Central Texas College Deforestation in Developing Countries Discussion

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People in developed nations are fond of warning people in developing nations to stop destroying rainforest. People of developing nations often respond that this is hypocritical, because the developed nations became wealthy by deforesting their land and exploiting its resources in the past. What would you say to the president of a developing nation, such as Indonesia, in which a great deal of forest is being cleared?

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Essential Environment: The Science Behind the Stories
Sixth Edition
Chapter 9
Forests, Forest Management,
and Protected Areas
Lecture Presentations prepared by
James Dauray
College of Lake County
Copyright ©2019, 2015. Pearson Education, Inc. All Rights Reserved.
This lecture will help you understand:
• Ecological and economic contributions of forests
• History and current scale of deforestation
• Resource management, methods of harvesting timber, and
aspects of forest management
• Federal land management agencies
• Types of parks and protected areas
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Central Case Study: Saving the World’s
Greatest Rainforest (1 of 4)
• The Amazon rainforest captures water, regulates climate,
is very biodiverse, and absorbs carbon dioxide while
releasing oxygen.
– One-fifth of the rainforest area has been lost over the
past 50 years.
• Brazil is pushing into the Amazon basin to relieve crowding
and poverty in its cities.
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Central Case Study: Saving the World’s
Greatest Rainforest (2 of 4)
• Rising demand for soy, sugar, corn, and palm oil and the
growth of cattle ranching in the area have fueled further
destruction of the rainforest.
Figure 9.1 Large areas of Amazon rainforest have been cleared for cattle ranching and
soybean farming.
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Central Case Study: Saving the World’s
Greatest Rainforest (3 of 4)
• The consequences of the loss of
the rainforest are diverse:
– Loss of biodiversity
– Increased death rates in
indigenous peoples due to
introduced diseases and loss
of land
– Acceleration of global climate
change
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Central Case Study: Saving the World’s
Greatest Rainforest (4 of 4)
• In response, Brazil
strengthened its Forest
Code, now mandating that
landowners in the Amazon
conserve 80% of their land
as forest and other rural
landowners conserve 20%.
Figure 9.2 Annual forest loss has slowed in the
Brazilian Amazon.
• Purchasers of agricultural
products have either
demanded sustainably
grown products or put a
moratorium on new
production.
• Since 2004, deforestation
rates have fallen sharply.
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Forest Ecosystems and Forest Resources
• A forest is any ecosystem with a high density of trees.
• Forest biomes include boreal forest, tropical rainforest,
temperate deciduous forests, temperate rainforests, and
tropical dry forests.
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There are many types of forests (1 of 2)
• Within each forest biome, differences in soil and climate
will alter the community.
• Forest types are classifications of forests based on their
predominant tree species.
Figure 9.3 This maple-birch-beech forest from the Upper Peninsula of Michigan belongs to 1 of 23
forest types found in the continental United States.
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There are many types of forests (2 of 2)
• Altogether, forests cover 31% of Earth’s land surface.
Figure 9.4 Forests cover 31% of Earth’s land surface.
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Forests are ecologically complex (1 of 3)
• Forests are structurally complex, with each level providing niches for
many different organisms.
• The canopy is the upper level of leaves and branches in the treetops.
Figure 9.5 A mature forest is complex in its structure.
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Forests are ecologically complex (2 of 3)
• The subcanopy is the middle portion of the forest, found
beneath the tree crowns of the canopy.
• The shaded lower level consisting of shrubs and small
trees is the understory.
• The forest floor contains groundcover plants.
Figure 9.5 A mature forest is complex in its structure.
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Forests are ecologically complex (3 of 3)
• Dead and dying trees, called snags, are homes for
insects, which in turn provide food sources for birds.
• Fallen trees create openings called treefall gaps, areas
where sunlight encourages the growth of early
successional plants.
Figure 9.5 A mature forest is complex in its structure.
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Forests provide ecosystem services (1 of 2)
• Tree roots stabilize soil and
draw up minerals from deep
soil layers.
• Leaves and leaf litter slow
runoff by intercepting water,
increasing water infiltration
into soil and aquifers.
Figure 9.6 A forest provides us with a diversity of
ecosystem services, as well as resources that we can
harvest.
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Forests provide ecosystem services (2 of 2)
• Forest plants filter pollution,
take in carbon dioxide, and
produce oxygen that we
breathe.
