8,000 between the
years 2011-2016 (42) with 1 in 3 animals having died in the winter of
2015-2016 (41, 43). It was enough for me to declare that the
Oostvaardersplassen is the closest we have in Europe to a demonstration of an
ecological meltdown from unrestrained herbivory, that conclusion being
reinforced by a rough calculation which showed that the total herbivore
numbers present at the Oostvaardersplassen in the Netherlands is four times
greater than the herbivore density that is the threshold for woodland
regeneration (44). This is a level of herbivore pressure at its food-limited
carrying capacity, and which most evidently damages ecosystems (44). Two
recent pieces of evidence support this. Steve Carver, by way of Twitter (45)
took a pop at Guardian/Observer journalist Patrick Barkham for a facile
article in which Barkham regurgitated the usual untrue rubbish about the
Steve noted that Barkham was patently wrong, as there are no glades or wooded groves at the Oostvaardersplassen, and wondered if Barkham had ever been there. Barkham tritely replied that Vera's theories were certainly borne out at Knepp (more later) but Steve asked again whether Barkham had ever been to the Oostvaardersplassen, and presented a time-tour using Google Earth's historical imagery that showed the complete loss of shrubs and trees from two sample locations between 2004-2015, except for where there were small areas of fencing that excluded the herbivores (45). As Steve said, it’s a sobering comparison. The other piece of evidence is that supplemental feeding was carried out this month to stave off the intensity of winter starvation that happens at the Oostvaardersplassen because of the herbivores being at food-limited carrying capacity, as was also carried out in 2010 (47,48). However, the repulsion about the deaths at the Oostvaardersplassen has massively increased since 2010, and so another reason for the feeding this month was to prevent social unrest.
Well, that hasn’t worked: a week after the supposed supplemental feeding started, Dutch MEP Annie Schreijer-Pierik tabled a Parliamentary question to the European Parliament on the starvation of large grazing animals in the Natura 2000 area Oostvaardersplassen (49). She noted that between December 2017 and February 2018, “at least 1,755 large grazing animals died a cruel death from starvation in the Oostvaardersplassen”. She identified that the “persistent starvation” was caused by an excessively large population of animals being fenced in, and attributed the habitat destruction to that. Her questions were whether the Commission was aware of the adverse impact of the current policy, would it intervene, and wasn’t it a contravention of the EU’s animal welfare and nature management principles. It should be remembered that this ecological devastation is still carrying on after there has been two international commissions reporting in 2006 and 2010 that were constituted specifically to deal with the issues that Annie Schreijer-Pierik is raising yet again (24,40). Then two weeks after that, Dutch animal welfare activist Norma Miedema posted a video of herself and colleagues throwing hay over a fence at the Oostvaardersplassen, and with the Heck cattle rushing to eat it (50). During a second video of feeding elsewhere on the boundary fence, you can hear her say “killing fields” on the sound track and the camera zooms in to a notice posted on the fence that says “Oostvaardersplassen killing fields” (51). In both videos you can see the devastating degradation of the landscape within the Oostvaardersplassen from overgrazing. The responsibility for all this rests on the monumental ego of Frans Vera. If he had genuinely been interested in maintaining the water birds at the Oostvaardersplassen, then all it needed was some seasonal conservation grazing to manage for grassland, but instead we got his ecologically illiterate experiment in nature development that has resulted in what must be well over 10,000 deaths. Given all the foregoing, then nature development as demonstrated by the Oostvaardersplassen is definitely a zombie idea in ecology, although the trophic imbalance and its consequences pretty much bars it from being recognised as ecology.
A particularly wanton agenda
I’m going to stretch the concept a little for my next zombie idea in ecology, but it is befitting in this case for the organisation that perpetrates it. REFARMING (Rewilding) Europe continually massages ecology to suit its purpose, a primary action being to assert that the outcome of its actions creates the original natural landscape, and which it visually portrays as being open and savannah-like. Well, it’s true that its actions, the equivalence of maintaining a farming pressure, create and maintain open landscapes, but it’s a leap of faith, or a particularly wanton agenda, to believe there is any evidence that this is the original natural landscape. You can see these fantasy future visualizations of the landscapes of their project areas on the project pages of their website, but more easily in one place in their annual review for 2016 (52). The key, as always, with REFARMING Europe, is that their approach involves dumping lots of herbivores into their project areas, often in places where there are no large carnivores. REFARMING Europe doesn’t call it nature development, but it has a close association with one of its founding partners that does since it is “specialized in bottom-up nature development based on natural processes” (53). That organisation is ARK Nature, yet another Dutch foundation, and it is revealing that its name in the Netherlands is ARK Natuurontwikkeling, the latter word being Dutch for nature development (54). I have frequently documented my antipathy towards REFARMING Europe, not least that it has made a good job of destroying the real meaning of rewilding, but it is where they seek to push changes in policy and even legislation to their own advantage that shows it to be the bullying organisation that it is.
