Rewilding E-Book

Cain Blythe

• Herausgeber: Icon Books
• Kategorie: Lebensstil
• Serie: Hot Science
• Sprache: Englisch

Seitenzahl: 289

Veröffentlichungsjahr: 2020

Beschreibung

'A hugely useful and fascinating resume of rewilding - what it means, where it came from, why it's important and where it's going. Jepson and Blythe have done a masterly job, explaining the science behind rewilding in an accessible, honest and compelling way. It deserves to be widely read and become a book of great influence.' Isabella Tree, author of Wilding 'Compelling ... [a] succinct and objective account' Financial Times Rewilding is the first popular book on the ground-breaking science behind the restoration of wild nature. As ecologists Paul Jepson and Cain Blythe show, rewilding is a new and progressive approach to conservation, blending radical scientific insights with practical innovations to revive ecological processes, benefiting people as well as nature. Its goal is to restore lost interactions between animals, plants and natural disturbance that are the essence of thriving ecosystems. With its sense of hope and purpose, rewilding is breathing new life into the conservation movement, and enabling a growing number of people - even urban-dwellers - to enjoy thrilling wildlife experiences previously accessible only in remote wilderness reserves. 'De-domesticated' horses galloping across a Dutch 'Serengeti'; beavers creating wetlands in the British countryside; giant tortoises restoring the wildlife of the Mauritian islands; perhaps one day even rhinos roaming the Australian outback - rewilding is full of exciting and inspirational possibilities.

Leseprobe

The

radical

new

science

of

ecological

recovery

Re

wilding

The

illustrated

edition

The

radical

new

science

of

ecological

recovery

Re

wilding

Paul Jepson & Cain Blythe

The

illustrated

edition

ICON BOOKS

This illustrated edition published in the UK in 2021

by Icon Books Ltd, Omnibus Business Centre,

39–41 North Road, London N7 9DP

email: [email protected]

www.iconbooks.com

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41 Sir Lowry Road, Woodstock 7925

Distributed in Canada by Publishers Group Canada,

76 Stafford Street, Unit 300

Toronto, Ontario M6J 2S1

ISBN: 978-1-78578-753-9

Text copyright © 2020 Icon Books Ltd

The authors have asserted their moral rights.

No part of this book may be reproduced in any form, or by any

means, without prior permission in writing from the publisher.

Layout and Design Copyright (©) UniPress Books Limited 2021

Project Management: Jason Hook

Design: Luke Herriott

Illustration: Robert Brandt / Paul Oakley

Picture Research: Sharon Dortenzio

Printed in China

Contents

Introduction

6

Geological Timeline

10

New Horizons

12

Megafauna Pasts

22

Downgrading our Planet

42

Rewilding’s Practical Origins

72

Cascades, Spaces, Networks & Engineers

98

Earth System Impacts

116

Rewilding Politics & Ethics

138

Scaling up Rewilding

164

10 Predictions for the Future

190

Sources & Further Reading

214

Index

218

Acknowledgements

224

1

2

3

4

5

6

7

8

9

6

Rewilding

Introduction

Rewilding, a term coined in the 1990s,

is now entering the mainstream of

scientific and popular debate on how

to govern the complex relationship

between human societies and nature.

The number of scientific papers and

media articles with rewilding in their title

is growing exponentially, and 20 March

2021 marked the first World Rewilding

Day organised by the newly formed

Global Rewilding Alliance. A critical

mass is building, calling for a shift from a

defensive focus on nature protection to a

proactive agenda of nature recovery.

As you begin this book, we invite you to

pause for a moment and reflect on an

intriguing question. Why now? Why, at the

beginning of the third decade of the 21st

century, are you settling down to read the

first popular science book on rewilding?

Why didn’t rewilding emerge into the

scientific consciousness at the beginning

of this millennia or twenty years hence?

There is clearly something happening now.

In our view, rewilding signifies the coming

together of three interacting developments,

namely: theoretical advances in ecosystem

and interdisciplinary conservation science;

innovations in natural area management;

and a desire, perhaps even a need,

for a new, hopeful and empowering

environmental narrative. The aim of this

book is to offer an accessible synthesis

of the science, practice and politics of

rewilding. Our hope is that it will motivate

and empower readers to read further,

visit rewilding areas, engage in considered

debate on the merits of rewilding and

actively engage in helping to shape a

rewilding movement.

