1. Chapter 12 Lecture Outline*
William P. Cunningham University of Minnesota
Mary Ann Cunningham Vassar College
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
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2. Outline World Forests Deforestation Old Growth Harvest Methods
Grasslands
Parks and Preserves
Terrestrial
Marine

3. World Forests
A forest is any area where trees cover more than 10% of the land.
Most remaining forests are in tropical and boreal regions.
Savannas - trees cover less than 20% of ground
Closed canopy - tree crowns cover most of ground
Highest rates of forest loss in Africa and South America

4. World Forests Carbon sink for carbon dioxide
Moisture contributes to rainfall.
Old growth forests - cover a large enough area and have been undisturbed by humans long enough that trees can live out a natural life cycle and ecological processes are normal
Home to much of world’s biodiversity, endangered species and indigenous people

5. Forests Provide Products
Wood and paper
Developed countries provide less than half of industrial wood, but 80% of consumption.
Paper pulp is 1/5 of all wood consumption.
Fuel accounts for 1/2 of global wood use.
One quarter of world’s forests are managed for wood production, much of it in single species monoculture forestry.
Successful reforestation plans in China, Korea and Japan

6. Tropical Forests are Being Cleared
Tropical forests occupy less than 10% of land surface but contain half of all species.
FAO estimates that 12.3 million ha are deforested every yr, the equivalent of one football field every second.

7. Causes of Deforestation
Logging
Building roads to remove trees also allows entry to forest by farmers, miners, hunters.
Conversion of forest to agriculture
Accounts for 2/3 of destruction in tropics
Shifting cultivation (“slash and burn”) is only sustainable if populations are small. Repeated cropping over a short time leads to permanent deforestation.

8. Causes of Deforestation
As forests are cleared, plant transpiration and rainfall decrease.
This leads to drought.
Drought kills more vegetation.
Fires become more numerous and extensive.
More of the forest is lost.

9. Forest Protection
Some places are being reforested (U.S. and China have had greatest gains.)
About 12% of world’s forests are protected.
Guanacaste National Park, Costa Rica
Chipko Andolan movement in India. Women hugged trees to prevent logging and preserve firewood for their families.
Debt for Nature Swaps - conservation organizations buy debt obligations, then offer to cancel the debt if the debtor country protects biologically important areas

10. Temperate Forests have Competing Uses
U.S. Forest Service managed for “multiple uses” but many were conflicting e.g. bird watching and dirt biking.
Old growth forests vs. logging
Less than 10% of old growth forest remains in U.S. and 80% of that is scheduled to be logged.
Spotted owl vs. logging jobs
Compromise forest management plan allows some logging, but protects some prime habitat. But may not be enough to save the salmon and steelhead in northwestern rivers.

11. Old Growth Forest
Temperate rainforest and the spotted owl. Only 2,000 remain in the old growth forests of the Pacific Northwest.

12. Harvest Methods
Clear cutting - every tree in a given area is cut regardless of size
Increases erosion and eliminates habitat
Shelterwood harvesting - mature trees are removed in a series of two or more cuts
Strip cutting - all the trees in a narrow corridor are harvested
Selective cutting - only a small percentage of the mature trees are taken in each 10 to 20 year rotation

13. Harvesting
Top photo shows clear cutting (removal of all trees) in Washington’s Gifford Pinchot National Forest.
Bottom photo shows selective harvesting.

14. Logging on Public Lands?
Some are calling for an end to all logging on public lands.
Lands provide ecological services such as clean water, rivers for fish, irrigation, recreation. Worth $224 billion.
Federal government builds roads, manages forests, fights fires and then sells the timber to logging companies for less than their costs. This is a subsidy for the logging industry. Worth $4 billion.

15. Logging on Public Lands?
Timber companies claim logging produces jobs, supports rural communities, keeps forests healthy.
Roads on public lands are another controversy. Economists argue it opens up land for motorized recreation and industrial uses. Wildlife supporters see it as disruptive.
Clinton protected 23.7 million ha of wilderness from roads; Bush overturned this and ordered expedited logging and mining.