Chapter 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach

1. Chapter 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach

2. Individuals Matter: Wangari Maathari and Kenya’s Green Belt Movement • Green Belt Movement: 1977 • Self-help group of women in Kenya • Success of tree planting • 50,000 members planted 40 million trees • Women are paid for each tree that survives • Slows soil erosion • Shade and beauty • Combats global warming • Nobel Peace Prize: 2004

3. Wangari Maathari Fig. 10-1, p. 217

4. 10-1 What Are the Major Threats to Forest Ecosystems? • Concept 10-1A Forest ecosystems provide ecological services far greater in value than the value of raw materials obtained from forests. • Concept 10-1B Unsustainable cutting and burning of forests, along with diseases and insects, all made worse by projected climate change, are the chief threats to forest ecosystems.

5. Forests Vary in Their Make-Up, Age, and Origins • Old-growth or primary forest (36%) • Uncut, or not disturbed for several hundred years • Reservoirs of biodiversity • Second-growth forest (60%) • Secondary ecological succession • Tree plantation, (tree farm, commercial forest) (4%) • May supply most industrial wood in the future

6. Natural Capital: An Old-Growth Forest Fig. 10-2, p. 219

7. Rotation Cycle of Cutting and Regrowth of a Monoculture Tree Plantation Fig. 10-3, p. 219

8. Weak trees removed 25 yrs Clear cut 30 yrs 15 yrs Years of growth Seedlings planted 5 yrs 10 yrs Fig. 10-3a, p. 219

9. Forests Provide Important Economic and Ecological Services (1) • 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 • Habitats

10. Forests Provide Important Economic and Ecological Services (2) • Wood for fuel • Lumber • Pulp to make paper • Mining • Livestock grazing • Recreation • Employment

11. Natural Capital: Major Ecological and Economic Services Provided by Forests Fig. 10-4, p. 220

12. Natural Capital Forests Ecological Services Economic Services Support energy flow and chemical cycling Fuelwood Lumber Reduce soil erosion Absorb and release water Pulp to make paper Purify water and air Mining Influence local and regional climate Livestock grazing Store atmospheric carbon Recreation Provide numerous wildlife habitats Jobs Fig. 10-4, p. 220

13. Science Focus: Putting a Price Tag on Nature’s Ecological Services • Forests valued for ecological services • Nutrient cycling • Climate regulation • Erosion control • Waste treatment • Recreation • Raw materials • $4.7 trillion per year

14. Estimated Annual Global Economic Values of Ecological Services Provided by Forests Fig. 10-A, p. 221

15. 400 350 300 250 200 Worth (billions of dollars) 150 100 50 0 Recreation Raw materials Nutrient cycling Climate regulation Waste treatment Erosioncontrol Ecological service Fig. 10-A, p. 221

16. Unsustainable Logging is a Major Threat to Forest Ecosystems (1) • Increased erosion • Sediment runoff into waterways • Habitat fragmentation • Loss of biodiversity

17. Unsustainable Logging is a Major Threat to Forest Ecosystems (2) • Invasion by • Nonnative pests • Disease • Wildlife species • Major tree harvesting methods: • Selective cutting • Clear-cutting • Strip cutting

18. Natural Capital Degradation: Building Roads into Previously Inaccessible Forests Fig. 10-5, p. 221

19. New highway Old growth Fig. 10-5a, p. 221

20. Highway Cleared plots for grazing Cleared plots for agriculture Fig. 10-5b, p. 221

21. Cleared plots for grazing New highway Highway Cleared plots for agriculture Old growth Stepped Art Fig. 10-5, p. 221

22. Major Tree Harvesting Methods Fig. 10-6, p. 222

23. (a) Selective cutting Clear stream Fig. 10-6a, p. 222

24. (b) Clear-cutting Muddy stream Fig. 10-6b, p. 222

25. (c) Strip cutting Cut 1 year ago Uncut Dirt road Cut 3–10 years ago Uncut Clear stream Fig. 10-6c, p. 222

26. (a) Selective cutting (b) Clear-cutting Clear stream Muddy stream Uncut (c) Strip cutting Cut 1 year ago Dirt road Cut 3–10 years ago Uncut Clear stream Stepped Art Fig. 10-6, p. 222