Struggling hard to get its plastic aurochs (back-bred, domestic cattle) accepted as wild animals, REFARMING Europe alighted on the wheeze to push the use of another big herbivore in the bison, which at least has a rightful claim to being a wild animal, except that REFARMING Europe deliberately chooses to disregard paleoecological evidence that indicates bison weren’t a native animal of the Netherlands (55). Tricky that, when REFARMING Europe and ARK Natuurontwikkeling’s favoured first-try dumping ground for their fantasies is the Netherlands. One of those dumping grounds for ARK Natuurontwikkeling is a series of reserves in the Kempen-Broek corridor that runs through farmland in the Limburg Province in the south of the Netherlands, on its border with Belgium. ARK Natuurontwikkeling has five grazing units spread along the corridor populated with 85 tauros (plastic aurochs) one of which - Tungelroyse Beek (brook) – is 2.3km north of Stramproy (see map on pg. 16 in (56)). This corridor is touted locally as a great place for walking, except that three years ago, ARK Natuurontwikkeling had to shoot three of the plastic aurochs in Tungelroyse Beek, as well as four other oxen after being anesthetized, from amongst the herd of 21 animals (57). Its explanation was that the despatched animals had become so nervous that their "character no longer fits a possible encounter between humans and cattle”. Well, you would have thought that it was an aim of nature development for these plastic aurochs to have been as wild as possible, but I guess not as wild as the real thing.
REFARMING Europe doesn’t restrict its lobbying just to the Netherlands, making a big play for the Konik horses it introduced in its project area in the Rhodope Mountains in Bulgaria to be legally recognised as wild animals (58). It’s not just the horses either, as its plans for the future of the project area show - “By 2024, a more supportive legal framework is in place that better allows for further tangible rewilding actions, like legally accepting the wild horse, the bison and the aurochs as wild native species” (59). The situation of legally accepting free living bison in Bulgaria is potentially feasible, but REFARMING Europe are dishonest in naming aurochs, an extinct animal that their back-bred fakes from domestic cattle will never be a replacement for, and van Vuure from the Netherlands exploded the myth that Konik horses should ever be called wild (55,60). As they did for bison (61) REFARMING Europe produced a glossy brochure on rewilding horses in Europe (62) as part of their Wildlife Recovery Programme that certainly has borne out its early intention of “focusing on large herbivores to start with” (63). This recovery of wild horses is a bit confusing as the Wild Horse Rewilding Action Plan notes REFARMING Europe’s usual approach of back breeding from likely candidate breeds, as was done in producing plastic aurochs, because there are “already a number of different wild horse types” (64). However, to the contrary, the brochure says that the “emphasis of this document is currently on rewilding, not on back breeding” (62). This so-called rewilding is about choosing the “right breeds and characteristics of existing horses for rewilding purposes” combined with this aspiration - “Future scientific knowledge can and should be used to improve the rewilding process and end product, such as adding or excluding certain gene variants from the rewilded herds”. It seems that rewilding horses will be about finding some space where REFARMING Europe can dump a diverse group of horses, about 150, chosen allegedly for their wild characteristics, and let them get on with it. If this doesn’t satisfy your need to understand what is meant by rewilding horses, then contemplate this from the brochure -“Rewilding is about respect for the authentic wildness of wild animals and thus respect for the potential wildness of rewilded animals”
It is easy to have a poke at the absurdity of
REFARMING Europe, but it is more serious when it makes spurious claims that in
relation to supranational legislation are wrong. It is in that brochure on
rewilding horses that we get the claim that “Przewalski’s horse is a genuine
wild horse and does not need to be rewilded” and “they are not domesticated or
changed”. On the back of that, REFARMING Europe makes this astonishing
What it is saying is that there should be no bar on introducing Przewalski’s horse to free living, as it represents a still-living, wild species like the bison (see above). REFARMING Europe should have been more cautious about asserting that, and taken more heed of their own prescription that “Future scientific knowledge can and should be used to improve the rewilding process” (see above). A year after that assertion, a paper was published that showed that up to 25% of the genomes of Przewalski’s horse consisted of gene variants inherited from domesticated horses (65). Then last month, a study of the genetic analysis of ancient horse bones indicates that Przewalski’s horses are the feral descendants of horses herded at Botai in the Central Asian steppes, and not truly wild horses (66). I can find nothing on REFARMING Europe’s website that acknowledges that this destroys their assertion. REFARMING Europe will probably shrug this off like it did the inconvenient bison paleoecological evidence, and for that reason I conclude that its constant bending of the ecological reality of its favoured herbivores is another zombie idea in ecology.
