ECOS 43 (2): Passive Rewilding: A case for more trees on peat and fewer species reintroductions

A smorgas board of sophisticated rewilding initiatives are springing up across the UK, capturing the imagination of groups with “nature first”¹ values, but also drawing in others and sparking controversy. Meanwhile, it is worth reminding ourselves that in its purest form rewilding is simply ‘letting go’. Unlike most current rewilding projects, passive rewilding can be relatively uncomplicated, inexpensive, scaleable, and potentially a game-changer for nature recovery.  Passive rewilding as “de-management” is key to this, a hands-off approach even when trees start to grow unchecked on peatland and species from the past remain absent.

Passive rewilding can contribute significantly to nature recovery, a key aim of the UK government^2,3 linked to combating climate change and a “green recovery”⁴. Passive rewilding shares elements of more active ‘mainstream’ rewilding  and  has  the  potential  to  boost  rural  economies  and  generate jobs^5,6,7, provide spaces for outdoor recreation in both urban and rural environments^8,9,10, improve health^11,12,13, improve habitats^14,15,16, encourage afforestation^17,18,19, support protected species, and genetic, taxonomic, and ecosystemic biodiversity^20,21,22, reverse soil carbon losses and increase carbon sequestration^23,24,25, reduce flood and drought risks^26,27,28, improve air and water quality^29,30,31, and address Britain’s reputation as one of the most nature-depleted countries in Europe^32,33.

Passive rewilding also has the potential to generate benefits cited in Britain’s 25 Year Environment Plan sooner and more cost-effectively than other UK nature recovery strategies either tested or proposed.

However, passive rewilding opportunities are underminedby science that fails to articulate the ‘big picture’^34,35, particularly the importance of ecosystems that assemble and change on their own terms.  This leads to rewilding solutions being overcomplicated from a conservation management perspective: too much emphasis on restoration of particular species, habitats and processes, not enough natural autonomy or ‘wild nature’.

Narrow framing of evidence informing conservation action and policy continues to presume primacy of historical species, habitats and processes, often at a cost to more diverse, dynamic and productive novel ecosystems which can emerge through the “do nothing” option. Opportunities and benefits for humans also emerge by allowing nature to develop passively with minimal or no intervention.

In favour of more unguided ecosystems and passive rewilding this paper aims to correct two ‘false assumptions’. These are regularly deployed as ecological arguments against passive rewilding. The first relates to resistance to natural regeneration on peatland: that maintaining a high water table and ‘peatland plant species’ should top all other ecological concerns. The second assumption is that reintroductions are beneficial for rewilding overall. These examples have wider relevance for passive rewilding beyond the UK, particularly where there are extensive modified peatlands or in geographically isolated locations where reintroductions of even relatively mobile mammals and birds are presumed necessary.

An overview of rewilding is provided with a brief discussion of current rewilding definitions, setting out how “passive rewilding” is distinct from those definitions. Two debates relevant to rewilding in the UK are then critically reviewed: Are trees on peatlands a threat to biodiversity, hydrology and climate? Are reintroductions worthwhile in terms of ecological benefits or ecosystem services?

What is Rewilding?

Coined by American activist Dave Foreman around 1990, “rewilding” gained purchase in restoration ecology in the late 1990s^36,37. The term has entered into popular usage in the UK and parts of mainland Europe in the past decade. What it means to make areas ‘wild’ is now a topic of animated debate among academics, policymakersand practitioners^38,39. Both the North American movement, labeled “Cores [untouched wilderness], Corridors [strips between cores] and Carnivores”⁴⁰, and contemporary European naturalistic grazing and reintroduction approaches, show through in British rewilding ambitions. For example, rewilding uninhabited upland landscapes, grazing regimes using ponies and cattle simultaneously, and beaver reintroductions. However, more often in the UK traditional conservation aims such as preserving meadows and tree planting are co-opted and rebranded as rewilding. Similarly, conservation actions taken up to 60 years ago in the UK are now said to have been examples of rewilding⁴¹.

Accordingly, geographers Steve Carver and Ian Convery remark rewilding is “in danger of becoming all things to all people”⁴² and therefore meaningless. Definitions of rewilding provided by conservation professionals, academic researchers, advocacy groups, and commentators in the media vary considerably. There are also geographical discrepancies, particularly between approaches in North America and Europe.

Rewilding definitions provided by conservation professionals and academics from the life sciences still lead public debate and tend to present rewilding as an ambitious form of ecological restoration. Rewilding definitions used in the UK context tend to centre on principles of the Lawton Review, “more, bigger, better, and joined” spaces for nature⁴³ with greater focus on animal reintroductions. Proponents claim rewilding is the restoration of 1) natural functions and processes 2) keystone species 3) biodiversity, according to historical baselines aimed at ensuring future self- sustaining ecosystems with reduced future intervention and 4) the return of people and the revitalisation of rural economies.  Lastly and fast gaining traction among policymakers, conservationists and academics in the UK, rewilding is 5) the restoration of ‘ecosystem services’ with economic value or ‘natural capital’.

What is Passive Rewilding?

Passive rewilding is a distinct subset of rewilding based on “hands-off” management principles, or the “absence of sustained human intervention.”⁵⁴ Pettorelli and colleagues define passive rewilding as follows:

“Passive rewilding refers to abandoned post-agricultural landscapes that are no longer actively managed [or with] limited active management to facilitate natural processes and allow them to regain dominance.”⁵⁵

They define active rewilding as:

“. . .the reorganisation of biota and ecosystem processes to set an identified social– ecological system on a preferred trajectory, leading to the self-sustaining provision of ecosystem services with minimal ongoing management.”⁵⁶

Building on this distinction, passive rewilding may also extend to any area of previously actively managed land, rural or urban, that is now undergoing extremely limited active management or none at all

This aligns with the definition from author and campaigner Isabella Tree in which rewilding is simply “allowing natural processes to happen, and having no pre-determined targets to meet, no species or numbers to dictate the plan.”⁵⁷

In a departure from both definitions, this paper does away with the concept of “natural processes”, refigured rather as “mainly unguided” processes acknowledging the very real possibility outcomes may not seem natural at first because they may not compare closely with a historical baseline⁵⁸. Furthermore, visitors may continue to shape nature albeit in a minor way compared to previous management practices. The following definition of passive rewilding is therefore proposed.

Passive rewilding involves making an educated guess that outcomes will fall within a range of favourable possibilities, and at the same time finding ways to value novel, at times unexpected ecosystems. Passive rewilding does not exclude people but does fully curtail organised extraction and active management, including conservation actions.

Landscape outcomes from passive rewilding, of which some possibilities are discussed below, are inherently more speculative than from traditional conservation, gardening or farming. More is left to chance. However, based on ecological, meteorological, geographical, historical and social site comparisons with existing passive or near-passive rewilding sites in the UK and western/northwestern Europe, evidence does allow for short-medium term prognoses. These may be carried out with satisfactory certainty for many sites ‘left alone’, especially pursuant to more synoptic measures such as biomass, habitat heterogeneity and species biodiversity.

Passive rewilding on peat: Good or bad?

Passive rewilding regularly offers the conditions for natural regeneration of shrubs, scrub and trees in the UK to 650m elevation⁶⁰ and occasionally higher. On peatlands which dominate at those higher levels, natural regeneration is often prejudicially viewed as a threat to the water table, its associated species, habitats, and soil carbon with climate implications. Passive rewilding on peatlands is regularly viewed negatively due to the potential for vascular plants and trees to establish affecting water tables and soil carbon. Natural woodland or scrub regeneration is often therefore unjustly eschewed for reasons of climate.

Blanket opposition to possible natural regeneration/afforestation through passive rewilding, even on mainly saturated peatlands, is misplaced. A body of evidence reveals 1) no evidence of a climate threat from natural regeneration on peat—only from activities necessary for maintenance of open peatland or mechanical planting and 2) relative paucity of biodiversity and abundance of wildlife on Britain’s peatlands compared to similar soils elsewhere. These harbour more vegetation heterogeneity including trees—and so point to an opportunity for biodiversity gains on UK peatlands.

