Human Interaction
Chapter 12
• “Sustainability” is a popular idea these
days.
• What does “sustainability” in the
ecosystem mean?
• What does “sustainability” in human
communities mean?
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The term “ecological footprint”
means:
1. The ecological
services of a natural
area.
2. The complete biocapacity of Earth.
3. The land and water
area needed to
sustain humans.
4. The risk of a species
to extinction.
25%
1
25%
2
25%
3
25%
4
Natural Communities
• Natural, self-renewing communities
share several features:
• Stable populations at or below carrying
capacity
• Biological diversity
• Recycling of all raw materials
• Reliance on sustainable energy (solar)
Human Communities
• How well does our community score on
each of these four points?
• Stable populations at or below carrying
capacity
• Biological diversity
• Recycling of all raw materials
• Reliance on sustainable energy
Human Population
bubonic plague
Date Billions Time to add
each billion
(years)
All of human
1804
1
history
1927
2
123
1960
3
33
1974
4
14
1987
5
13
1999
6
12
2012
7*
13
*projected
billions of people
2012*
2006
1999
1987
1975
1960
1930
1830
Technical and
cultural advances
Agricultural advances
Industrial and
medical
advances
We know that human population is increasing
exponentially. Our resources are not.
Poll: The human species:
33%
33%
33%
1. Is approaching
carrying capacity.
2. Has overshot
carrying capacity.
3. Can never reach
carrying capacity.
1
2
3
Consequences of exceeding K.
Population
overshoots
carrying
capacity;
environment
is damaged.
K
(original)
K
(reduced)
Low damage;
resources recover,
population fluctuates.
Extreme
damage;
population
dies out.
High damage;
carrying capacity
permanently lowered.
0
time
The problem is, we don’t know for sure where we are
on this graph.
Bear in mind that this is what “overshoots carrying
capacity” looks like.
When resources are highly limited, most individuals
have access to only a small share of those
resources.
population (billions)
2006: 6.5 billion
developing countries
developed countries
year
Presently, populations in developing nations are
increasing, while developed nations are stabilizing.
World average: 1.2%
World regions
Developing countries average: 1.4%
Africa: 2.2%
Latin America/Caribbean: 1.6%
Asia (excluding China): 1.6%
China: 0.6%
Developed countries average: 0.3%
N. America: 0.6%
Europe: –0.1%
natural increase per year (percent)
Breakdown of population increases in different parts
of the world.
Population pyramids for Mexico
Mexico 2007
male
female
High birth rates increase
population, but also
provide many young
people to support their
elderly relatives.
Population pyramids for Sweden
percent
Sweden 2007
male
Low birth rates reduce or level
off the population, but leave
less support for the aging
segment of the population.
percent
female
U.S. population (in millions)
Even with a modest
0.6% increase in the
population each year,
the U.S. shows
exponential growth.
year
In which area of Earth is the human
population growing the fastest?
25%
1.
2.
3.
4.
25%
25%
25%
North America
Europe
Africa
Asia
1
2
3
4
On which continent are natural
resources being used the fastest?
25%
1.
2.
3.
4.
25%
25%
25%
North America
Europe
Asia
Africa
1
2
3
4
While populations in developed
nations are increasing slowly,
individuals in developed nations use
many times the amount of resources
as individuals in developing nations.
What happens if developing nations
adopt the U.S. lifestyle?
This group
promotes zero
population growth,
birth control, and
social justice as
means to improve
society.
In some countries, such as the United States,
population control is a highly controversial issue.
This group rejects birth control,
believes people should have as
many children as possible, and
supports the rights of the individual.
In some developing
nations, women’s
education programs
have taught women
to read, write, and
run small
businesses. Where
women are
educated and most
people have
meaningful work,
birth rates slow
down and the quality
of life improves.
Growth curves for the human population
show that our species is experiencing:
25%
1.
2.
3.
4.
25%
25%
25%
Logistic growth
S-shaped growth
Exponential growth
Declining growth
1
2
3
4
Age structure diagrams show that human population
is declining in which part of the world?
20%
1.
2.
3.
4.
5.
20%
20%
2
3
20%
20%
China
Latin America
United States
Africa
Europe
1
4
5
Humans affect natural
populations
• We are living in the middle of a massextinction event, and we are the cause.
• We humans change our environment to
meet our needs for food, shelter, and
other resources. In doing so, we impact
other species dramatically.
• The larger our population gets, the faster
we use up limited resources.
Extinction Risks
• Specialization and resource partitioning
increase diversity.
• However, the tradeoff is that organisms
become more vulnerable to extinction if
the environment drastically changes.
Localized Distribution
• By living in a limited
area, a population
avoids competition
with other
populations.
• The risk is that a
natural disaster will
destroy the limited
habitat.
The Devil’s Hole Pupfish lives
in a single waterhole in
Nevada.
Overspecialization
• Organisms that have
specialized feeding
habits reduce
competition with
other species.
• If the limited food
source goes extinct,
so does the species
feeding on it.
Fender’s Blue Butterfly feeds
only on Kinkaid’s Lupine.
