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Wetland destruction


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Wetland destruction

  1. 1. Wetland destruction : causes and consequences Nayana.P and Jitendra Kumar Dept.of FRM College of fisheries
  2. 2. Introduction  Wetland degradation is the impairment of wetland functions as a result of human activity.  “Wetland degradation” is a direct humaninduced impact resulting from wetland conversion to a specific sectoral or multisectoral economic use, causing an increase in GHG emissions and loss of carbon stocks.
  3. 3. Wetland Loss  Wetland loss is the loss of wetland area, due to the conversion of wetland to nonwetland habitats, as a result of human activity.  The United States alone has lost more than half of its original wetlands, and we continue to lose over 100,000 wetland acres a year.
  4. 4. Asia  27%  wetland loss has been occurring for thousands of years  Lowland rice cultivation began in SE Asia about 6,500 years ago  no trace remains of the natural floodplain wetlands of the Red River delta in Vietnam, which originally covered 1.75 million hectares
  5. 5. Cont,…  virtually nothing left of the one million hectares of natural floodplain vegetation which once covered most of the Sylhet Basin in Bangladesh  Much of the 40 million hectares of rice cultivation in the central plains of India must have been developed at the expense of natural wetlands
  6. 6. Major Effects of Wetland Losses  50% loss of spawning grounds for fish  50% loss of waterfowl habitat  50% loss of flood control capability  50% loss of erosion control and sediment-trapping capability
  7. 7. Why So Much Wetland Loss?  Perception of wetlands as “wastelands” and “swamps” (= ignorance)  Economic incentives for development and urban sprawl
  8. 8. Major Causes of Wetland Loss & Degradation A) Biological Alterations B) Chemical Alterations C) Physical Destruction or Degradation
  9. 9. A) Biological Alterations 1. Removal of wetland or riparian ( the interface between land and a river or stream )vegetation 2. Introduction of non-native/exotic species
  10. 10. Removal of riparian vegetation next to stream due to residential development.
  11. 11. Farming up to edge of stream.
  12. 12. Livestock corral adjacent to stream
  13. 13. Introduced weeds and non-native plants, i.e. purple loosestrife need to be controlled through biological, chemical and/or mechanical means or prevented by proper land management, i.e. minimize disturbance.
  14. 14. Chemical Alterations 1. Release of pollutants & toxic chemicals 2. Change in nutrient levels
  15. 15. Agricultural runoff carries pesticides, fertilizers and manure.
  16. 16. Livestock corral on streams allows manure (nutrients) to enter stream unfiltered by vegetation.
  17. 17. Sediment plume discharging into river and then entering lake.
  18. 18. Physical Destruction or Degradation_____ 1. Filling 2. Draining 3. Dredging & Stream Channelization 4. Peat Mining 5. Flooding & Changes in Sediment Deposition Patterns due to Dam Construction. 6. ATV/Recreational Uses
  19. 19. Stream channelization = straightening of rivers & streams for railroad and highways.
  20. 20. Flooding (and flood damage) is much greater when streams are straightened and riparian vegetation has been removed.
  21. 21. Peat Mining  Michigan is largest peat producer.  Other large peat producers are: Florida, Illinois, Indiana, and Minnesota  Peat land crop production (sod, carrots, onions, celery, potatoes, lettuce, cranberries, mint, radishes.  Horticultural use; containerized seedlings used in forest industry.
  22. 22. Impact of Wetland Loss  Wetland acreage has diminished to the point where environmental and socioeconomic benefits (i.e., ground water supply and water quality, shoreline erosion, floodwater storage and trapping of sediments) are now seriously threatened  Role of wetlands in global climate change currently being debated
  23. 23.