Sustaining Terrestrial Biodiversity: The Ecosystem Approach

Chapter 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach

Chapter Overview Questions  How have human activities affected the earth’s

biodiversity?  How should forest resources be used, managed, and sustained globally and in the United States?  How serious is tropical deforestation, and how can we help sustain tropical forests?  How should rangeland resources be used, managed, and sustained?

Chapter Overview Questions (cont’d)  What problems do parks face, and how

should we manage them?  How should we establish, design, protect, and manage terrestrial nature reserves?  What is wilderness, and why is it important?  What is ecological restoration, and why is it important?  What can we do to help sustain the earth’s terrestrial biodiversity?

Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles.

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InfoTrac: Cloud over Puerto Rico rain forest. Chicago Tribune, March 20, 2006. InfoTrac: Can't log the forest for the trees? Roger Harris. American Scientist, March-April 2006 v94 i2 p120(2). InfoTrac: The cry of the wild. Thomas L. Friedman. The New York Times, June 28, 2006 pA21(L). NASA: Tropical Deforestation Greenpeace: Eating Up the Amazon

Core Case Study: Reintroducing Wolves to Yellowstone  Endangered Species 

1850-1900 two million wolves were destroyed.

 Keystone Species 

 

Keeps prey away from open areas near stream banks. Vegetation reestablishes. Species diversity expands. Figure 10-1

HUMAN IMPACTS ON TERRESTRIAL BIODIVERSITY  We have depleted

and degraded some of the earth’s biodiversity and these threats are expected to increase.

Figure 10-2

Human Population Size and resource use

Human Activities Agriculture, industry, economic production and consumption, recreation

Direct Effects Degradation and destruction Changes in number and of natural ecosystems distribution of species Alteration of natural chemical Pollution of air, water, cycles and energy flows and soil

Climate change

Indirect Effects Loss of Biodiversity Fig. 10-2, p. 192

Why Should We Care About Biodiversity?  Use Value: For the

usefulness in terms of economic and ecological services.  Nonuse Value: existence, aesthetics, bequest for future generations. Figure 10-3

MANAGING AND SUSTAINING FORESTS  Forests provide a

number of ecological and economic services that researchers have attempted to estimate their total monetary value.

Figure 10-4

Natural Capital Forests Ecological Services Support energy flow and chemical cycling Reduce soil erosion Absorb and release water

Economic Services Fuelwood Lumber Pulp to make paper Mining

Purify water and air

Livestock grazing

Influence local and regional climate

Recreation

Store atmospheric carbon

Jobs

Provide numerous wildlife habitats Fig. 10-4, p. 193

Types of Forests  Old-growth forest: uncut

or regenerated forest that has not been seriously disturbed for several hundred years.  

22% of world’s forest. Hosts many species with specialized niches.

Figure 10-5

Types of Forests

 Second-growth forest: a stand of trees

resulting from natural secondary succession.  Tree plantation: planted stands of a particular tree species. Figure 10-6

Weak trees removed

Clear cut 25 30

Seedlings planted

15

Years of growth

10 5

Fig. 10-6, p. 195

Global Outlook: Extent of Deforestation  Human activities

have reduced the earth’s forest cover by as much as half.  Losses are concentrated in developing countries. Figure 10-7

Natural Capital Degradation Deforestation

• Decreased soil fertility from erosion • Runoff of eroded soil into aquatic systems • Premature extinction of species with specialized niches • Loss of habitat for native species and migratoryspecies such as birds and butterflies • Regional climate change from extensive clearing • Release of CO2 into atmosphere • Acceleration of flooding

Fig. 10-7, p. 196

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 Should there be a global effort to sharply

reduce the cutting of old-growth forests? 



a. Yes. Old-growth forests can only be saved by rapid international action and the setting aside of large reserves of the forests. b. No. Only local citizens and not global efforts led by the UN can save these forests.

Case Study: Deforestation and the Fuelwood Crisis  Almost half the people in the developing

world face a shortage of fuelwood and charcoal.  

In Haiti, 98% of country is deforested. MIT scientist has found a way to make charcoal from spent sugarcane.

Harvesting Trees

 Building roads into previously inaccessible

forests paves the way for fragmentation, destruction, and degradation. Figure 10-8

Highway

Old growth

Cleared plots for grazing

Highway

Cleared plots for agriculture

Fig. 10-8, p. 197

Harvesting Trees  Trees can be harvested

individually from diverse forests (selective cutting), an entire forest can be cut down (clear cutting), or portions of the forest is harvested (e.g. strip cutting).

