Transcript Presentation: Rewilding

Rewilding
A new approach to
ecosystem management
and habitat restoration
Simon Oakes
Philip Allan Publishers © 2016
Presentation outline
• What is rewilding?
• Key terms
• The Environmental Kuznet curve
• Ecosystem restoration, feedback and system changes
• How ‘wolves changed rivers’ in Yellowstone
• Rewilding initiatives in Europe
• The rewilding debate
Philip Allan Publishers © 2016
Key terms
Keystone species
An animal with a disproportionately large influence in relation
to its small population size. Apex predators at the top of the
food web, such as wolves, are often keystone species.
Trophic cascade
A series of ecological ‘knock-on effects’ which starts at the top
Do you know what these terms mean?
of a food chain. The reintroduction of carnivores reduces
Click to reveal the definitions
herbivore numbers, and so on.
Ecosystem services
Benefits humans gain from ecosystems, including estimates of
economic value.
Philip Allan Publishers © 2016
What is rewilding?
 The reintroduction of long-vanished apex
species like wolves is the starting point.
 Nature is then left to ‘take its course’.
 Changes ripple through the food web as
herbivore and autotroph populations are
affected by the reintroduction of wolves or
other species.
 This approach to management has ethical
and economic advantages.
 Ethically, restoration can seem like ‘the
right thing to do’ from viewpoints informed
by religion and science alike.
 Economically, it may be cost-effective.
Wolves control herbivore numbers and in
turn protect vegetation from over-grazing.
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In the absence of
predators, herbivores may
experience a ‘population
explosion’. Uncontrolled
growth of deer or rabbits
causes vegetation loss
and soil erosion. The
reintroduction of
carnivores mitigates these
costly problems
Environmental Kuznet curve
This hypothesised
relationship shows
environmental
improvement as
national income rises
above a certain value.
Anti-pollution laws are
strengthened. The
growth of service and
tourist industries not
only means less
pollution but also
encourages restoration
Low-income
societies have a
small ecological
footprint prior to
industrialisation.
There is very
little population
growth or
environmental
damage
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During industrialisation, environmental damage
peaks. Law-making has not had time to catch up
with rapid economic growth and there are
insufficient pollution controls. Many people work
in pollution-emitting industries. Agro-industry
causes harm to biodiversity in rural areas
Ecosystem restoration,
feedback and system changes
 The feedback effects are not limited to ecosystems and food webs.
 Changes in animal numbers and behaviour affect the landscape too.
Reintroduction of
apex predator (grey
wolf)
Population reduction
and behavioural
change among
herbivores (deer)
Soil, slope and
bankside stabilisation
in river valleys
Changing river
processes and
landforms (less
meander movement)
Philip Allan Publishers © 2016
Increased vegetation
growth on
floodplains now
abandoned by deer
How ‘wolves changed rivers’
in Yellowstone
Wolves were reintroduced
in 1995 to Yellowstone
National Park in the USA
after being absent for 70
years. Because there was
nothing to hunt them, the
number of deer had built
up in Yellowstone Park
during that time
Frank Waßerführer/Fotolia
Philip Allan Publishers © 2016
How ‘wolves changed rivers’
in Yellowstone
In the past, many species were hunted to
extinction without a full understanding of
how this could affect ecosystem balance
In Europe and the USA, removal of
dangerous wolves and bears eradicated a
risk to people and their cattle. But without
carnivores, rabbit and deer populations
quickly multiply in size. They eat all
available vegetation, stripping the land
bare, leading to soil erosion
Despite efforts by humans to control them,
the deer had managed to remove much of
the vegetation in Yellowstone
Philip Allan Publishers © 2016
How ‘wolves changed rivers’
in Yellowstone
•
The wolves also killed coyotes, and, as a result, the number of rabbits and mice began to rise,
which meant more hawks, weasels, foxes and badgers. Ravens and bald eagles came down to
feed on carrion (dead coyotes and deer) that the wolves left. Bears fed on it too and their
population rose. The bears reinforced the impact of the wolves by killing more deer.