Opposition arises partly from tradition and aesthetics but also because trees and shrubs can lower the water table, at the expense of communities dominated by peat-forming bryophytes, also increasing soil respiration. A drop in water table and transformation of graminoid plant communities towards vegetation dominated by vascular plants including trees is a possible outcome of natural regeneration on ombrotrophic peatlands⁶¹—although trees do not always lower peatland water tables⁶². Elevated soil respiration in the short term is also a likely outcome due to the presence of oxygen in formerly saturated soils. However, landscape-scale potential for water attenuation, biomass, biodiversity—the diversity of all life—and other benefits across all types of peatland outweigh these considerations.

There is already precedent for highly valued forest habitat on peatlands within the UK and worldwide. However, the implied transition from open moorland or fen to a less open, more forested landscape through passive rewilding generates resistance.

Trees on peat: CO2e balance

By lowering the water table, resulting in increased decomposition, trees on peat could cause emissions of carbon dioxide from soil carbon stores, threatening the climate. However, evidence is lacking that passive rewilding would cause this, even if natural regeneration of trees did occur over significant areas of intact peat bogs—the small proportion of peatlands with high enough water tables and the right peat-forming vegetation to sequester carbon. The CO2e balance of existing forest, of naturally regenerating woodland, and of planted woodland on peatland are all important to whether trees on peat really threaten the climate.

Forested peatlands can sequester CO2

Ecosystems comprised of old growth trees such as Canadian black spruce on peat are shown to be carbon sinks, particularly with a partial ground covering of peat-forming species such as sphagnum mosses⁷⁹. Deciduous forest on peat also acts as a carbon sink, although much forested peatland in the UK is conifer plantation which is thought to be a net carbon emitter⁸⁰. It is claimed therefore UK plantations should be felled and “restored” to tree-less blanket bog⁸¹. Although this claim misses the full carbon cost of active transition and assumes it is possible to fully restore a nationally significant proportion of felled areas, it is also a moot point as most are likely to be felled anyway for wood. The pertinent CO2e question is if and how those forests are replaced, rewetted or not, and if and how new wooded areas establish⁸².

No evidence natural regeneration drives net CO2e emissions on peatland

The main peatland restoration approach of rewetting mitigates climate warming. However, there are numerous exceptions⁸³. Carbon-intensive methods including helicopter drops and use of excavators are rarely accounted for, and partial restoration can have adverse effects⁸⁴. There is a particular paucity of evidence around climate impacts of natural regeneration on peat in the mid latitudes including the UK. Where trees are allowed to regenerate naturally on peat in boreal regions there is no evidence to suggest carbon sequestration is reversed. A UK estimate of sequestration potential, among other factors, would need to account for tree biomass accumulation above and below the peat, increase in mass of shrubs and deadwood, mycorrhizal and other soil biota development⁸⁵, mass of fauna present within the above ground ecosystem, all modelled in the context of a changing climate and possibly changing fire regimes⁸⁶. The CO2e balance of a blanket bog, versus a possible complex scrub or woodland ecosystem, from a baseline of a degraded peatland in the UK is not proven to be significantly different.

Furthermore, rewetting and natural regeneration are not mutually incompatible as is often presumed. Natural regeneration on peat, a possible localised outcome of passive rewilding, does not require soils to be mechanically disturbed for drainage and planting, so a key mechanism by which afforestation can generate emissions is eliminated^87,88. Trees can establish on some peatlands with high water tables and continue to thrive. There is no evidence to suggest natural regeneration ends continuing sequestration to peat layers⁸⁹ and factors relating to stability may play an increasingly important role. On steep slopes trees can stabilise peat and block gullies potentially increasing overall attenuation and accumulation⁹⁰.

Even planting trees on peat can sequester CO2

Tree-planting would not fall under the definition of passive rewilding provided but shows the extent to which trees on peat need not threaten climate. In the UK, Scotland’s Centre of Expertise on Climate Change stated in 2018 it is “‘very probable’ that moderate and high productivity forests planted on shallower peat soils with limited disturbance provide a substantial net carbon uptake over the forest cycle”, with the main emissions being associated with ground preparation, not a factor in natural regeneration. Deep peats too, due to the reduced methane output, could in some circumstances become CO2e sinks over relatively few growth cycles when planted using shallow soil disturbance methods⁹¹.

Trees reduce peat runoff and peak flows downstream

Trees on peat intercept a sizeable proportion of precipitation reducing runoff and peak flow and increase evaporation through transpiration with the same effect⁹². Furthermore, where runoff from peatlands with flowing drains contributes to flooding, afforestation through passive rewilding in peat gullies may be a faster and more cost- effective method of mitigating this risk, for instance compared with mechanically blocking peat drains/burns. The high elevation ‘birch belt’ of southern Norway offers an interesting comparison to Scotland where deciduous woodland up to 1200m, regularly on peat or peaty podzols, provides an “effective ‘sponge’ for rainfall, reducing flood and erosion risk”^93,94.

Trees on peat: Biodiversity

Passive rewilding on peat can increase habitat and within-habitat heterogeneity, particularly through increased variety in vegetation height and type including trees⁹⁵, which in turn improves biodiversity outcomes, species abundances and productivity. More species are likely to benefit than experience declines in range and population through passive rewilding, particularly in the long term. Avian studies offer perhaps the best evidence to date. On Deeside in Scotland, avian species richness in mature birch forests was four times that of moorland, and higher diversity of species in areas of natural regeneration⁹⁸. In the Cairngorms, only 3% of internationally important taxa present prefer moorland as their primary habitat, the rest benefit more from different vegetation assemblages⁹⁹.

Although positive overall, the potential impact of passive rewilding on biodiversity is uneven⁹⁶. Change will not impact all species equally and may disadvantage some—although habitat stasis through preservation has the same effect. Species such as juniper, dwarf or downy birch, capercaillie, black grouse, golden eagle⁹⁷, red squirrel, hedgehog, wildcat, and roe deer are likely to benefit from passive rewilding on peatland. Clearly locations will differ markedly and in some, introduced species such as muntjac, feral cats, nonnative conifers or rhododendron may also thrive. Greater tolerance for introduced species, which may anyway exhibit only temporary or highly localised proliferations, is a prerequisite for large-scale passive rewilding. Also necessary is an acknowledgement they may contribute to an overall increase in the diversity of life in a landscape context.

Passive Rewilding not reintroductions

Reintroductions regularly fail

A literature review published in 2000 found only a quarter of wildlife reintroductions worldwide were successful at creating viable, self-sustaining populations, supplementing populations, or reducing human-wildlife conflict. Another quarter were considered failures, and half the outcomes were unknown¹⁰⁰. In 2008, reintroduction success remained poor across multiple species and locations^101,102 and again in 2011, in a global study, unsatisfactory reintroduction outcomes across many taxa were reported, including plants^103,104. In 2018, research showed improvement in global reintroduction outcomes although with the incorporation of ‘partial successes’ in that assessment and significantly higher average funding¹⁰⁵. Definitions of success are loose with particular questions remaining around what should constitute a viable population¹⁰⁶, but it is clear reintroduction outcomes are at best a mixed bag. Reintroductions into the wild are high risk to those translocated individuals and demand expensive preparation and monitoring¹⁰⁷. Furthermore, successes may not be lasting with fast-changing conditions. The UK’s first conservation reintroduction, the Capercaillie in the 1830s, might have been considered successful but the bird is now in danger of going extinct for a second time^108,109.