• Forests also provide cultural,
aesthetic, and recreation
values to people.
Figure 9.6 A forest provides us with a diversity of
ecosystem services, as well as resources that we can
harvest.
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Forests provide us valuable resources
• Forests also contain plants we use for medicines and
dyes; animals, plants, and fungi for food; and wood from
the trees themselves.
• Industrial harvesting has increased our ability to extract
timber, with most of it coming from countries with boreal
forests like Canada and Russia or rainforests such as
Brazil or Indonesia.
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Forest Loss
• Deforestation is the clearing of forests more quickly than
they can regrow.
– Deforestation leads to biodiversity loss, soil
degradation, and desertification, as well as contributing
to climate change.
• Satellite analysis conducted by the Food and Agriculture
Organization (FAO) of the United Nations concluded that
we are eliminating 7.6 million hectares of forest each year.
– Accounting for regrowth, that is an annual net loss of
3.3 million hectares.
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Agriculture and demand for wood put pressure on
forests
• The growing human population and its demand for timber
and agricultural land have spurred further deforestation.
• In 2015, the UN Food and Agriculture Organization (FAO)
reported that we are losing a net 3.3 million hectares of
forest per year.
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We deforested much of North America (1 of 2)
• Heavy deforestation through the mid-1800s in North
America has resulted in very little primary forest being left
behind.
– Primary forest is natural forest left uncut by people.
Figure 9.7 Areas of primary (uncut) forest have been dramatically reduced.
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We deforested much of North America (2 of 2)
• Most of the trees in today’s forests are ones that have
sprouted and grown to partial maturity since the old-growth
trees were cut.
– These forests are called secondary forests and may
have a very different species composition, structure,
and nutrient balance.
Figure 9.7 Areas of primary (uncut) forest have been dramatically reduced.
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Forests today are cleared most rapidly in developing
nations (1 of 5)
• Uncut primary forests still remain in many developing
countries, but are being harvested much more rapidly due
to powerful industrial technologies.
– The deforestation is spurred by a desire to expand
human settlements, boost economic growth, and
provide fuelwood for heating and cooking needs.
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Forests today are cleared most rapidly in developing
nations (2 of 5)
• In contrast, parts of Europe and the United States are
gaining forest as they recover from past deforestation.
Figure 9.8 Tropical forests are being lost.
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Forests today are cleared most rapidly in developing
nations (3 of 5)
• Brazil is a good example of deforestation, as it has lost
forests rapidly as a result of expanding soybean farming,
cattle ranching, and settlement.
Figure 9.9 Deforestation of Amazonian rainforest has been rapid.
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Forests today are cleared most rapidly in developing
nations (4 of 5)
• Developing nations may allow their timber to be extracted
by large multinational corporations, who pay them fees
called concessions.
– The timber is then exported to wealthier nations.
• Concessions often lead to short-term economic benefits,
but many environmental consequences for the developing
nations.
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Forests today are cleared most rapidly in developing
nations (5 of 5)
• In Southeast Asia, swaths
of tropical rainforest are
being cut to establish palm
oil plantations.
– Palm oil is used as a
biofuel and is also found
in many processed
foods.
Figure 9.10 Oil palm plantations are replacing
primary forest across Southeast Asia and
Indonesia.
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Solutions are emerging
• Conservation organizations are pursuing community-based
stewardship projects that empower local people to act as
stewards for their forests.
– Other organizations directly pay concessions to
preserve forested land or offer a debt-for-nature swap.
• Reducing Emissions from Deforestation and Forest
Degradation (REDD+) is a program where developing
nations are paid concessions by developed countries, who
earn credits to offset their own emissions.
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Forest Management
• Forestry is the practice of managing society’s demand for
forests against maintaining them as ecosystems.
– Timber is renewable, as long as it is not exploited too
rapidly.
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Resource managers follow several strategies (1 of 3)
• Resource management describes the overall strategy of
managing and regulating the harvest of renewable
resources.
• Resource managers try to determine the maximum
sustainable yield, allowing them to achieve the greatest
amount of resource extraction without depleting the
resource.
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Resource managers follow several strategies (2 of 3)
• Achieving maximum sustainable yield usually means a
harvest at about the middle of the logistic growth curve.
• The downside is that the tree population is limited to about
half its normal size.
