Instructor’s Manual for Environmental Science, 15th edition
Digital Integration
Correlation to Global Environment Watch
Biodiversity Fisheries Land Management
Community-Based Conservation Fishing Land Use
Conservation Forests and Deforestation Oceans and Seas
Correlation to Virtual Field Trips
Ecosystem Approach to Sustaining Biodiversity
Correlation to Explore More
Aquatic Ecosystems Environmental History Rangeland
Biodiversity Forests Saving Species
Conservation Biology Indigenous Cultures Water Pollution
Environmental Economics Overfishing
Suggested Answers to End of Chapter Questions
Answers will vary but these represent phrases from this chapter. The following are examples of the material
that should be contained in possible student answers to the end of chapter questions. They represent only a
Review
Core Case Study
1. Summarize the story if Costa Rica’s effort to preserve its rich biodiversity
• In the mid-1970s, Costa Rica established a system of nature reserves and national parks (Figure 9.1) that,
Chapter 9: Sustaining Biodiversity: The Ecosystem Approach
Section 9-1
2. What are the two key concept for this section? Distinguish among an old-growth (primary) forest, a
second-growth forest, and a tree plantation (tree farm or commercial forest). What major
ecological and economic benefits do forests provide? Describe the efforts of scientists and
economists to put a price tag on the major ecosystem services provided by forests and other
ecosystems.
• CONCEPT 9.1A Forest ecosystems provide ecosystem services far greater in value than the
value of raw materials obtained from forests.
• CONCEPT 9.1B Unsustainable cutting and burning of forests and projected climate change
are the chief threats to forest ecosystems. An old-growth forest is an uncut or regenerated
primary forest that has not been seriously disturbed by human activities or natural disasters for
several hundred years or more. Old-growth forests are reservoirs of biodiversity because they
provide ecological niches for a multitude of wildlife species.
• A second-growth forest is a stand of trees resulting from secondary ecological succession. These
forests develop after the trees in an area have been removed by human activities such as clear-
• See SCIENCE FOCUS: Putting a Price Tag on Nature’s Ecological Services for prices of goods
and services. Through market tools such as regulations, taxes, and subsidies that encourage
protection of biodiversity, the world’s forests and other ecosystems will continue to be degraded.
3. Describe the harm caused by building roads into previously inaccessible forests. Distinguish among
selective cutting, clear-cutting, and strip cutting in the harvesting of trees. What are the major
advantages and disadvantages of clear-cutting forests? What are two types of forest fires? What are
some ecological benefits of occasional surface fires? What effects might projected climate change have
on forests?
• See Figure 9-5 for natural capital and new highway degradation. Building roads into previously
inaccessible forests paves the way to fragmentation, destruction, and degradation of forest
ecosystems. Harmful effects include increased erosion and sediment runoff into waterways,
Instructor’s Manual for Environmental Science, 15th edition
o They free valuable mineral nutrients tied up in slowly decomposing litter and undergrowth;
release seeds from the cones of lodgepole pines; stimulate the germination of certain tree
4. What is deforestation and what parts of the world are experiencing the greatest forest losses? List some
major harmful environmental effects of deforestation. Summarize the story of reforestation in the
United States. Explain how increased reliance on tree plantations can reduce overall forest biodiversity
and degrade forest topsoil. Summarize the trends in tropical deforestation. What are four major causes
of tropical deforestation? Explain how widespread tropical deforestation can convert a tropical forest
to tropical grassland (savanna).
• Deforestation is the temporary or permanent removal of large expanses of forest for agriculture,
settlements, or other uses.
• Tropical rainforests are experiencing great forest losses.
• There are many harmful environmental effects of deforestation, which can reduce biodiversity and
the ecological services provided by forests (see Figures 9-4 and 9-9):
o Decreased soil fertility from erosion.
• Forests in the United States (including tree plantations) cover more area than they did in 1920 (see
CASE STUDY: Many Cleared Forests in the United States Have Grown Back Today). Protected
forests make up about 40% of the country’s total forest area, mostly in the National Forest System,
which consists of 155 national forests managed by the U.S. Forest Service (USFS).
• The downside of tree plantations is that, with only one or two tree species, they are much less
• Tropical deforestation results from a number of underlying and direct causes (see Figure 9-12).
