Chapter 10

1. Chapter 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach

2. Chapter Overview Questions • How have human activities affected the earth’s biodiversity? • Why should we care about Biodiversity? • What’s the natural capital involved with Forests? • What are the characteristics of the different ages of forests? • What are the different tree harvesting methods and which more sustainable?

3. 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

4. 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

5. 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 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

6. Why Should We Care About Biodiversity? • Biodiversity has two types of value: • Intrinsic – We care because these components exist, regardless of use. • Instrumental – We care because of the usefulness to us in the form of economic and ecological services. Figure 10-3

7. Why should we care about biodiversity? • Biodiversity also helps maintain the structure and function of the ecosystem. • Yellowstone Gray Wolf • Instrumental Value take two forms: • Use Value: benefits us in the form of economic goods and services, ecological services, recreation, scientific information, and preservation. • Nonuse Value: Similar to intrinsic value but can takes into consideration Aesthetics.

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. 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 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. • Largest Forests are in Canada and Russia • 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 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 migratory species such as birds and butterflies • Regional climate change from extensive clearing • Release of CO2 into atmosphere • Acceleration of flooding Fig. 10-7, p. 196

15. 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

16. (a) Selective cutting Fig. 10-9a, p. 198

17. (b) Clear-cutting Fig. 10-9b, p. 198

18. (c) Strip cutting Uncut Cut 1 year ago Dirt road Cut 3–10 years ago Uncut Stream Fig. 10-9c, p. 198

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

20. Trade-Offs Clear-Cutting Forests Advantages Disadvantages 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 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 Fig. 10-11, p. 198

21. 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

22. 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

23. STOP HERE

24. Questions for Today • What are the basic parts of fire? • What are the different types of forest fires? • Who is Smokey? • Are all Forest Fires bad? • What is the Healthy Forest Restoration Act?

25. 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.

26. 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

27. Fire Traingle • Science Behind Fire • There are three parts to make fire. • Fuel • Heat • Oxygen • Usually Forest Wildfires have an overabundance of fuel which leads to uncontrolled burns.

28. Three Types of Fires • Surface Fires: • Usually burn undergrowth and leaf litter on the forest floor. • Kills seedling and small trees but not mature, old growth trees. • Benefits: • Burn away flammable ground material • Release valuable nutrients • Release seeds • Open up habitats for new species of fauna

29. Types of Fires • Crown Fires: • Extremely Hot • May start from the ground, but eventually burn the whole tree • Usually occur from forest that have not had any surface fires for decades. • Ground Fires • Surface fires that go underground • Burns decayed leaves and peat • Can burn and smolder for days before being noticed.

30. Solutions: Controversy Over Fire Management • Back in World War II, the US Government Introduced Smokey Bear to the population to increase awareness of Forest Fires. • Smokey Bear’s Tagline: • “Only YOU can prevent Forest Fires” • It helped convince that all Forest Fires are bad and should be extinguished. • Led 40% of forest being threatened by wildfires. • Why?

31. Solutions: Controversy Over Fire Management • Preventing all forest fires leads to an accumulation of leaf litter or highly flammable logging debris called slash. • Ecologist have proposed several strategies for reducing fire-related harm: • Prescribed fires • Setting small, contained surface fires in high risk forest areas. • Biological Prevention • Using grazing animals to eat away at the underbrush.

32. 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.

33. STOP

34. Questions for Today • How should National Forests be used? • How do we degrade Tropical Rainforests? • How do we manage and sustain Grassland areas? • What are ways the government have protected Terrestrial Ecosystems? • What can you do to maintain and sustain Terrestrial Ecosystems?

35. 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

36. Trade-Offs Logging in U.S. National Forests Advantages Disadvantages 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 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 Fig. 10-14, p. 202

37. 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

38. 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.

39. 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

40. 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

41. 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

42. Solutions Sustaining Tropical Forests Prevention Restoration Protect most diverse and endangered areas Educate settlers about sustainable agriculture and forestry Phase out subsidies that encourage unsustainable forest use Add subsidies that encourage sustainable forest use Protect forests with debt-for-nature swaps and conservation easements Certify sustainably grown timber Reduce illegal cutting Reduce poverty Slow population growth Reforestation Rehabilitation of degraded areas Concentrate farming and ranching on already-cleared areas Fig. 10-20, p. 207

43. 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.

44. 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

45. 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

46. 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.

47. 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

48. 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

49. 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.

50. 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