Reintroductions in the UK fail less but overall benefits are limited

Although recent reintroductions into the UK have seen above average success in terms of population growth and distribution, costs and ongoing support have been high. For example, the Great Bustard reintroduction cost at least €2.2million/£1.9 million¹¹⁰ between 2010 and 2015. Direct costs associated with the latest of multiple Sea Eagle reintroductions reached £235,000¹¹¹ in just one year and the ongoing Scottish Sea Eagle Management Scheme cost £874,000¹¹² between 2015 and 2019. The Scottish Beaver Trial was estimated in 2015 to cost £2.1 million¹¹³ and The River Otter Beaver Trial has so far cost lead partner Devon Wildlife Trust £500,000¹¹⁴. The initial three-year Kent bison project “Wilder Blean” will cost at least £1.125 million with ongoing costs to be met through partnerships and donations¹¹⁵. The Scottish Wildcat project will cost at least £3.6 million¹¹⁶. Although economic returns such as through increased tourism are possible, benefits of reintroduced species to nature remain difficult to establish and species individuals can experience suffering.

Red Kites (Milvus milvus)

Red kites were reintroduced into the UK in the Chilterns in 1990 and the programme continued to bolster numbers through translocation of chicks in subsequent years. As with all raptors, the environmental/ecological impacts of red kite reintroduction are difficult to measure given their ability to fly long distances from release sites and the dispersed nature of their feeding and breeding activities during a potentially decadal lifetime. Significant other contemporaneous environmental changes have taken place over thirty years which make the effects of the species even more difficult to isolate.

Although their environmental impacts are little known, the welfare of the reintroduced birds and their offspring is better understood. Red kite individuals are at risk from lead poisoning. Although practices have now changed, in the past this resulted from lead in their food in captivity. Lead poisoning continues from lead in carrion and in live prey¹¹⁷, mainly arising from organised shoots. Elevated, dangerous and even deadly levels of lead have been found in red kites, especially post-mortem¹¹⁸. Deliberate and accidental poisoning by rodenticides has also been reported¹¹⁹ and raptor persecution on estates including shooting persists¹²⁰ as well as traffic collisions and electrocution¹²¹.

The success of the reintroduction programme is easily evidenced in terms of population growth, increased distribution, and breeding success, particularly since the mid-2000s^122,123,124. However, the suffering of individuals mutes this success and there is a lack of evidence for wider environmental benefits.

White Tailed Sea Eagle (Haliaeetus albicilla)

Sea eagles are another raptor, making their environmental effects following reintroduction difficult to assess. They were introduced to western Scotland in 1983 and currently number around 123 pairs nationwide¹²⁵, numbers low enough that they are red listed “needing urgent action”¹²⁶ nearly forty years on.

A much larger predator than the red kite, it is suggested that they may control numbers of hooded crows, ravens, and foxes which are thought to be overrepresented within species assemblages, for instance in parts of Ireland¹²⁷. It is also suggested that they reduce carrion in livestock farming areas which is beneficial to farmers. Research has pointed to the disturbance of seabird nesting sites by sea eagles as potentially devastating for seabird colonies¹²⁸, but other factors are strongly implicated in the apparent disappearance of seabirds in locations where they cohabit¹²⁹. There is no consensus, within the scientific community or otherwise, whether sea eagles’ environmental/ecological effects are widely observable.

On the basis of wider ecological impacts, there are few conclusions to be drawn regarding the success of White Tailed Sea Eagle reintroduction, although the birds themselves seem to tolerate conditions in the UK and are breeding in the wild. Given their ability to fly great distances and the costs of reintroduction, it may have been sensible to await their arrival from Europe, and simply focus on reducing pressures on inshore marine habitats, fish stocks and potential nesting sites, with benefits to multiple species.

Great Bustard (Otis tarda)

After a failed attempt in the 1970s, the Great Bustard was reintroduced to Salisbury Plain in Wiltshire in 2004, using eggs collected in Russia. For the first 10 years of the trial, breeding success remained anaemic, the birds also unexpectedly migrated to locations in the south of England and even France, then disappeared¹³⁰. Numbers have risen to 100 individuals, but they have not established breeding sites in other locations¹³¹. Their possible impacts on the environment are limited to a single site and they are not considered “landscape changers” by conservationists¹³². This project has had such limited geographical and ecological impact that cost and time factors outweigh localised species-population benefits.

Passive rewilding achieves comparable beneficial outcomes for free

The opportunity cost of reintroductions with high capital investment and resource-allocation^133,134 makes reintroductions difficult to justify from an ecological standpoint. The three UK reintroduction case studies presented highlight ecological benefits are largely unknown. A final UK case study shows even when wider ecological benefits and ecosystem services are apparent, other passive options may still be preferable.

Simpler alternatives Eurasian Beaver (Castor fiber)

Beaver reintroductions have had measurable ecological success in the UK, although they have also drawn more financial and expert resources than any other reintroduction.

Beavers went extinct in the UK in the 16th century (earlier in England)¹³⁵ and are shown to have an “overwhelmingly positive” effect on biodiversity based on a meta- analysis of studies from across their range in Europe, Asia and North America¹³⁶. Beavers are predicted to benefit species of conservation concern in the UK such as otters, and great crested newts, as well as boosting species biodiversity overall in river and stream corridors. The risks to habitats and species in the UK are considered minor, associated with felling of trees in the absence of rapid regeneration.

The mechanisms by which beavers are said to engineer ecosystems and support biodiversity are cited in the first proposed definition of an “ecosystem engineer”: a species active in the “creation, modification and maintenance of habitats”¹³⁷, and therefore central to natural processes favoured in rewilding. Clive Jones and colleagues state, by “cutting trees and using them to construct dams [beavers] alter hydrology, creating wetlands that may persist for centuries.”. Naiman and colleagues explain: “These activities retain sediments and organic matter in the channel [. . .] modify nutrient cycling and decomposition dynamics, modify the structure and dynamics of the riparian zone, influence the character of water and materials transported downstream, and ultimately influence plant and animal community composition and diversity”¹³⁸. The basic processes of beaver habitat management are well understood, with habitat heterogeneity/within-habitat heterogeneity also said to benefit greatly due to the uneven intensity of impacts, from largely untouched stands of vegetation to permanently flooded areas^139,140,141.

Studies are relatively recent in the UK. The first beavers were introduced illegally onto the River Otter in Devon around 2007¹⁴²/2008¹⁴³. Later formalised as The River Otter Beaver Trial they were eventually permitted to remain by the government in 2020¹⁴⁴. A devolved matter, the first beavers were released legally in Scotland at Knapdale in 2009 but had appeared through illegal release in the Tayside catchment by 2006¹⁴⁵. The Knapdale release became The Scottish Beaver Trial. These studies offer the longest running monitoring providing for tentative conclusions about early environmental impacts in the UK. Beaver impacts are highly context-specific with variable intensity, type and location, layered onto different existing land or water uses in that area¹⁴⁶.

Results in both cases are in line with research outside the UK, with benefits to sediment load and flows^147,148 potentially reducing river erosion, flooding and benefitting riverine aquatic organisms¹⁴⁹. Fish abundance increased, probably due to the introduction of woody debris, flow refuge and increased invertebrates^150,151,152.

Beaver reintroductions are one of multiple strategies for improving river catchment attenuation/hydrology and riverine biodiversity including ecosystem diversity. Another low cost strategy is to reduce or cease mowing, cutting or grazing of river banks, gullies and flood plains to allow natural regeneration of scrub and trees, particularly willow.

This slows and reduces runoff into watercourses^153,154,155, and on the lower banks allows for material capture creating living dams, or for the death and collapse/felling of trees into the flow with similar effect^156,157,158. Although resulting pools and dams/logjams may be less substantial than larger beaver dams, potentially limiting ecological and species biodiversity benefits at those sites, cost savings against existing management regimes and against future costly beaver reintroductions would be considerable. This would allow for investment in further schemes with greater overall ecological benefit.

Based on the costs of beaver trials to date, and potential future reintroductions, simply reducing bank and floodplain clearances allowing natural regeneration would offer more cost-effective solutions, with slightly different benefits, of equal value to hydrology, and wild flora and fauna. This would also provide habitat for beavers to spread naturally over the coming decades and multiply those benefits.

