CHAPTER 9
SUSTAINING BIODIVERSITY: SAVING ECOSYSTEMS AND
ECOSYSTEM SERVICES
Outline
9-1 What are the major threats to forest ecosystems?
A. Forests vary in their age, make-up, and origins.
2. Two major types based on their age and structure:
a. An old growth forest is an uncut or regenerated primary forest that has not been
3. A tree plantation, also called a tree farm or commercial forest, is a managed tract with
4. Forests provide important economic and ecological services.
a. Forests remove CO2 from the atmosphere and store it in organic compounds (biomass)
through photosynthesis.
b. Forests help to stabilize the earth’s temperature and slow projected climate change.
B. Unsustainable logging is a major threat to forest ecosystems.
1. The first step in harvesting trees is to build roads for access and timber removal, but they can
cause the following problems:
2. Methods of harvesting trees:
3. SCIENCE FOCUS: Putting a Price Tag on Nature’s Ecological Services.
a. Market tools such as regulations, taxes, and subsidies can encourage protection of
biodiversity.
b. The world’s forests and other ecosystems will continue to be degraded with current
prices of goods and services.
C. Fire can threaten or benefit forest ecosystems.
1. Surface fires usually burn only undergrowth and leaf litter on the forest floor.
a. Kills seedlings and small trees but spares most mature trees and allows most wild
animals to escape.
2. Crown fires are extremely hot fires that leap from treetop to treetop, burning whole trees.
3. CONNECTIONS: Climate Change and Forest Fires.
a. Rising temperatures and increased drought from projected climate change will likely
make many forest areas more suitable for insect pests, which would then multiply
and kill more trees.
b. Drying forests will probably experience more fires, producing increases in the
greenhouse gas CO2, which then increases atmospheric temperatures.
D. Almost half of the world’s forests have been cut down.
1. Deforestation is the temporary or permanent removal of large expanses of forest for
agriculture, settlements, or other uses.
3. If current deforestation rates continue, about 40% of the world’s remaining intact forests will
have been logged or converted to other uses within two decades, if not sooner.
5. The net total forest cover in several countries changed very little or even increased between
6. Some scientists are concerned about the growing amount of land occupied by commercial tree
7. CASE STUDY: Many Cleared Forests in the United States Have Grown Back.
a. Forests that cover about 30% of the U.S. land area provide habitats for more than 80%
of the country’s wildlife species and supply about two-thirds of the nation’s surface
water.
b. Today, forests in the United States (including tree plantations) cover more area than they
did in 1920, primarily due to secondary succession.
E. Tropical forests are disappearing rapidly.
1. Tropical forests cover about 6% of the earth’s land area.
3. Brazil has more than 30% of the world’s remaining tropical rain forest in its vast Amazon
basin.
4. At the current rate of global deforestation, 50% of the world’s remaining old-growth tropical
forests will be gone or severely degraded by the end of this century.
F. Causes of tropical deforestation are varied and complex.
1. Tropical deforestation results from a number of interconnected underlying and direct causes.
a. Pressures from population growth and poverty, push subsistence farmers and the
landless poor into tropical forests, where they try to grow enough food to survive.
b. Government subsidies can accelerate the direct causes such as logging and ranching by
2. CONNECTIONS: Burning Tropical Forests and Climate Change.
a. The burning of tropical forests releases CO2 into the atmosphere, which is projected to
9-2 How should we manage and sustain forests?
A. We can manage forests more sustainably.
2. Removing government subsidies and tax breaks that encourage deforestation would also help.
B. We can improve the management of forest fires.
1. In the United States, the Smokey Bear educational campaign has:
2. Trying to prevent all forest fires can make matters worse by increasing the likelihood of
3. There are several strategies for reducing fire-related harm to forests and people.
a. Prescribed burns are small, contained surface fires to remove flammable small trees and
underbrush in the highest-risk forest areas.
