maintaining terrestrial biomes n.
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Maintaining Terrestrial Biomes. In the United States, the government manages public lands including forests, parks, and refuges. Their use varies from resource extraction to farming to recreation. Multiple use lands include those in the National Forest System

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Presentation Transcript
slide2
In the United States, the government manages public lands including forests, parks, and refuges.
  • Their use varies from resource extraction to farming to recreation.
slide3
Multiple use lands include those in the
    • National Forest System
      • Managed by the U.S. Forest Service
    • National Resource Lands
      • Managed by the Bureau of Land Management
    • National Wildlife Refuges
      • Managed by the U.S. Fish and Wildlife Service
examples
Examples:
  • Northern Spotted Owl
    • Endangered species
    • Habitat: Old-growth forests

Of pacific northwest

slide12
Versus:
  • Jobs and harvesting resources: the old-growth trees are of high commercial value
slide15
Some public lands are restricted in use
    • National Park System
      • Managed by the National Park Service (NPS)
      • First established National Park???
    • Only camping, hiking, fishing, and boating (motorized cars/boats are allowed)
slide36
Other public lands are very restricted – meant to be preserved in their natural condition
    • National Wilderness Preservation System
      • Established by the Wilderness Act (1964)
      • Managed by multiple agencies (BLM, USFWS, USFS, and NPS)
    • National Wild and Scenic Rivers (1968)
    • Non-motorized recreation ONLY
types of forests
Types of Forests:
  • Old-growth: has not been cut/disturbed by human activity for hundreds of years.
    • Example: Redwood

Forest

slide41
Since 1600, 90% of the virgin forests that once covered much of the lower 48 states have been cleared away.  Most of the remaining old-growth forests in the lower 48 states and Alaska are on public lands.  In the Pacific Northwest about 80% of this forestland is slated for logging.   
    • Global Deforestation Lecture, The University of Michigan: Global Change
slide43
Tree plantation or tree farm:
    • Monoculture (example: Christmas tree farm)
types of forest management
Types of Forest Management:
  • Even-aged: Maintaining trees at about the same age and size (tree plantation)
    • Goal: economically desirable species
  • Uneven-aged: Maintaining a variety of trees at many ages and sizes
    • Goal: sustainable production
types of tree harvesting
Types of Tree Harvesting:
  • Selective cutting: medium or mature trees in uneven-aged stand cut singly or in small groups.
slide47
Shelterwood cutting: remove all mature trees in an area in a series of cuttings.
    • First cut: mature trees (mostly canopy trees)
    • Second cut: more mature canopy trees but leaves a few mature trees to “shelter” the young trees (which are shade tolerant)
    • Third cut: remove remaining mature trees now that the younger ones are growing to maturity
slide48
Seed-tree cutting: harvesting nearly all trees in one cutting, but leaving a few uniformly distributed seedlings.
slide50
Clear cutting: removes ALL trees in a single area. MOST devastating to an ecosystem; causes massive soil erosion if done on sloped land.
types of forest fires
Types of Forest Fires
  • Surface: Usually burn only undergrowth and leaf litter on forest floor.
slide52
Ground: surface fire that goes underground (most common in areas that contain peat – northern peat bogs). Difficult to detect and extinguish.

(peat bog)

slide53
Crown: May start on ground but eventually burn up whole tree and leap tree-top to tree-top.
  • MOST DANGEROUS!
prescribed burning
Prescribed burning:
  • Controlled burning of flammable materials to prevent build-up of fire-prone debris.
  • Used to prevent major fires in populated areas, but remember, not all fire is bad – some plants and even biomes need fire to regenerate.
    • Grasslands and Chaparral
    • Aspen trees in Yellowstone
healthy forests initiative hfi
Healthy Forests Initiative (HFI):
  • Passes by Congress in 2003
  • Timber companies are allowed to cut down economically valuable large trees in return for clearing away fire-prone underbrush.
  • Removes large, more fire-resistant trees.
  • Leaves fire-prone slash: unwanted branches, tops, stumps.