Interactions
• Isolation reduces
competition and
predation.
• If a new predator or
competitor is
introduced, a formerly
isolated species may
be hunted or outcompeted to
Many Hawai’ian birds were driven
extinction.
to extinction by introduced
predators.
Habitat Loss
• The greatest cause
of extinction is
habitat loss.
• Organisms with
highly specialized
habitat needs may
avoid competition,
but risk extinction if
their habitat is
threatened.
Tropical rain forests are being
logged at an alarming rate, mostly
for grazing cattle.
“HIPPO” and Extinctions
• Humans activity can contribute greatly to
species extinction.
• The acronym “HIPPO” can help us
remember the major contributors to
human-caused extinctions.
H
Habitat destruction
Humans plow up land
for farms and housing
developments, strip
soil from mountains
to mine minerals,
damage ocean
bottoms with deepwater nets, and cut
down forests for
wood products. All of
these are habitats for
wildlife.
I
Invasive Species
Kudzu – there’s a house
under there.
Ivy
Purple
Loosestrife
Starling
Humans have
introduced species
into areas where
they have no natural
predators. Without
natural controls, the
invasive species
overpopulate
rapidly, crowing out
native species.
Pollution
P
Debris, oil spills, and toxic
chemicals pollute
waterways, air, and soil.
Pesticides and herbicides
used on farms, lawns
gardens, and golf courses
contribute to local pollution.
P
Population
Human population
has increased
exponentially and is
still climbing. Large
populations need
large amounts of
resources, but at the
same time occupy
land that might
otherwise have
supplied resources.
Overharvest
O
Ancient bison in North
American may have
been hunted to
extinction. The dodo,
the passenger pigeon,
and the Great Auk have
all gone extinct due to
overhunting.
Of the five HIPPO factors, which
causes extinctions the fastest?
20%
1.
2.
3.
4.
5.
20%
20%
2
3
20%
20%
Habitat destruction
Invasive species
Population (human)
Pollution
Overharvest
1
4
5
So why don’t people…
• …simply stop polluting, reproducing
excessively, and start using resources
wisely?
• The “Tragedy of the Commons” scenario
helps explain the human mindset that
interferes with this “simple” solution.
Common Pool
Resources
These are resource that:
1) are available in limited
supply (either they do
not renew, or renew
more slowly than they
are being used)
2) are openly available
for use, and
3) it is costly to prevent
people from using the
resources.
When it comes to
Common Pool
Resources:
It is in the community’s
best interest to control
how the resource is used
so that the resource will
not be depleted and will
be available for all.
It is in the individual’s
best interest to get as
much of the resource as
possible.
Part of the problem is that nations all over the world have
economies that rely on a linear system of resource
extraction and disposal. Our linear system relies on overexploitation of common pool resources.
Linear systems are not
sustainable. Material extraction
MUST be tied to material
recovery and re-use, just like a
natural ecosystem, to be
sustainable.
It has been estimated that if everyone in the world
lived as people do in Western nations, we would
need about 4 Earths to sustain us.
We don’t have these.
We only
have this.
This is the definition of
“overshooting carrying capacity.”
The current situation was no
accident. In the 1950s, the
U.S. made a deliberate
move from being a nation of
producers to being a nation
of consumers in order to
grow the economy.
In 2013, Earth Overshoot Day fell on
August 20 – the day when the world has
used as much of Earth’s resources as
Earth can replace in one year.
Victor Lebow, U.S. economist under
Eisenhower.
Is it hopeless?
• Never in the history of the Earth has one
species had such an enormous effect.
• However, unlike other organisms,
humans have choices about how they
live and how they use resources.
• Our past decisions have gotten us into
this mess. Our future decisions can solve
the problem.
Lessons from Nature
• Remember the features of a renewable,
self-sustaining natural community:
• Stable populations at or below carrying
capacity
• Biological diversity
• Recycling of all raw materials
• Reliance on sustainable energy (solar)
Stable populations at or below carrying capacity
Humans, unlike other
organisms, have the ability to
choose whether to reproduce
or not. Some societies have
created laws to regulate
populations. Others have
relied on incentives, or have
left the issue to individual
choice.
The issue becomes complex
if a society depends on a
large number of young
people to support the aged.
Okay, not
like this.
What are some
unexpected
effects of small
families?
Biological diversity
Preserving biological
diversity in nature, in
agriculture, and even in
our human communities
is becoming
increasingly important.
Ecosystem services
Directly used substances
• food plants and animals
• building materials
• fiber and fabric materials
• fuel
• medicinal plants
• oxygen replenishment
Indirect, beneficial services
• maintaining soil fertility
• pollination
• seed dispersal
• waste decomposition
• regulation of local climate
• flood control
• erosion control
• pollution control
• pest control
• wildlife habitat
• repository of genes
“Ecosystem services” are direct and indirect benefits
humans receive from the environment.
Humans have directly benefitted from biodiversity.
Drugs derived from plants and animals.
Forest mushrooms
Tropical fruits
Andean Potatoes
A diverse ecosystem yields a diversity of foods.
