Environmental crisis lecture 8

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Lecture 8 for NAU Environmental Crisis

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Environmental crisis lecture 8

  1. 1. Environmental Science A Study of Interrelationships Thirteenth Edition Enger & Smith Chapter 11 Biodiversity Issues Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  2. 2. Biodiversity Issues
  3. 3. 11.1 Biodiversity Loss and Extinction  Biodiversity • diversity of genes, species, and ecosystems in a region.
  4. 4. 11.1 Biodiversity Loss and Extinction  Extinction is the elimination of all the individuals of a particular species. • Natural and common event in the history of biological evolution. • Major consequence of human domination of the Earth. – humans increased the extinction rate 1,000 to 10,000 times above background rates
  5. 5. Kinds of organisms prone to extinction  Local extinctions • Species may not have a future  Some genetic diversity lost. • As population is reduced in size  Certain kinds of species are more likely to go extinct than others: • Species with small, dispersed populations – Successful breeding is difficult.
  6. 6. 11.1 Biodiversity Loss and Extinction • Organisms in small, restricted areas, such as islands. – Environmental changes have large effect. • Specialized organisms – Relying on constancy of a few key factors. • Organisms at higher trophic levels. – Low population sizes and reproductive rates.
  7. 7. 11.1 Biodiversity Loss and Extinction
  8. 8. 11.2 The Value of Biodiversity  We are dependent on the diversity of organisms • Services provided by ecosystems/organisms  Nutrient Cycling • Carbon, nitrogen, phosphorus • cycled through ecosystems  Cultural Uses • Enjoyment of landscapes, scientific study • Educational activities, spiritual significance of places
  9. 9. 11.2 The Value of Biodiversity  Water regulation and supply • Intact soil and vegetation slow water flow • Water penetrate soil to recharge aquifers • Water available for agriculture, industry, and domestic use.
  10. 10. 11.2 The Value of Biodiversity  Disturbance regulation and erosion control • Land disturbed by fire, flood, windstorms, landslides, or human actions. • Plants and animals heals the scars and prevents continued damage.  Waste Treatment • Decomposer organisms remove excess nutrients and pollutants from air, water, and soil.
  11. 11. 11.2 The Value of Biodiversity  Food and Raw Materials • Harvest wild plants and animals as food and medicine. • Plants feed livestock, provide building materials, and firewood.  Atmospheric and Climate Services – Removal of carbon dioxide in photosynthesis helps control the warming of the planet. – Nitrogen and sulfur are modified by organisms. – Ozone provides protection from UV light.
  12. 12. 11.2 The Value of Biodiversity  Recreation • Natural areas provide recreational opportunities.  Biological Control Services • All organisms have complex interrelationships. Some help remove pests.
  13. 13. 11.2 The Value of Biodiversity  Pollination Services • insects are pollinators. • Insecticides can negatively affect agricultural production.  Habitat/Refuges • Protect species • nursery sites • temporary stopping places for migratory species.
  14. 14. 18 miles N Omaha
  15. 15. 11.2 The Value of Biodiversity  Genetic Resources • If organism goes extinct – lost the ability to use it for our own needs. • 50% of our common drugs come from plants and animals.  Soil Formation • Weathering of rock builds soil – aided by bacteria, fungi, tiny animals, and plants roots – Food supply depends on protection and management of soil.
  16. 16. 11.2 The Value of Biodiversity  Approximate values • 33.3 trillion (1997) • 50 trillion • Agriculture (670 billion) • Forestry (200 billion) • Fisheries (80 billion)
  17. 17. 11.2 The Value of Biodiversity  A case can be made that all species have an intrinsic value and a fundamental right to exist. • Extinction is not necessarily bad, but human-initiated extinction is. • Experiencing natural landscapes and processes is an important human right.
