Human Impacts on the Biosphere

1. Human Impactson the Biosphere Chapter 49

3. The Sixth Great Mass Extinction 5 great mass extinctions Previous mass extinctions occurred as a result of global catastrophes Many species are currently endangered or threatened as a result of human activity 6th great mass extinction

4. Why be concerned about biodiversity loss if extinction is a fact of life?

5. Main Causes of Species Decline E. O. Wilson uses the acronym HIPPO to list them: Habitat destruction Introduced and invasive species Pollution Population overpopulation Consider the words of Nobel Peace Prize laureate (2004), Ms. Wangari Maathai of Kenya: “Protecting the global environment is directly related to securing peace”

6. Major drivers of endangerment

7. Endangered and Threatened Species Endangered species A species that has population levels so low that it faces extinction in all or part of its range Threatened species A species that is likely to become endangered in the near future

8. Extinct as the Dodo When humans arrived on Mauritius in 1600, dodos were plentiful – 80 years later, they were extinct

9. Living or Extinct? Extinction by lumbering in the 1940s – reports of sightings are not conclusively confirmed

10. Species with highly specific resource requirements are particularly vulnerable Endemic species A species confined to the limited area in which it evolved Current Threats to Species

11. Habitat Loss, Fragmentation, and Degradation Species decline when humans destroy or fragment natural habitat, or degrade it through pollution or withdrawal of an essential resource

12. Two North American Species Under Threat Eastern fringed prairie orchid and Texas blind salamander Example: Development of prairies and meadows threatens the eastern fringed prairie orchid Example: Excessive withdrawals and pollution of an aquifer endanger the Texas blind salamander Example: Development of prairies and meadows threatens the eastern fringed prairie orchid Example: Excessive withdrawals and pollution of an aquifer endanger the Texas blind salamander

13. Giant Panda: An Endangered Species Endangered due to habitat loss Pandas feed almost exclusively on bamboo

14. Overharvesting and Poaching Overharvesting has caused the collapse or extinction of many commercially valuable species Commercial hunting (passenger pigeon) Commercial fishing (cod, abalone) Poaching – the illegal harvest of species – is a particular threat in less-developed countries Food sources, black market profits

16. Passenger Pigeon-extinct

17. American Bison-

18. Orinoco Caiman- critically endangeredBlack Caiman- locally depleted Killed for their skins Very expensive leather

19. Species Introductions Exotic predators, such as rats and snakes, endanger many island species Intentionally introduced exotic species often outcompete native ones Exotic pathogens, such as avian malaria, are carried by introduced species (chytrid fungus)

20. Introduced Snake on Guam Nine of the 11 species of native forest-dwelling birds have been extirpated from Guam.  Five of these were endemic at the species

21. Interacting Effects Most endangered species are affected by multiple threats Example: When buffalo were hunted to near extinction, running buffalo clover declined, and is now near extinction due to habitat conversion, competition from introduced plants, and attacks by introduced insects and pathogens

22. The Unknown Losses Existing endangered species lists focus on vertebrates; we have only begun to evaluate the threats to invertebrates and plants Our impact on protists and fungi is essentially unknown; prokaryotes are not even addressed

23. 2007 Global List of Threatened Species

24. Assessing Biodiversity 3 levels of biodiversity Genetic Species ecosystem

25. Monitoring Indicator Species Indicator species A species that alerts biologists to habitat degradation and impending loss of diversity when its populations decline Example: Lichen frogs

26. Identifying Regions at Risk Hot spots Habitats that are rich in endemic species and face a high degree of threat Hot spots take priority Ecoregions Larger areas characterized by physical factors and species composition Ecoregions represent all of Earth’s biomes

27. Hotspots These hotspots of biodiversity account for only 1.5% of the Earth’s land, but if they were destroyed, 1/3 of Earth’s species would go extinct

29. Important Land Ecoregions

30. Critical or Endangered US Ecoregions

31. Assessing Biodiversity Our knowledge of species is biased toward large land animals Conservation biologists assess the state of ecosystems and their biodiversity, with the goal of preserving as much of it as possible

32. Effects of Development and Consumption As human populations soar, their need for energy and other resources puts pressure on native species Developed areas displace wild species and also harm them indirectly, as by introducing competing plants or causing light pollution

33. Negative Impact on Biodiversity Cities displace wild species and require huge amounts of resources

34. Effects of Resource Consumption Processes that extract or capture energy can destroy or degrade habitat Oil spills, coal runoff, hydroelectric dams Obtaining raw materials used in consumer products frequently involves degradation of the environment, which can reduce biodiversity Petroleum for plastics, copper for electronics

36. The Threat of Desertification Human activities have potential not only to harm individual species, but to transform entire biomes Desertification Conversion of productive grassland or woodland into a desertlike region in which little grows Result of poor agricultural practices or overgrazing

37. The Dust Bowl Drought and poor agricultural practices allowed winds to strip tons of topsoil from the ground Prairies of the southern Great Plains were plowed for crops, exposing rich topsoil to winds

38. Modern Dust Clouds Desertification now threatens vast areas Africa: Northwest China:

39. The Trouble With Trash The US generates millions of tons of garbage Plastics: Don’t biodegrade- persist for ? Oceans You can minimize your environmental impact by avoiding disposable goods, and by recycling

40. Eat Plastics and Die Its parents fed this albatross chick more than 300 pieces of plastic gathered from the ocean

42. Harmful Practices Building homes, using energy, purchasing products, raising crops, and discarding trash all have harmful environmental effects that endanger species and ecosystems BUT ULTIMATLEY THE PROBLEM IS……. OVERPOPULATION

43. What Can You Do?

44. Sustainable Uses of Biological Wealth Using genetic biodiversity Mexico set aside a reserve for wild maize, which might help domesticated corn resist viruses Discovering useful chemicals Costa Rica searches native plants for new medical or commercial chemicals Ecotourism Costa Rica created the Monteverde Cloud Forest Reserve as a profitable sanctuary

45. Sustainable Use of Biological Wealth Strip logging yields sustainable economic benefits while minimizing erosion

46. Sustainable Use of Biological Wealth Excluding cattle from riparian zones (narrow corridors of vegetation along river banks) has many benefits Flood protection Water conservation Habitat for wildlife Preservation of biodiversity

47. Riparian Restoration San Pedro River before and after restoration