Figure 9.11 Maximum sustainable yield maximizes the amount of resource harvested while
sustaining the harvest.
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Resource managers follow several strategies (3 of 3)
• An alternative system is ecosystem-based management,
where managers try to minimize impacts on the ecosystem
and its processes.
– Protect certain areas of the forest.
– Restore ecologically important habitats.
– Consider patterns at the landscape level.
• This system is difficult to implement because ecosystems
are so complex that scientists often disagree on how to set
it up.
• Adaptive management involves testing different
approaches and trying to improve methods over time.
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We extract timber from private and public lands (1 of 3)
• The United States established and began managing the
national forest as high rates of deforestation gave rise to
fears of a national “timber famine.”
Figure 9.12 U.S. residents enjoy over 250 million ha (600 million acres) of public lands.
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We extract timber from private and public lands (2 of 3)
• Today, almost 90% of the
timber harvesting in the
United States takes place
on private land.
– Timber companies
pursue maximum
sustainable yield to
maximize yearly
profits.
Figure 9.13 In the United States, trees are growing
faster than they are being removed.
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We extract timber from private and public lands (3 of 3)
• The Forest Service sells timber below its own costs,
creating a situation where taxpayers subsidize private
timber harvesting on public land.
– Only about 2% of U.S. forest acreage is harvested for
timber each year.
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Plantation forestry has grown (1 of 2)
• Today’s timber industry focuses on monocultures of fastgrowing trees that are all planted at the same time.
– These trees are said to be even-aged, since the trees
are all the same age.
– Stands are cut after a certain number of years, called
the rotation time, and replanted with seedlings.
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Plantation forestry has grown (2 of 2)
• Even-aged stands lack the biodiversity and habitat
offerings of regular forests and are highly vulnerable to
pest insects.
• Uneven-aged stands create a mix of ages (and species),
which creates greater structural diversity and more
habitats and is generally more similar to what a national
forest would look like.
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We harvest timber in several ways (1 of 2)
• The simplest method of harvesting is clear-cutting, where
all the trees are cut at once.
– This increases erosion and alters microclimates due to
increased sunlight penetration.
Figure 9.14 Clear-cutting is cost-efficient for timber companies but has ecological consequences.
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We harvest timber in several ways (2 of 2)
• Other approaches include:
– The seed-tree approach, where some seed-producing
trees are left to reseed the harvested area.
– The shelterwood approach, which leaves some mature
trees behind to shelter growing seedlings.
– Selection systems, which maintain uneven-aged
stands by only removing some trees.
• Selection systems are the least cost-effective method.
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Fire can help or hurt forests (1 of 2)
• For much of its existence,
the Forest Service
suppressed fire whenever
it broke out.
– Scientists now know
that fire is an
important part of forest
ecology.
– Fire suppression has
also led to an increase
in large, catastrophic
fires.
Figure 9.15 Wildfires have been burning more
acreage across the United States.
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Fire can help or hurt forests (2 of 2)
• To reduce fuel loads, protect property, and improve forest
conditions, land management areas will now use
intentionally set, low-intensity fires called prescribed
burns.
Figure 9.16 Prescribed fire helps to promote forest health and prevent larger damaging fires.
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Climate change and pest outbreaks are altering
forests (1 of 2)
• Warmer, drier weather has led to outbreaks of fire in the
Amazon, an ecosystem that is not adapted to fire.
• Deforestation can worsen the impacts of climate change,
as transpiration is reduced in the absence of forests,
reducing precipitation in nearby areas.
• An outbreak of the pine bark beetle insect in North America
has killed billions of conifer trees, leaving them as fodder
for fire.
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Climate change and pest outbreaks are altering
forests (2 of 2)
• Pine bark beetle outbreaks
have worsened for two
reasons:
– Even-aged plantation
forests have high
numbers of trees that
are at the perfect age
for beetle infestation.
– Milder winters allow the
beetles to overwinter
further
north than usual, and
warmer summers
increase their activity
and feeding rates.
Figure 9.17 Climate change is enabling bark beetles
to destroy vast numbers of trees in North America.
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Sustainable forestry is gaining ground
• Organizations such as
the Forest Stewardship
Council (FSC) now
examine practices of
timber companies and
rate them.
Figure 9.18 Logs from trees harvested using certified
sustainable practices are marked with the FSC logo.
• Sustainable forest
certification is granted
to companies whose
methods are judged to
be sustainable.
