1. Sustaining Terrestrial Biodiversity: The Ecosystem Approach
Chapter
Sustaining Terrestrial Biodiversity: The Ecosystem Approach

2. 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?

3. 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?

4. Core Case Study: Reintroducing Wolves to Yellowstone
Endangered Species
two million wolves were destroyed.
Keystone Species
Keeps prey away from open areas near stream banks.
Vegetation reestablishes.
Species diversity expands.
Figure 10-1

5. 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

6. Agriculture, industry, economic production and consumption, recreation
Human Population
Size and resource use
Human Activities
Agriculture, industry, economic
production and consumption, recreation
Direct Effects
Degradation and destruction
of natural ecosystems
Changes in number and
distribution of species
Figure 10.2
Natural capital degradation: major connections between human activities and the earth’s biodiversity.
Alteration of natural chemical
cycles and energy flows
Pollution of air, water,
and soil
Indirect Effects
Climate
change
Loss of
Biodiversity
Fig. 10-2, p. 192

7. 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

8. 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

9. Support energy flow and chemical cycling
Natural Capital
Forests
Ecological
Services
Economic
Services
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
Fuelwood
Lumber
Pulp to make paper
Mining
Livestock grazing
Recreation
Jobs
Figure 10.4
Natural capital: major ecological and economic services provided by forests. QUESTION: Which two ecological services and which two economic services do you think are the most important?
Fig. 10-4, p. 193

10. 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

11. 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

12. Weak trees removed Clear cut Seedlings planted 25 15 10 30
Years of growth 5
Figure 10.6
Natural capital degradation: Short (25- to 30-year) rotation cycle of cutting and regrowth of a monoculture tree plantation in modern industrial forestry. In tropical countries, where trees can grow more rapidly year-round, the rotation cycle can be 6–10 years. Old-growth or secondary forests are clear-cut to provide land for growing most tree plantations.
Fig. 10-6, p. 195

13. 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

14. 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
Figure 10.7
Natural capital degradation: harmful environmental effects of deforestation that can reduce biodiversity and the ecological services provided by forests (Figure 10-4, left). QUESTION: What are the two direct and two indirect effects of your lifestyle on deforestation?
Fig. 10-7, p. 196

15. 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.

16. Harvesting Trees
Building roads into previously inaccessible forests paves the way for fragmentation, destruction, and degradation.
Figure 10-8

17. Cleared plots for grazing Highway Highway
Cleared plots for agriculture
Old growth
Figure 10.8
Natural capital degradation: Building roads into previously inaccessible forests paves the way to fragmentation, destruction, and degradation.
Fig. 10-8, p. 197

18. 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

19. (a) Selective cutting Fig. 10-9a, p. 198 Figure 10.9
Major tree harvesting methods.
Fig. 10-9a, p. 198

20. (b) Clear-cutting Fig. 10-9b, p. 198 Figure 10.9
Major tree harvesting methods.
Fig. 10-9b, p. 198

21. (c) Strip cutting Uncut Cut 1 year ago Dirt road Cut 3–10 years ago
Figure 10.9
Major tree harvesting methods.
Stream
Fig. 10-9c, p. 198

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

23. Clear-Cutting Forests
Trade-Offs
Clear-Cutting Forests
Advantages
Disadvantages
Higher timber yields
Maximum profits in shortest time
Can reforest with fast-growing trees
Short time to establish new stand of trees
Needs less skill and planning
Good for tree species needing full or moderate sunlight
Reduces biodiversity
Disrupts ecosystem processes
Destroys and fragments wildlife habitats
Leaves large openings
Increases water pollution, flooding, and erosion on steep slopes
Eliminates most recreational value
Figure 10.11
Trade-offs: advantages and disadvantages of clear-cutting forests. QUESTION: Which single advantage and which single disadvantage do you think are the most important?
Fig , p. 198

24. 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

25. • Identify and protect forest areas high in biodiversity
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
Figure 10.12
Solutions: ways to manage forests more sustainably. QUESTION: Which three of these solutions do you think are the most important?
Fig , p. 199

26. 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.

27. 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

28. 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.

29. 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 fire-prone trees and underbrush.
Some forest scientists believe this could increase severe fires by removing fire resistant trees and leaving highly flammable slash.

30. 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

31. Logging in U.S. National Forests
Trade-Offs
Logging in U.S. National Forests
Advantages
Disadvantages
Helps meet country’s timber needs
Cut areas grow back
Keeps lumber and paper prices down
Provides jobs in nearby communities
Promotes economic growth in nearby communities
Provides only 4% of timber needs
Ample private forest land to meet timber needs
Has little effect on timber and paper prices
Damages nearby rivers and fisheries
Recreation in national forests provides more local jobs and income for local communities than logging
Decreases recreational opportunities
Figure 10.14
Trade-offs: advantages and disadvantages of allowing logging in U.S. national forests. QUESTION: Which two advantages and which two disadvantages do you think are the most important?
Fig , p. 202

32. 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

33. 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 old-growth 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.