Figure 10-9

(a) Selective cutting

Fig. 10-9a, p. 198

(b) Clear-cutting

Fig. 10-9b, p. 198

(c) Strip cutting Uncut

Cut 1 year ago Dirt road Cut 3–10 years ago

Uncut

Stream

Fig. 10-9c, p. 198

Harvesting Trees

Effects of clear-cutting in the state of Washington, U.S. Figures 10-10 and 10-11

Trade-Offs Clear-Cutting Forests Advantages

Disadvantages

Higher timber yields

Reduces biodiversity

Maximum profits in shortest time

Disrupts ecosystem processes

Can reforest with fastgrowing trees

Destroys and fragments wildlife habitats

Short time to establish new stand of trees

Leaves large openings

Needs less skill and planning Good for tree species needing full or moderate sunlight

Increases water pollution, flooding, and erosion on steep slopes Eliminates most recreational value Fig. 10-11, p. 198

Solutions  We can use forests

more sustainably by emphasizing: 





Economic value of ecological services. Harvesting trees no faster than they are replenished. Protecting old-growth and vulnerable areas. Figure 10-12

Solutions Sustainable Forestry • Identify and protect forest areas high in biodiversity • Grow more timber on long rotations • Rely more on selective cutting and strip cutting • Stop clear-cutting on steep slopes • Cease logging of old-growth forests • Prohibit fragmentation of remaining large blocks offorest • Sharply reduce road building into uncut forest areas • Leave most standing dead trees and fallen timber for wildlife habitat and nutrient recycling • Certify timber grown by sustainable methods • Include ecological services of forests in estimating their economic value • Plant tree plantations on deforested and degraded land • Shift government subsidies from harvesting trees to planting trees Fig. 10-12, p. 199

CASE STUDY: FOREST RESOURCES AND MANAGEMENT IN THE U.S.  U.S. forests cover more area than in 1920.  Since the 1960’s, an increasing area of old

growth and diverse second-growth forests have been clear-cut.   

Often replace with tree farms. Decreases biodiversity. Disrupts ecosystem processes.

Types and Effects of Forest Fires



Depending on their intensity, fires can benefit or harm forests.  

Burn away flammable ground material. Release valuable mineral nutrients. Figure 10-13

Solutions: Controversy Over Fire Management  To reduce fire damage:  



Set controlled surface fires. Allow fires to burn on public lands if they don’t threaten life and property. Clear small areas around property subject to fire.

Solutions: Controversy Over Fire Management  In 2003, U.S. Congress passed the

Healthy

Forest Restoration Act: 





Allows timber companies to cut medium and large trees in 71% of the national forests. In return, must clear away smaller, more fireprone trees and underbrush. Some forest scientists believe this could increase severe fires by removing fire resistant trees and leaving highly flammable slash.

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 Do you support repealing or modifying the

Healthy Forests Restoration Act of 2003? 



a. Yes. Local officials and scientists are probably most qualified to manage their local forests. b. No. The initiative favors the timber companies rather than effectively protecting and managing the forests.

Controversy over Logging in U.S. National Forests  There has been an

ongoing debate over whether U.S. national forests should be primarily for:    

Timber. Ecological services. Recreation. Mix of these uses. Figure 10-14

Trade-Offs Logging in U.S. National Forests Advantages

Disadvantages

Helps meet country’s timber needs

Provides only 4% of timber needs

Cut areas grow back

Ample private forest land to meet timber needs

Keeps lumber and paper prices down

Has little effect on timber and paper prices

Provides jobs in nearby communities

Damages nearby rivers and fisheries

Promotes economic growth in nearby communities

Recreation in national forests provides more local jobs and income for local communities than logging Decreases recreational opportunities Fig. 10-14, p. 202

Solutions: Reducing Demand for Harvest Trees  Tree harvesting can

be reduced by wasting less wood and making paper and charcoal fuel from fibers that do not come from trees. 

Kenaf is a promising plant for paper production. Figure 10-15

American Forests in a Globalized Economy  Timber from tree plantations in temperate

and tropical countries is decreasing the need for timber production in the U.S. 





This could help preserve the biodiversity in the U.S. by decreasing pressure to clear-cut oldgrowth and second-growth forests. This may lead to private land owners to sell less profitable land to developers. Forest management policy will play a key role.

CASE STUDY: TROPICAL DEFORESTATION

 Large areas of ecologically and

economically important tropical forests are being cleared and degraded at a fast rate.

