Sustaining Biodiversity: The Ecosystem Approach

Chapter 8

Core Case Study: North American Gray Wolf

Reduced to a few hundred

Keystone species

Restoration proposal angered ranchers, hungers, loggers

1995, reintroduced in Yellowstone, 136 by 2007

Positive ripple effect after reintroduction

The Gray Wolf

Fig. 8-1, p. 149

8-1 How Are We Affecting the Earth’s Biodiversity and Why Should We Protect It?

Concept 8-1A We are degrading and destroying biodiversity in many parts of the world and these threats are increasing.

Concept 8-1B We should protect biodiversity because it exists and because of its usefulness to us and other species.

Loss of Biodiversity

Earth’s biodiversity depleted and degraded

83% land surface disturbed

Degradation of aquatic biodiversity

Ecological fishprint unsustainable

Why Protect Biodiversity

Intrinsic value

Instrumental value

Nonuse values• Existence

• Aesthetic

• Bequest

Endangered Orangutans

Fig. 8-2, p. 152

8-2 How Should We Manage and Sustain Forests?

Concept 8-2 We can sustain forests by recognizing the economic value of their ecological services, protecting old-growth forests, harvesting trees no faster than they are replenished, and making most paper from fast-growing plants and agricultural residues instead of trees.

Forest Services

Forests 30% of earth’s land surface

Economic services

Ecological services

Types of Forests

Old-growth forests

Second-growth forests

Tree plantation

Natural Capital: Forests

Fig. 8-3, p. 153

Old-growth Forest

Fig. 8-4, p. 154

Short Rotation Cycle Forestry

Fig. 8-5, p. 154

Years of growth

Weak treesremoved

Seedlingsplanted

Clear cut

30 yrs

25 yrs

5 yrs 10 yrs

15 yrs

Loss of Original Forests

46% in 8,000 years, most since 1950

Most in tropical areas, developing countries

Estimated loss of 40% intact forests within next 20 years

Natural Capital Degradation: Deforestation

Fig. 8-6, p. 155

Science Focus: Putting a Price Tag on Nature’s Ecological Services

Estimated value of earth’s ecological services• $33.2 trillion per year

• $4.7 trillion per year for forests

Need to start factoring values into land use

Roads and Forests

Fig. 8-7, p. 156

Cleared plotsfor agriculture

New highway

Old growth

HighwayCleared plotsfor grazing

Fig. 8-7, p. 156

New highway

Old growth

Cleared plotsfor agriculture

HighwayCleared plotsfor grazing

Stepped Art

Good News on Forests

2000–2005 net total forested area stabilized or increased

Most of the increase due to tree plantations

Net loss of terrestrial biodiversity

Return of Forests in the United States (1)

U.S. forests • Cover ~30% of land

• Contain ~80% of wildlife species

• Supply ~67% of nation’s surface water

Forest cover greater now than in 1920

Secondary succession

Return of Forests in the United States (2)

Second- and third-growth forests fairly diverse

More wood grown than cut

40% of forests in National Forest System

Forests transformed into tree plantations

Individuals Matter: Butterfly in a Redwood Tree

Julia Hill – “Butterfly” – two years on a platform of California redwood tree

Protest clear-cutting of the ancient trees

Nonviolent civil disobedience

Lost battle, but her tree was saved

Controversy over the National Forests

Forest service mandate• Principle of sustainable yield

• Principle of multiple use

Timber companies push for tree cutting to be primary goal

Harvest Methods (1)

Step one – build roads• Erosion

• Invasive species

• Open up for human invasion

Step two – logging operations• Selective cutting

• Strip cutting

• Clear cutting

Forest Harvesting Methods

Fig. 8-8a, p. 156

Clearstream

(a) Selective cutting

Fig. 8-8b, p. 156

Muddystream

(b) Clear-cutting

Fig. 8-8c, p. 156

Cut 1year ago

(c) Strip cuttingUncut

Clearstream

Uncut

Cut 3–10years ago

Dirt road

Clear-cut Logging

Fig. 8-9, p. 157

Trade-offs: Clear-cutting Forests

Fig. 8-10, p. 157

Forests and Fires

Surface fires • Burn undergrowth only

• Cool fire

• Ecological benefits

Crown fires • Burn the entire tree

• Hot fire

• Occur in forests with lack of surface fires

Management of Forest Fires

Fire suppression in all types of forests

Some forests naturally fire adapted

Restoration of fire’s natural role

Forest Fires

Fig. 8-11, p. 158

Science Focus: Certifying Sustainably Grown Timber

Forest Steward Council certification of forest operations• Environmentally sound practices