We came to rewilding from quite different

directions. One of us (Paul Jepson)

started out working on urban nature

regeneration projects in the UK, before

moving to Indonesia to help protect

forests and endangered wildlife from the

relentless forces of deforestation, and

then directing an MSc in biodiversity

conservation at Oxford University. The

other (Cain Blythe) started out working

in a raptor sanctuary in the UK and a

zoological park in Australia before training

to become a professional ecologist.

Over the past twenty years, he has built

an ecological and habitat restoration

company. We both came to realise that

the approach to nature conservation

developed in the 1980s was ageing

and, while it had achieved much, had

become overly bureaucratic, managerial,

pessimistic and conservative. For us,

the incipient field of rewilding offered

fresh and innovative ways of thinking

and the opportunity to become part of a

community of progressive conservation

professionals. However, from the

perspective of our different backgrounds

we quickly saw that rewilding unsettles

some of the fundamental tenets upon

which the professional institutions of

Introduction

7

Megafauna in the Pleistocene

During the Pleistocene epoch (around 2.6 million to 11,700 years ago), megafauna created open, savanna-

like landscapes. This reconstruction of what is now Patagonia, Argentina, shows (from back to foreground)

proboscideans (

Stegomastodon sp

.), a glyptodont (

Doedicurus sp

.), a giant ground sloth (

Megatherium

sp

.), hypsodonts (

Hippidion sp

.), sabre-toothed cats (

Smilodon sp

.) and litopterns (

Macrauchenia sp

.).

nature protection and management are

built. For this reason, we included the

word radical in the subtitle of this book.

Rewilding invites and requires a willingness

to reassess, revise and reimagine deeply

held beliefs on what is natural, what

species should and should not be where,

and what constitutes ‘best’ conservation

practice. We hope this book will prompt

you to re-examine and reflect on your

own views of what is possible in nature

conservation and leave you with a

renewed sense of clarity and purpose.

Our motivation for writing this book was

to create a bridge between new research

and concepts discussed in scientific and

technical literature and the realms of

popular political, professional and cultural

discourse. We think this is important for

several reasons, namely: to provide an

accessible ‘primer’ for citizens interested

in rewilding and busy professionals in

the field; to strengthen democratic

engagement in nature policy; and to help

create the conditions for the emergence

of an entrepreneurial rewilding sector.

In addition, writing a popular science

title helps to clarify concepts and make

new connections. Formal scientific

writing uses a lot of jargon, and for

good reason; but, as we discovered,

8

Rewilding

the process of translating jargon into

clear English often exposed our limited

understanding of the true meaning,

significance and interconnectedness of

scientific terms. Rewilding signifies a shift in

focus from the components of ecosystems

to the emergent properties of interactions

between ‘things’ in ecosystems. In short, it

represents a move from linear to systems

thinking, which by its very nature is more

challenging to explain in linear prose. For

this reason, we were delighted when our

publisher proposed an illustrated version.

As the old adage goes, ‘a picture is worth

a thousand words’, and the infographics

by Robert Brandt and Paul Oakley add

immensely to our efforts to explain the

complexity of rewilding science.

Our account of rewilding foregrounds the

role of mega-herbivores in the evolution

and recovery of diverse and resilient

ecosystems. This reflects the productive

interplay between pioneer practice led by

Rewilding Europe and emerging centres of

rewilding research in Aarhus, Wageningen,

Leipzig and Oxford universities in,

respectively, Denmark, the Netherlands,

Germany and England. As rewilding

projects get underway and populations

of large herbivores and carnivores are

slowly recovering across many continents,

the rewilding research and innovation

agenda is expanding. Since the writing of

this book, coordinated action to study the

effects of reintroducing mega-herbivores

has begun; tech companies are working

with rewilding initiatives to develop novel

and cost-effective ways to measure

European bison, Romania

The rewilding of large herbivores is a key feature of

restoring ecosystems. The release of European bison

in the Tarcu Mountains reserve, in the Southern

Carpathians, was actioned by Rewilding Europe

and WWF Romania.

rewilding progress and its value to society;

forward-looking government agencies

are commissioning studies to assess how

they can create a more enabling policy;

and environmental and theoretical work is

moving from the ‘mega’ to the ‘micro’, with

emerging research on the role of fungal

mycelial networks in ecosystem recovery.