4. SCIENCE FOCUS: Certifying Sustainably Grown Timber and Products Such as the Paper
Used in This Book.
a. The nonprofit Forest Stewardship Council has developed environmentally sound and
sustainable practices for use in certifying timber and timber products.
b. To be certified, a timber company must show that cutting of trees has not exceeded
long-term forest regeneration; roads and harvesting systems have not caused
C. We can reduce the demand for harvested trees.
1. Reduce inefficient use of construction materials, excess packaging, overuse of junk mail,
2. Paper can be made from fiber that does not come from trees.
D. Ways to reduce tropical deforestation.
1. Debt-for-nature swap can make it financially attractive for countries to protect their tropical
2. Conservation concessions occur when governments or private conservation organizations pay
nations for agreeing to preserve their natural resources.
3. Consumers can reduce the demand for products that are supplied through illegal and
unsustainable logging in tropical forests.
4. Individuals can plant trees.
5. CONNECTIONS: Good and Bad Bamboo
a. Growing bamboo, which is increasingly used for hardwood flooring, added to an
environmental problem while trying to be part of the solution.
9-3 How should we manage and sustain grasslands?
A. Some rangelands are overgrazed.
1. Grasslands provide many important ecological services, including soil formation, erosion control,
2. Rangelands are unfenced grasslands in temperate and tropical climates that supply forage, or
vegetation, for grazing (grass-eating) and browsing (shrub-eating) animals.
4. Overgrazing occurs when too many animals graze for too long and exceed the carrying capacity of
a rangeland area.
5. Limited data from surveys in various countries indicate that overgrazing by livestock has caused a
loss in productivity in as much as 20% of the world’s rangeland.
B. We can manage rangelands more sustainably.
1. Control the number of grazing animals and the duration of their grazing in a given area so the
carrying capacity of the area is not exceeded.
a. Rotational grazing in which cattle are confined by portable fencing to one area for a short
9-4 How should we manage and sustain parks and nature reserves?
A. National parks face many environmental threats.
2. Most too small to sustain many large animal species.
4. Some parks are so popular that large numbers of visitors are degrading the natural features that
make them attractive.
6. CASE STUDY: Stresses on U.S. Public Parks:
a. The U.S. national park system, established in 1912, includes 58 major national parks, along
with 335 monuments and historic sites. States, counties, and cities also operate public parks.
7. CONNECTIONS: National Parks and Climate Change.
a. Low-lying U.S. park properties in places such as Key West, Florida, Ellis Island in New York
Harbor, and Florida’s Everglades National Park will likely be underwater later in this century
B. Nature reserves occupy only a small part of the earth’s land.
1. As of 2010, less than 13% of the earth’s land area was strictly or partially protected in nature
reserves, parks, wildlife refuges, wilderness, and other areas.
3. Conservation biologists call for full protection of at least 20% of the earth’s land area in a global
system of biodiversity.
5. Ecologists and conservation biologists view protected areas as islands of biodiversity and natural
capital that help to sustain all life and economies and serve as centers of evolution.
7. By 2010, the United Nations had used this principle to create a global network of 553 biosphere
reserves in 109 countries.
8. SCIENCE FOCUS: Reintroducing the Gray Wolf to Yellowstone National Park.
9. CASE STUDY: Costa Rica—A Global Conservation Leader.
a. Tropical forests once completely covered Central America’s Costa Rica, but between 1963
and 1983 much of the country’s forests were cleared to graze cattle.
b. Costa Rica is a superpower of biodiversity, with an estimated 500,000 plant and animal
species.
c. Costa Rica now has a system of nature reserves and national parks that, by 2010, included
about a quarter of its land.
d. Costa Rica now devotes a larger proportion of its land to biodiversity conservation than does
C. Protecting wilderness is an important way to preserve biodiversity.
a. One way to protect undeveloped lands is to set them aside as wilderness, land officially
designated as an area where natural communities have not been seriously disturbed by
humans and where human activities are limited by law.