Chapter 9: Sustaining Biodiversity: The Ecosystem Approach
Section 9-2
5. What is the key concept for this section? What is certified sustainably grown timber? List four ways to
manage forests more sustainably. What is a prescribed fire? What are four ways to reduce the need to
harvest trees? Describe the global fuelwood crisis. What are five ways to protect tropical forests and
use them more sustainably?
• CONCEPT 9-2 We can sustain forests by emphasizing the economic value of their ecological
services, removing government subsidies that hasten their destruction, protecting old-growth
forests, harvesting trees no faster than they are replenished, and planting trees.
• See Solutions: More Sustainable Forestry for ways to manage forests sustainably.
o Identify and protect forest areas high in biodiversity.
o Rely more on selective cutting and strip cutting.
o No clear-cutting on steep slopes.
o No logging of old-growth forests.
• Four ways to reduce the need to harvest trees include reducing wood waste, using alternative
sources, reducing the use of throw-away paper products and embracing sustainable practices.
Section 9-3
6. What is the key concept for this section? Distinguish between rangelands and pastures. What is
overgrazing and what are its harmful environmental effects? What are three ways to reduce
overgrazing and use rangelands more sustainably?
See pages 187-188.
• CONCEPT 9-3 We can sustain the productivity of grasslands by controlling the number and
distribution of grazing livestock and by restoring degraded grasslands.
Instructor’s Manual for Environmental Science, 15th edition
Section 9-4
7. What is the key concept for this section? What are the major environmental threats to national parks in
the world and in the United States? Describe some of the ecological effects of reintroducing the gray
wolf to Yellowstone National Park in the United States. What percentage of the world’s land has been
set aside and protected as nature reserves, and what percentage should be protected, according to
conservation biologists? What is the buffer zone concept? How has Costa Rica applied this approach?
What is wilderness and why is it important, according to conservation biologists? Summarize the
history of wilderness protection in the United States.
See pages 188–191.
• CONCEPT 9-4 We need to put more resources into sustaining existing parks and nature reserves
and into protecting much more of the earth’s remaining undisturbed land area.
• National parks are threatened because they are too small and fragmented to sustain many large
animal species, because of invasions by nonnative species that compete with and reduce the
populations of native species, because many are so popular that large numbers of visitors are
degrading the natural features that make them attractive, and lack of funding to enforce protection
of biodiversity. Parks could be more sustainable with decreased degradation of the habitat and
resources, protection from illegal logging and poaching, and consolidation of green areas.
Chapter 9: Sustaining Biodiversity: The Ecosystem Approach
Section 9-5
8. What is the key concept for this section? Summarize the five-point strategy recommended by biologists
for protecting terrestrial ecosystems. What is a biodiversity hotspot and why is it important to protect
such areas? Explain the importance of protecting ecosystem services and list three ways to do this.
Define ecological restoration. What are four approaches to restoration? Summarize the science-based,
four step strategy for carrying out ecological restoration and rehabilitation. Describe the ecological
restoration of Guanacaste National Park in Costa Rica. Define and give three examples of reconciliation
ecology.
• CONCEPT 9.5 We can help to sustain terrestrial biodiversity and increase our beneficial
environmental impact by identifying and protecting biodiversity hotspots and employing
restoration ecology and reconciliation ecology.
• The ecosystems approach would generally employ the following five-point plan:
o 1. Map the world’s terrestrial ecosystems and create an inventory of the species contained
in each of them, along with the ecosystem services they provide.
o 3. Protect the most endangered terrestrial ecosystems and species, with emphasis on
protecting plant biodiversity and ecosystem services.
o 5. Make development biodiversity-friendly by providing significant financial incentives
(such as tax breaks and subsidies) and technical help to private landowners who agree to
help protect endangered ecosystems.
• Biodiversity hotspots are areas especially rich in plant species that are found nowhere else and are
in great danger of extinction. They are home for a large majority of the world’s endangered or
critically endangered species, and one-fifth of the world’s population.
• These hotspots cover only a little more than 2% of the earth’s land surface, they contain an
estimated 50% of the world’s flowering plant species and 42% of all terrestrial species.
• Ecological restoration is the process of repairing damage caused by humans to the biodiversity and
dynamics of natural ecosystems.