The United Nations has declared

2020–30 the International Decade of

Ecosystem Restoration. In response,

Europe’s leading rewilding scientist,

Professor Jens-Christian Svenning,

writing in the journal

One Earth

,

compellingly presented the evidence for

why rewilding ‘should be central to the

massive restoration efforts needed to

overcome the global biodiversity crisis

and enhancing the biosphere’s capacity

to mitigate climate change’. Rewilding

and the new science of ecosystem

recovery offer us the opportunity to be

the first generation in human history to

leave nature in a better place than we

found it. Achieving this pivot would be

a truly amazing achievement. We hope

this introduction to rewilding science

and practice will convince you that ‘we

have the technology’. We can rebuild

ecosystems and create a thriving future

for people and for nature. We just need

to collectively decide to go for it!

10

Rewilding

GEOLOGICAL TIMELINE

A geological timeline of Earth, with pull-outs

for the Pleistocene and Holocene epochs that

are central to the themes of the book.

Early

4.6 billion

years ago (ya)

Origin of

Earth

Stromatolites

2.5

billion

ya

4 billion ya

Oldest life forms

11,700 ya

8,000 ya

8,236 ya

Middle

Growth of settled agriculture in

Europe, Middle East, Asia

Hadean

Archean

Proterozoic

Phanerozoic

Vertebrates

Land plants

Fishes

Spiders

Forests

Mammals

Dinosaurs

Birds

Flowering plants

Cambrian

Ordovician

Silurian

Devonian

Carboniferous

Permian

Triassic

Jurassic

Cretaceous

Tertiary

Quaternary

Dinosaurs extinction

95% species extinction

Flying

insects

542 million ya

443 million ya

416 million ya

359 million ya

299 million ya

251 million ya

199 million ya

146 million ya

65 million ya

2.5 million ya

488 million ya

Geological Timeline

11

Invention of

the wheel

Mammoths still survive

on Wrangel Island

5,000 ya

4,250 ya

2,500 ya

75 ya

Anthropocene

Present day

Holocene

Quaternary

Late

Late

70,000 to 50,000 ya

126,000 ya

40,000 ya

30,000 to 10,000 ya

22,000 ya

15,000 ya

2.5 million ya

Pleistocene

Middle

773,000

ya

Early

Megafauna

extinctions

300,000 ya

Homo sapiens

evolve in Africa

Migration of modern

humans out of Africa

Humans settle

in Australia

Maximum extent of ice sheets and

acceleration in decline of megafauna

Humans cross

Bering Strait from

Asia to America

Chapter 1

New

Horizons

14

Chapter 1

Woolly mammoth

The mammoth symbolises the

megafauna ecosystems that have

been lost and those that can be

restored with a blend of science,

creativity and bold ambition.

This century is witnessing a fundamental reassessment of the science

and practice of nature conservation. An exciting and unsettling body

of new thinking is emerging, inspired by the realisation that we have

internalised ecological impoverishment in our science, culture and

institutions. This impoverishment is a consequence of the syndrome

of ‘shifting baselines’, where each generation assumes the nature they

experienced in their youth to be normal and unwingly accepts the

declines and damage of the generations before.

A generation ago, at the time of the

1992 Rio Earth summit, ecologists and

conservation biologists succeeded in

raising the fate of biodiversity to the top

of the environmental policy agenda. Their

science was rooted in the comparative

traditions of natural history and the

ecology of communities of species, and

strongly influenced by the protectionist

world views of 1970s environmentalism.

A focus on the components of nature –

species, sites and habitats – translated

into clear and powerful law and policy

aimed at protecting nature from the

wounding ways of humanity. Framing

nature as units or components enabled

biodiversity targets to be set, and

the development of an empirical and

international conservation science.

The science of biodiversity, and the

institutions it spawned, assumed that

the ecosystems that were present at the

beginning of the industrial era represented

the natural baselines that should be

conserved. Indeed, at this time it was

considered appropriate that such

baselines provided the foundations

New Horizons

15

upon which biodiversity was to be protected

and measured. This made intuitive sense

as, after all, the tropical rainforests, African

savannas and pastoral landscapes of Europe

all supported diverse and flourishing

natures that were disappearing fast in a

globalising world, characterised by increasing

population and resource demands.