1. CASE STUDY: Controversy over Wilderness Protection in the United States.
a. In the United States, conservationists have been trying to save wild areas from development
9-5 What is the ecosystem approach to sustaining terrestrial biodiversity and ecosystem services?
A. Here are four ways to protect ecosystems.
1. Most biologists and wildlife conservationists believe that the best way to keep from hastening the
2. Four-point plan of the ecosystems approach:
a. Map the world’s terrestrial and aquatic ecosystems and create an inventory of the species
contained in each of them and the ecosystem services they provide.
c. Seek to restore as many degraded ecosystems as possible.
B. Protecting global biodiversity hotspots is an urgent priority.
1. Some biodiversity scientists urge adoption of an emergency action strategy to identify and quickly
protect biodiversity hotspots, areas especially rich in plant species that are found nowhere else and
C. We can rehabilitate and restore ecosystems that we have damaged.
1. Almost every natural place on the earth has been affected or degraded to some degree by human
activities.
3. Examples of restoration include:
a. replanting forests
4. Four steps to speed up repair operations include the following:
a. Restoration.
5. Researchers have suggested a science-based, four-step strategy for carrying out most forms of
ecological restoration and rehabilitation:
6. SCIENCE FOCUS: Ecological Restoration of a Tropical Dry Forest in Costa Rica.
a. One of the world’s largest ecological restoration projects.
b. Small, tropical dry forest was burned, degraded, and fragmented for large-scale conversion of
D. We can share areas we dominate with other species.
1. Reconciliation ecology is the science that focuses on inventing, establishing, and maintaining new
habitats to conserve species diversity in places where people live, work, or play.
2. Examples include:
a. Protecting local wildlife and ecosystems can provide economic resources for their
communities by encouraging sustainable forms of ecotourism.
9-6 How can we help to sustain aquatic biodiversity?
A. Human activities are destroying and degrading aquatic biodiversity.
1. Human activities have destroyed or degraded a large portion of the world’s coastal wetlands,
3. Loss and degradation of many sea-bottom habitats caused by dredging operations and trawler
fishing boats.
4. In freshwater aquatic zones, dam building and excessive water withdrawal from rivers for
5. The deliberate or accidental introduction of hundreds of harmful invasive species threatens
aquatic biodiversity.
6. Thirty-four percent of the world’s known marine fish species and 71% of the world’s
freshwater fish species face premature extinction.
B. Overfishing: gone fishing; fish gone.
1. A fishery is a concentration of a particular wild aquatic species suitable for commercial
harvesting in a given ocean area or inland body of water.
3. Fifty-two percent of the world’s fisheries are fully exploited, 20% are moderately
overexploited, and 28% are overexploited or depleted.
5. When overharvesting causes larger predatory species to dwindle, rapidly reproducing invasive
species can more easily take over and disrupt ocean food webs.
6. CASE STUDY: Industrial Fish Harvesting Methods.
a. Industrial fishing fleets dominate the world’s marine fishing industry, using global
satellite positioning equipment, sonar fish-finding devices, huge nets and long fishing
lines, spotter planes, and gigantic refrigerated factory ships that can process and freeze
their catches.
b. Trawler fishing is used to catch fish and shellfish by dragging a funnel-shaped net held
open at the neck along the ocean bottom.
c. Purse-seine fishing, is used to catch surface-dwelling fish by using a spotter plane to
C. We can protect and sustain marine biodiversity.
1. Protecting marine biodiversity is difficult for several reasons.
Instructor’s Manual for Environmental Science, 15th edition
a. The human ecological footprint and fishprint are expanding so rapidly into aquatic areas
2. Several ways to protect and sustain marine biodiversity:
a. Protect endangered and threatened aquatic species.