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Parks and Protected Areas (1 of 4)
• The United States created the world’s first national parks
to preserve the American West for nature appreciation and
recreation.
• The National Park Service was created in 1916 to
administer the 408 total parks and monuments.
– The parks receive over 280 million reported recreation
visits per year.
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Parks and Protected Areas (2 of 4)
• Yellowstone National Park was established in 1872,
followed by Sequoia, General Grant (now Kings Canyon),
Yosemite, Mount Rainier, and Crater Lake.
Figure 9.19 The awe-inspiring beauty of America’s national parks draws millions of people for
recreation and wildlife-watching.
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Parks and Protected Areas (3 of 4)
• Another classification of protected area is the national
wildlife refuge; these areas are meant to be havens for
wildlife.
– The U.S. Fish and Wildlife Service administers the
refuges.
– Noncommercial hunting, fishing, photography, and
environmental education are all encouraged at refuges.
• In 1964, the U.S. Congress passed the Wilderness Act,
allowing some federal areas to be designated wilderness
areas.
– These areas are off-limits to development but open to
hiking and other low-impact public recreation.
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Parks and Protected Areas (4 of 4)
• Each U.S. state has agencies that manage public lands, as
do counties and municipalities.
– Nearly 7000 state parks are found across the United
States.
• Private nonprofit groups may also purchase land for
preservation, creating land trusts.
– Examples include California’s Big Sur, Jackson Hole in
Wyoming, and Maine’s Mount Desert Island.
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Parks and reserves are increasing internationally (1 of 3)
• Worldwide area of protected parks and reserves has
increased nearly sevenfold since 1970.
– Parks in developing countries often do not have the
funding needed to manage them and protect them from
poaching.
– These are called paper parks, because they are
covered on paper but not in reality.
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Parks and reserves are increasing internationally (2 of 3)
• The United Nations has established protected areas called biosphere
reserves that have exceptional levels of biodiversity and benefit local people.
– Biosphere reserves contain three zones, each of which has different
restrictions.
Figure 9.20 Biosphere reserves couple preservation with sustainable development.
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Parks and reserves are increasing internationally (3 of 3)
• The U.N. also designates world heritage sites, which
have special natural or cultural values and span the
borders of multiple countries.
– One example is a mountain gorilla reserve that
integrates parklands owned by three African countries.
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Habitat fragmentation makes preserves more vital (1 of 2)
• Expanding agriculture,
cities, highways, and
logging can all divide
up large areas of
habitat into small,
disconnected ones.
Figure 9.21 Forest fragmentation has
ecological consequences.
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Habitat fragmentation makes preserves more vital (2 of 2)
• When forests are fragmented,
large species that need large areas
of habitat may disappear.
[Figure 9.21 Continued]
• Other species may experience
edge effects, where the conditions
along a fragment’s edge differ from
the conditions in the interior.
– Birds, like the wood thrush, that
live near the edges of habitats
may be attacked by predators
and parasites that favor open
areas.
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Climate change threatens protected areas
• As temperatures become warmer, species’ ranges shift
toward the poles and upward in elevation.
– If the landscape is fragmented, this movement may not
be possible.
– High-elevation species have nowhere to go.
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Copyright
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Essential Environment: The Science Behind the Stories
Sixth Edition
Chapter 8
Biodiversity and
Conservation Biology
Lecture Presentations prepared by
James Dauray
College of Lake County
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This lecture will help you understand:
• The scope of Earth’s biodiversity
• The benefits of biodiversity
• The extinction crisis
• Causes of biodiversity loss
• Conservation biology
• Conservation of species
• Conservation above the species level
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Will We Slice Through the Serengeti? (1 of 3)
• Each year, millions of wildebeest,
zebras, and antelope migrate across
Africa during the change from wet to
dry season.
• The Maasai, people native to this
region, are semi-nomadic herders who
have sustainably lived with the
ecosystem for many generations.
• The Serengeti includes two protected
areas that fall within the countries of
Tanzania and Kenya.
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Will We Slice Through the Serengeti? (2 of 3)
• The reserves have effectively isolated people living in northern
Tanzania from the rest of the country, creating dire poverty.
• Tanzania’s president promised to build a paved commercial highway
through the Serengeti, connecting these communities with cities to the
east and ports on the Indian Ocean.