Less is More: Less managed peatlands and fewer reintroductions

Passive rewilding as de-management can benefit ecosystems in the UK. Positive outcomes for species biodiversity and wildlife abundance are more likely through passive rewilding compared with employing active rewilding or restoration strategies. Positive outcomes also become more likely for hydrology and species individuals. Passive rewilding’s potential is greater still in relation to broader notions of life’s complexity in which we must find novel aspects of biodiversity value, for instance new kinds of human-wildlife interactions and aesthetics. Crucially passive rewilding can be much less complex and expensive than active approaches, so resources stretch further.

Likely outcomes from passive rewilding include natural regeneration on some UK peatlands. This should be tolerated and even encouraged from an ecological perspective. On peatlands, passive rewilding could simultaneously reduce management costs, improve species and habitats diversity, and benefit flood management. Greater acknowledgement of the scientific unknowns regarding climate-oriented land use strategies, which currently seem to go against passive rewilding on peatlands, would contribute to better nature recovery policies. The CO2e balance of passively rewilded peatland in the UK, either modified or “near-natural”, twenty or a hundred years into the future is indeterminable. Yet in the absence of evidence afforestation is framed as a potential climate disaster¹⁵⁹. Meanwhile, working with what we do know, on peatland passive rewilding is more likely than preservation, and even active rewilding or restoration, to provide increased genetic, taxonomic, and ecosystemic biodiversity at scale, and flood management benefits.

Reintroductions, a central tenet of current UK rewilding schemes, provide few additional ecological benefits compared to passive rewilding strategies and require high capital input. This is particularly the case with introduced large mammals which must be fenced and closely managed. Notwithstanding the lure of exotic—if technically “native”—beasts, resources should instead be allocated towards higher impact passive rewilding in more locations; for instance, incentivising land managers to undertake much less active management, an approach that has long been utilised through agri-environment schemes but must be far more ambitious. Passive rewilding, by reducing direct management, frees up resources and leads to ecological outcomes which benefit both wild nature and ourselves. Although sometimes less certain, ecological outcomes fall within a beneficial range of possibilities to achieve this. With nature recovery ‘Less is more’.

References

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² For example a speech by Environment Secretary May 2021: https://www.gov.uk/government/news/environment-secretary-to-set-out-plans-to-restore-nature-and-build-back-greener-from-the-pandemic

³ For example Local Nature Recovery Strategies in the new Environment Bill (2021): https://publications.parliament.uk/pa/bills/cbill/58-01/0009/20009.pdf

⁴ George Eustice Blog, Thursday, 29 July 2021 “Green Recovery Challenge Fund”: http://georgeeustice.blogspot.com/

⁵ Rewilding Europe (2019) “Nature based economies”: https://rewildingeurope.com/rewilding-in-%20action/nature-based-economies/

⁶ Rewilding Britain (2021) “Rewilding and the Rural Economy: How Nature-Based Economies can help boost and sustain local communities”: https://s3.eu-west-2.amazonaws.com/assets.rewildingbritain.org.uk/documents/nature-based-economies-rewilding-britain.pdf

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¹³ Mills, J. G., Weinstein, P., Gellie, N. J., Weyrich, L. S., Lowe, A. J., & Breed, M. F. (2017). Urban habitat restoration provides a human health benefit through microbiome rewilding: the Microbiome Rewilding Hypothesis. Restoration ecology, 25(6), 866-872.

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¹⁵ Morel, L., Barbe, L., Jung, V., Clément, B., Schnitzler, A., & Ysnel, F. (2020). Passive rewilding may (also) restore phylogenetically rich and functionally resilient forest plant communities. Ecological Applications, 30(1), e02007.

¹⁶ Thers, H., Bøcher, P. K., & Svenning, J. C. (2019). Using lidar to assess the development of structural diversity in forests undergoing passive rewilding in temperate Northern Europe. PeerJ, 6, e6219.

¹⁷ UK Centre for Ecology & Hydrology. “Passive rewilding can rapidly expand UK woodland at no cost.” ScienceDaily. ScienceDaily, 17 June 2021. <www.sciencedaily.com/releases/2021/06/210617145808.htm>.

¹⁸ Citizen Zoo (2021) “Why we must embrace nature in the fight against climate break down” 12th November: https://www.citizenzoo.org/2021/11/cop26-nature-based-solutions-and-the-role-of-rewilding/

¹⁹ Broughton, Richard K., James M. Bullock, Charles George, Ross A. Hill, Shelley A. Hinsley, Marta Maziarz, Markus Melin, J. Owen Mountford, Tim H. Sparks, and Richard F. Pywell (2021) “Long-term woodland restoration on lowland farmland through passive rewilding.” Plos one 16 (6): e0252466.

²⁰ Tree, I. (2018) Wilding: The Return of Nature to a British Farm, Pan Macmillan.

²¹ Deinet, S., Ieronymidou, C., McRae, L., Burfield, I.J., Foppen, R., Collen, B., & Böhm, M. (2013). Wildlife comeback in Europe: The recovery of selected mammal and bird species. London: Zoological Society of London.

²² Plieninger, T., Hui, C., Gaertner, M., & Huntsinger, L. (2014). The impact of land abandonment on species richness and abundance in the Mediterranean Basin: a meta-analysis. PloS one, 9(5), e98355.

²³ Rewilding Britain (2021) Rewilding and Climate Breakdown: https://www.rewildingbritain.org.uk/news-and-views/research-and-reports/rewilding-and-climate-breakdown

²⁴ Increased soil biota could mean increased carbon storage: Artz, R. R., Anderson, I. C., Chapman, S. J., Hagn, A., Schloter, M., Potts, J. M., & Campbell, C. D. (2007). Changes in fungal community composition in response to vegetational succession during the natural regeneration of cutover peatlands. Microbial Ecology, 54(3), 508-522.

²⁵ Natural regeneration stabilises peat: Bain, C. G., Bonn, A., Stoneman, R., Chapman, S., Coupar, A., Evans, M. & Worrall, F. (2011). IUCN UK commission of inquiry on peatlands. IUCN UK Peatland Programme.

²⁶ Dixon, S. J., Sear, D. A., Odoni, N. A., Sykes, T., & Lane, S. N. (2016). The effects of river restoration on catchment scale flood risk and flood hydrology. Earth Surface Processes and Landforms, 41(7), 997-1008.

²⁷ Rewilding Britain (2016) “How Rewilding Reduced Flood Risk”: https://www.rewildingbritain.org.uk/news-and-views/research-and-reports/how-rewilding-reduces-flood-risk-2

²⁸ Stratford, C., Miller, J., House, A., Old, G., Acreman, M., DuenasLopez, M. A., Nisbet, T., Newman, J., Burgess-Gamble, L., Chappell, N., Clarke, S., Leeson, L., Monbiot, G., Paterson, J., Robinson, M., Rogers, M. & Tickner, D. (2017) Do trees in UK relevant river catchments influence fluvial flood peaks? A systematic review, NERC/Centre for Ecology & Hydrology (Ed.). Wallingford, UK

²⁹ Lehmann, S. (2021). Growing Biodiverse Urban Futures: Renaturalization and Rewilding as Strategies to Strengthen Urban Resilience. Sustainability, 13(5), 2932.

³⁰ Brazier R. (no date) “The Restoration Game. How landscape restoration reduces flooding, improves water quality and combats climate change”, Policy Briefs, Exeter University: https://www.exeter.ac.uk/media/universityofexeter/research/gateway/feature/research/pdfs/Exeter__policy_briefing.pdf

³¹ Cerqueira, Y., Navarro, L., Maes J., Marta-Pedroso C., Honrado J., & Pereira H. (2015) “Ecosystem Services: The Opportunities of Rewilding in Europe” In Pereira, H. & Navarro L. [eds.] Rewilding European Landscapes. 1st Ed. Ch. 3.