  18. 18. Threats caused by Humans  Five major human activities threaten to reduce biodiversity. • • • • • Habitat loss Overexploitation Introduction of exotic species Predator and pest control activities Climate change
  19. 19. 11.3 Threats to Biodiversity  Habitat Loss • Human activities – Convert natural ecosystems to human-dominated – Farming, forestry, grazing  (IUCN) • 80%-90% of threatened species are under threat • habitat loss or fragmentation – major cause of past extinctions.
  20. 20. 11.3 Threats to Biodiversity  40% of the world’s land surface • converted to cropland and permanent pasture.  Most productive natural ecosystems • (forests and grasslands) are the • first to be modified by humans.  Pressure to Modify the environment • greatest in areas with high population density.
  21. 21. 11.3 Threats to Biodiversity  Historical forests • ½ of U.S., ¾ Canada; most of Europe  Deforestation • process of destroying a forest, • often for the purposes of fuel, building materials, or to clear land for farming.
  22. 22. 11.3 Threats to Biodiversity Changes in forest area
  23. 23. 11.3 Threats to Biodiversity  Modern forest management practices • compromise • allows economic exploitation while maintaining some environmental values of the forest • Logging – Selective – Shifts species diversity
  24. 24. Forestry Practices • Forested areas effectively: – – – – – Habitat for plants/animals Reduce erosion. Reduce runoff. Modify the climate. Provide recreational opportunities. Marsupial-the Numbat
  25. 25. 11.3 Threats to Biodiversity  Clear cutting • removal of all trees in an area • economical but increases erosion – especially on steep slopes
  26. 26. Forest Harvesting Methods  Patchwork clear cutting • Use of sites with steep slopes • clear cutting in small, unconnected patches; • preserves biodiversity.  Selective harvesting • single species tree harvesting • not as economical • reduces ecosystem damage.
  27. 27. 11.3 Threats to Biodiversity  Tropical forests • greater species diversity than any other ecosystem • not as likely as temperate forests to regenerate • poor soil characteristics.
  28. 28. 11.3 Threats to Biodiversity  Tropical deforestation: • Reduces species diversity in the world. • Impacts the climate via lowered transpiration. • Deforested lands are easily eroded. • Without the forests to trap CO2, there may be increased global warming.
  29. 29. Discussion  http://www.youtube.com/watch?v=2OA7FB2vrMo
  30. 30. 11.3 Threats to Biodiversity  Rangelands • lands too dry to support crops • receive enough precipitation to support grasses and drought-resistant shrubs  Raise livestock  Wildlife are usually introduced species not native to the region.
  31. 31. 11.3 Threats to Biodiversity Use of rangelands
  32. 32. 11.3 Threats to Biodiversity  Conversion of rangelands to grazing • Major impacts on biodiversity. • Eating habits of livestock – reduce certain species of native plants and encourage others. • Regulate number of livestock on rangelands, especially in dry areas. – Overgrazing – Desertification--converting arid or semiarid land to desert because of improper human use.
  33. 33. 11.3 Threats to Biodiversity Desertification
  34. 34. 11.3 Threats to Biodiversity  In marine ecosystems, • Harvest is restricted to shallow parts of the ocean • bottom-dwelling fish can be easily harvested.  Trawls are nets dragged along the bottom. • disturb the seafloor and cause habitat damage.  25% of catch is discarded • dead • further alters the ecological nature of the seafloor.
  35. 35. Habitat Loss in Aquatic Ecosystems  Freshwater systems • modified for navigation, irrigation, flood control, or power production.
  36. 36. Threats caused by Humans: Overexploitation  Overexploitation is responsible • 30% of endangered animal species • 8% of endangered plant species. • Overexploitation occurs – when humans harvest organisms faster than the organisms are able to reproduce – threatening some, and causing extinction in others.