Figure 8.1 A proposed highway
would slice through Serengeti
National Park.
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Will We Slice Through the Serengeti? (3 of 3)
• This plan raised many concerns with conservationists:
– Migration routes could be blocked.
– Many animals would die from traffic collisions.
– Poachers would have easier access.
– Human development would be accelerated along the edges
of the reserves.
• The East Africa Court of Justice blocked the plan, and an
alternative route that wrapped around the southern Serengeti
was planned instead.
• In 2016, a new president announced plans to build an oil
pipeline through the Serengeti, sparking many of the same
protests.
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Life’s Diversity on Earth (1 of 4)
• Biodiversity is the variety of life across all levels of
biological organization (genes through ecosystems).
• A species is a set of organisms that share unique
characteristics and can breed and produce fertile offspring.
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Life’s Diversity on Earth (2 of 4)
• Species diversity describes
the number or variety of
species found in a region.
– Species richness
describes the number of
species.
– Evenness or relative
abundance describes how
much the species differ
from each other in
numbers of individuals.
Figure 8.2 The concept of biodiversity
encompasses multiple levels in the
hierarchy of life.
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Life’s Diversity on Earth (3 of 4)
• Genetic diversity includes
differences in DNA composition
among individuals.
– Populations with little genetic
diversity are more likely to suffer
inbreeding depression and be
vulnerable to environmental
change, as they lack the
variation needed to help adapt
to new conditions.
[Figure 8.2 Continued]
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Life’s Diversity on Earth (4 of 4)
• Ecosystem diversity refers to the
number and variety of ecosystems,
communities, or habitats.
[Figure 8.2 Continued]
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Biodiversity is unevenly distributed (1 of 2)
• Some groups of
organisms include
more species than
others.
– Insects, for
example, are the
most diverse group
of organisms.
Figure 8.3 Some groups contain more species than
others.
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Biodiversity is unevenly distributed (2 of 2)
• Biodiversity also varies based on location.
• Species richness generally increases as one approaches the
equator, due to:
– Greater geographic area.
– More solar energy.
– Stability of tropical climates.
– Lack of disruptive glaciation events.
• Species diversity also tends to increase in areas with more
diverse habitats.
• Structurally diverse habitats, like forests, are generally more
biodiverse.
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Many species await discovery
• So far, about 1.8 million species of plants, animals, and
microorganisms have been identified.
– Estimates for the total number range from 3–100
million.
• Our species knowledge is incomplete because most of the
unknown species are small, such as bacteria,
roundworms, fungi, and protists.
– Other organisms may appear to be the same species,
but are found to be different under further examination.
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Benefits of Biodiversity (1 of 2)
• Biodiverse regions provide many benefits, such as
potential new or unused food sources.
– Wild relatives of crops we already use also provide
genetic diversity to protect against disease.
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Benefits of Biodiversity (2 of 2)
• The table below lists promising new food sources from
Central and South America.
Table 8.1 Potential New Food Sources*
*The wild species shown here—all native to Latin America—are just a few of the many plants and animals that could
supplement our food supply. Adapted from Wilson, E.O., 1992. The diversity of life. Cambridge, MA: Belknap Press.
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Organisms provide drugs and medicines
• About half of today’s pharmaceuticals are derived from chemical
compounds in wild plants.
Table 8.2 Natural Plant Sources of Pharmaceuticals*
*Shown are just a few of the many plants that provide chemical compounds of medical benefit. Adapted
from Wilson, E.O., 1992. The diversity of life. Cambridge, MA: Belknap Press.
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Biodiversity provides ecosystem services
• Biodiversity provides many free benefits, including:
– Food, fuel, fiber, and shelter
– Air and water purification
– Waste decomposition
– Climate stabilization (reduction in droughts, floods, etc.)
– Pollination of plants
– Controlling pests and diseases
– Maintaining genetic diversity for crop varieties and
livestock
– Cultural and aesthetic benefits
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Biodiversity helps maintain ecosystem function
• Biodiversity increases the resilience of an ecosystem—its
ability to withstand disturbance, recover from stress, or
adapt to change.
– If a keystone species like a top predator is lost,
consequences will cascade down the entire food chain.
– If an ecosystem engineer is lost, the entire structure of
an ecosystem can change.
▪ The removal of elephants from some of Africa’s
savannas has caused scrubby vegetation to
overgrow, turning them into scrub forests.