3. INDIVIDUALS MATTER: Sylvia Earle—Champion of the Oceans
a. Sylvia Earle is an oceanographer, explorer, author, and lecturer. For decades, she has
been a global leader in publicizing the urgent need to increase our understanding of the
global ocean that helps support all life and to protect much more of it from harmful
human activities.
b. Earle’s research has focused on the ecology and conservation of marine ecosystems,
D. Taking an Ecosystem Approach to Sustaining Aquatic Biodiversity
1. Strategies for applying the ecosystem approach to aquatic biodiversity include:
a. Complete the mapping of the world’s aquatic biodiversity, identifying and locating as
many plant and animal species as possible.
b. Identify and preserve the world’s aquatic biodiversity hotspots and areas where
2. The harmful effects of human activities on aquatic biodiversity and ecosystem services could
3. This chapter’s three big ideas are:
a. The economic values of the important ecological services provided by the world’s
ecosystems are far greater than the value of raw materials obtained from those systems.
Chapter 9: Sustaining Biodiversity: The Ecosystem Approach
Objectives
9-1 What are the major threats to forest ecosystems?
CONCEPT 9-1 Forest ecosystems provide ecosystem services far greater in value than the value of raw
materials obtained from forests.
2. Describe several ways to harvest trees and list the problems associated with deforestation.
4. Define deforestation, its economic and environmental effects, and changed that have occurred in the
forest area of the United States.
9-2 How should we manage and sustain forests?
CONCEPT 9-2 We can sustain forests by emphasizing the economic value of their ecosystem services,
removing government subsidies that hasten their destruction, protecting old-growth forests, harvesting trees no
faster than they are replenished, and planting trees.
1. Describe methods to manage forests more sustainably and to improve the management of forest fires.
3. List ways to reduce the demand for harvested trees and tropical deforestation.
9-3 How should we manage and sustain grasslands?
CONCEPT 9-3 We can sustain the productivity of grasslands by controlling the number and distribution of
grazing livestock and by restoring degraded grasslands.
2. List ways to manage rangelands more sustainably.
9-4 How should we manage and sustain parks and nature reserves?
CONCEPT 9-4 Sustaining biodiversity will require more effective protection of existing parks and nature
reserves, as well as the protection of much more of the earth’s remaining undisturbed land area..
2. Compare the percentage of the earth that is currently protected by nature reserves to the percentage
3. Define wilderness and describe the controversy over wilderness protection in the United States.
9-5 What is the ecosystem approach to sustaining terrestrial biodiversity and ecosystem services?
CONCEPT 9-5 We can help to sustain terrestrial biodiversity and increase our beneficial environmental impact
by identifying and protecting biodiversity hotspots and employing ecology and reconciliation ecology.
2. Define biodiversity hotspot and discuss the distribution of endangered or critically endangered species
and the human population in relation to hotspots.
4. Define reconciliation ecology and give three examples.
9-6 How can we help to sustain aquatic biodiversity?
CONCEPT 9-6 We can help to sustain aquatic biodiversity and increase our beneficial environmental impact
by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing
overfishing.
2. List factors that threaten the marine and freshwater aquatic zones.
4. Discuss ways to protect marine biodiversity and the difficulties involved.
Instructor’s Manual for Environmental Science, 15th edition
5. List strategies for applying the ecosystem approach to aquatic biodiversity.
Key Terms
biodiversity hotspots
commercial forests
ecological restoration
deforestation
fishprint
fishery
old-growth primary forests
overgrazing
pastures
principles of sustainability
rangelands
reconciliation ecology
second-growth
forests
tree plantations
tree farms or commercial
forests
wilderness
Teaching Tips
Use the case study to introduce the idea of human effect on, and management of, ecosystems. Begin this
discussion by reminding students that the area they lived in was once untouched by human civilization.
• Ask them what that area was like before humans settled there—species and forests or grasslands
present. Coax them to tell you how human history has carved its impact into the land and sea.
• Use this as a bridge to the discussion about whether humans have an ethical responsibility to
preserve and manage ecosystems, or whether ecosystems are present simply to provide for species,
such as ourselves.