  37. 37. 11.3 Threats to Biodiversity  70% of world’s marine fisheries • overexploited or • fully exploited and in danger of being overexploited • Sign of overexploitation – Marketing fish that once were “unacceptable”
  38. 38. 11.3 Threats to Biodiversity  Fish farming (aquaculture) • important as a source of fish production.  60% of all aquaculture production is from freshwater systems.  The environmental impacts • Nutrient overloads • Escape into natural waters • Land conversion
  39. 39. 11.3 Threats to Biodiversity: Unsustainable harvesting  Meat from wild animals is often referred to as bush meat. • 70% of wildlife species in Asia and Africa • 40% of species in Latin America are being hunted unsustainably. • Part of all subsistence cultures. • Delicacies and are highly prized for the home and restaurant trade.
  40. 40. 11.3 Threats to Biodiversity  Pet and aquarium trade • The method of capture is often problematic. – Destruction of bird nests. – Toxins used to stun fish.  Parts of the animal have particular value. – Ivory and animal skins – Traditional medicines
  41. 41. 11.3 Threats to Biodiversity: Control of Predators and Pests  Systematic killing • certain organisms that interfere with human activities • Large predators have been locally exterminated because they preyed on domestic animals. • Control pests (cowbird) is helping
  42. 42. 11.3 Threats to Biodiversity  The role of climate change, survival of species • Many species live near the limit of their physiological tolerance. – slight change in the temperature may push them over the brink. • Amphibians, corals, and arctic species are greatly affected by climate change. – Planet warming may have caused a fungal disease in frogs. – Melting sea ice is changing migration patterns and food availability.
  43. 43. 11.3 Threats to Biodiversity
  44. 44. 11.4 What Is Being Done to Preserve Biodiversity?  The World Conservation Union (IUCN) lists over 16,000 species as threatened with extinction. • IUCN classifies species in danger of extinction into four categories: – Endangered – Vulnerable – Rare – Indeterminate
  45. 45. 11.4 What Is Being Done to Preserve Biodiversity?  In the U.S., • Endangered Species Act (1973). • Designates species as endangered or threatened and • Gives the U.S. government jurisdiction over those species. • No activity by a government agency should lead to the extinction of an endangered species. • Government agencies to use whatever means necessary to preserve the species in question.
  46. 46. 11.4 What Is Being Done to Preserve Biodiversity?  Endangered species • small numbers that they are in immediate danger of becoming extinct.  Threatened species • could become extinct if a critical environmental factor is changed. • 1/8 of bird species, 1/4 of mammal species, 1/3 of amphibian species, and 1/2 of turtle species are threatened.
  47. 47. 11.4 What Is Being Done to Preserve Biodiversity?  Habitat Analysis and Management • Managing a particular species • Understanding of the habitat needs of that species. – habitat must provide food, water, and cover. • Modifications made to enhance the success of a species are known as habitat management.
  48. 48. 11.4 What Is Being Done to Preserve Biodiversity?  Wildlife management • harvesting for sport and meat • Important population management technique. • managed so they do not exceed carrying capacity of their habitat.  When populations get too small, artificial introductions can be implemented. • Native species can be reintroduced to areas where they had been extinct.
  49. 49. 11.4 What Is Being Done to Preserve Biodiversity? Managing a wildlife population
  50. 50. 11.4 What Is Being Done to Preserve Biodiversity?  Coastal regions are most productive regions of the oceans. • Sunlight penetration of shallow water makes it warm. • Nutrient deposition from land makes this region fertile. • Fishing pressure is concentrated here.  Management of marine fisheries • achieving agreement on harvest limits
  51. 51. Summary  Loss of biodiversity has become a major concern.  Ecosystems involve the interactions of organisms and their physical environment.  Functioning ecosystems and their component organisms provide many valuable services that are often overlooked because they are not easily measured in economic terms.
  52. 52. Summary  Many people also consider the loss of biodiversity to be an ethical problem.  The primary causes of habitat loss are by: • Humans converting ecosystems to agriculture and grazing. • Overexploitation by harvesting species at unsustainable levels. • Introduction of exotic species that disrupt ecosystems and compete or prey on native organisms. • Purposeful killing of pest organisms such as large predators.
  53. 53. Summary  Protection of biodiversity typically involves legal protections by national laws and international agreements, and management of the use of species and ecosystems at sustainable levels.

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