Figure 10-16

CASE STUDY: TROPICAL DEFORESTATION  At least half of the

world’s terrestrial plant and animal species live in tropical rain forests.  Large areas of tropical forest are burned to make way for cattle ranches and crops. Figure 10-17

Why Should We Care about the Loss of Tropical Forests?

 About 2,100 of the 3,000 plants identified by

the National Cancer Institute as sources of cancer-fighting chemicals come from tropical forests. Figure 10-18

Rauvolfia Rauvolfia sepentina, Southeast Asia Tranquilizer, high blood pressure medication

Fig. 10-18a, p. 205

Foxglove Digitalis purpurea, Europe Digitalis for heart failure

Fig. 10-18b, p. 205

Pacific yew Taxus brevifolia, Pacific Northwest Ovarian cancer Fig. 10-18c, p. 205

Cinchona Cinchona ledogeriana, South America Quinine for malaria treatment

Fig. 10-18d, p. 205

Rosy periwinkle Cathranthus roseus, Madagascar Hodgkin's disease, lymphocytic leukemia

Fig. 10-18e, p. 205

Neem tree Azadirachta indica, India Treatment of many diseases, insecticide, spermicide

Fig. 10-18f, p. 205

Causes of Tropical Deforestation and Degradation  Tropical

deforestation results from a number of interconnected primary and secondary causes.

Figure 10-19

• Oil drilling • Mining • Flooding from dams • Tree plantations • Cattle ranching • Cash crops • Settler farming • Fires • Logging • Roads

Secondary Causes

• Not valuing ecological services • Exports • Government policies • Poverty • Population growth

Basic Causes Fig. 10-19, p. 206

Solutions Sustaining Tropical Forests Prevention Protect most diverse and endangered areas

Restoration Reforestation

Educate settlers about sustainable agriculture and forestry Phase out subsidies that encourage unsustainable forest use Add subsidies that encourage sustainable forest use

Rehabilitation of degraded areas

Protect forests with debt-for-nature swaps and conservation easements Certify sustainably grown timber Reduce illegal cutting Reduce poverty Slow population growth

Concentrate farming and ranching on already-cleared areas Fig. 10-20, p. 207

Kenya’s Green Belt Movement: Individuals Matter  Wangari Maathai

founded the Green Belt Movement.  The main goal is to organize poor women to plant (for fuelwood) and protect millions of trees.  In 2004, awarded Nobel peace prize. Figure 10-10A

MANAGING AND SUSTAINING GRASSLANDS  Almost half of the world’s livestock graze on

natural grasslands (rangelands) and managed grasslands (pastures).  We can sustain rangeland productivity by controlling the number and distribution of livestock and by restoring degraded rangeland.

MANAGING AND SUSTAINING GRASSLANDS  Overgrazing (left)

occurs when too many animals graze for too long and exceed carrying capacity of a grassland area. Figure 10-21

MANAGING AND SUSTAINING GRASSLANDS

 Example of restored area along the San

Pedro River in Arizona after 10 years of banning grazing and off-road vehicles.

Figure 10-22

Case Study: Grazing and Urban Development in the American West  Ranchers, ecologists, and environmentalists

are joining together to preserve the grasslands on cattle ranches. 



Paying ranchers conservation easements (barring future owners from development). Pressuring government to zone the land to prevent development of ecologically sensitive areas.

NATIONAL PARKS  Countries have established more than 1,100

national parks, but most are threatened by human activities. 







Local people invade park for wood, cropland, and other natural resources. Loggers, miners, and wildlife poachers also deplete natural resources. Many are too small to sustain large-animal species. Many suffer from invasive species.

Case Study: Stresses on U.S. National Parks  Overused due to

popularity.  Inholdings (private ownership) within parks threaten natural resources.  Air pollution. Figure 10-23

 Suggestions for

sustaining and expanding the national park system in the U.S.

Figure 10-24

Solutions National Parks • Integrate plans for managing parks and nearby federal lands • Add new parkland near threatened parks • Buy private land inside parks • Locate visitor parking outside parks and use shuttle buses for entering and touring heavily used parks • Increase funds for park maintenance and repairs • Survey wildlife in parks • Raise entry fees for visitors and use funds for park management and maintenance • Limit the number of visitors to crowded park areas • Increase the number and pay of park rangers • Encourage volunteers to give visitor lectures and tours • Seek private donations for park maintenance and repairs

Fig. 10-24, p. 211

NATURE RESERVES  Ecologists call for protecting more land to

help sustain biodiversity, but powerful economic and political interests oppose doing this.  