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Biodiversity boosts economies through tourism and
recreation
• Visitors to natural areas spend money at local businesses,
hire locals as guides, and support parks that employ
residents.
– For Tanzania, ecotourism provides a quarter of all
foreign money entering the economy.
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People value connections with nature
• A biologist named Edward
O. Norton suggested that
human beings share an
instinctive love for nature
and feel an emotional bond
with other living things.
– He called this biophilia.
Figure 8.4 An Indonesian girl gazes into a flower of
Rafflesia arnoldii, the largest flower in the world.
• Others believe that a lack of
outdoor experiences and
direct contact with wild
organisms contributes to
the emotional stress, angst,
and anxiety felt by many
young people.
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Do we have ethical obligations to other species?
• Many feel that all living organisms have an inherent right to
exist.
– We need to use resources and consume other
organisms to survive, but we can make deliberate
decisions to preserve biodiversity.
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Biodiversity Loss and Extinction (1 of 2)
• The alteration of ecosystems creates “winners” and
“losers” among the world’s animals and plants.
• Humans have a tendency to change ecosystems so that
they are more similar to each other, more open in
structure, and more polluted.
– This favors generalists, which can adapt to the
changing conditions, and harms specialists, which rely
on mature, stable ecosystems.
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Biodiversity Loss and Extinction (2 of 2)
• Organisms that benefit from human development also
tend to be geographically widespread, small and fastreproducing, and lower on the food chain.
Table 8.3 Characteristics of Winning and Losing Species
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Many populations are declining (1 of 2)
• As a population shrinks, it loses both genetic diversity and
geographic range.
– Both make the population vulnerable to further
declines.
• The United Nations Environment Programme (UNEP)
developed the Living Planet Index as a way to express
how large the average population size of a species is now
compared to a baseline year of 1970.
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Many populations are declining (2 of 2)
• The Living Planet Index fell by 58% between 1970 and
2012.
Figure 8.5 Populations of vertebrate animals are less than one-half the size today that they were
just 42 years ago.
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Extinction is irreversible (1 of 2)
• Extinction occurs when the
last member of a species dies
and the entire species ceases
to exist.
Figure 8.6 The black rhinoceros has
disappeared from most of its range across
Africa.
• Extirpation is the loss of a
species from one area, but not
the entire world.
– The black rhino has been
extirpated from most of its
historic range but is not yet
extinct.
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Extinction is irreversible (2 of 2)
• Human impact is responsible for most extirpation and
extinction today, but these processes do also occur
naturally.
• The background extinction rate is the pace at which
organisms independently go extinct.
– Based on the fossil record, scientists estimate this rate
at an average of 1 out of every 1–10 million mammal
and marine animals going extinct each year.
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Earth has experienced five mass extinction events
• Mass extinction events are events that eliminated at least half of the
species on the Earth.
– Five have already occurred, and we are in the midst of the sixth
due to human impacts.
Figure 8.7 Scientists have documented five mass extinction events in the past 500 million years.
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We are setting the sixth mass extinction in motion (1 of 2)
• The current extinction rate
is 100–1000 times greater
than the background rate.
– This includes many
North American birds,
such as the ivory-billed
woodpecker.
Figure 8.8 The ivory-billed woodpecker was one of
North America’s most majestic birds.
• The International Union for
Conservation of Nature
(IUCN) maintains the Red
List, which is a list of all
species at high risk of
extinction.
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We are setting the sixth mass extinction in motion (2 of 2)
• The 2017 Red List reported that the following animals were
threatened with extinction:
– 21% of mammal species
– 13% of bird species
– 20% of reptile species
– 32% of amphibian species
– 14% of fish species
• For other groups, not enough data are available to make
global assessments.
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Several major causes of biodiversity loss stand out (1 of 9)
• Habitat loss is the greatest threat to biodiversity today.
– Humans have altered, degraded, or destroyed
habitat through urban sprawl, farming, grazing,
clearing forests, and damming rivers.
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Several major causes of biodiversity loss stand out (2 of 9)
• Habitat loss most
commonly occurs through
gradual, piecemeal
degradation called habitat
fragmentation.
– This makes habitats
smaller, and prevents
movement of
organisms between
habitats.
– The proposed
Serengeti highway
would have caused
habitat fragmentation.