Humans also benefit indirectly from intact, diverse
ecosystems.
Natural rivers meander, creating a richly diverse
wetland ecosystem.
Channelizing rivers, reducing
wetlands, and cutting down
trees along rivers changes
the ecosystem.
Loss of wetland diversity
means loss of species.
Sediments that would be
deposited along the river
system and in islands
around the mouth of the
river flows straight out to
sea.
New Orleans was once
protected by the many
islands in the
Mississippi Delta.
Much of the sediment
that built those islands
now runs out to the sea.
The islands have
eroded, leaving less
protection against
hurricanes.
The term “ecosystem services”
refers to:
1. Direct and indirect
benefits humans
receive from the
ecosystem.
2. How the ecosystem
supplies our needs
even when we extract
resources at a high
rate.
3. When humans do
service projects to help
restore ecosystems.
33%
1
33%
2
33%
3
Yellowstone
National Park
On a large scale, National Parks, the wildlife refuge
system, and public lands can contribute to the
preservation of habitat and biodiversity.
core
reserve
Protected; may allow
animal monitoring and
low impact development.
Allows developments and
tourism, as well as sustainable
fishing, forestry and agriculture.
buffer
zone
transition
area
Allows experimental research,
education, training, tourism,
and low impact development.
Biologists are studying how biological reserves can
co-exist with human communities and allow for
multiple uses.
Connecting
reserves with
wildlife corridors
vastly increases
the value of
individual
reserves. Animals
can make use of a
much larger area
of land, which
benefits top
carnivores that
need large
territories.
core reserve
buffer zones
small
reserve
corridors
core reserve
Wildlife preserves in our current Wildlife
Refuge system can be considered:
33%
33%
33%
1. Corridors
2. Core reserves
3. Buffer zones
1
2
3
Routes that are maintained between
preserved habitat are called:
25%
1.
2.
3.
4.
25%
25%
25%
Core zones
Preserves
Corridors
Transits
1
2
3
4
Modern agriculture relies on vast monocultures of
crop plants; the exact opposite of diversity.
Monocultures are easier to harvest, but more
vulnerable to diseases and pests than mixed crops.
Sustainable agricultural practices help preserve
topsoil, reduce the need for pesticides and fertilizers,
and can help support natural diversity as well.
Most sustainable agriculture is currently practiced on a
small scale, but sustainably-grown food can be found
at farmer’s markets, “U-pick” farms, and from
Community Supported Agriculture (CSA) farms.
Permaculture and
mixed-crop agriculture
supports a diverse soil
food web, which
supports the crops.
These methods tend to
be more labor-intensive.
A good place to buy sustainably
grown food is:
25%
25%
25%
25%
1. McDonald’s
2. A major grocery
store
3. A farmer’s market
4. A mall
1
2
3
4
Recycling of all raw materials
In nature, all materials
are recycled. Humans
can also recycle raw
materials. Making new
products from recycled
materials uses much
less energy than
making products from
raw materials from
nature. BUT recycling
only works if there is a
market for recycled
products.
Besides recycling to
conserve natural resources,
reusing items, repairing
items, and reducing overall
consumption are important:
Reduce, Reuse, Repair,
then Recycle.
“Use it up, wear it out,
make it do, or do
without”
Not buying stuff in the first place helps reduce material
consumption and resource over-exploitation. When you shop
for gifts or are thinking of what to do with the weekend, think
of “doing” rather than “consuming.”
Movie or concert
tickets
Take someone
outdoors and do
something fun.
Zoo or museum
memberships
Help someone with their
cleaning or gardening.
Reliance on sustainable energy
Wind, solar, and
geothermal energy are
available from nature in
unlimited supply. Using
these in a sustainable
way means developing
energy-harvesting
methods that are
efficient, cost-effective,
have a low impact in
nature, and produce far
more energy than the
energy required to
manufacture them.
Harvest of renewable
energy can be practiced
on a community-wide or
individual basis.
New material technologies make alternative energy more
reliable, accessible, and feasible. Solar glass and roof tiles,
for example, integrate solar energy collection into building
design, turning entire structures into electricity generators.
And hey… Solar freakin’
roadways!
Real change requires more than just recycling your pop
cans. Real change requires a change in thinking – from
“More is better” to “Better is better.” Better stuff rather
than more stuff. Better energy sources rather than
more energy use. Better, more active living rather than
more shopping.
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THIS project was started
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Jane Goodall
Jane Goodall makes the point that to save the
environment, we must also help the people who
depend on that environment.
Jane Goodall talk on the TED site
• Discuss and list specific ways in which your
community contributes to:
• Preservation of biodiversity
• Recycling materials (also, Reduce,
Reuse, Repair)
• Using renewable energy
• Which of these have you participated in?
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Recap
• Humans as a species have a huge and
devastating effect on biodiversity
worldwide.
• The “Tragedy of the Commons” scenario
pits long-term benefits to the community
against short-term benefits to the
individual.
• Humans can make conscious choices.
We can choose to contribute or not
contribute to environmental destruction.