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Chapter 10

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Chapter 10

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  1. Chapter 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach

  2. Core Case Study: Reintroducing Wolves to Yellowstone • Keystone Species • Keeps prey away from open areas near stream banks (riparian zones) • Vegetation reestablishes. • Species diversity expands. Figure 10-1

  3. Core Case Study: Reintroducing Wolves to Yellowstone • Endangered Species • 1850-1900 two million wolves were destroyed. • Prey populations soared • Willow and Aspen stands decimated leading to erosion • Re-introduced in the early 1990’s • Stability and biodiversity re-establised Figure 10-1

  4. Video: Wolf Pack

  5. HUMAN IMPACTS ON TERRESTRIAL BIODIVERSITY • Gray wolves are just one of many species humans have impacted • We have depleted and degraded some of the earth’s biodiversity and these threats are expected to increase. Figure 10-2

  6. HUMAN IMPACTS ON TERRESTRIAL BIODIVERSITY • Gray wolves are just one of many species humans have impacted • We have depleted and degraded some of the earth’s biodiversity and these threats are expected to increase.

  7. HUMAN IMPACTS ON TERRESTRIAL BIODIVERSITY • 83% of global land impacted by human activities. • Filling wetlands • Deforestation for crops and urban areas

  8. Why Should We Care About Biodiversity? • INSTRUMENTAL (Use) Value: • Usefulness in terms of economic and ecological services. • Food, jobs, recreation, tourism, medicine, water quality, etc Figure 10-3

  9. Why Should We Care About Biodiversity? • INTRINSIC (Nonuse) Value: • Ethical • Based on existence, aesthetics, bequest for future generations. Figure 10-3

  10. 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

  11. 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

  12. Types of Forests • Second-growth forest: a stand of trees resulting from natural secondary succession. • Tree plantation (tree farm): planted stands of a particular tree species (monoculture), clear-cut, replanted. Figure 10-6

  13. Global Outlook: Extent of Deforestation • Human activities have reduced the earth’s forest cover by as much as half. • Short-term economic benefit for the few • Long-term degradation for the many • Losses are concentrated in developing countries. Figure 10-7

  14. Global Outlook: Extent of Deforestation • Primary Causes of tropical deforestation • Population growth & poverty • Subsidies • Poor are given title to cleared land • International lending agencies encourage development Figure 10-7

  15. Animation: Hubbard Brook Experiment Animations/hubbard_brook.html

  16. 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. • Can change regional climate & forests will NOT regenerate • Emits CO2 – takes ~200yrs to re-accumulate in a 2nd growth forest

  17. Case Study: Deforestation and the Fuelwood Crisis

  18. Case Study: Deforestation and the Fuelwood Crisis • Reducing the crisis: • Community forests work best when owned and managed by locals • Can be used as protein-source (nuts) • Provide for better efficiency stoves or solar ovens • Also reduces health issues and death related to air quality • Government re-forestation programs based on villages cooperatives

  19. Harvesting Trees • FIRST STEP: Logging roads • fragmentation, erosion, sedimentation and loss of biodiversity. • Opens invasion by nonnatives, pests, off-road vehicles, farmers, miners, hunters, ranchers, etc • Automatically disqualify land for wilderness protection Figure 10-8

  20. 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

  21. (a) Selective cutting • Uneven aged forests • Intermediate-aged or mature trees cut singly or in small groups • Reduces crowding, diseases, encourages growth & maintains diversity & multiple use • CREAMING – all largest trees removed • Degrades environment Fig. 10-9a, p. 198

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

  23. (b) Clear cutting Effects of clear-cutting in the state of Washington, U.S. Figures 10-10 and 10-11

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

  25. Other Methods • Shelterwood cutting • Removes some • Used to regenerate moderately shade-tolerant species like Oak • Seed-tree cutting • Removes most; leaves a few to seed next generation • Used primarily used for conifers Figure 10-12

  26. Solutions • Use forests sustainably by emphasizing: • Economic value of ecological services. • Harvesting trees no faster than they are replenished. • Protecting old-growth and vulnerable areas. • Buy only certified lumber Figure 10-12

  27. 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 replaced with tree farms. • Decreases biodiversity. • Disrupts ecosystem processes.

  28. Forestry Management: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. • Destroy wildlife, increase erosion (especially in suppressed areas) Figure 10-13

  29. Types of Forest Fires

  30. 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.

  31. 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. Fire suppression. • Some trees need fire to germinate • Seems like a cover for a ‘give-away’ to business interests

  32. Solutions: Controversy Over Fire Management • ECOLOGICAL STRATEGIES • Prescribed burns • Use grazers (like goats) to eat away flammable underbrush • Allow public lands fires to burn • Thin forest edges (200 feet) in fire-prone areas & eliminate flammable building materials

  33. Controversy over Logging in U.S. National Forests • Ongoing debate over whether U.S. national forests should be primarily for: • Timber. • Ecological services. • Recreation. • Mix of these uses. • Current timber-cutting is not profitable and is highly subsidized Figure 10-14

  34. Solutions: Reducing Demand for Harvest Trees • 60% of wood consumed in US is wasted • Inefficient construction • Excess packaging • Junk mail • Inadequate recycling • Lack of re-use Figure 10-15

  35. 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. • China uses rice straw • Kenaf is a promising plant for paper production. Figure 10-15

  36. American Forests in a Globalized Economy • INTENSIVE TREE PLANTATIONS (temperate and tropical) • Decreases need for timber production in U.S. • Preserves biodiversity in the U.S. by decreasing pressure to clear-cut. • May lead to private land owners to sell less profitable land to developers. • Can compromise biodiversity and watershed protection. • Results in less money for forest management and restoration • Forest management policy will play a key role.

  37. 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

  38. 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

  39. 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

  40. Rauvolfia Rauvolfia sepentina, Southeast Asia Tranquilizer, high blood pressure medication Fig. 10-18a, p. 205

  41. Foxglove Digitalis purpurea, Europe Digitalis for heart failure Fig. 10-18b, p. 205

  42. Pacific yew Taxus brevifolia, Pacific Northwest Ovarian cancer Fig. 10-18c, p. 205

  43. Cinchona Cinchona ledogeriana, South America Quinine for malaria treatment Fig. 10-18d, p. 205

  44. Rosy periwinkle Cathranthus roseus, Madagascar Hodgkin's disease, lymphocytic leukemia Fig. 10-18e, p. 205

  45. Neem tree Azadirachta indica, India Treatment of many diseases, insecticide, spermicide Fig. 10-18f, p. 205

  46. Causes of Tropical Deforestation and Degradation • Tropical deforestation results from a number of interconnected primary and secondary causes. Figure 10-19

  47. 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 (or concessions) 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

  48. Kenya’s Green Belt Movement:Individuals Matter • Wangari Maathai founded the Green Belt Movement. • The main goal is to organize poor women to plant (for fuelwood) and protect millions of trees. • In 2004, awarded Nobel peace prize. Figure 10-10A

  49. MANAGING AND SUSTAINING GRASSLANDS • ECOLOGICAL SERVICES: • Soil formation, erosion control, nutrient cycling, carbon storage, gene pools, biodiversity, habitats • After forests – most widely used and altered by humans