Figure 8.9 Habitat fragmentation occurs as human impact
creates gaps that expand and eventually come to dominate
the landscape, stranding islands of habitat.
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Several major causes of biodiversity loss stand out (3 of 9)
• Habitat loss has affected every biome, with wetlands being
especially threatened.
• Habitat loss is the primary source of population decline in
more than 80% of threatened birds and mammals.
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Several major causes of biodiversity loss stand out (4 of 9)
• Pollution harms organisms in many ways.
– Air pollution degrades forests and affects the
atmosphere and climate.
– Noise and light pollution affect the behavior and habitat
use of animals.
– Water pollution directly harms fish and amphibians.
– Agricultural runoff affects the food webs of aquatic
ecosystems.
– Persistent pollutants like heavy metals directly poison
people and wildlife.
– Plastic in the ocean can strangle, drown, or choke
marine animals.
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Several major causes of biodiversity loss stand out (5 of 9)
• Our growth in population and consumption is leading us to
remove species at faster rates than they can reproduce.
– Valuable trees, like teak and mahogany, are
disappearing quickly.
– Gorillas and other primates killed for “bush meat” could
face extinction.
– Many ocean fish stocks are overharvested.
– Thousands of sharks are killed each year for their fins.
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Several major causes of biodiversity loss stand out (6 of 9)
• Poaching is the illegal killing of wildlife for meat or body
parts.
– The illegal trade for wildlife products has led to steep
population declines for many animals, including tigers,
rhinoceros, and elephants.
Figure 8.10 Poachers slaughter elephants to sell their tusks for ivory.
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Several major causes of biodiversity loss stand out (7 of 9)
• Invasive species, non-native species introduced to new
environments, can proliferate and displace native species.
Table 8.4 Invasive Species
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Several major causes of biodiversity loss stand out (8 of 9)
• Species native to islands are particularly vulnerable, as
they have been isolated from new parasites, predators,
and competitors.
[Table 8.4 Continued]
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Several major causes of biodiversity loss stand out (9 of 9)
• Climate change is also hurting biodiversity, with the warming
temperatures causing some animals to shift their ranges to be closer
to the poles or higher in altitude.
– Organisms already living in these places, such as the polar bear,
have nowhere left to go and are especially vulnerable.
Figure 8.11 The polar bear
became the first species
listed under the Endangered
Species Act as a result of
climate change.
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A mix of causes threatens many species (1 of 2)
• For many species, multiple factors are contributing to decline.
– Monarch butterflies are in decline because of the loss of
milkweeds due to herbicide use and habitat loss in their
overwintering forests in Mexico.
Figure 8.12 The once-abundant monarch butterfly has undergone alarming declines due to
herbicides, pesticides, and habitat loss.
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A mix of causes threatens many species (2 of 2)
• The worldwide collapse of amphibians is due to a “perfect
storm” of factors, including habitat destruction, chemical
pollution, invasive species, climate change, and disease.
Figure 8.13 The world’s amphibians are vanishing.
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Conservation Biology: The Search for
Solutions
• Conservation biology is a study that seeks to understand
the loss, protection, and restoration of biological diversity.
Figure 8.14 Conservation biologists use many approaches to study the loss, protection, and
restoration of biodiversity, seeking to develop scientifically sound solutions.
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Conservation biology responds to biodiversity loss
• Conservation geneticists determine the minimum viable
population size—how small a population can become and
how much genetic variation it can lose before encountering
inbreeding depression.
– By determining this size, they can help wildlife
managers make plans for increasing the size of a
population.
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Endangered species are a focus of conservation efforts
(1 of 5)
• The Endangered Species Act (ESA) of 1973 offers
protection to species that fall within two categories:
– Endangered, or in danger of becoming extinct in the
near future.
– Threatened, likely to become endangered soon.
• The ESA forbids the U.S. government and citizens from
taking actions that destroy individuals within identified
species.
– As of 2016, 1229 species were listed as endangered
and 367 were listed as threatened.
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Endangered species are a focus of conservation efforts
(2 of 5)
• Early successes of the ESA include the recovery of the
bald eagle, peregrine falcon, brown pelican, and other
birds following the ban of DDT in 1973.
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Endangered species are a focus of conservation efforts
(3 of 5)
• Federal authorization for spending under the ESA expired
in 1992 and has not been re-authorized since.
– As a result, a number of species judged in need of
protection have not been added to the law.
