Sustaining The Earth’s Biodiversity

1. Sustaining The Earth’s Biodiversity Chapters 10 and 11

2. HUMAN IMPACTS ON TERRESTRIAL BIOMES • Human activities have damaged or disturbed more than half of the world’s terrestrial ecosystems. • Humans have had a number of specific harmful effects on the world’s deserts, grasslands, forests, and mountains.

3. Causes and consequences of climate change

4. The Numbers • We have disturbed: • 95% of the virgin forest • 83% of all land surfaces • 98% of the plains grassland in the Midwest • 99% of the grasslands in California • 85% of the Redwood forests in California

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. 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

7. Why Biodiversity? Biodiversity maintains an ecosystem!!!!!

8. Core Case Study: The Passenger Pigeon - Gone Forever • Once the most numerous bird on earth. • In 1858, Passenger Pigeon hunting became a big business. • By 1900 they became extinct from over-harvest and habitat loss. Figure 11-1

9. SPECIES EXTINCTION • Species can become extinct: • Locally: A species is no longer found in an area it once inhabited but is still found elsewhere in the world. • Ecologically: Occurs when so few members of a species are left they no longer play its ecological role. • Globally (biologically): Species is no longer found on the earth.

10. Global Extinction • Some animals have become prematurely extinct because of human activities. Figure 11-2

11. SPECIES EXTINCTION • Some species have characteristics that make them vulnerable to ecological and biological extinction. Figure 11-4

12. SPECIES EXTINCTION • Scientists use measurements and models to estimate extinction rates. • The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species. • The 2004 Red List contains 15,589 species at risk for extinction. Figure 11-5

13. SPECIES EXTINCTION • Percentage of various species types threatened with premature extinction from human activities. Figure 11-5

14. SPECIES EXTINCTION • Scientists use models to estimate the risk of particular species becoming extinct or endangered. Figure 11-6

15. IMPORTANCE OF WILD SPECIES • We should not cause the premature extinction of species because of the economic and ecological services they provide. • Some believe that each wild species has an inherent right to exist. • Some people distinguish between the survival rights among various types of species (plants vs. animals).

16. Endangered and Threatened Species: Ecological Smoke Alarms • Endangered species: so few individual survivors that it could soon become extinct. • Threatened species: still abundant in its natural range but is likely to become endangered in the near future. Figure 11-3

17. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • Conservation biologists summarize the most important causes of premature extinction as “HIPPO”: • Habitat destruction, degradation, and fragmentation • Invasive species • Population growth • Pollution • Overharvest

18. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • The greatest threat to a species is the loss, degradation, and fragmentation of where it lives. Figure 11-7

19. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • Reduction in ranges of four wildlife species, mostly due to habitat loss and overharvest. Figure 11-8

20. Case Study: A Disturbing Message from the Birds • Human activities are causing serious declines in the populations of many bird species. Figure 11-9

21. Case Study: A Disturbing Message from the Birds • The majority of the world’s bird species are found in South America. • Threatened with habitat loss and invasive species. Figure 11-10

22. INVASIVE SPECIES • Many nonnative species provide us with food, medicine, and other benefits but a a few can wipe out native species, disrupt ecosystems, and cause large economic losses. Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats. Figure 11-A

23. INVASIVE SPECIES • Many invasive species have been introduced intentionally. Figure 11-11

24. INVASIVE SPECIES • Many invasive species have been introduced unintentionally. Figure 11-11

25. INVASIVE SPECIES • The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. • Most probably from ships. • No natural predators. Figure 11-12

26. INVASIVE SPECIES • Prevention is the best way to reduce threats from invasive species, because once they arrive it is almost impossible to slow their spread. Figure 11-13

27. Characteristics of Successful Invader Species Characteristics of Ecosystems Vulnerable to Invader Species • High reproductive rate, short generation time (r-selected species) • Pioneer species • Long lived • High dispersal rate • Release growth-inhibiting chemicals into soil • Generalists • High genetic variability • Climate similar to habitat of invader • Absence of predators on invading species • Early successional systems • Low diversity of native species • Absence of fire • Disturbed by human activities Fig. 11-13, p. 236

28. POPULATION GROWTH, POLLUTION, AND CLIMATE CHANGE • Population growth, affluenza, and pollution have promoted the premature extinction of some species. • Projected climate change threatens a number of species with premature extinction.

29. Pollution • Each year pesticides: • Kill about 1/5th of the U.S. honeybee colonies. • 67 million birds. • 6 -14 million fish. • Threaten 1/5th of the U.S.’s endangered and threatened species. Example of biomagnification of DDT in an aquatic food chain. Figure 11-15

30. OVEREXPLOITATION • Some protected species are killed for their valuable parts or are sold live to collectors. • Killing predators and pests that bother us or cause economic losses threatens some species with premature extinction. • Legal and illegal trade in wildlife species used as pets or for decorative purposes threatens some species with extinction.