³² Wingate, S. (2021) “UK is one of world’s most nature-depleted countries, new data shows”: https://www.standard.co.uk/news/uk/natural-history-museum-none-earth-china-japan-b959693.html

³³ Davis J. (2020) “UK has ‘led the world’ in destroying the natural environment”, Natural History Museum: https://www.nhm.ac.uk/discover/news/2020/september/uk-has-led-the-world-in-destroying-the-natural-environment.html

³⁴ Lacks discussion of natural regeneration or woodland on peat: Anderson, R., Vasander, H., Geddes, N., Laine, A., Tolvanen, A., O’sullivan, A., & Aapala, K. (2016). Afforested and forestry-drained peatland restoration. In A. Bonn, T. Allott, M. Evans, H. Joosten, & R. Stoneman (Eds.), Peatland Restoration and Ecosystem Services: Science, Policy and Practice (Ecological Reviews, pp. 213-233). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139177788.013

³⁵ Fails to mention opportunity cost of Lynx reintroduction to other conservation activities: White, Chris, Ian Convery, Adam Eagle, Paul O’Donoghue, Steve Piper, Petrina Rowcroft, Darrell Smith, and Erwin van Maanen. “Cost-benefit analysis for the reintroduction of lynx to the UK: Main report.” (2015): 1-47.

³⁶ Johns, D. (2019). History of rewilding: Ideas and practice. In N. Pettorelli, S. Durant, & J. Du Toit (Eds.), Rewilding (Ecological Reviews, pp. 12-33). Cambridge: Cambridge University Press. doi:10.1017/9781108560962.002

³⁷ Soulé, Michael & Reed Noss (1998) “Rewilding and biodiversity: complementary goals for continental conservation.”, Wild Earth, 7:3, pp. 19–28.

³⁸ The following exchange published in Biological Conservation and self-published:

1. Hayward, M.W., Scanlon, R.J., Callen, A., Howell, L.G., Klop-Toker, K.L., Di Blanco, Y., Balkenhol, N., Bugir, C.K., Campbell, L., Caravaggi, A. and Chalmers, A.C. (2019) Reintroducing rewilding to restoration–Rejecting the search for novelty. Biological conservation, 233, pp.255-259.
2. Derham, T.T., (2019) In defence of ‘rewilding’–a response to Hayward et al.(2019). Biological Conservation, 236, p.583.
3. Hayward, M.W., Jachowski, D.S., Bugir, C.K., Clulow, J., Krishnamurthy, R., Griffin, A.S., Chalmers, A.C., Linnell, J.D., Montgomery, R.A., Somers, M.J. and Kowalczyk, R. (2019). The search for novelty continues for rewilding: https://repository.up.ac.za/bitstream/handle/2263/71851/Hayward_Search_2019.pdf?sequence=1

³⁹ Yeo S. (2021) “One quarter of English councils have plans to rewild. Does yours?”, Blog: Incap Journal, 19th May 2021: https://www.inkcapjournal.co.uk/council- rewilding-england/

⁴⁰ Foreman, Dave. 2004. Rewilding North America: A Vision For Conservation In The 21st Century. Washington D.C., Island Press, 129

⁴¹ Marley J. (2021) “Monks Wood Wilderness: 60 years ago, scientists let a farm field rewild – here’s what happened”, Blog: The Conversation, 22nd July 2021: https://theconversation.com/monks-wood-wilderness-60-years-ago-scientists-let-a-farm-field-rewild- heres-what-happened-163406

⁴² Carver S. and Convery I. “Time to put the wild back into rewilding” ECOS vol. 42(3), ECOS 2021, British Association of Nature Conservationists: https://www.ecos.org.uk/time-to-put-the-wild-back-into-rewilding/

⁴³ Lawton, J.H., Brotherton, P.N.M., Brown, V.K., Elphick, C., Fitter, A.H., Forshaw, J., Haddow, R.W., Hilborne, S., Leafe, R.N., Mace, G.M., Southgate, M.P., Sutherland, W.J., Tew, T.E., Varley, J., & Wynne, G.R. (2010) Making Space for Nature: a review of England’s wildlife sites and ecological network. Report to Defra: https://webarchive.nationalarchives.gov.uk/ukgwa/20130402170324/http:/archive.defra.gov.uk/environment/biodiversity/documents/201009space-for-nature.pdf

⁴⁴ Lorimer, J., Sandom, C., Jepson, P., Doughty, C., Barua, M., & Kirby, K. J. (2015). Rewilding: science, practice, and politics. Annual Review of Environment and Resources, 40, 40.

⁴⁵ Nogués-Bravo, D., Simberloff, D., Rahbek, C., & Sanders, N. J. (2016). Rewilding is the new Pandora’s box in conservation. Current Biology, 26(3), R87-R91. 88.

⁴⁶ Du Toit, J. T., & Pettorelli, N. (2019). The differences between rewilding and restoring an ecologically degraded landscape. Journal of Applied Ecology, 56(11), 2467.

⁴⁷ Seddon, P. J. (2010). From reintroduction to assisted colonization: moving along the conservation translocation spectrum. Restoration Ecology, 18(6), 796-802.

⁴⁸ Donlan, J., Greene, H.W., Berger, J., Bock, C.E., Bock, J.H., Burney, D.A., Estes, J.A., Foreman, D., Martin, P.S., Roemer, G.W., Smith, F.A., Soulé, M.E., 2005. Re- wilding North America. Nature 436, 913–914.

⁴⁹ Svenning, Jens-Christian, Michael Munk, and Schweiger, A. (2019) “Trophic rewilding: ecological restoration of top-down trophic interactions to promote self-regulating biodiverse ecosystems.” Rewilding 73.

⁵⁰ Soulé, M., & Noss, R. (1998). Rewilding and biodiversity: complementary goals for continental conservation. Wild Earth 8, 19.

⁵¹ Tweedale, Aimee. (2021) “How rewilding can fight climate change by restoring the UK’s natural beauty”. Blog post for Ovo Energy. 7th Jan 2021: https://www.ovoenergy.com/blog/green/what-is-rewilding-and-how-does-it-work

⁵² The Woodland Trust (2017) Position Statement on Rewilding: https://www.woodlandtrust.org.uk/media/1718/rewilding-position-statement.pdf

⁵³ Rewilding Europe Website (2021) “What is Rewilding?”: https://rewildingeurope.com/what-is-rewilding-2/.

⁵⁴ Delibes-Mateos, M and Barrio, IC and Barbosa, AM and Martínez-Solano, I and Fa, JE and Ferreira, CC (2019) Rewilding and the risk of creating new, unwanted ecological interactions. In: Rewilding. Ecological Reviews . Cambridge University Press, pp. 355-374. ISBN 9781108472678. 12.

⁵⁵ Pettorelli, Durant, Du Toit, Pettorelli, Nathalie, and Durant, Sarah M. (2019) Rewilding. Print. Ecological Reviews. 8-9.

⁵⁶ Pettorelli, Nathalie, Jos Barlow, Philip A. Stephens, Sarah M. Durant, Ben Connor, Henrike Schulte to Bühne, Christopher J. Sandom, Jonathan Wentworth, and Johan T. du Toit. (2018) “Making rewilding fit for policy.” Journal of Applied Ecology 55, no. 3: 1114.

⁵⁷ Tree, I. (2018). Wilding: The return of nature to a British farm. Pan Macmillan. 9.

⁵⁸ Klop‐Toker, K., Clulow, S., Shuttleworth, C., & Hayward, M. W. (2020). Are novel ecosystems the only novelty of rewilding?. Restoration Ecology, 28(6), 1318-1320.

⁵⁹ Carver, S. (2019). Rewilding through land abandonment. In N. Pettorelli, S. Durant, & J. Du Toit (Eds.), Rewilding (Ecological Reviews, pp. 99-122). Cambridge: Cambridge University Press. doi:10.1017/9781108560962.006. 107.

⁶⁰ Scottish Natural Heritage (2000) Montane Scrub: https://www.nature.scot/sites/default/files/2017-06/Publication%202002%20-%20Montane%20Scrub.pdf

⁶¹ Breeuwer, Angela, Bjorn JM Robroek, Juul Limpens, Monique MPD Heijmans, Matthijs GC Schouten, and Frank Berendse (2009) “Decreased summer water table depth affects peatland vegetation.” Basic and Applied Ecology 10, no. 4 (2009): 330-339.