•
But while a trophic cascade was expected, the real surprise was how landform systems were
affected. The wolves, even though they were few in number, radically changed the behaviour of
the deer. The deer migrated away from the parts of the park where they could be trapped most
easily, like the floodplain. Immediately, those places started to regenerate. In some areas, the
height of the trees quintupled in just 6 years. Bare valley sides became a forest of aspens,
willows and cottonwood.
•
In turn, the rivers began to meander less; there was less erosion, the channels narrowed and
more pools and ripple sections formed. The regenerating forest stabilised the banks so that they
collapsed less often, so the rivers become more fixed in their course.
•
The wolves, though small in number, transformed not just the ecosystem of the Yellowstone
National Park but also its physical geography.
•
Hear the full story from George Monbiot at: https://www.youtube.com/watch?v=ysa5OBhXz-Q
Philip Allan Publishers © 2016
Rewilding initiatives in the UK
Norfolk and
Cumbria
(lynx)
1,300 years after Britain’s last lynx was killed, the
Lynx UK Trust wants to bring it back, arguing that
big cats reduce deer numbers and restore
ecosystem balanc.
Argyll, Scotland
(beaver)
Reintroduced beavers build river dams. These
eventually drain to create meadows, thereby
creating an important habitat for other species
Isle of Mull,
Scotland (whitetailed eagle)
In the 1980s, a breeding programme reintroduced
the white-tailed eagle after 70 years of decline.
Sixteen pairs are now established on the island
Isle of Arran,
Scotland
(seabed
restoration)
An example of marine rewilding, Scotland’s first nofishing zone was established in 2008. Lobsters,
crabs, scallops and fish are all thriving in these
‘wild’ waters
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The National Trust
for Scotland has
been able to argue
that the beavers are
‘contributing to
biodiversity,
enhancing natural
wetland processes,
and promoting
tourism’. Find out
more at:
www.rewildingbrit
ain.org.uk/
The rewilding debate
 Rewilding is simply not possible or practical in many places.
 Farming unions have spoken out about farmers suffering financial loss from the
reintroduction of beavers. The UK’s National Sheep Association is opposed to the
lynx’s possible return.
 Ethical dilemmas arise too. In Holland, a rewilded area called Oostvaardersplassen
attracted criticism because horses were left to die when food became scarce in
winter. Animal rights groups objected to ‘nature taking its course’ there. They argued
that rewilding is really a form of scientific experiment. Logically, the horses are not
truly wild and so, under law, deserve humane treatment.
 Other critics ask: why is the end of the Pleistocene (around 14,000 years ago) used
as the base line for rewilding? Further back, 115,000 years ago, the UK was home to
elephants and rhinos. Why not make this the base line instead? Who has the power
to make these decisions, and why?
Philip Allan Publishers © 2016
Questions for discussion
1
Should predator species be reintroduced to the UK, given the risks attached?
2
Rewilding Europe aims to rewild 1 million hectares of land by 2020. Is this goal
achievable and how can success be measured?
3
Is the right rewilding ‘base line’ being used?
How would you feel about hill
walking in a region where
wolves, bears or big cats had
been released? How safe would
you be?
Philip Allan Publishers © 2016
Who benefits most from the
reintroduction of vanished
predator species and who gains
least? Can you make a financial
case for rewilding?
Further research
Rewilding Britain website: http://www.rewildingbritain.org.uk/
Rewilding Europe project: https://www.rewildingeurope.com/
Guardian newspaper report on rewilding: www.tinyurl.com/p399ll9
Philip Allan Publishers © 2016
This resource is part of GEOGRAPHY REVIEW, a magazine written for A-level
students by subject experts. To subscribe to the full magazine go
to: http://www.hoddereducation.co.uk/geographyreview
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