By the turn of the millennium, biodiversity

science had become accomplished and

influential. But, like progressive rock

in the 1970s, it had also become a

little self-serving and out of touch with

trends in science and wider society. In

particular, the relentless telling of stories

of biodiversity decline and an impending

sixth-extinction crisis, combined with

newer anxieties over climate change, had

led to a growing sense of despondency

within the conservation movement. Many

had started to lose hope and question

whether they still wanted to devote their

lives and careers to lessening harm and

fruitlessly cataloguing the end of nature.

Mega-herbivores

Then, in 2005 and 2006, the prestigious

journals

Science

and

The American

Naturalist

published papers proposing

audacious new agendas for conservation

science. In the first, entitled ‘Pleistocene

Park: return of the mammoth’s

ecosystem’, Sergey Zimov pointed out

that, up until 10,000 years ago, much

of the Arctic was covered by steppe

grasslands, created and maintained

by vast herds of mega-herbivores. He

argued that their disappearance could be

attributed to human hunting pressure,

and that the mammoth steppe ecosystem

can and should be restored as a strategy

to reduce carbon emissions from the

thawing yedoma (permafrost) soils.

The second paper, authored by a group

of US conservation scientists led by

Josh Donlan, was ‘Pleistocene Rewilding:

an optimistic agenda for twenty-first

century conservation’. This group pointed

out that assemblies of large vertebrates

produce complex food webs, and that

continental-scale declines of megafauna

over the millennia have resulted in the

downgrading of nature. They outlined an

agenda to restore ecological functions

through the reassembly of the remaining

large herbivore guilds (groups of

particular herbivore species that exploit

the same resources, or exploit different

resources in related ways). These include

elk, bison and feral horses – and even

introduced species from different faunal

regions, such as camels. The belief was

that such surviving wild herbivores could

‘do the ecological job’ of lost species,

and that this ‘rewilding’ was a better

alternative than doing nothing or relying

on the ageing and failing protectionist

approach of the 1970s.

To continue the music analogy, it was as if

punk rock had hit the conservation science

scene. The agendas introduced in these

two papers were brash, energising, novel

and controversial. They signified a desire

to shake up the present but also expressed

an ambition to shape a new and inspiring

16

Chapter 1

future. The Pleistocene rewilding concept

was robustly criticised by some in the

conservation establishment, who accused

the authors of opening a Pandora’s box

and proposing the creation of ‘Frankenstein

ecosystems’. Yet the arguments in both

papers gave new expression to a scientific

riff called ‘functionalism’, which has

subsequently become the scientific basis

of rewilding practice.

Functionalism

A functionalist approach focuses on the

connections between the biological and

physical components of an ecosystem

and the properties that emerge from

these relationships. It takes its lead from

Charles Darwin’s evolutionary theory

and the insight that interactions between

organisms and their environment drive

the evolution of physical and behavioural

traits, e.g. large body size or spines and

thorns as protection against browsing,

or secretive behaviours to avoid

predation. However, functional ecology

goes beyond evolutionary biology and

seeks to understand the role of different

ecosystem components in the creation of

flows of energy, water, gases, nutrients

and organisms – the processes that are

vital to the functioning of an ecosystem.

Although from different cultures and

continents, Zimov, Donlan and colleagues

were making the same point, namely that

megafauna play a disproportionate role

in the functioning of ecosystems, and

that it is time for conservation to expand

its horizons and restore such ‘functional’

species whose presence generates

ripples of ecological interactions – and

to allow these interactions, rather than

human interventions, to steer the future

trajectory of natural systems.

Rewilding projects differ in their degree

of innovation, but all emphasise the

restoration of ecological functions and

encourage a better understanding of the

processes, dynamics and connectivity of

ecosystems. In this book, we will explore

these ideas further. We will also provide an

understanding of the interactions between

new insights from ecology and pioneering

rewilding projects, and how this is leading

to the formation of powerful conservation

agendas and movements. We use the word

‘interaction’ deliberately because rewilding

also signifies a promising new dialogue

between scientists and networks of

grounded conservation professionals, who

are coming together to drive innovation in

ecological recovery and societal change.

REWORDING REWILDING

Since 2005, there has been an explosion of

scientific and popular articles on rewilding.