⁶² Price, J., Evans, C., Evans, M., Allott, T. & Shuttleworth, E. (2016). Peatland restoration and hydrology. In A. Bonn, T. Allott, M. Evans, H. Joosten, & R. Stoneman (Eds.), Peatland Restoration and Ecosystem Services: Science, Policy and Practice (Ecological Reviews, pp. 86). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139177788.006

⁶³ Evans, C., Artz, R., Moxley, J., Smyth, M.A., Taylor, E., Archer, E., Burden, A., Williamson, J., Donnelly, D., Thomson, A. and Buys, G., 2017. Implementation of an emissions inventory for UK peatlands (pp. 1-88). Centre for Ecology and Hydrology.

⁶⁴ Richard Lindsay claims peat over 30cm totals 7Mha across all UK territories “Wider implications of peatland erosion”, presentation to Rewilding the Soil and Land Conference, Day 2, 21st September 2021 (online)

⁶⁵ Sunström, E., & Hånell, B. (1999). Afforestation of low-productivity peatlands in Sweden—the potential of natural seeding. New forests, 18(2), 113-129.

⁶⁶ Painting, A. (2021) “Regeneration: 25 years of ecological restoration at Mar Lodge”, Online talk to North East Scotland Members’ Group (John Muir Trust), 28th October 2021.

⁶⁷ Tooze, B. (2020) “Blanket bogs, a natural asset”, Natural England Blog: https://naturalengland.blog.gov.uk/2020/11/04/blanket-bogs-a-natural-asset/

⁶⁸ Tanneberger, F., Appulo, L., Ewert, S., Lakner, S., Ó Brolcháin, N., Peters, J., & Wichtmann, W. (2021). The Power of Nature‐Based Solutions: How Peatlands Can Help Us to Achieve Key EU Sustainability Objectives. Advanced Sustainable Systems, 5(1), 2000146: https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/adsu.202000146

⁶⁹ Gewin V. (2020) “How Peat Could Protect the Planet”: https://www.nature.com/articles/d41586-020-00355-3

⁷⁰ Federal Ministry of Food and Agriculture (2021) “German Forests: Forests for Nature and People”, 39: https://www.bmel.de/SharedDocs/Downloads/EN/Publications/german-forests.pdf?__blob=publicationFile&v=7

⁷¹ Vanguelova, E., Chapman, S., Perks, M., Yamulki, S., Randle, T., Ashwood, F., & Morison, J. (2018). Afforestation and restocking on peaty soils–new evidence assessment. Report to. CXC (ClimateXChange), Scotland, 6: https://www.climatexchange.org.uk/media/3137/afforestation-and-restocking-on-peaty-soils.pdf

⁷² Lindsay, R., Charman, D. J., Everingham, F., O’reilly, R. M., Palmer, M. A., Rowell, T. A., & Stroud, D. A. (1988). The flow country: the peatlands of Caithness and Sutherland. Joint Nature Conservation Committee. 22 & 58.

⁷³ Graham, L. L., & Page, S. E. (2012). Artificial bird perches for the regeneration of degraded tropical peat swamp forest: a restoration tool with limited potential. Restoration Ecology, 20(5), 631-637.

⁷⁴ Gunawan, H., Kobayashi, S., Mizuno, K., & Kono, Y. (2012). Peat swamp forest types and their regeneration in Giam Siak Kecil-Bukit Batu Biosphere Reserve, Riau, East Sumatra, Indonesia. Mires & Peat, 10.

⁷⁵ Life Peat Restore Website (2021) “Project: Germany”: https://life-peat-restore.eu/en/project/germany/

⁷⁶ A. Bonn, T. Allott, M. Evans, H. Joosten, & R. Stoneman (Eds.), Peatland Restoration and Ecosystem Services: Science, Policy and Practice (Ecological Reviews, pp. 86). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139177788.00

⁷⁷ Nieminen, M., Hökkä, H., Laiho, R., Juutinen, A., Ahtikoski, A., Pearson, M. & Ollikainen, M. (2018). Could continuous cover forestry be an economically and environmentally feasible management option on drained boreal peatlands?.Forest ecology and management, 424, 78-84.

⁷⁸ Sunström, E., & Hånell, B. (1999). Afforestation of low-productivity peatlands in Sweden—the potential of natural seeding. New forests, 18(2), 113-129.

⁷⁹ Beaulne, J., Garneau, M., Magnan, G., & Boucher, É. (2021). Peat deposits store more carbon than trees in forested peatlands of the boreal biome. Scientific reports, 11(1), 1-11.

⁸⁰ Bradfer‐Lawrence, T., Finch, T., Bradbury, R. B., Buchanan, G. M., Midgley, A., & Field, R. H. (2021). The potential contribution of terrestrial nature‐based solutions to a national ‘net zero’climate target. Journal of Applied Ecology, 58(11), 2349-2360.

⁸¹ Günther, A., Barthelmes, A., Huth, V., Joosten, H., Jurasinski, G., Koebsch, F., & Couwenberg, J. (2020). Prompt rewetting of drained peatlands reduces climate warming despite methane emissions. Nature communications, 11(1), 1-5.

⁸² Joosten, H., Sirin, A., Couwenberg, J., Laine, J., & Smith, P. (2016). The role of peatlands in climate regulation. In A. Bonn, T. Allott, M. Evans, H. Joosten, & R. Stoneman (Eds.), Peatland Restoration and Ecosystem Services: Science, Policy and Practice (Ecological Reviews, pp. 63-76). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139177788.005.

⁸³ Günther, A., Barthelmes, A., Huth, V., Joosten, H., Jurasinski, G., Koebsch, F., & Couwenberg, J. (2020). Prompt rewetting of drained peatlands reduces climate warming despite methane emissions. Nature communications, 11(1), 1-5.

⁸⁴ Anderson, R., Vasander, H., Geddes, N., Laine, A., Tolvanen, A., O’sullivan, A., & Aapala, K. (2016). Afforested and forestry-drained peatland restoration. In A. Bonn, T. Allott, M. Evans, H. Joosten, & R. Stoneman (Eds.), Peatland Restoration and Ecosystem Services: Science, Policy and Practice (Ecological Reviews, pp. 213-233). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139177788.013

⁸⁵ Artz, R. R., Anderson, I. C., Chapman, S. J., Hagn, A., Schloter, M., Potts, J. M., & Campbell, C. D. (2007). Changes in fungal community composition in response to vegetational succession during the natural regeneration of cutover peatlands. Microbial Ecology, 54(3), 508-522.

⁸⁶ Joosten, H., Sirin, A., Couwenberg, J., Laine, J., & Smith, P. (2016). The role of peatlands in climate regulation. In A. Bonn, T. Allott, M. Evans, H. Joosten, & R. Stoneman (Eds.), Peatland Restoration and Ecosystem Services: Science, Policy and Practice (Ecological Reviews, pp. 63-76). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139177788.005

⁸⁷ Macmillan D. (2020) “Towards a rewilding strategy for Scotland” Scottish Forestry 74 (2), 31: https://www.researchgate.net/publication/349608812_Towards_a_rewilding_strategy_for_Scotland.

⁸⁸ Armstrong H. (2019) “Revive: A Better Way”, Broomhill Ecology: http://revive-scot.stackstaging.com/wp-content/uploads/A-Better-Way-Web-Version.pdf

⁸⁹ Joosten, H., Sirin, A., Couwenberg, J., Laine, J., & Smith, P. (2016). The role of peatlands in climate regulation. In A. Bonn, T. Allott, M. Evans, H. Joosten, & R. Stoneman (Eds.), Peatland Restoration and Ecosystem Services: Science, Policy and Practice (Ecological Reviews, pp. 63-76). Cambridge: Cambridge University Press. doi:10.1017/CBO9781139177788.005

⁹⁰ Bain, C. G., Bonn, A., Stoneman, R., Chapman, S., Coupar, A., Evans, M. & Worrall, F. (2011). IUCN UK commission of inquiry on peatlands. IUCN UK Peatland Programme.

