Maintaining Terrestrial Biomes
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Transcript of Maintaining Terrestrial Biomes
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• 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
Permitted activities include:
• logging
• mining
• oil and gas extraction
• livestock grazing
• farming
• How should they be managed? Who should be permitted to use the lands? Ongoing controversy…
Examples:
• Northern Spotted Owl– Endangered species– Habitat: Old-growth forests
Of pacific northwest
Versus:
• Jobs and harvesting resources: the old-growth trees are of high commercial value
Should we “drill baby drill”???
ANWR
• 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)
Yosemite
The Grand Canyon
Denali
Arches
Volcano
Carlsbad Caverns
Big Bend
Glacier
The Badlands
Great Smokey Mountains
• 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:
• Old-growth: has not been cut/disturbed by human activity for hundreds of years.– Example: Redwood
Forest
• Second-growth: forest that has grown back after it had been cut/removed by human activities.
• 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
• Tree plantation or tree farm: – Monoculture (example: Christmas tree farm)
• (example: apple orchard)
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:• Selective cutting: medium or mature trees
in uneven-aged stand cut singly or in small groups.
• 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
• Seed-tree cutting: harvesting nearly all trees in one cutting, but leaving a few uniformly distributed seedlings.
• Strip cutting: removes all trees in an area in a single cutting (in a strip)
• 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
• Surface: Usually burn only undergrowth and leaf litter on forest floor.
• Ground: surface fire that goes underground (most common in areas that contain peat – northern peat bogs). Difficult to detect and extinguish.
(peat bog)
• Crown: May start on ground but eventually burn up whole tree and leap tree-top to tree-top.
• MOST DANGEROUS!
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):
• 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.