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HUMAN IMPACT

This article explores the detrimental effects of human activities on Earth's ecosystems, including habitat destruction, species extinction, and pollution. It delves into the importance of biodiversity conservation and sustainable development practices to mitigate these impacts. From deforestation to introduced species, the text raises awareness about the urgent need for environmental protection and species preservation.

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HUMAN IMPACT

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  1. HUMAN IMPACT • One-third of all plant and vertebrate species live on just 1.5% of Earth’s land • Every year, humans destroy an area of tropical rain forest equal to the size of West Virginia

  2. Introduced Species • Introduced species • #2 cause of extinction and loss ofEarth’s biodiversity; border questions

  3. Kudzu, a Japanese plant

  4. HUMAN IMPACT ON ECOSYSTEMS • Burning of fossil fuels is the mostlikely cause of global warming

  5. Impact on the Carbon Cycle • The increased use of fossil fuels • raises the level of CO2 in the atmosphere

  6. Impact on the Nitrogen Cycle • Sewage treatment facilities and fertilizers • add large amounts of nitrogen and phosphates to aquatic systems, causing heavy growth of algae

  7. Impact on the Water Cycle • Destruction oftropical rain forest • alters local and global weather patterns • the water cycle?

  8. Deforestation and Chemical Cycles: A Case Study • The Hubbard Brook Experimental Forest is a study site for nutrient cycling in a forest ecosystem Altered Completion of tree cutting Control

  9. The Release of Toxic Chemicals to Ecosystems • Humans are adding new toxics to ecosystems and they often cannot be degraded by microorganisms

  10. Biological magnification DDT concentration increase of 10 million times DDT in fish-eating birds 25 ppm DDT in large fish 2 ppm DDT in small fish 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm

  11. It was once thought that the atmospherecould absorb our gaseous waste products; smog

  12. Depletion of Atmospheric Ozone • The ozone layer • absorbs UV radiation, preventing most of it from striking organisms in the biosphere • has nothing to do with global warming

  13. Our protectiveozone layer (a) Ozone hole (b) Thickness of ozone layer • started thinning due to the build up of CFCs (chlorofluorocarbons) Monthly averages for October

  14. The consequences of ozone depletion • are quite severe for all life on Earth

  15. The Loss of Species • The current mass extinction • caused by human activity • broader and faster than other past extinctions • boom and echo? • At the current rate of destruction over one half of all plant and animal specieswill be gone by the end of this century

  16. The Three Main Causes of the Biodiversity Crisis • 1. Human destruction of habitat; interaction?

  17. Introduced Species • 2. Introduced species

  18. Overexploitation • 3. Overexploitation of wildlife

  19. Why Biodiversity Matters • Humans rely on biodiversity for • food, clothing, shelter • oxygen, soil fertility, medicinal substances

  20. CONSERVATION BIOLOGY • Conservation biology • a goal-oriented science that seeksto counter the loss of biodiversity

  21. Biodiversity “Hot Spots” • A biodiversity hot spot • a relatively small area with anexceptional concentration of species

  22. Equator Tropical forest hot spots Chaparral hot spots

  23. Endemic species • found nowhere else; common in hot spots • highly sensitive to habitat degradation

  24. Conservation at the Species Level • Much of the discussion of thebiodiversity crisis centers on species • The U.S. Endangered Species Act • an endangered species is “in danger of extinction throughout all or a significant portion of its range”

  25. Conserving Species amid Conflicting Demands • Conservation biology • deals with relationships between biology and society • Competing demands for habitat are always an issue

  26. Sustainable Development • Sustainable development • balances human needs withthe health of the biosphere • The goal of sustainable development • the long-term prosperity of human societiesand the ecosystems that support them

  27. Habitat Fragmentation • Population fragmentation • the splitting and consequent isolation of portions of populations by habitat destruction

  28. Corridors • A movement corridor • a narrow strip or series of small clumps of quality habitat connecting otherwise isolated populations An artificial corridor

  29. Corridors • promote dispersal and help sustain populations • especially important to species thatmigrate between different habitats

  30. Zoned Reserves • A zoned reserve • an extensive region of land that includesone or more areas undisturbed by humans

  31. The areas surrounding zoned reserves are buffer zones that support both agriculture and tourism

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