• Science-based, four-point strategy for carrying out ecological restoration and rehabilitation:
o Identify the causes of the degradation (such as pollution, farming, overgrazing, mining, or
invasive species).
o Stop the abuse by eliminating or sharply reducing these factors. This would include
removing toxic soil pollutants, improving depleted soil by adding nutrients and new
topsoil, preventing fires, and controlling or eliminating disruptive nonnative species.
o If necessary, reintroduce species—especially pioneer, keystone, and foundation species—
to help restore natural ecological processes, as was done with wolves in the Yellowstone
ecosystem.
o Protect the area from further degradation and allow secondary ecological succession to
Instructor’s Manual for Environmental Science, 15th edition
Section 9-6
9. What is the key concept for this section? Summarize the threats to aquatic biodiversity resulting from
human activities. What is ocean acidification and why is it a major threat? Define fishery and
summarize the threats to marine fisheries. Briefly describe the major industrial fish harvesting methods.
What is a fishprint? Why is it difficult to protect marine biodiversity? What are three ways in which we
could try to protect marine biodiversity? What percentage of the world’s oceans is strictly protected
from harmful human activities in marine reserves? Summarize the contributions of Sylvia Earle to the
protection of aquatic biodiversity. How can the ecosystem approach be applied to protecting 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.
• Major human threats to aquatic diversity include climate change and loss and degradation of many
sea-bottom habitats, caused by dredging operations and trawler fishing boats.
• Protecting marine biodiversity is difficult for several reasons.
o First, the human ecological footprint and fishprint are expanding so rapidly that it is difficult
to monitor their impacts.
o Second, much of the damage to the oceans and other bodies of water is not visible to most
people.
o Third, many people incorrectly view the seas as an inexhaustible resource that can absorb an
almost infinite amount of waste and pollution and still produce all the seafood we want.
Fourth, most of the world’s ocean area lies outside the legal jurisdiction of any country.
Thus, much of it is an open-access resource, subject to overexploitation—a classic case of
the tragedy of the commons.
• There are several ways to protect and sustain marine biodiversity.
Chapter 9: Sustaining Biodiversity: The Ecosystem Approach
• The following strategies can be used to apply the ecosystems approach to aquatic biodiversity:
o Complete the mapping of the world’s aquatic biodiversity, identifying and locating as many
plant and animal species as possible.
• Ocean acidification is a change in ocean chemistry. The oceans have absorbed about one-fourth of
the excess CO2 that human activities have added to the atmosphere. When this absorbed CO2
combines with ocean water, it forms carbonic acid (H2CO3), a weak acid also found in carbonated
drinks. The problem is that many aquatic species, including phytoplankton, corals, sea snails, crabs,
and oysters, use carbonate ions to produce calcium carbonate (CaCO3), the main component of
their shells and bones.
10. What are this chapter’s three big ideas? Explain the relationship between preserving biodiversity as it
is done in Costa Rica and the six principles of sustainability.
• Here are the three big ideas in this chapter:
o
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.
o
We can sustain terrestrial biodiversity by protecting severely threatened areas, protecting
remaining undisturbed areas, restoring damaged ecosystems, and sharing with other species
• Preserving terrestrial and aquatic biodiversity involves applying the three scientific principles of
sustainability. First, it means respecting biodiversity and understanding the value of sustaining it.
Also, if we rely less on fossil fuels and more on direct solar energy and its indirect forms, such as
wind and flowing water, we will generate less pollution and interfere less with chemical cycling and
• The relationship between Wangari Maathai’s Green Belt Movement (Core Case Study) and the
three principles of sustainability is that preserving terrestrial and aquatic biodiversity involves
applying the three principles of sustainability.
o First, it means respecting biodiversity and understanding the value of sustaining it.
o Then, in helping to sustain biodiversity by planting trees for example, we also help to restore
and preserve the flows of energy from the sun through food webs and the cycling of nutrients
within ecosystems.
Instructor’s Manual for Environmental Science, 15th edition
Critical Thinking
1. Why do you think Costa Rica (Core Case Study) has set aside a much larger percentage of its land for
biodiversity conservation than the United States has? Should the United States reserve more of its land
for this purpose? Explain.
Answers will vary. However, Costa Rico has accomplished much in terms of saving ecosystems for
biodiversity.
2. If we fail to protect a much larger percentage of the world’s remaining old-growth forests and tropical
rain forests, describe three harmful effects that this failure is likely to have on any children and
grandchildren you might have.
Deforestation can have highly deleterious effects, such as:
• Water pollution and soil degradation from erosion
3. In the early 1990s, Miguel Sanchez, a subsistence farmer in Costa Rica, was offered $600,000 by a
hotel developer for a piece of land that he and his family had been using sustainably for many years.
