Chapter 12 Forests

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Chapter 12 Forests
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Opening of Forests

• Forest is a ________________ resource.
• What are the uses of forests? Can you think about
  several examples?
• Timber, paper-pulp
• Wildlife habitat
• Recreational uses
• Ecosystem support
• Watershed enhancement
• Issue discussed efficient allocation and
  deforestation

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Statistics of Forests

• Globally, it is estimated that there are about
  between 5 and 30 million species on Earth.
  Forests provide habitat for two-thirds of these.
• Approximately one half of the world's forest
  carbon is found in boreal forests and over one
  third in tropical forests.
• http//forests.wri.org/.

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Statistics of Forests

• According to 1994 estimates, forests provide
  approximately US969 per hectare per year (a
  total of US4.7 trillion per year) in goods and
  services annually.
• These functions include nutrient cycling, climate
  regulation, and raw materials.

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Statistics of Forests

• Some 60 million people (indigenous and
  non-indigenous) inhabit forests and depend on
  them for their livelihoods.
• In the early 1990s, the production and
  manufacturing of industrial wood products
  contributed US400 billion to the global economy,
  approximately 2 percent of the global GDP.

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Statistics of Forests
Original forests extent
Current forests cover
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Statistics of Forests

• There are 747 million acres of forestland in the
  United States, about 71 as much as there was in
  1630.
• America's forests are owned by private
  individuals (54), public agencies (37), and
  private industries (9).
• The United States of America is home to nearly
  430 million acres of privately owned forest.

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Statistics of Forests

• The science of forestry was established in the
  United States at the turn of the century, at a
  time when vast areas of forests had been cut down
  with little thought of the future.
• Foresters have done a magnificent job in
  restoring Americas forests. Our forests now grow
  nearly four times more wood each year than in
  1920.

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Statistics of Forests

• There are a total of 247 billion trees above 1"
  diameter in the US on all lands, according to the
  last forest inventory.
• Each year about 1.4 billion tree seedlings are
  planted roughly four million a day more than
  making up for those that are harvested. If you
  include naturally regenerated trees the net
  growth exceeds the harvesting by 33 due to good
  forest management.

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Statistics of Forests

• The average American uses about 749 pounds of
  paper every year and 95 of the houses built are
  done so using wood. That means that the average
  person uses the equivalent of a 100 foot high, 16
  inches in diameter tree each year for their wood
  and paper needs.
• Parks, wildlife refuges, and other preserves span
  166 million acres of the nations total land
  mass and the National Wilderness Preservation
  System covers an additional 104 million acres a
  total of 270 million acres set aside for parks,
  refuges, or wilderness areas.
• The first set aside wilderness area was the Gila
  in New Mexico.

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Statistics of Forests

• The forest industry ranks among the top 10
  employers in 40 of the 50 states.
• About 45 percent of the paper consumed in the
  United States is recovered for recycling.
  Recycled paper, however, is not "pure" so it must
  contain some new wood fiber for strength.

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Statistics of Forests

• 3 well-placed mature trees around a house can cut
  air-conditioning costs by 10-50 percent, while
  trees and other landscaping can increase property
  value by 5-10 percent.
• One mature tree absorbs approximately 13 pounds
  of carbon dioxide a year. For every ton of wood a
  forest grows, it removes 1.47 tons of carbon
  dioxide and replaces it with 1.07 tons of oxygen.

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Statistics of Forests

• Today, the United States has about the same
  amount of land covered by trees (or slightly
  less) as it did in 1907.
• (Above information provided by the Society of
  American Foresters.)

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Statistics of Forests

• 42 million acres of tropical forests cleared each
  year, and area of the size of Washington.
• Half of timber harvested is for fuel.

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Special attributes of Timber Resource

• Timber is both an output and a capital good.
• The harvest decision involves how much timber to
  harvest, how often to harvest it and whether to
  replant after harvesting.
• Standing trees are a capital asset. Tree growth
  increases the harvestable volume and standing
  trees provide watershed protection and wildlife
  habitat.
• Forest managers will decide between harvesting
  today and waiting to harvest. Unlike many other
  harvestable resources, harvest rotations are
  typically 25 years or more.
• Forestry is subject to an unusual large variety
  of externalities.

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Forest Biology

• Tree growth is measured on a volume basis.
• Young trees will grow tall quickly, but volume
  growth is slow.
• Medium aged trees increase in volume rapidly.
• Mature trees grow very slowly and eventually stop
  growing or reverse growth.
• Growth will also be affected by weather, soil
  fertility, disease, forest fires, etc.

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Forest Biology

• When should a stand of trees be harvested?
• The mean annual increment (MAI) is the cumulative
  volume of the stand at the end of each decade
  divided by the cumulative number of years the
  stand has been growing. The MAI rises during the
  early stages of growth and then falls during the
  later ages. Figure 12.1 exhibits volume as a
  function of age for Douglas firs.

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Figure 12.1 Model of tree Growth in a Stand of
Douglas Fir
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Table 12.1
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Table 12.2
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Table 12.3