Currently 12% of earth’s land area is protected. Only 5% is strictly protected from harmful human activities. Conservation biologists call for full protection of at least 20% of earth’s land area representing multiple examples of all biomes.

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 Should at least 20% of the Earth's land area

be strictly protected from economic development? 



a. No. Such protections would encourage people to poach and illegally extract resources from the expanded reserves. b. Yes. The project is desperately needed to protect the Earth's biodiversity.

NATURE RESERVES  Large and medium-sized reserves with buffer

zones help protect biodiversity and can be connected by corridors.  Costa Rica has

consolidated its parks and reserves into 8 megareserves designed to sustain 80% if its biodiversity. Figure 10-10B

Guanacaste

Nigaragua

Caribbean Sea Llanuras de Tortuguero

Costa Rica

Arenal

Bajo Tempisque

La Amistad

Panama

Cordillera Volcanica Central Pacifico Central

Pacific Ocean

Peninsula Osa

Fig. 10-B, p. 213

NATURE RESERVES  A model biosphere

reserve that contains a protected inner core surrounded by two buffer zones that people can use for multiple use.

Figure 10-25

Biosphere Reserve

Core area

Buffer zone 1 Buffer zone 2

Tourism and education center

Human Settlements

Research Station Fig. 10-25, p. 214

NATURE RESERVES  Geographic Information System (GIS)

mapping can be used to understand and manage ecosystems. 



Identify areas to establish and connect nature reserves in large ecoregions to prevent fragmentation. Developers can use GIS to design housing developments with the least environmental impact.

NATURE RESERVES  We can prevent or slow down losses of

biodiversity by concentrating efforts on protecting global hot spots where significant biodiversity is under immediate threat.  Conservation biologists are helping people in communities find ways to sustain local biodiversity while providing local economic income.



34 hotspots identified by ecologists as important and endangered centers of biodiversity. Figure 10-26

NATURE RESERVES  Wilderness is land legally set aside in a large

enough area to prevent or minimize harm from human activities.  Only a small percentage of the land area of the United States has been protected as wilderness.

ECOLOGICAL RESTORATION  Restoration: trying to return to a condition as

similar as possible to original state.  Rehabilitation: attempting to turn a degraded ecosystem back to being functional.  Replacement: replacing a degraded ecosystem with another type of ecosystem.  Creating artificial ecosystems: such as artificial wetlands for flood reduction and sewage treatment.

ECOLOGICAL RESTORATION  Five basic science-based principles for

ecological restoration:  

  

Identify cause. Stop abuse by eliminating or sharply reducing factors. Reintroduce species if necessary. Protect area form further degradation. Use adaptive management to monitor efforts, assess successes, and modify strategies.

Will Restoration Encourage Further Destruction?  There is some concern that ecological

restoration could promote further environmental destruction and degradation. 



Suggesting that any ecological harm can be undone. Preventing ecosystem damage is far cheaper than ecological restoration.

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

Should we mount a massive effort to restore ecosystems we have degraded even though this will be quite costly? 



a. No. Less expensive alternatives, such as remediation, replacement, and the creation of artificial ecosystems, should be readily considered. b. Yes. Alternatives will probably not achieve the same biodiversity as ecological restoration.

WHAT CAN WE DO?  Eight priorities for protecting biodiversity: 

 

 

Take immediate action to preserve world’s biological hot spots. Keep intact remaining old growth. Complete mapping of world’s biodiversity for inventory and decision making. Determine world’s marine hot spots. Concentrate on protecting and restoring lake and river systems (most threatened ecosystems).

WHAT CAN WE DO? 

 

Ensure that the full range of the earths ecosystems are included in global conservation strategy. Make conservation profitable. Initiate ecological restoration products to heal some of the damage done and increase share of earth’s land and water allotted to the rest of nature.

What Can You Do? Sustaining Terrestrial Biodiversity • Adopt a forest. • Plant trees and take care of them. • Recycle paper and buy recycled paper products. • Buy sustainable wood and wood products. • Choose wood substitutes such as bamboo furniture and recycled plastic outdoor furniture, decking, and fencing. • Restore a nearby degraded forest or grassland. • Landscape your yard with a diversity of plants natural to the area. • Live in town because suburban sprawl reduces biodiversity.

Fig. 10-27, p. 219