Allowed to scrub up BEFORE livestock were introduced
My last zombie idea is closer to home, but is not entirely unconnected with what has gone before. Last November, Steve Carver and I were puzzling over the disjointed spatial distribution of scrub shown in an aerial video of Knepp in Sussex (67) the heavily subsidised meat factory where it’s “‘rewilding’ is ‘process-led’ conservation” (68). We also pondered another puff-piece video of Knepp, working out all the inconsistencies within what was being said (69). We could not correlate locations shown in either video with farm layout, and so we turned to satellite imagery, where Steve did a time sequence on Knepp. It was not as dramatic in reverse as the changes illustrated at the Oostvardersplassen (see above) but the arrival of the new swimming pool and solar farm stuck out. I would make no connection between the arrival of these and the amounts of subsidy money that Knepp receives in Single Farm Payment (now Basic Payment) and Higher Level Stewardship (70).
It seemed to us that scrub development was concentrated in the southern block of the estate. To understand the spatial anomaly in this development, I speculated about why some areas may be grazed at Knepp more than others, the former areas being maintained as pasture by the grazing through chewing off any woody regeneration, while the latter areas had scrubbed up and been covered in ruderal weeds like thistles. I suspected it correlated with areas that were previously permanent pasture to support the dairy business, and thus will have had their grassland varieties improved over time, whereas the scrubby areas will be those that were previously used in arable cultivation and which thus did not have the improved grassland cover when they were brought into the project, nor would they necessarily have gained a grassland cover subsequently on their own. The cows obviously preferred to graze where the grass was better in the permanent pasture of the northern block, and where I walked around in 2007, especially during the months of the growing season, whereas they would exert much less pressure on any herbage that developed on the former arable areas. This allowed the scrub species seeding in to get away in the ex-arable areas, as well as the hedgerows around the arable fields. The ruderal weeds were more likely to establish in ex-arable than they were in permanent pasture.
It was a bit of a stretch as an argument, but
what I found out subsequently was that the south block, the predominantly
former arable area, was allowed to scrub up BEFORE livestock were introduced,
so that the scrub there developed without an influence of the cattle. This was
noted in a Year 10 report for Knepp from 2011 in which the southern block is
described as an area that was farmed intensively for arable crops from the
1980s to 2004 and then pretty much all set-aside or left fallow by 2006 (see
the fig. on pg. 16 in (71)). There are a number of before and after photos of
the scrubby nature of the former arable fields dotted through that report. The
text explains what happened (pg.21 in (71)):
I found confirmation of this in another video from Knepp in 2016 that was a BBC news report. Isabella Tree, the wife of Charlie Burrell, was being interviewed surveying a scrubby scene – “It would have been wheat, barley, maize ….flat as far as the eye can see, it would have been monoculture, arable” (at 0.26m in (72)). Later, the BBC reporter is walking in another scrubby area full of ruderals with Tony Whitbread, CEO of Sussex Wildlife Trust and long associated with Knepp. In the narration over the shot, the reporter, after explaining that the longhorn cattle introduced by Charlie are farmed for meat, then notes that “critics say that this kind of rewilding is, in the end, little more than a glorified theme park”. He asks Whitbread if he would “describe it as wild?”. Whitbread’s response – “In a word, no” is one of the rare moments of honesty about Knepp to go with the admission in the 10 year report that the scrub developed in the ex-arable area before cattle were introduced.
Does this admission about the scrub development matter?