27. Clear-Cut Logging in Washington State Fig. 10-7, p. 222

28. Trade-offs: Advantages and Disadvantages of Clear-Cutting Forests Fig. 10-8, p. 223

29. Trade-Offs Clear-Cutting Forests Advantages Disadvantages Higher timber yields Reduces biodiversity Destroys and fragments wildlife habitats Maximum profits in shortest time Can reforest with fast-growing trees Increases water pollution, flooding, and erosion on steep slopes Good for tree species needing full or moderate sunlight Eliminates most recreational value Fig. 10-8, p. 223

30. Fire, Insects, and Climate Change Can Threaten Forest Ecosystems (1) • Surface fires • Usually burn leaf litter and undergrowth • May provide food in the form of vegetation that sprouts after fire • Crown fires • Extremely hot: burns whole trees • Kill wildlife • Increase soil erosion

31. Fire, Insects, and Climate Change Can Threaten Forest Ecosystems (2) • Introduction of foreign diseases and insects • Accidental • Deliberate • Global warming • Rising temperatures • Trees more susceptible to diseases and pests • Drier forests: more fires • More greenhouse gases

32. Surface and Crown Fires Fig. 10-9, p. 223

33. Nonnative Insect Species and Disease Organisms in U.S. Forests Figure 10, Supplement 8

34. We Have Cut Down Almost Half of the World’s Forests • Deforestation • Tropical forests • Especially in Latin America, Indonesia, and Africa • Boreal forests • Especially in Alaska, Canada, Scandinavia, and Russia • Encouraging news • Net total forest cover has stayed the same or increased in U.S. and a few other countries between 2000 and 2007

35. Natural Capital Degradation: Harmful Environmental Effects of Deforestation Fig. 10-12, p. 226

36. Case Study: Many Cleared Forests in the United States Have Grown Back • Forests of the eastern United States decimated between 1620 and 1920 • Grown back naturally through secondary ecological succession in the eastern states • Biologically simplified tree plantations reduce biodiversity and deplete nutrients from soil

37. Tropical Forests are Disappearing Rapidly • Majority of loss since 1950 • Africa, Southeast Asia, South America • 98% will be gone by 2022 • Role of deforestation in species’ extinction • Secondary forest can grow back in 15-20 years

38. Natural Capital Degradation: Extreme Tropical Deforestation in Thailand Fig. 10-11, p. 226

39. Species Diversity in Tropical Forests Fig. 10-13, p. 227

40. Causes of Tropical Deforestation Are Varied and Complex • Population growth • Poverty of subsistence farmers • Ranching • Lumber • Plantation farms: palm oil • Begins with building of roads • Many forests burned • Can tilt tropical forest to tropical savanna

41. Major Causes of the Destruction and Degradation of Tropical Forests Fig. 10-14, p. 228

42. Natural Capital Degradation Major Causes of the Destruction and Degradation of Tropical Forests Underlying Causes Direct Causes • Not valuing ecological services • Roads • Cattle ranching • Crop and timber exports • Fires • Logging • Government policies • Settler farming • Tree plantations • Poverty • Cash crops • Population growth Tree plantations Cattle ranching Logging Cash crops Settler farming Fires Roads Fig. 10-14, p. 228

43. NATURAL CAPITAL DEGRADATION Major Causes of the Destruction and Degradation of Tropical Forests • Not valuing ecological services Basic Causes Secondary Causes • Government policies • Roads • Cattle ranching • Fires • Logging • Crop and timber exports • Poverty • Settler farming • Tree plantations • Population growth • Cash crops Cattle ranching Tree plantations Logging Cash crops Settler farming Fires Roads Stepped Art Fig. 10-14, p. 228

44. Natural Capital Degradation: Large Areas of Brazil’s Amazon Basin Are Burned Fig. 10-15, p. 228

45. 10-2 How Should We Manage and Sustain Forests? • Concept 10-2 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.

46. Solution: Sustainable Forestry Fig. 10-16, p. 230

47. Science Focus: Certifying Sustainably Grown Timber • Collins Pine • Owns and manages protective timberland • Forest Stewardship Council • Nonprofit • Developed list of environmentally sound practices • Certifies timber and products • 2009: 5% of world’s forest have certified to FSC standards • Also certifies manufacturers of wood products

48. We Can Improve the Management of Forest Fires • The Smokey Bear educational campaign • Prescribed fires • Allow fires on public lands to burn • Protect structures in fire-prone areas • Thin forests in fire-prone areas

49. We Can Reduce the Demand for Harvested Trees • Improve the efficiency of wood use • 60% of U.S. wood use is wasted • Make tree-free paper • Kenaf • Hemp

50. Solutions: Fast-Growing Plant: Kenaf Fig. 10-17, p. 231