ENVIRONMENTAL SCIENCE 13e CHAPTER 9: Sustaining Biodiversity: The Ecosystem Approach.

ENVIRONMENTAL SCIENCE 13e

CHAPTER 9:Sustaining Biodiversity: The Ecosystem Approach

Wangari Maathai and the Green Belt Movement

• Began in Kenya in 1977• Organizes poor women in rural Kenya• 50,000 members protect forests• Planted 20 million trees

– Fruits– Building materials– Firewood

• Similar programs in 30 African countries• 2004: Nobel Peace Prize

9-1 What Are Major Threats to Forest Ecosystems?

• Concept 9-1 Ecologically valuable forest ecosystems are being cut and burned at unsustainable rates in many parts of the world.

Types of Forests

• Forests cover 30% of earth’s land surface

• Old-growth forests

• Second-growth forests

• Tree plantation

Fig. 9-2, p. 180

Fig. 9-3, p. 180

Years of growth

Weak treesremoved

Seedlingsplanted

Clear cut

30 yrs

25 yrs

5 yrs 10 yrs

15 yrs

Fig. 9-3, p. 180

Fig. 9-3, p. 180

Fig. 9-4, p. 181

Fig. 9-4, p. 181

Natural Capital

Fuelwood

Lumber

Pulp to makepaper

Mining

Livestockgrazing

Recreation

Jobs

Support energy flow and chemical cycling

Reduce soil erosion

Absorb and release water

Purify water and air

Influence local and regional climate

Store atmospheric carbon

Provide numerous wildlife habitats

EcologicalServices

EconomicServices

Forests

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

• Ecological services can be a sustainable source of ecological income

Fig. 9-A, p. 181

Harvest Methods

• Step one: build roads– Erosion– Invasive species– Open up for human invasion

• Step two: logging operations– Selective cutting– Clear cutting– Strip cutting

Fig. 9-5, p. 182

Cleared plotsfor agriculture

New highway

Old growth

HighwayCleared plotsfor grazing

Fig. 9-5, p. 182

New highway

Old growth

Cleared plotsfor agriculture

HighwayCleared plotsfor grazing

Stepped Art

Fig. 9-5, p. 182

Fig. 9-6, p. 182

Clearstream

(a) Selective cutting

Fig. 9-6, p. 182

Fig. 9-6, p. 182

Muddystream

(b) Clear-cutting

Fig. 9-6, p. 182

Fig. 9-6, p. 182

Cut 1year ago

(c) Strip cuttingUncut

Clearstream

Uncut

Cut 3–10years ago

Dirt road

Fig. 9-6, p. 182

Stepped Art

(b) Clear-cutting

Muddy stream

UncutCut 1 year ago

Dirt road

Cut 3–10 years ago

Uncut

Clear stream

(a) Selective cutting

(c) Strip cutting

Clear stream

Fig. 9-6, p. 182

Fig. 9-7, p. 182

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

Fig. 9-8, p. 183

Loss of Original Forests

• Deforestation

• 46% in 8,000 years, most since 1950

• Most in tropical areas, developing countries

• Estimated loss of 40% intact forests within next 20 years

Fig. 9-9, p. 184

Fig. 9-10, p. 184

Good News on Forests

• 2000–2007 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

• Some forests transformed into tree plantations

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

• Some second-growth forests

Causes of Tropical Forest Deforestation and Degradation

• Population growth and poverty

• Economic reasons– Logging

– Ranching

– Farming

• Government subsidies

• Fires raise temperatures and reduce rainfall

Fig. 9-11, p. 186

Fig. 9-11, p. 186

Natural Capital Degradation

• Not valuing ecological services

• Crop and timber exports

• Government policies

• Poverty

• Population growth

• Roads

• Fires

• Settler farming

• Cash crops

• Cattle ranching

• Logging

• Tree plantations

Basic Causes Secondary Causes

Settler farming

Cattle ranching

Tree plantations

Cash crops

Logging

RoadsFires

Major Causes of the Destruction and Degradation of Tropical Forests

Fig. 9-12, p. 187

9-2 How Should We Manage and Sustain Forests?