⁹¹ Vanguelova, E., Chapman, S., Perks, M., Yamulki, S., Randle, T., Ashwood, F., & Morison, J. (2018). Afforestation and restocking on peaty soils–new evidence assessment. Report to. CXC (ClimateXChange), Scotland, 6: https://www.climatexchange.org.uk/media/3137/afforestation-and-restocking-on-peaty-soils.pdf

⁹² Van Seters, T. E., & Price, J. S. (2001). The impact of peat harvesting and natural regeneration on the water balance of an abandoned cutover bog, Quebec. Hydrological processes, 15(2), 246.

⁹³ Halley D. (2021) “Bringing Back the Birch Belt – Scotland’s Lost Mountain Woodland”: https://www.ukclimbing.com/articles/features/bringing_back_the_birch_belt_-

_scotlands_lost_mountain_woodland-14025

⁹⁴ Aas, B. (1969). Climatically raised birch lines in southeastern Norway 1918-1968. Norwegian Journal of Geography 23:3, 119-130, DOI: 10.1080/00291956908542805

⁹⁵ Thers, H., Bøcher, P. K., & Svenning, J. C. (2019). Using lidar to assess the development of structural diversity in forests undergoing passive rewilding in temperate Northern Europe. PeerJ, 6, e6219.

⁹⁶ Carver, S. (2019). Rewilding through land abandonment. In Pettorelli, Durant, Du Toit, Pettorelli, Nathalie, and Durant, Sarah M. Rewilding. Print. Ecological Reviews. 107.

⁹⁷ Armstrong H. (2019) “Revive: A Better Way”, Broomhill Ecology: http://revive-scot.stackstaging.com/wp-content/uploads/A-Better-Way-Web-Version.pdf

⁹⁸ Fuller, R. & Calladine,  J. (2014) “Landscape transition through natural processes: implications for biodiversity of tree regeneration on moorland”, BOU Proceedings– Ecology and conservation of birds in upland and alpine habitats: https://bou.org.uk/wp-content/uploads/2020/06/BOU2014-uplands-fullercalladine.pdf

⁹⁹ Shaw, P. Thompson, D.B.A. (2006) “Patterns of species diversity in the Cairngorms”. In The nature of the Cairngorms: diversity in a changing environment (ed. P. Shaw & D. Thompson), pp. 395–411. The Stationery Office, Edinburgh.

¹⁰⁰ Fischer, J., & Lindenmayer, D. B. (2000). An assessment of the published results of animal relocations. Biological conservation, 96(1), 1-11

¹⁰¹ Armstrong, D. P., & Seddon, P. J. (2008). Directions in reintroduction biology. Trends in ecology & evolution, 23(1), 20-25.

¹⁰² Soorae, P. S., editor. 2008. Global re-introduction perspectives: More case studies from around the world. IUCN/SSC Re-introduction Specialist Group & Environment Agency, Abu Dhabi.

¹⁰³ IUCN/SSC Re-introduction Specialist Group & Environment Agency (2011). Global re-introduction perspectives: More case studies from around the world. Abu Dhabi.

¹⁰⁴ Godefroid, S., Piazza, C., Rossi, G., Buord, S., Stevens, A. D., Aguraiuja, R. & Vanderborght, T. (2011). How successful are plant species reintroductions?. Biological Conservation, 144(2), 672-682.

¹⁰⁵ P Soorae, Global Reintroduction Perspectives: Case studies from around the globe (IUCN/SSC Reintroduction Specialist Group & Environment Agency Abu Dhabi 2018)

¹⁰⁶ Robert, A., Colas, B., Guigon, I., Kerbiriou, C., Mihoub, J. B., Saint‐Jalme, M., & Sarrazin, F. (2015). Defining reintroduction success using IUCN criteria for threatened species: a demographic assessment. Animal Conservation, 18(5), 397-406.

¹⁰⁷ Nichols, J. D., & Armstrong, D. P. (2012). Monitoring for reintroductions. Reintroduction biology: integrating science and management, 223-255.

¹⁰⁸ Burnside, R. J. (2012). Reintroduction and conservation of the Great Bustard Otis tarda (Doctoral dissertation, University of Bath).

¹⁰⁹ Beattie K. (2021) “Scotland’s capercaillie population could now be below 1,000, researchers warn”: https://www.pressandjournal.co.uk/fp/news/highlands/3224335/scotlands-capercaillie-population- could-now-be-below-1000-researchers-warn/

¹¹⁰ LIFE+ Project (2011) “Reintroducing the Great Bustard England (LIFE09/NAT/UK/020) Year 1 Summary 01/09/2010 – 31/08/2011”. 87: https://www.rspb.org.uk/globalassets/downloads/documents/conservation-projects/year-1-summary.pdf

¹¹¹ The Newsroom (2011) ”£235,000 nest egg to protect rare sea eagles”, The Scotsman: https://www.scotsman.com/news/ps235000-nest-egg-protect-rare-sea-eagles-1667850

¹¹² NatureScot (2020) “White-tailed Eagle Action Plan Review 2020”: https://www.nature.scot/doc/white-tailed-eagle-action-plan-review-2020

¹¹³ Gaywood M. [Ed.] (2015) “Beavers in Scotland: A Report to the Scottish Government”, Scottish Natural Heritage. 113: https://www.nature.scot/sites/default/files/Publication%202015%20-%20Beavers%20in%20Scotland%20A%20report%20to%20Scottish%20Government.pdf

¹¹⁴ Devon Wildlife Trust (2020) “Government says beavers can stay in their Devon home”: https://www.wildlifetrusts.org/news/government-says-beavers-can-stay-their-devon-home

¹¹⁵ Kent Wildlife Trust (2020) “Wilder Blean”: https://www.kentwildlifetrust.org.uk/wilderblean

¹¹⁶ Vision Media (2021) “Funding boost for Scottish Wildcat conservation“, news article: https://vnonline.co.uk/vn/news/20495/Funding-boost-for-Scottish-Wildcat-conservation

¹¹⁷ Zuberogoitia, I. (2011). Ecology and conservation of European forest-dwelling raptors (pp. 168-175). J. E. Martínez (Ed.). Bilbao, Spain: Diputación Foral de Bizkaia.

¹¹⁸ Pain, D. J., Carter, I., Sainsbury, A. W., Shore, R. F., Eden, P., Taggart, M. A. & Raab, A. (2007). Lead contamination and associated disease in captive and reintroduced red kites Milvus milvus in England. Science of the Total Environment, 376(1-3), 116-127.

¹¹⁹ Molenaar, F. M., Jaffe, J. E., Carter, I., Barnett, E. A., Shore, R. F., Rowcliffe, J. M., & Sainsbury, A. W. (2017). Poisoning of reintroduced red kites (Milvus milvus) in England. European Journal of wildlife research, 63(6), 94.

¹²⁰ Madden, K. K., Rozhon, G. C., & Dwyer, J. F. (2019). Conservation letter: raptor persecution. Journal of Raptor Research, 53(2), 230-233.

¹²¹ Zuberogoitia, I. (2011). Ecology and conservation of European forest-dwelling raptors (pp. 168-175). J. E. Martínez (Ed.). Bilbao, Spain: Diputación Foral de Bizkaia.

¹²² Stevens, M., Murn, C., & Hennessey, R. (2020). Population change of Red Kites Milvus milvus in central southern England between 2011 and 2016 derived from line transect surveys and multiple covariate distance sampling. Acta Ornithologica, 54(2), 243-254.

¹²³ RSPB (no date) “Red Kite: Distribution and Population Size”: https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/red-kite/distribution-and-population-size/

¹²⁴ Chilterns AONB (no date) “Red Kite”: https://www.chilternsaonb.org/about-chilterns/red-kites.html

¹²⁵ British Trust for Ornithology (no date) Bird Facts: White-tailed Eagle Haliaeetus albicilla”: https://app.bto.org/birdfacts/results/bob2430.html

¹²⁶ RSPB (no date) “UK conservation status explained”: https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/uk-conservation-status-explained/

¹²⁷ O’Rourke, E. (2014). The reintroduction of the white-tailed sea eagle to Ireland: People and wildlife. Land Use Policy, 38, 129-137.