31. OVEREXPLOITATION • Rhinoceros are often killed for their horns and sold illegally on the black market for decorative and medicinal purposes. Figure 11-16

32. Case Study: Rising Demand for Bushmeat in Africa • Bushmeat hunting has caused the local extinction of many animals in West Africa. • Can spread disease such as HIV/AIDS and ebola virus. Figure 11-17

33. PROTECTING WILD SPECIES: LEGAL AND ECONOMIC APPROACHES • International treaties have helped reduce the international trade of endangered and threatened species, but enforcement is difficult. • One of the most powerful is the 1975 Convention on International Trade of Endangered Species (CITES). • Signed by 169 countries, lists 900 species that cannot be commercially traded.

34. Endangered Species • 1973 Endangered Species Act protected species in danger of extinction • Species in such small numbers that extinction is imminent • Species that are threatened by environmental factors that could decimate the population

35. Case Study: The U.S. Endangered Species Act • One of the world’s most far-reaching and controversial environmental laws is the 1973 U.S. Endangered Species Act (ESA). • ESA forbids federal agencies (besides defense department) to carry out / fund projects that would jeopardize an endangered species. • ESA makes it illegal for Americans to engage in commerce associated with or hunt / kill / collect endangered or threatened species.

36. Case Study: The U.S. Endangered Species Act • Biodiversity hotspots in relation to the largest concentrations of rare and potentially endangered species in the U.S. Figure 11-18

37. Endangered Species • Because of scarcity of inspectors, probably no more than 1/10th of the illegal wildlife trade in the U.S. is discovered. Figure 11-19

38. Endangered Species • Congress has amended the ESA to help landowners protect species on their land. • Some believe that the ESA should be weakened or repealed while others believe it should be strengthened and modified to focus on protecting ecosystems. • Many scientists believe that we should focus on protecting and sustaining biodiversity and ecosystem function as the best way to protect species.

39. How Would You Vote? Should the Endangered Species Act be modified to protect and sustain the nation's overall biodiversity? • a. No. Protecting entire habitats will only further interfere with the rights of landowners. • b. Yes. Protecting endangered habitats is more efficient and effective than saving individual species.

40. ECOLOGICAL RESTORATION • Five basic science-based principles for ecological restoration: • Identify cause. • Stop abuse by eliminating or sharply reducing factors. • Reintroduce species if necessary. • Protect area form further degradation. • Use adaptive management to monitor efforts, assess successes, and modify strategies.

41. ECOLOGICAL RESTORATION • Restoration • Rehabilitation • Replacement • Creating artificial ecosystems

42. ECOLOGICAL RESTORATION • Restoration: trying to return to a condition as similar as possible to original state. • Rehabilitation: attempting to turn a degraded ecosystem back to being functional.

43. ECOLOGICAL RESTORATION • Replacement: replacing a degraded ecosystem with another type of ecosystem. • Creating artificial ecosystems: such as artificial wetlands for flood reduction and sewage treatment.

44. PROTECTING WILD SPECIES: THE SANCTUARY APPROACH • The U.S. has set aside 544 federal refuges for wildlife, but many refuges are suffering from environmental degradation. Pelican Island was the nation’s first wildlife refuge. Figure 11-20

45. PROTECTING WILD SPECIES: THE SANCTUARY APPROACH • Gene banks, botanical gardens and using farms to raise threatened species can help prevent extinction, but these options lack funding and storage space. • Zoos and aquariums can help protect endangered animal species by preserving some individuals with the long-term goal of reintroduction, but suffer from lack of space and money.

46. RECONCILIATION ECOLOGY • Reconciliation ecology involves finding ways to share places we dominate with other species. • Replacing monoculture grasses with native species. • Maintaining habitats for insect eating bats can keep down unwanted insects. • Reduction and elimination of pesticides to protect non-target organisms (such as vital insect pollinators).

47. Using Reconciliation Ecology to Protect Bluebirds • Putting up bluebird boxes with holes too small for (nonnative) competitors in areas where trees have been cut down have helped reestablish populations. Figure 11-B

48. 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

49. Keystone species • Keystone species are those organisms that play a major role (niche) in the functionality of an ecosystem

50. Wolves Keystone? • After the wolf population was nearly destroyed, there was an increase in grazing herds • Moose, deer, antelope • These herds decimated the vegetation because their natural predators were in such small numbers