• A common perception of the law is that it imperils the
livelihoods of some, such as loggers in the Pacific
Northwest who have reduced timber harvesting due to the
endangered northern spotted owl and marbled murrelet.
– This leads to “shoot, shovel, and shut up,” a practice of
concealing the presence of endangered species on
private land.
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Endangered species are a focus of conservation efforts
(4 of 5)
• Despite this perception, the ESA does not always stop
development projects—it can promote cooperation with
landowners.
– Habitat conservation plans allow the landowner to
harm some individuals of a species if the overall habitat
is improved.
– A safe harbor agreement is a promise that the
government will not pursue additional action if the
landowner pursues actions that assist in the species’
recovery.
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Endangered species are a focus of conservation efforts
(5 of 5)
• A recent battle took place
between federal officials,
cattle ranchers, and oil and
gas drillers over the
potential listing of the
greater sage grouse as
endangered.
– A voluntary campaign
was waged to lessen
impacts on grouse
populations, which
federal officials deemed
adequate to conserve
the species.
Figure 8.15 Populations of the greater sage grouse
have declined steeply.
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Treaties promote conservation
• The 1973 Convention on International Trade in
Endangered Species of Wild Fauna and Flora (CITES)
bans the international transport of the body parts of rare
species.
• The Convention on Biological Diversity is a treaty that
provides funding and incentives for conservation in
developing countries.
– Successes include promoting ecotourism at the
Serengeti National Park, promoting sustainable crops
like shade-grown coffee, and discouraging the use of
pesticide-intensive farming.
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Captive breeding, reintroduction, and cloning are
being pursued (1 of 4)
• Zoos and botanical gardens have become centers for
captive breeding, where endangered individuals such as
black rhinos are bred and raised with the intention of
reintroducing their progeny into the wild.
– 65 plant and animal species now exist only in captivity.
Figure 8.16 We can reestablish populations by
reintroducing them to areas where they were
extirpated.
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Captive breeding, reintroduction, and cloning are
being pursued (2 of 4)
• The California condor was a victim of hunting and lead shot poisoning,
dwindling to only 22 individuals by 1982.
– Captive breeding programs have released 268 condors into the
wild, with 167 still in captivity.
– Lead shot poisoning is still a problem, although California is
banning lead shot as of 2019.
Figure 8.17 California condors are
being bred in captivity and released to
the wild, gradually rebuilding their
population.
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Captive breeding, reintroduction, and cloning are
being pursued (3 of 4)
• A new idea is to take DNA from an endangered species,
insert it into an egg from a related species (that lacks a
nucleus), and implant it into a female.
– Several mammals have been cloned in this way, and
scientists believe that extinct species may be
recovered from DNA in preserved body parts.
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Captive breeding, reintroduction, and cloning are
being pursued (4 of 4)
• The protection of umbrella species helps to protect many
others.
– The wildebeest of the Serengeti, for example, have a
huge range. Protecting them results in the protection of
many other species as well.
• Environmental organizations use large charismatic
vertebrates as flagship species to promote conservation.
– The symbol of the World Wildlife Fund, for example, is
a giant panda.
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Several strategies help to protect habitats,
communities, and ecosystems (1 of 2)
• Biodiversity hotspots are regions that support a large number of
species that are found nowhere else.
– Defined as harboring at least 1500 endemic plant species and
having already lost 70% of habitat area.
Figure 8.18 Biodiversity hotspots are priority regions for habitat preservation.
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Several strategies help to protect habitats,
communities, and ecosystems (2 of 2)
• Parks and preserves are protected areas that seek to
maintain habitats and ecological services.
– May still be affected from illegal logging, poaching, and
resource extraction.
• Areas of the ocean are also beginning to be set aside for
similar reasons.
• Ecosystems can also be restored by reestablishing the
natural processes that were interrupted by human
development.
– U.S. restoration efforts have focused on the Illinois
prairie, Florida Everglades, and southeastern longleaf
pine forests.
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Community-based conservation is growing
• In the past, conservationists from developed countries
would work to preserve ecosystems while neglecting the
needs of the local people.
• Today, community-based conservation actively engages
local people such as the Maasai.
– The Maasai had been forcibly evicted from the
Serengeti and forbidden from hunting wildlife, but are
now given some authority over wildlife management.
• This approach will be vital to preserve biodiversity in the
face of growing future human populations.
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