It does if you perpetuate myths that the cattle are the drivers of the landscape at Knepp – “a fundamental and necessary force of natural disturbance” as promulgated by Frans Vera, the inspiration for Knepp and the perpetrator of my first zombie idea (73). It smacks of being untrustworthy when the assertions at Knepp have patently been untrue, such as that it is a "‘process-led’, non-goal-orientated project where, as far as possible, nature takes the driving seat - an approach that has come to be known as ‘rewilding’” (74). Another stinker in terms of this alleged lack of goal orientation is – "The key to establishing and maintaining this rich mosaic of habitats is to ensure that there are neither too many, nor too few, grazing animals" (75). Well, this is fiddling with grazing levels, the stockman having to check animal condition at the end of each winter because they mostly live off body reserves during that period – he had to use supplementary feed in 2010, as did the Oostvardersplassen (see above) – and then judging how many cattle can be taken for meat (76). It’s going to get trickier to fettle that land as the scrub develops more, because the cattle won’t bother with areas where grass doesn’t grow in the shade created by low growing scrub. They will, anyway, find it increasingly difficult to push their way through that scrub, and their next opportunity to get in there is when the canopy rises, as the scrub turns into trees. It’s simple natural woodland dynamics. This is not what Charlie is looking for when his patently goal orientated engineering of a mosaic of habitats within a wood pasture landscape (77) just sounds like the dogma of mainstream conservation gardening.
It could easily have been predicted that exclusion of grazing pressure in the ex-arable areas at Knepp would have given rise to scrub development– and apparently it was predicted, as shown in the 10 year review (see above) the scrub development described elsewhere as “pop-up scrub”(69). This scrub, long with thistles and other ruderals, would have been an encouragement to many invertebrate and avian species. The latter are thus not there because of any cattle grazing. As I have written elsewhere, and spoke about recently at a meeting on rewilding in Co Durham, It is the axiom in Britain that a withdrawal of farming pressure is a pre-condition of moving landscapes substantially along the wild land continuum through a recruitment of the species lost by ecological simplification created by that agriculture (78,79). The scrub development would thus explain the gushing reports of the turtle doves, nightingales and blue emperor butterflies at Knepp (80) even though the scrub and some of the ruderal weeds are in breach of the standards of Cross Compliance under which Charlie received his Single Farm Payment, now called Basic Payment Scheme, and which requires both to be controlled (see above and (81)). How does Charlie get away with it?
The presence of these successes at Knepp owe everything to the scrub and nothing to the cattle
You would just have to read the report on the nature conservation value of scrub in Britain to confirm this, since amongst the many virtues of scrub, it says a mix of grassland, scrub and woodland may be an advantage to many invertebrate species, providing a range of conditions in close proximity, and several invertebrates associated with scrub may be more usefully defined as woodland/grassland transition species (82). Many invertebrates are phytophagous, feeding on woody plant genera – willows, which appear to be one of the more abundant scrub species at Knepp, has at 752 the most insect species associated with it (ch 3 in (82)). Scrub habitats appear to be of increasing importance to the declining English population of nightingales, more so than coppice, since they seem to prefer the safety afforded by dense thickets (ch 3,4 in (82)). Scrub is also important for the turtle dove, closed-canopy scrub is among one of its main nesting habitats, though the birds obtain much of their food (seeds) from adjacent open habitats. Neither of these birds, or even the butterfly, would be a real boost to the trophic ecology of the farm. Thus turtle doves don’t eat fruiting seeds, but instead mostly fumitory, knotgrass, chickweed and cereal grains, so they don’t disperse shrub or tree seeds and, anyway, it’s a migratory bird. So if scrub is the key to the species at Knepp, and this can develop without any human intervention, why is Knepp sucking up so much public money on the back of a few cows? Surely the money would be better used buying land out from farming so that there would be no burden of exploitative income, and wild nature can be given time and space conserve itself.
Knepp makes big play of cow pats, dung beetles and little owls (69, 80). Little owl was introduced to the UK in the 19th century, and it’s long been known that dung beetles are among the five most abundant insects found in their diet (83). However, little owls also eat worms, small mammals like mice and voles, and a few bird species. I wonder how important the dung beetles are to the little owl at Knepp when, as would be expected from the taller vegetation and litter layer in the less grazed areas, there has been an explosion in harvest mouse, wood mouse, yellow-necked field mouse, bank vole, field vole and common shrew (80, 84). Given that these small mammals are the preferred food of our native owls - short and long eared, tawny and barn owl - then it explains the presence of all the owls at Knepp more convincingly than the cow pats. It also argues against the influence of grazing as being important, since it’s the lack of grazing, like at Carrifran and South House Moor, that led to taller vegetation and increases in small mammals, and which are feasted on by short-eared owls at South House Moor (79).