• 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.

Fig. 9-13, p. 188

Management of Forest Fires (1)

• Fire suppression in all types of forests

• Increased amounts of underbrush

• Increased probability of crown fires

Management of Forest Fires (2)

• Prescribed fires

• Allow some fires to burn

• Thin vegetation from forests

• Thin around vulnerable homes

• Decrease flammability of homes

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

Trees and Paper

• Many trees are cut for paper production

• Alternatives– Pulp from rice straw and agricultural

residues (China)

– Kenaf (U.S.)

– Hemp

Fig. 9-14, p. 189

Ways to Reduce Tropical Deforestation

• Debt-for-nature swaps

• Conservation concessions

• Gentler logging methods

• Encourage use of wood substitutes

Fig. 9-15, p. 190

Fig. 9-15, p. 190

Sustaining Tropical Forests

Protect the most diverse andendangered areas

Educate settlers aboutsustainable agriculture andforestry

Subsidize only sustainableforest use

Protect forests withdebt-for-nature swaps andconservation concessions

Certify sustainably growntimber

Reduce poverty

Slow population growth

Encourage regrowththrough secondarysuccession

Rehabilitate degradedareas

Concentrate farmingand ranching inalready-cleared areas

Prevention

Solutions

Restoration

9-3 How Should We Manage and Sustain Grasslands?

• Concept 9-3 We can sustain the productivity of rangeland by controlling the number and distribution of grazing livestock and by restoring degraded grasslands.

Grasslands

• Provide important ecological services

• Second most used and altered ecosystem by humans

• 42% grazed by cattle, sheep, and goats – rangeland (open) and pasture (fenced)

• Overgrazing

Fig. 9-16, p. 191

Manage Rangelands Sustainably

• Practice rotational grazing

• Fence out riparian zone areas

• Suppress invader plants– Herbicides

– Mechanical removal

– Controlled burning

– Short-term trampling

Fig. 9-17, p. 191

9-4 How Should We Manage and Sustain Parks and Nature Reserves?

• 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

• >1,100 national parks in 120 countries• Only 1% of parks in developing

countries are protected– Local people invade parks to survive– Logging– Mining– Poaching

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

• 58 major national parks

• Biggest problem is popularity

• Damage from nonnative species

• Threatened islands of biodiversity

• Need $6 billion for overdue repairs

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

• “Ecological insurance policy”

• Buffer zones around protected areas

• Locals to manage reserves and buffer zones

• United Nations: 531 biosphere reserves in 105 countries

Science Focus: Reintroducing the Gray Wolf to Yellowstone National Park

• Reduced to a few hundred in lower 48 by 1973

• Keystone species

• Restoration proposal angered ranchers, hunters, loggers

• 1995 - reintroduced in Yellowstone, 124 by 2008

• Positive ripple effect after reintroduction

Fig. 9-B, p. 193

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• Boosts ecotourism

Fig. 9-18, p. 194

Fig. 9-18, p. 194

Caribbean SeaNicaragua

Panama

CostaRica

Buffer zone

National parkland

Pacific Ocean

Protecting Wilderness Protects Biodiversity

• Wilderness

• Preserves biodiversity

• Centers for evolution

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

• 1964 Wilderness Act

• Ten-fold increase from 1970 to 2008

• 4.6% of U.S. land protected, 75% of that in Alaska

9-5 How Can We Help to Sustain Terrestrial Biodiversity? • Concept 9-5 We can help to sustain

terrestrial biodiversity by identifying and protecting severely threatened areas (biodiversity hotspots), rehabilitating damaged ecosystems (using restoration ecology), and sharing with other species much of the land we dominate (using reconciliation ecology).