• Sustainable yield harvest

• Minimal erosion from operations

• Retention of dead wood for wildlife habitat

Solutions: Sustainable Forestry

Fig. 8-12, p. 159

Trees and Paper

Many trees are cut for paper production

Alternatives• Pulp from rice straw and agricultural residues

(China)

• Kenaf (U.S.)

Solutions: Kenaf

Fig. 8-13, p. 159

8-3 How Serious Is Tropical Deforestation and How Can It Be Reduced?

Concept 8-3 We can reduce tropical deforestation by protecting large forest areas, teaching settlers about sustainable agriculture and forestry, using government subsidies that encourage sustainable forest use, reducing poverty, and slowing population growth.

Tropical Forests

Cover 6% of earth’s land area

Habitat for 50% of terrestrial plants and animals

Vulnerable to extinction – specialized niches

Rapid loss of 50,000–170,000 km2 per year

Burning of a Tropical Forest

Fig. 8-14, p. 160

Destruction of Tropical Forests

Fig. 8-15, p. 161

Causes of Tropical Forest Deforestation and Degradation

Population growth and poverty

Government subsidies

International lending agencies encourage development

Effects of Tropical Deforestation

Fragmentation of remaining patches

Remaining forests get drier and may burn• Degrades biodiversity

• CO2 to the atmosphere

• Accelerates climate change

How to Protect Tropical Forests

Teach settlers to practice small-scale sustainable agriculture

Harvest renewable resources from the forests

Debt-for-nature swaps

Conservation concessions

Gentler logging methods

Solutions: Sustaining Tropical Forests

Fig. 8-16, p. 162

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

Backyard small tree nursery

Organized poor women

Women paid for each surviving seedling planted• Breaks cycle of poverty

• Reduces environmental degradation

• People walk less distance to get fuelwood

Sparked projects in +30 African countries

8-4 How Should We Manage and Sustain Grasslands?

Concept 8-4 We can sustain the productivity of rangeland by controlling the number and distribution of livestock and by restoring degraded rangeland.

Grasslands

Provide important ecological services

Second most used and altered ecosystem by humans

42% grazed by cattle, sheep, and goats – rangeland and pasture

Overgrazing

Manage Rangelands Sustainably

Practice rotational grazing

Fence out riparian zone areas

Suppress invader plants

Replant barren soil with seeds

Employ controlled burns to control exotic vegetation

San Pedro River Rangelands

Fig. 8-17, p. 164

8-5 How Should We Manage and Sustain Parks and Nature Reserves?

Concept 8-5 Sustaining biodiversity will require protecting much more of the earth’s remaining undisturbed land area, starting with the most endangered biodiversity hot spots.

National Parks

>1,100 national parks in 120 countries

Only 1% of parks in developing countries are protected

Local people invade parks to survive

Problems Protecting National Parks

Illegal logging

Illegal mining

Wildlife poaching

Most parks too small to protect large animals

Invasion of nonnative species

Stresses on U.S. National Parks

Biggest problem popularity

Damage from nonnative species

Threatened islands of biodiversity

Natural Capital Degradation: Off-road Vehicles

Fig. 8-18, p. 165

Nature Reserves Occupy a Fraction of Earth

12% of earth’s land protected

Only 5% fully protected – 95% reserved for human use

Need for conservation• Minimum 20% of land in biodiversity reserves

• Protection for all biomes

Solutions for Protection

Requires action – bottom-up political pressure

Nature Conservancy – world’s largest private system of reserves

Buffer zones around protected areas

Locals to manage reserves and buffer zones

Solutions: National Parks

Fig. 8-19, p. 166

Case Study: Costa Rica

Superpower of biodiversity

Conserved 25% of its land, 8 megareserves

Government eliminated deforestation subsidies

Paid landowners to maintain and restore tree coverage

Goal to make sustainable forestry profitable

Model Biosphere Reserve

Fig. 8-20, p. 167

Fig. 8-20, p. 167

Biosphere Reserve

Buffer zone 2

Humansettlements

Researchstation

Visitoreducationcenter

Core area

Buffer zone 1

Costa Rica’s Megareserve Network

Fig. 8-21, p. 167

Protecting Wilderness Protects Biodiversity

Wilderness

Minimum size >4,000 km2

Preserves natural capital

Centers for evolution

Case Study: Controversy over Wilderness Protection in the U.S.

