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HABITAT DEGRADATION

HABITAT DEGRADATION. Habitat degradation has been an unfortunate trait of humans for a long time, at least in recorded history since the the Phoenicians cut the Atlas Mountain forests for ship timbers. Even Ptolemy lamented the loss of the Cedars of Lebanon.

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HABITAT DEGRADATION

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  1. HABITAT DEGRADATION

  2. Habitat degradation has been an unfortunate trait of humans for a long time, at least in recorded history since the the Phoenicians cut the Atlas Mountain forests for ship timbers. Even Ptolemy lamented the loss of the Cedars of Lebanon.

  3. The ancient arabic name for the mountainous region of North Africa was “land of eternal shade”Today these are barren sun-blasted slopes.

  4. Herblock from 1929

  5. 1921 NOW Cartoonist Ding Darling

  6. Will we ever recover forests made up of such old growth giants?? Fortunately, a federal court has just turned down, as “incredulous”, a federal proposal to log one of the last remaining stands of giant Sequoia redwoods.

  7. Timber harvest from public lands

  8. Note: without the Okeefenokee, Georgia’s wetland losses would be over 60%

  9. The message is that humans have a long unfortunate history of degrading their ecosystems and habitats. The good news is that by far the majority of people recognize the short and long term bad consequences of degradation. And, they are willing to pass legislation and assume some personal cost so that good environmental stewardship becomes the norm. And, this is not a rich-poor or cultural divide. What is our role as academics?

  10. African oil palm grown in Malaysia for biodiesel: When green is bad.

  11. Habitat degradation…. • Ratio of BR:DR declines, species specific or community average • Vulnerability to external/internal threats increases • Ecosystem properties shift from historical conditions such that the characteristic biotic community is at risk • Invasive species do well

  12. Some examples of degradation • Native species displaced by invasives (tamarisk along desert streams) • Toxins (macro and micro) increase (heavy metals around smelters) • Nutrients are depleted or some are overly enriched (soils versus water) • Habitat is fragmented (next lectures)

  13. Dealing with habitat degradation • Protection: legislative, community, incentives • Restoration after the fact • Off-site mitigation But…can we really go all the way back once we screw up the environment??

  14. 1973 Marshes of the fertile crescent: Iraq

  15. 2000 Marsh drained during Saddam Hussein’s regime

  16. Date palms..after Images of the fertile crescent marsh

  17. Based on the amount of water that can now be sent into the marsh area, at most the marsh may recover about 20-30% of its former area. And, what about the functions and biodiversity of the marsh ecosystem? How much can be recovered?

  18. Results of dynamiting reefs for fish. How would you restore it???

  19. Large scale land conversion. Note second growth forest next to farmland.

  20. Land conversion may leave small areas of natural habitat with large edge effects

  21. Large scale clear cuts are a major type of habitat destruction

  22. However, small scale clear cuts may have the best chance of rapid return to the original forest matrix. Does this mean that the size and distribution of clear cuts should approximate natural disturbances such as from tree falls and storm windfalls?

  23. Islands of forest are scattered throughout this harvested forest to maximize forest regrowth..a sustainable harvest practice. Note this could also have the negative effects of fragmentation.

  24. Silvacultural practices can minimize forest degradation..an example of selective harvesting and understory protection

  25. Return of the eastern and southern forests

  26. wetlands loss, 1780s–1980s Number w/in state=thousands of hectares

  27. Can we “mitigate” wetland losses and degradation?

  28. How mitigation currently works. • Authorized by interpretation of sect. 404 of CWA and wetland preservation legislation. • Complex series of credits • Emphasis on trading within sub-basins • Monitoring? New degradation?

  29. Exxon Valdez spill along 1900km coast

  30. Oil spills tell us…. • Some toxics have long-lasting effects. • Short-term responses may create additional damage • We really don’t know how to assign monetary value to imperiled animals and plants in order to assign liability. • Scientists and attorneys need to talk!!

  31. Increased nitrogen deposition

  32. More nitrogen=less species in prairie

  33. Coastal dead zones

  34. Pharmaceuticals: a new kind of pollution • Biologically very active, tiny amounts (ppb-ppt) are significant at lowest levels of detection • Structurally stable • May interfere with general biological systems, e.g., endocrine disruptors • May have unexpected effects in non-target organism • Note first three are market-driven properties

  35. Indian vulture decline….Three species of Gyps vultures (giant griffon vultures) have declined 97%. Role not replaced by other vultures. Now Bombay uses solar reflectors to decompose carcasses.

  36. A solution to pharmaceutical pollution of rivers?? Constructed wetlands for waste water treatment may destroy endocrine disruptors (and provide wildlife habitat)

  37. Habitat fragmentation……..future lecture

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