Three Principles to Protect Ecosystems

1. Map and inventory the world’s terrestrial and aquatic ecosystems

2. Locate and protect the most endangered ecosystems, with a focus on biodiversity

3. Seek to restore as many degraded ecosystems as possible

Protecting Global Biodiversity Hotspots

• 17 megadiversity countries, mostly in tropics and subtropics– Two-thirds of biodiversity

• Developing countries economically poor and biodiversity rich

• Protect biodiversity hotspots

Fig. 9-19, p. 196

Supplement 4, Fig. 2, p. S16

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

Restoration Ecology

• Creating new habitats to conserve species diversity in areas where people live, work, play

• People learn to protect local species and ecosystems

• Sustainable ecotourism

• Golden Gate Park in San Francisco

Fig. 9-20, p. 198

9-6 How Can We Help to Sustain Aquatic Biodiversity?

• Concept 9-6 We can help to sustain aquatic biodiversity by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing overfishing.

Impacts on Aquatic Ecosystems (1)

• Destroyed or degraded by human activities

• Coastal habitats disappearing 2-10 times faster than tropical forest

• Rising sea levels will destroy coral reefs and some low islands

• Ocean floor degradation 150 times larger

than area clear-cut annually

Impacts on Aquatic Ecosystems (2)

• Freshwater habitat disruption– Dams

– Water withdrawals from rivers

• Likely extinction– 34% marine fish species

– 71% freshwater species

– Greater than any other group of species

Fig. 9-21, p. 199

Overfishing

• Fishery

• Fishprint

• 157% overfishing

• 90% of large open-ocean fishes have disappeared since 1950

Fig. 9-22, p. 200

Case Study: Industrial Fish Harvesting Methods

• Trawler fishing

• Purse-seine fishing

• Longlining

• Drift-net fishing

Fig. 9-23, p. 201

Fig. 9-23, p. 201

Float

Trawlerfishing

Drift-net fishing

Purse-seine fishingSonar

Long line fishing

lines withhooks

Fish farmingin cage Spotter airplane

Deep seaaquaculture cage Fish caught

by gills

Buoy

Fish farming in cage Spotter airplane

Trawler fishing

Sonar Purse-seine fishing

Long line fishing

lines with hooks

Deep sea aquaculture cage

Drift-net fishing

Float Buoy

Fish caught by gills Stepped Art

Fig. 9-23, p. 201

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

Fig. 9-24, p. 202

Fig. 9-24, p. 202

Managing FisheriesFishery Regulations

Set catch limits well below themaximum sustainable yield

Improve monitoring andenforcement of regulations

Economic Approaches

Sharply reduce or eliminatefishing subsidies

Charge fees for harvesting fishand shellfish from publiclyowned offshore waters

Certify sustainable fisheries

Protect Areas

Establish no-fishing areas

Establish more marineprotected areas

Rely more on integratedcoastal management

Consumer Information

Label sustainably harvested fish

Publicize overfished andthreatened species

Bycatch

Dump ballast water far atsea and replace withdeep-sea water

Filter organisms from shipballast water

Kill organisms in ship ballast water

Nonnative Invasions

Depend more onherbivorous fish species

Control pollution morestrictly

Restrict coastal locations for fish farms

Aquaculture

Ban throwing edible andmarketable fish back intothe sea

Use net escape devices forseabirds and sea turtles

Use wide-meshed nets toallow escape of smaller fish

Solutions

Three Big Ideas from This Chapter - #1

The economic values of the important ecological services provided by the world’s ecosystems need to be included in the prices of goods and services.


We can sustain terrestrial biodiversity by protecting severely threatened areas, restoring damaged ecosystems, and sharing with other species much of the land we dominate.


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

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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ENVIRONMENTAL SCIENCE 13e CHAPTER 9: Sustaining Biodiversity: The Ecosystem Approach.

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Transcript of ENVIRONMENTAL SCIENCE 13e CHAPTER 9: Sustaining Biodiversity: The Ecosystem Approach.