However, early in 2019, an international

group of scientists published a paper

arguing that the term has become fuzzy

and should be abandoned because it lacks

the precision necessary for robust scientific

analysis. This view, while understandable,

misses the fact that rewilding is already

being applied to, and adopted by,

pioneering conservation initiatives in

different contexts and continents.

MEGA-HERBIVORES IN A FUNCTIONING ECOSYSTEM

Mega-herbivores play a disproportionately significant role at the heart of

a naturally functioning ecosystem. Their biological functions and physical

behaviours create a ripple effect that flows out through interconnected

ecological interactions to impact upon essential ecosystem processes.

Mega-herbivore

Micro-habitat

diversity

Vegetation

Biodiversity

Behavioural

evolution

Structural

diversity

Nutrient

cycling

Carbon draw

down

Physical

evolution

Albedo

effect

Nutrient

dispersal

Browsing

Defecating

Wallowing

Dying

Moving

Smashing

Grazing

Scavengers

Seed

dispersal

Predators

Parasites

Physical

disturbance

of plants

E

c

o

s

y

s

t

e

m

P

r

o

c

e

s

s

e

s

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o

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g

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F

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ti

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s

18

Chapter 1

SELF-WILLED

NATURE

In order to understand the potential of rewilding and its argument for

multiple biodiversity baselines we will, in the next chapter, delve back

into the Pleistocene epoch, with its roaming aurochs and mammoths

and prowling sabre-toothed tigers. But, before exploring the vibrant

ecological pasts that paint the scene for possible multicoloured

futures, we will give a brief history of rewilding and reveal the

thinking of its original proponents.

The term ‘rewilding’ was coined in the

mid-1990s by a group of US conservation

biologists, led by Dave Foreman and

influenced by wilderness and deep ecology

philosophy. They presented rewilding

as a continental-scale agenda to restore

self-regulating land communities through

the creation of large wilderness complexes

supporting populations of top predators

(notably wolves in Yellowstone National

Park) that reassert top-down trophic

controls. ‘Trophic’ refers to the transfer of

energy between vegetation and animals via

food webs, e.g. prey and predators.

Independently, the Netherlands

embarked on a radical new conservation

restoration agenda during the 1980s

termed ‘nature development’. This had

similarities to the US rewilding agenda,

specifically the creation of an ecological

network to connect remaining natural

areas and the aspiration for ‘self-willed’

natures – ecological systems that would

function and evolve without the constant

intensive management required in

many European reserves.

The Oostvaardersplassen (OVP)

The policy of nature development

was catalysed by a radical public

experiment in nature restoration at the

Oostvaardersplassen (OVP), located

about 20 miles to the north-east of

Amsterdam. It was conceived by a

group of progressive ecologists within

the Dutch nature conservation agency

Staatsbosbeheer, led by Frans Vera.

Individuals such as Vera broke away

from the more traditional ecological

models, such as those relating to ‘climax’

vegetation developed by Frederic

CORES

CORRIDORS

CARNIVORES

THE 3CS

The model of rewilding presented by US

conservation biologists has become known

as the 3Cs: core protected areas enlarge

habitat; corridors enable migration; and

carnivores regulate the ecosystem.

New Horizons

19

Clements in 1936 (see p.50). Driven by

a tailwind of widespread biodiversity

decline, Vera and his colleagues sought

new ways to re-establish nature, and on

a larger scale and with greater ambition

than previously seen in Europe.

The OVP experiment involved the

reassembly of a guild of large herbivores

to create a Serengeti-like landscape. The

results were startling – populations of

birds and small mammals rebounded but

also exhibited ‘boom and bust’ cycles

on the reserve that caused species

to disperse into the wider landscape.

The novel OVP ecosystem challenged

foundational tenets of ecological science

and the belief that the ‘natural’ vegetation

of Europe is closed-canopy forest. It

became a magnet for nature-minded

people seeking a practical demonstration

of rewilding ideas – and we will discuss

its origins and significance in detail in

The Oostvaardersplassen landscape with Konik ponies

Dutch conservationists embarked on an innovative new conservation approach

30 years ago involving the ‘reassembly’ of Europe’s lost megafauna guild from a

mix of wild deer species and ‘wilded’ breeds of ponies and cattle.