An area under rapid development surrounded the land, which contained an old-growth rain forest and a
black sand beach.. Sanchez refused the offer. Explain how Sanchez’s decision was an application of
the social science principles of sustainability. What would you have done if you were in Miguel
Sanchez’s position? Explain.
4. Should more-developed countries provide at least half of the money needed to help preserve the
remaining tropical forests in less-developed countries? Explain. Do you think that the long-term
economic and ecological benefits of doing this would outweigh the short-term economic costs?
Explain.
Answers will vary but one possible answer is:
5. Are you in favor of establishing more wilderness areas in the United States, especially in the lower
48 states (or in the country where you live)? Explain. What might be some drawbacks of doing
this?
Answers will vary. One possible answer is given below.
Ensuring that current wilderness areas remain protected would be a main priority. Then an
6. You are a defense attorney arguing in court for preserving an old-growth forest that developers want to
clear for a suburban development. Give your three strongest arguments for preserving this ecosystem.
How would you counter the argument that preserving the forest would harm the economy by causing a
loss of jobs in the timber industry?
One possible answer is:
Old growth forests perform many ecosystem functions, such as, they are reservoirs of biodiversity
7. What do you think are the three greatest threats to aquatic biodiversity and aquatic ecosystem services?
For each of them, explain your thinking. Imagine that you are a national official in charge of setting
policy for preserving aquatic biodiversity and outline a plan for dealing specifically with these threats.
The following is an example of an acceptable response but several other answers are acceptable.
Three of the greatest threats to aquatic biodiversity are habitat destruction, increased pollution from
Instructor’s Manual for Environmental Science, 15th edition
8. Some scientists consider ocean acidification to be one of the most serious environmental and economic
threats that the world faces. How do you think you might be contributing to ocean acidification in your
daily life? What are three things you could do to help reduce the threat of ocean acidification?
Answers will vary, but most students may come up with the idea that industries that rely on fossil
fuels are contributing greenhouse gases, such as carbon dioxide (mainly responsible for ocean
acidification). Inasmuch as we rely on coal-fired plants for electricity and internal combustion
vehicles, we are contributing to it.
Global Environment Watch Exercise
Go to the Forests and Deforestation portal and next to the Statistics heading click “View All.” On this page,
click on “Share of Tropical Deforestation, 2000–2005.” Choose one of these countries and research the
deforestation in this country further (tip: use the World Map feature). Write a report on your findings and
include possible solutions for this problem. Solutions may include those legislated by governments, as well
as those being tried by private individuals or companies.
Chapter 9: Sustaining Biodiversity: The Ecosystem Approach
Ecological Footprint Analysis
1. What is the annual rate of tropical rain forest loss, as a percentage of total forest area, in each of
the five countries? Answer by filling in the blank column in the table.
E.g., the annual percentage rate of rain forest loss in country A is:
50,000 square kilometers/ 1,800,000 square kilometers x 100 = 0.028 X 100 = 2.8% per year.
Country
Area of tropical rain
forest (square
kilometers)
Area of deforestation
per year (square
kilometers)
Annual rate of
tropical forest loss
A
1,800,000
50,000
2.8
B
55,000
3,000
5.5
C
22,000
6,000
27.3
D
530,000
12,000
2.3
E
80,000
700
0.9
2. What is the annual rate of tropical deforestation collectively in all of the countries represented in
the table?
3. According to the table, and assuming the rates of deforestation remain constant, which country’s
tropical rain forest will be completely destroyed first?
4. Assuming the rate of deforestation in country C remains constant, how many years will it take for
all of its tropical rain forests to be destroyed?
5. Assuming that a hectare (1.0 hectare = 0.01 square kilometer) of tropical rain forest absorbs 0.85
metric tons (1 metric ton = 2,200 pounds) of carbon dioxide per year, what would be the total
annual growth in the carbon footprint (carbon emitted but not absorbed by vegetation because of
deforestation) in metric tons of carbon dioxide per year for each of the five countries in the table?
Instructor’s Manual for Environmental Science, 15th edition
A: 50,000 square kilometers X 1 hectare/0.01 square kilometer= 5,000,000 hectares
5,000,000 hectares x 0.85 metric tons of carbon/hectare = 4,250,000 metric tons of carbon not
absorbed per year