At the beginning of one of the videos, Isabella Tree says that Knepp is not interested in managing for individual species (69) but the only way the changes at Knepp are characterised is in bead counting species, rather than communities of species, none of which has any real ecological impact other than the owls and, even then those bead-counted species were not predicted to migrate in, have not been related either to the baseline ecological survey from 2006 (85) or to the habitat changes that could have been predicted in the absence of grazing, or even to the impact of any new food chains that have developed - a small owl eating a dung beetle has less impact than a little eared owl eating a herbivorous field vole or a common shrew eating a slug. Be aware that Isabella Tree has a book about Knepp coming out this May (86) and which has already been plugged by two Guardian journalists, who must have had an early sight of it, and one of whom – Patrick Barkham (him again) - is an inveterate and uncritical promoter of Knepp, recently regurgitating the wheeze of the public subsiding “pop-up Knepps” for 25 years (87-89). I expect Isabella Tree’s book will be the usual procession of inconsistencies, but I also expect there will be a lot of pleading for the continued and substantial public funding of Knepp, but which has no certainty now that the current subsidy system is being revised (90). Given the promotion over substance; the inconsistencies; the cost to the public of this massively subsidised meat factory; and the damage it has done in Britain to the concept of rewilding (41) I judge Knepp to be a charade and thus a zombie idea in ecology.
Mark Fisher 26 March 2018
A drone survey of vegetation at Knepp
I came across a drone study from 2017 of the southern block of Knepp that stitched together a series of low-level, aerial photos to produce a digital surface model of its vegetation, the intention being that this would be a method to monitor changes over the years (91). Given my observations above about how the scrub developed there initially in the absence of grazing, I was interested to see what this study told me about its current distribution, since it would be more detailed than any satellite imagery. The results show that, in most places, it is essentially just a grow-out of the field boundary hedges (see the three Change Detection graphics in (91)). This is confirmation of the impression I had gained from satellite imagery, but the aerial videos had showed that there were also areas where there was a general, autogenic development of scrub from seeding in to the arable areas. This can been seen from the satellite imagery, and which marks out the southern area from the poor scrub development in the northern area. One of the denser areas of scrub development is into arable fields below, but mostly above, Hammer Pond, a water feature that is often seen in videos of Knepp, and where unsurprisingly willows, or sallows as Ms Tree preciously calls them (69,72) are more likely than the suckering blackthorn of the hedges. What is odd, though, is why some fields in the southern block have scrub development within the middle of what was an open, arable field, while others don’t, or have much less, although all show signs of the out-growing of the hedges (92). I’ve had a quick look at the year in which each field in the south block came out of arable use, and where there were small areas of permanent pasture, but I see no quick correlation that explains this (71).
The expansion of hedgerows was predicted as an early consequence at Knepp in a feasibility study from 2007 (93). The study based its analysis of the possible changes at Knepp on what Sussex Wildlife Trust had seen at their Butcherland site, a hedged area of arable fields that was added to its wood pasture reserve site of Ebernoe Common in 2001 (94). The feasibility study predicted that the existing hedges at Knepp would start to thicken and spread in a clumpy manner – “It will take many years before the hedged structure of the landscape disappears. Within fields and around areas of scrapes there will be clumps of scrub and young woodland which become established and start to grow” (93). The presumption was that over a 25 year period, scrub and trees in clumps would develop within the middle of what was open field, and that the hedges would thicken and change, but the overall hedged landscape would persist.
The drone report described monitoring of this growing out of the hedges as being beneficial to tracking changes in that habitat at Knepp, and which had seen an increase in pairs of nightingales associated with it. It pointed to a student's study at Knepp that had shown that nightingales preferred overgrown hedges with a width of 8m or more at the base and the presence of protective blackthorn (see above and (95)). This broad width was needed to enable the central portion of the hedge to establish maturity and provide a portion of open ground beneath the hedge canopy, and was thus an indicator for nightingale distribution. So, on balance, apart from the willows and their attraction to invertebrate species like the blue emperor butterfly (see above) the south block of Knepp is mostly about hedge expansion from suckering blackthorn rather than open landscape tree regeneration. I don’t see anything to change the fact that the gap before grazing began in the south block is why there is more woody regeneration, even if it is predominantly hedgerow expansion.
3 February 2019
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