Chapter 3. However, the OVP also

provoked protests from farmers and

citizens who believed that allowing cattle

and ponies to starve in hard winters is

cruel and unjustifiable.

This European version of rewilding is

generally regarded as even more radical and

unsettling than the original US model. It is

producing natures that are novel from both

an ecological and cultural perspective, and

which are out of alignment with established

law, policy and social norms. The natural

‘cycle of life’ disappeared from the

everyday experiences of most Europeans

long ago, and over time a set of binaries

have shaped and ordered European

landscapes, imaginations and institutions.

These binaries include wild–domestic,

natural–cultivated and humane–inhumane.

European rewilding unsettles and blurs

these boundaries, and this makes it political

and potentially transformative.

20

Chapter 1

Radical Rewilding

Rewilding has not been confined to

North America and Europe. Initiatives

are emerging on every continent and

even in island nations. On Mauritius,

for example, non-native tortoises have

been successfully introduced as ‘taxon

substitutes’ for an endemic giant tortoise,

the extinction of which had caused

ecosystem dysfunction and loss of native

wildlife. Moreover, some consider the

restoration of southern Africa’s wildlife –

which was almost wiped out during the

anti-apartheid struggle for independence

– a constrained form of rewilding. The

policy to allow landowners to claim

wildlife on their land as property initiated

a large-scale transformation of struggling

farms to private game reserves and the

creation of a thriving wildlife economy,

based on a blend of safari tourism, game

hunting and wild meat production.

The possibility of moving beyond the

protection of past, natural baselines to

the restoration of new and healthy wild

places is driving innovation and a fresh

philosophy of conservation. For many,

rewilding offers a new and complementary

agenda that is empowering, hopeful and

ambitious. Conservation science and

practice in the 20th century did much

to protect important natural areas and

avoid extinctions. Rewilding builds

on these successes by reintroducing

functional species in natural areas,

restoring degraded lands into thriving,

new natural assets.

Many leading rewilders are motivated

by visions of working with recovering

forces of nature to develop nature-based

solutions to contemporary social, economic

and environmental challenges, such as

rural depopulation, soil degradation and

climate change. A body of practice and

scientific evidence is building to suggest

that rewilding could generate value in

terms of natural flood management,

carbon sequestration, control of invasive

species, nature-based economies and

public health. Several leading European

rewilders believe that rewilding is also

about reconnecting wilder nature with

modern society; they see nature as an

ally in solving modern, socio-economic

issues. Later in this book, we will take a

tour of some rewilding initiatives that

exemplify this potential, and which are

simultaneously shaping an applied science

of ecological recovery.

This change in narrative, from protecting

nature as an obligation, to nature recovery

using rewilding approaches as a solution,

is attracting interest from policymakers,

thought leaders and investors. As we

shall see, leading ecology research

groups, aided by major developments in

technology, are rising to this challenge

and policymakers are beginning to create

spaces where a new integrative ecology

can be trialled and developed.

Rewilding science is exciting – and it is

happening. Although a scientific definition

has yet to be agreed, there is an emerging

consensus that rewilding aims to restore

2

3

4

5

6

7

8

9

New Horizons

21

food webs and natural disturbance

and dispersal, and that the interactions

between these ecological processes foster

complex and self-organising ecosystems.

What makes this science radical is its

interplay with the new approaches to

ecological restoration being pioneered

by progressive conservationists. This is

imbuing the conservation movement with

new purpose, ambition and confidence

and raising the prospect of positive

21st-century environmentalism that acts

to recover our planet’s biosphere for the

benefit of all life – human and non-human.

Giant tortoise, Mauritius

Giant tortoises were the mega-herbivores of oceanic

islands and created the conditions for other island

creatures to evolve into unique species. Only the

Aldabra giant tortoise avoided extinction at the

hands of hungry seafarers, and is now being used

as a taxon substitute for extinct giant tortoises.

We start by exploring how grasslands and mega-herbivores co-evolved

and interacted with woody vegetation to produce a rich array of micro-

habitats; and how, over the millennia, our human ancestors caused the

demise of megafauna and then ordered and simplified landscapes such that

nature became impoverished.

Drawing on this insight, we review four pioneering rewilding projects

(including those just mentioned) that broke from the traditional focus on

endangered species and habitats to experiment with restoring the dynamic

interactions between large animals and the ecosystem.