Maintaining a high level of biodiversity is one of the text’s primary goals in maintaining a sustainable
world. Ask your students to think of a park or refuge that they have visited. They can present or write about
the following items specific to their park or refuge.
Discussion Topics
1. Why are tropical rain forests important for U.S. imports and biodiversity?
2. What are the different types of public land in the United States? How are these public lands used to
increase biodiversity? What are the environmental values derived from these lands?
3. What is the difference between the National Parks System, the U.S. Forest Service lands and the
National Wilderness System?
7. What types of activities (such as mining) should be allowed in national wildlife refuges?
8. Should parts of the wilderness areas be set aside for wildlife only?
Activities and Projects
2. As a class field trip, visit a forest managed for pulp and paper production or industrial timbering. What
specific methods are used to maximize economic returns and to curb ecosystem damage? Contrast the
appearance of commercial forestland and relatively undisturbed forestland. Which do you like best?
Why?
3. As a class project, compile a list of commodities for sale in your community whose production or
harvesting contributes to the destructive exploitation of tropical forests. Are vendors and consumers
aware of the consequences? Do they care about the consequences?
4. If there are rangelands in your locale, try to schedule a class visit to examples of well- and poorly-
managed grazing lands. Compare the quantity and quality of vegetation present.
6. If possible, visit a national park or wilderness area. Assess its current problems and analyze plans to
address those problems.
Attitudes and Values Assessment
1. What wildlife is most common in your area?
2. Where are the nearest locations in your area to go to observe wildlife?
3. What are your feelings toward wildlife species? What relationship between humans and wildlife do
you find most desirable?
4. Do you feel that humans have the right to relate to other species in any way they wish? If not, what
limits do you see on human behavior toward other species?
5. Do you use products that come from the tropical forest? Do the products you use result in destruction
of forest or continued sustainable use of the forest?
10. Do you feel it is right to destroy cultures that live sustainably in the tropical rain forests? If not, what
steps do you support to protect these cultures?
11. What steps do you feel should be taken to support human cultures and wildlife species in ways that
create sustainable societies?
12. Have you ever visited a mine? How did you feel about the mine? What benefits do you enjoy as a
result of mining activity?
13. Have you ever visited rangeland? How did you feel about the land? What benefits do you enjoy as a
result of cattle grazing?
Laboratory Skills
Wells, Edward. Lab Manual for Environmental Science. 2009. Lab #2: The Tragedy of the Commons – A
Classroom Simulation Exercise.
Wells, Edward. Lab Manual for Environmental Science. 2009. Lab #15: Oil Spill!
News Videos
Darwin’s Galapagos under Threat, The Brooks/Cole Environmental Science Video Library 2009, ©2011,
DVD ISBN-13: 978-0-538-73355-7
Additional Videos
After the Storm (Documentary, free DVD)
Looks at watersheds and their importance in various parts of the U.S.
Chapter 9: Sustaining Biodiversity: The Ecosystem Approach
Frontline: World, Mexico: The Business of Saving Trees (Documentary, 2008, Online)
A look at how the carbon credit system has been use to create jobs in Mexico.
http://www.pbs.org/frontlineworld/rough/2008/03/mexico_the_busi.html
Livable Landscapes (Documentary, 2002)
How growth and sprawl affect the quality of life in New England, and some possible solutions.
http://www.bullfrogfilms.com/catalog/ll.html
Major World Ecosystems (Documentary, 2004)
Covers a variety of ecosystems and their requirements.
http://www.amazon.com/Major-World-Ecosystems/dp/B00004T01Y
Valley at the Crossroads (Documentary, 2002)
The battle over sprawl in California’s Central Valley, where 50% of America’s fruits and vegetables are
Web Resources
Bridge
http://www.vims.edu/bridge/
A variety of resources for teachers that may be adaptable to the college level.