1964 Wilderness Act

Roadless Rule protects 400,000 sq. miles

Pressure from oil, gas, mining, and logging

Protecting Global Biodiversity Hotspots

17 megadiversity countries in tropics and subtropics

Two-thirds of biodiversity

Developing countries economically poor and biodiversity rich

Protect biodiversity hotspots

34 Global Hotspots

Fig. 8-22, p. 169

Biodiversity Hotspots in the U.S.

Fig. 8-23, p. 169

8-6 What Is the Importance of Restoration Ecology?

Concept 8-6 Sustaining biodiversity will require a global effort to rehabilitate and restore damaged ecosystems.

Ecological Restoration

Ecological Restoration

Restoration

Rehabilitation

Replacement

Creating artificial ecosystems

Science-based Principles for Restoration

Identify cause of degradation

Stop abuse by reducing factors

Reintroduce species if necessary

Protect area from further degradation

Case Study: Ecological Restoration of Tropical Dry Forest in Costa Rica

One of world’s largest ecological restoration projects

Restore a degraded tropical dry forest and reconnect it to adjacent forests

Involve 40,000 people in the surrounding area – biocultural restoration

Ecotourism

Will Restoration Encourage Further Degradation

Some worry environmental restoration suggests any harm can be undone

Scientists disagree• Restoration badly needed

• Altered restored site better than no restoration

What Can You Do?

Fig. 8-24, p. 171

8-7 How Can We Help Sustain Aquatic Biodiversity?

Concept 8-7 We can sustain aquatic biodiversity by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing overfishing.

Three Patterns of Aquatic Biodiversity

Greatest biodiversity in coral reefs, estuaries, and deep-ocean floor

Higher near the coast than in open sea

Higher in the bottom region of ocean than in surface layer

Human Impacts on Aquatic Ecosystems

Destroyed or degraded by human activities

Ocean floor degradation 150 times larger than area clear-cut annually

75% of most valuable fish species overfished

Likely extinction• 34% marine fish species

• 71% freshwater species

Effects of Bottom Trawling

Fig. 8-25, p. 172

Why Is Protection of Marine Biodiversity So Difficult?

Human aquatic ecological footprint expanding

Not visible to most people

Viewed as an inexhaustible resource

Most ocean areas outside jurisdiction of a country

Solutions for Marine Ecosystems

Protect endangered and threatened species

Establish protected marine sanctuaries

Marine reserves – work well and quickly

Integrated coastal management

Protect existing coastal wetlands

Solutions: Managing Fisheries

Fig. 8-26, p. 173

8-8 What Should Be Our Priorities for Protecting Biodiversity?

Concept 8-8 Sustaining the world’s biodiversity requires mapping terrestrial and aquatic biodiversity, protecting terrestrial and aquatic hotspots and old-growth forests, initiating ecological restoration projects worldwide, and making conservation profitable.

Priorities for Protecting Biodiversity

Map terrestrial and aquatic biodiversity

Immediately preserve biodiversity hotspots

Keep old-growth forests intact

Protect and restore lakes and rivers

Initiate ecological restoration

Make conservation profitable

Animation: Ocean Provinces

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Animation: Humans Affect Biodiversity

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Animation: Habitat Loss and Fragmentation

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Animation: Area and Distance Effects

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Animation: Succession

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Animation: Hubbard Brook Experiment

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Animation: Effects of Air Pollution in Forests

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Animation: Effects of Deforestation

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Animation: Biodiversity Hot Spots

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Animation: Resources Depletion and Degradation

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Animation: Species Diversity By Latitude

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Video: Easter Island

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Video: New Species Found

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Video: Bachelor Pad at the Zoo

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Video: Desertification in China

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Video: U.S. Forests

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Video: Marine Sanctuary

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Video: Sea Turtle Release

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