We then introduce the latest ecological thinking on how interactions

between megafauna, vegetation and natural disturbance cause ecosystems

to expand and diversify; and the new connections that are being made

between the demise of megafauna and the functioning of ecological

systems at the continental and even planetary scale.

In the last part of the book we explore some of the ethical, political and practical

aspects of rewilding, and look at the complexities of real-world action.

We end with ten predictions for the future direction of rewilding that we

hope will inspire discussion and debate.

HOW THIS BOOK WORKS

The science of rewilding is underpinned by a new appreciation of the role of megafauna in

creating the conditions for biological diversity and abundance to emerge. This account of

rewilding science ranges around this central thread through colour-coded chapters:

Chapter 2

MEGAFAUNA

PASTS

24

Chapter 2

If we stop and take a moment to think

about the natural regions of our planet, a

picture of oceans, ice-caps, deserts, tropical

rainforests and temperate woodlands is likely

to come to mind. Some of us may also picture the

African savannas, Asian steppes and American prairies,

but a common view is that, on land, trees are the natural vegetation

except in the more extreme climatic conditions of high mountains and

the polar regions. This view is undergoing revision as palaeoecology

reveals that, for millions of years, abundant megafauna (animals weighing

more than 40 kilograms) were a feature of our land and oceans.

On land, mega-herbivores co-evolved

alongside grasses and thorny scrub to

cover vast areas of the planet. These

grassland ecosystems were characterised

by a diversity of micro-habitats that

produced abundant and diverse natures.

Then, between 30,000 and 10,000 years

ago, in human pre-history, something

dramatic happened to our planet’s

ecology. Megafauna disappeared

from much of the planet, and many

species became extinct. As megafauna

disappeared, many terrestrial ecosystems

transitioned from grassland to scrub and

then towards different, often more woody,

habitats at the beginning of the Holocene

epoch. Some, such as the American

great plains and Indochinese savannas,

survived into the last century – and the

African savannas are thankfully still with

us, although under constant threat.

Elsewhere, cattle- and goat-herding,

shepherding and ranching maintained

Megafauna Pasts

25

simplified yet biodiverse grassland and

wood-pasture ecosystems, but these

have gone into sharp decline as a result

of intensive livestock farming, land

abandonment and rural depopulation

in the lowlands.

Overall, our planet’s terrestrial

ecosystems have moved towards the

extremes of the wood-pasture gradient:

less productive and abandoned lands

have become woodier, and lands with

more productive soils have become

intensively managed grasslands or

agricultural fields. As a result, natural

grasslands and all their gradations

towards scrub and forest are at risk.

Rewilding is in part about recovering

these grasslands and gradations, and the

ecological richness they produce. We will

explore these Earth systems further, for

both mega-herbivores and marine fauna,

in Chapter 6.

First we need to reveal the evidence

supporting the view that mega-herbivores

and grasslands co-evolved, and that

different combinations (mosaics) of

grassland, scrub and woodland once

covered vast swathes of our planet for

millennia. This is technical to illustrate

but worth the effort, because it offers an

enticing view of what is possible in terms

of rewilding, and provides a potential

baseline for socio-ecological ‘well-being’

and biodiversity to be measured.

Humpback whale

Declines in marine megafauna such as

whales are more recent than those on

land, but no less significant. The causes –

commercial hunting, over-fishing and marine

pollution – are well understood, but the

marine environment lacks the fossil beds and

sediments needed for scientists to build a

picture of past marine ecosystems.

THE

EVIDENCE

FOR

GRASSLANDS

When thinking about how to save or restore the planet, most of us

probably imagine trees rather than grasses. Grasses seem somehow

domesticated: we know them as sports pitches, lawns, pastures and

vast fields of wheat. It is easy to overlook the fact that humble grasses

are the basis of one of our planet’s most productive ecosystems – and

one that we could restore and rewild. However, as the disciplines of

plant ecology, palaeontology and evolution come together, this is just

what many scientists are starting to think.

Pleistocene grasslands and megafauna

New research techniques described on the following pages have provided evidence that, up until about

15,000 years ago, the high Arctic was a steppe-like landscape maintained and populated by (from left

to right) horses (

Equus caballus

), woolly mammoths (

Mammuthus primigenius

), reindeer (

Rangifer

tarandus

), cave lions (

Panthera spelaea

) and woolly rhinoceros (

Coelodonta antiquitatis

). Winter

snow drifted across this landscape, reflecting the sun’s rays, freezing the earth and cooling the planet.

