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Land and Water Use

Land and Water Use. Part 2. Forestry. Ecological Services. Providing wildlife habitat Carbon sinks Affecting local climate patterns Purifying air and water Reducing soil erosion Providing energy and nutrient cycling. Tree Plantations.

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Land and Water Use

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  1. Land and Water Use Part 2

  2. Forestry

  3. Ecological Services • Providing wildlife habitat • Carbon sinks • Affecting local climate patterns • Purifying air and water • Reducing soil erosion • Providing energy and nutrient cycling

  4. Tree Plantations • Large, managed commercial farm with uniformly aged trees of one species

  5. Tree Plantations • Primary uses • Trees harvested by clearcutting

  6. Tree Plantations • Species choice

  7. Tree Plantations Pros Cons • Easy to harvest • Economical • More wood production • Little biodiversity • Damage to wetlands • Much smaller food webs • Little decaying wood

  8. Old-Growth Forests • Have not been seriously impacted by humans • Much biodiversity

  9. Old-Growth Forests • Depletion increases risk of climate change • High economic value, but mature slowly • Mahogany, oak

  10. Old-Growth Forests

  11. Forest Fires • Each forest is unique • Number of fires • Frequency of fires

  12. Changes in Forest Fires • Wild fire frequency has increased (4X average 1970-1986) • Area burned has increased (7X previous) • Wild fire season lengthened by 78 days

  13. Reasons for Changes • Appears to be linked to spring and summer temperatures • Fire management has changed

  14. Crown Fires • Occurs where no fires have occurred in long time • Extremely hot • Burn entire tree • Hop from tree to tree • Kills wildlife, increases soil erosion, destroys structures

  15. Yellowstone 1988

  16. Ground Fires • Occur underground and burn partially decayed leaves • Common in peat bogs • Difficult to detect and extinguish • Summer 2008 - Pocosin Lakes National Wildlife Refuge

  17. Surface Fires • Burns undergrowth and leaf litter. • Kills seedlings and small trees • Releases minerals back into soil • Stimulates germination • Control pathogens and insects

  18. Controlling Fires • Prevention • Prescribed burning

  19. Deforestation • Conversion of forested areas to non-forested areas

  20. Deforestation • Natural causes • Human reasons

  21. Results of Deforestation

  22. Methods to Manage and Harvest • Selective cutting • Strip cutting • Clear-cutting

  23. Clear Cutting Pros Cons • Practical method for trees that require full or moderate sunlight • Genetically improved – resist disease, grow faster • Increased economic returns • Produces high yield of timber • Provides jobs • Reduces recreational value of the land • Causes soil erosion, water pollution, flooding on steeply sloped surfaces • Reduces biodiversity • Decaying wood is absent

  24. Effect on Hydrologic Cycle • Decreased evapotranspiration • Lessens downwind precipitation • Increased runoff to rivers/ocean

  25. Causes of Deforestation • Growing number of poor • “Open-access property rights” • Entrepreneurs

  26. Forest Management • Forests cover 1/3 world land surface • Most forests in N. America, S. America, Russia • Forests cover 1/3 of US • 2/3 nonfederal

  27. Forest Management • Forest Service • 1905 • Agency of USDA • Manages public land in national forests and grasslands (193 million acres) • Logging, farming, recreation, hunting, fishing, mining, oil/gas extraction, livestock grazing

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