¹²⁸ Hipfner, M. J., Blight, L. K., Lowe, R. W., Wilhelm, S. I., Robertson, G. J., Barrett, R. T. & Good, T. P. (2012). Unintended consequences: how the recovery of sea eagle Haliaeetus spp. populations in the northern hemisphere is affecting seabirds. Marine Ornithology 40: 39–52.

¹²⁹ Cockburn H. (2020) “Climate crisis: British seabird numbers decline by up to 70 per cent, due to more frequent storms and lack of food”: https://www.independent.co.uk/climate-change/news/climate-change-crisis-seabirds-britain-decline-rspb-government-figures-a9395446.html

¹³⁰ Alonso, J. C. (2015). The Great Bustard: past, present and future of a globally threatened species. Ornis Hungarica 22(2):1-13

¹³¹ Great Bustard Group Website (no date): https://greatbustard.org/

¹³² Wiltshire Wildlife Trust (no date) “The return of the Great Bustards”: https://www.wiltshirewildlife.org/blog/the-return-of-the-great-bustards

¹³³ Hilbers, J. P., Huijbregts, M. A., & Schipper, A. M. (2020). Predicting reintroduction costs for wildlife populations under anthropogenic stress. Journal of Applied Ecology, 57(1), 192-201.

¹³⁴ Nogués-Bravo, D., Simberloff, D., Rahbek, C., & Sanders, N. J. (2016). Rewilding is the new Pandora’s box in conservation. Current Biology, 26(3), R87-R91.

¹³⁵ South, A. B., Rushton, S. P., Macdonald, D. W., & Fuller, R. (2001). Reintroduction of the European beaver (Castor fiber) to Norfolk, UK: a preliminary modelling analysis. Journal of Zoology, 254(4), 473-479.

¹³⁶ Stringer, A. P., & Gaywood, M. J. (2016). The impacts of beavers Castor spp. on biodiversity and the ecological basis for their reintroduction to Scotland, UK. Mammal review, 46(4), 270-283.

¹³⁷ Jones, C. G., Lawton, J. H., & Shachak, M. (1994). Organisms as ecosystem engineers. In Ecosystem management (pp. 130-147). Springer, New York, NY. 130.

¹³⁸ Naiman, R. J. (1988). Animal influences on ecosystem dynamics. BioScience 38: 750–752.

¹³⁹ Law A, Jones KC, Willby NJ (2014) Medium vs. short-term effects of herbivory by Eurasian beaver on aquatic vegetation. Aquatic Botany 116: 27–34.

¹⁴⁰ Smith, J. M., & Mather, M. E. (2013). Beaver dams maintain fish biodiversity by increasing habitat heterogeneity throughout a low‐gradient stream network. Freshwater Biology, 58(7), 1523-1538.

¹⁴¹ Willby, N. J., Law, A., Levanoni, O., Foster, G., & Ecke, F. (2018). Rewilding wetlands: beaver as agents of within-habitat heterogeneity and the responses of contrasting biota. Philosophical Transactions of the Royal Society B: Biological Sciences, 373(1761), 20170444.

¹⁴² Auster, R. E., Puttock, A., & Brazier, R. (2020). Unravelling perceptions of Eurasian beaver reintroduction in Great Britain. Area, 52(2), 364-375.

¹⁴³ Devon Wildlife Trust (no date) “Government landmark decision means Devon’s beavers can stay!”: https://www.devonwildlifetrust.org/what-we-do/our-projects/river-otter-beaver-trial#:~:text=Government%20landmark%20decision%20means%20Devon’s%20beavers%20can%20stay!&text=It%20was%20the%20first%20legally,now%20has%20a%20secure%20future.

¹⁴⁴ Devon Wildlife Trust (no date) “Government says beavers can stay in their Devon home”: https://www.devonwildlifetrust.org/news/government-says-beavers-can-stay-their-devon-home

¹⁴⁵ Ward, K. J., & Prior, J. (2020). The Reintroduction of Beavers to Scotland. Conservation & Society, 18(2), 103-113.

¹⁴⁶ Brazier, R.E., Elliott, M., Andison, E., Auster, R.E., Bridgewater, S., Burgess, P., Chant, J., Graham, H.A., Knott, E., Puttock, A.K. and Sansum, P. (2020). River otter beaver trial: Science and evidence report. University of Exeter: https://www.exeter.ac.uk/creww/research/beavertrial.17.

¹⁴⁷ Alison J. & Wentworth J. (2016) “Rewilding and Ecosystem Services” POSTnote for UK Parliament: https://post.parliament.uk/research-briefings/post-pn-0537/

¹⁴⁸ Brazier, R.E., Elliott, M., Andison, E., Auster, R.E., Bridgewater, S., Burgess, P., Chant, J., Graham, H.A., Knott, E., Puttock, A.K. and Sansum, P. (2020) River otter beaver trial: Science and evidence report. University of Exeter. https://www.exeter.ac.uk/creww/research/beavertrial.70.

¹⁴⁹ Brazier, R.E., Elliott, M., Andison, E., Auster, R.E., Bridgewater, S., Burgess, P., Chant, J., Graham, H.A., Knott, E., Puttock, A.K. and Sansum, P. (2020) River otter beaver trial. 77: Science and evidence report. University of Exeter. https://www.exeter.ac.uk/creww/research/beavertrial

¹⁵⁰ Law, A., Levanoni, O., Foster, G., Ecke, F. & Willby, N. J. (2019) Are beavers a solution to the freshwater biodiversity crisis? Diversity and Distributions 25, 1763–1772.

¹⁵¹ Blackmore M. (2020) “Of Casters and Castors”: https://beavertrust.org/index.php/2020/10/07/2370/

¹⁵² Kemp, P. S., Worthington, T. A., Langford, T. E., Tree, A. R., & Gaywood, M. J. (2012). Qualitative and quantitative effects of reintroduced beavers on stream fish. Fish and Fisheries, 13(2), 158-181.

¹⁵³ Scottish Environment Protection Agency (2015) Flood Management Handbook: https://www.sepa.org.uk/media/163560/sepa-natural-flood-management-handbook1.pdf

¹⁵⁴ Stratford, C., Miller, J., House, A., Old, G., Acreman, M., DuenasLopez, M. A., Nisbet, T., Newman, J., Burgess-Gamble, L., Chappell, N., Clarke, S., Leeson, L., Monbiot, G., Paterson, J., Robinson, M., Rogers, M. & Tickner, D. (2017). Do trees in UK relevant river catchments influence fluvial flood peaks? A systematic review. In: NERC/Centre for Ecology & Hydrology (ed.). Wallingford, UK

¹⁵⁵ Metcalfe, P., Beven, K., Hankin, B., & Lamb, R. (2017). A modelling framework for evaluation of the hydrological impacts of nature‐based approaches to flood risk management, with application to in‐channel interventions across a 29‐km2 scale catchment in the United Kingdom. Hydrological Processes, 31(9), 1734-1748.

¹⁵⁶ Sear, D. A., Millington, C. E., Kitts, D. R., & Jeffries, R. (2010). Logjam controls on channel: floodplain interactions in wooded catchments and their role in the formation of multi-channel patterns. Geomorphology, 116(3-4), 305-319.

¹⁵⁷ Dixon, S. J., Sear, D. A., Odoni, N. A., Sykes, T., & Lane, S. N. (2016). The effects of river restoration on catchment scale flood risk and flood hydrology. Earth Surface Processes and Landforms, 41(7), 997-1008.

¹⁵⁸ Thomas, H. and Nisbet, T.R. (2012) Modelling the hydraulic impact of reintroducing large woody debris into watercourses. Journal of Flood Risk Management 5(2):164-174.

¹⁵⁹ Prof. Gideon Henderson, Chief Scientific Adviser to DEFRA, presentation at Magdalene College, Cambridge, Thursday 16th Jan 2020 with follow-up email exchange.