Advances in technology are bringing

about a step-change in our ability to

analyse and understand past ecosystems

and the evolution of plants and animals

over time. Until recently, the general

view was that the natural vegetation of a

region was the outcome of interactions

between climate, topography and latitude

(in effect, temperature and sunlight). This

is now being revised as evidence builds

for the role of grazing and disturbance

by large herbivores in shaping the natural

vegetation of an area.

This new insight is a key pillar of the

science of rewilding and the resulting

efforts to reassemble the once

widespread mixes of large herbivore

species, something we will discuss in

more detail in Chapter 8.

New techniques have created a picture

of the past which is clear enough to show

that grassland herbivore systems were

once much more widespread, and that

therefore this is the ‘natural’ situation for

our planet. As these techniques continue

to improve, the resolution for our picture

of the ecosystems of 15,000 years

ago will also improve and the story will

become even more intriguing.

Phytoliths

Technological advances in

microscopy have provided scientists

with a new indicator: the tiny silica

particles called phytoliths that

form the cellulose which creates

the supportive structures of grass

leaves. Phytoliths are micro-fossils

that can only be distinguished at

magnifications greater than 1,000.

They tend to survive longer than

pollen and bones, and will not have

been blown around like pollen.

Furthermore, phytoliths differ in

shape and it’s possible to identify

different genera of plants from them.

This new addition to the research

toolkit is helping scientists create

a clearer picture of the relative

abundance of grassy and woody

vegetation in past ecosystems, and

to understand vegetation changes

over time.

THE NEW RESEARCH TOOLKIT

In many areas of ecological research, scientists use proxies, or markers,

to build a picture of ecosystems. Long-term ecologists – those who

try to reconstruct past systems – have traditionally used pollen and

carbon-14 dating as indicators of the composition of past vegetation.

Pollen grains persist over thousands of years in sediment cores, taken

from areas such as lakes, where sediment has built up over millennia.

Carbon-14 enables different segments of the core to be dated

precisely, thereby allowing the construction of vegetation histories.

We are now beginning to realise, however, that grass pollen is more

fragile than that of trees and other woody plants. As a result, it

does not persist in the cores to the same extent. Put another way,

the pollen record offers evidence of past woody vegetation but not the

overall vegetation composition of a region or a biome (a large, naturally

occurring community of species occupying a major habitat such as

a savanna or forest).

Pioneering techniques such as those shown here are now being

used to analyse past ecosystems and the evolution of plants and

animals; and to create a much fuller picture of the overall vegetation

composition of regions and biomes.

Long phytolith

Short phytolith

Databases

The power of new techniques is

enhanced by the development of large

databases of fossil mammals, plants

and, increasingly, invertebrates. These

databases make it easier for scientists

to identify species in their samples,

identify associations between species,

build evolutionary trees and locate

sudden or rapid changes in vegetation

and animals.

Ancient DNA

The latest addition to the

scientific toolbox is ancient DNA.

Powerful computer programs can

now match and assemble tiny

fragments of DNA into strings.

These can be compared against

reference collections of gene

sequences of known species and

even particular environmental

locations such as river systems.

Fossil soils and animal remains

Other forms of evidence showing

the shift

in balance from woody to

grassland vegetation are emerging

from the study of fossil soils and the

teeth from animal remains. Grasses

evolved mat-like root structures,

which interact with worms and soil

organisms to create dark, organic

soils. These form distinct soil layers

called mollic epipedons that enable

researchers, in combination with other

factors, to identify and date past

ecosystems. Studying the wear on

fossil teeth is a means to understand

the broad types of vegetation that

were eaten by ancient herbivores, at

least towards the end of their life.

MAMMOTH TOOTH

Scratch patterns on the

enamel reveal information

about the type of plants

that were eaten.

Carbon isotope ratios in

layers of dentin laid down

over the animal's lifetime

yield data about diet.

30

Chapter 2

Origins of Grasslands

Following the disappearance of

the dinosaurs 65 million years ago,

woody plants had a chance to thrive.

Palaeontologists describe the world after

the dinosaurs as a ‘hot house’: an epoch