Transcript Forest Resources

Case Study:
Remember Wolves In Yellowstone
Endangered Species
– 1850-1900 two million wolves
were destroyed
 Keystone Species
– Keeps herbivore population in
check (elk, moose)
– Vegetation reestablishes
– Species diversity expands
(beavers & ducks return)
Figure 10-1
Types of “Protected” Lands in U.S.
 Multiple-use lands
 National Forest (U.S.F.S.)
 sustainable yield
 multiple use
 used for logging, mining, grazing, farming,
oil, recreation, hunting and conservation
 National Resource lands (BLM)
 mostly out west and Alaska
 multiple use
 used for mineral and oil extraction/
grazing
Types of “Protected” Lands
 Moderately Restricted-Use Lands
 National Wildlife Refuges
(USFWS)
 522 refuges
 24% designated as wilderness
 protect habitats
 oil, farming, hunting, mineral
extraction are allowed as long as
Dept. of Interior says OK
Types of Protected Lands
 Restricted-Use lands
 National Park System (NPS)
 55 National Parks and 324 recreation
areas, battlefields, memorials, etc.
 Preserve and interpret the country’s
historic and cultural heritage and
protect wilderness areas
 Parks can be used for camping, hiking,
fishing and boating
 Rec areas: also mining and oil
 49% of National Park system is
wilderness
Locations of Parks, Preserves, Forests and
Refuges
Types of Forests
Old-growth forest: uncut or
regenerated forest that has not
been seriously disturbed for
several hundred years
– 22% of world’s forest
– Hosts many species with
specialized niches
Due to human activities over
50% of the earth’s original
forests have been removed.
Figure 10-5
Types of Forests
Second-growth forest: a stand of trees resulting from
natural secondary succession
Tree plantation: planted stands of a particular tree
species
Figure 10-6
Impact of Deforestation
Figure 10-7
Case Study: Deforestation and the
Fuelwood Crisis
• Almost half the people in the developing world
face a shortage of fuelwood and charcoal
– In Haiti, 98% of country is deforested
– MIT scientist has found a way to make charcoal
from spent sugarcane
Harvesting Trees
Increased erosion and runoff
Habitat fragmentation
Pathways for exotic species
Accessibility to humans
Figure 10-8
Harvesting Trees
• Trees can be harvested
individually from diverse
forests (selective cutting)
• an entire forest can be cut
down (clear cutting)
• portions of the forest is
harvested (strip cutting)
Figure 10-9
Harvesting Trees
Effects of clear-cutting in the
state of Washington, U.S.
Figures 10-10 and 10-11
Types and Effects of Forest Fires
• Depending on their intensity, fires can benefit or harm
forests
– Burn away flammable ground material
– Release valuable mineral nutrients
Figure 10-13
Fire
Surface fires
Surface fire
Crown fires
Crown fire
Solutions:
Controversy Over Fire Management
• To reduce fire damage:
– Set controlled surface fires
– Allow fires to burn on public lands if they don’t
threaten life and property
– Clear small areas around property subject to fire
Controversy over Logging in U.S.
National Forests
• There has been an
ongoing debate over
whether U.S. national
forests should be
primarily for:
–
–
–
–
Timber
Ecological services
Recreation
Mix of these uses
Figure 10-14
Solutions:
Reducing Demand for Harvest
Trees
• Tree harvesting
reduced by wasting
less wood, making
paper and charcoal
fuel from fibers that
don’t come from trees
– Kenaf is promising
plant for paper
production
Figure 10-15
American Forests in a Globalized
Economy
• Timber from tree plantations in temperate and
tropical countries is decreasing the need for
timber production in the U.S.
– This could help preserve the biodiversity in the U.S.
by decreasing pressure to clear-cut old-growth and
second-growth forests
– This may lead to private land owners to sell less
profitable land to developers
– Forest management policy will play a key role
CASE STUDY: TROPICAL
DEFORESTATION
• Large areas of ecologically and economically
important tropical forests are being cleared and
degraded at a fast rate
Figure 10-16
CASE STUDY: TROPICAL
DEFORESTATION
• At least half of the
world’s terrestrial plant
and animal species live in
tropical rain forests
• Large areas of tropical
forest are burned to make
way for cattle ranches and
crops
Figure 10-17
Why Should We Care about the
Loss of Tropical Forests?
• About 2,100 of the 3,000 plants identified by the
National Cancer Institute as sources of cancerfighting chemicals come from tropical forests.
Figure 10-18
MANAGING AND SUSTAINING
GRASSLANDS
• Almost half of the world’s livestock graze on
natural grasslands (rangelands) and managed
grasslands (pastures)
• We can sustain rangeland productivity by
controlling the number and distribution of
livestock and by restoring degraded rangeland
MANAGING AND SUSTAINING
GRASSLANDS
• Overgrazing (left)
occurs when too
many animals graze
for too long and
exceed carrying
capacity of a
grassland area.
Figure 10-21
MANAGING AND SUSTAINING
GRASSLANDS
• Example of restored area along the San Pedro
River in Arizona after 10 years of banning
grazing and off-road vehicles.
Figure 10-22
Case Study: Grazing and Urban
Development in the American West
• Ranchers, ecologists, and environmentalists
joining together to preserve grasslands on cattle
ranches
– Paying ranchers conservation easements (barring
future owners from development)
– Pressuring government to zone land to prevent
development of ecologically sensitive areas
NATIONAL PARKS
• Countries established more than 1,100 national
parks, but most threatened by human activities
– Local people invade park for wood, cropland, &
other natural resources
– Loggers, miners, & wildlife poachers also deplete
natural resources
– Many are too small to sustain large-animal species
– Many suffer from invasive species
Case Study: Stresses on U.S.
National Parks
• Overused due to
popularity
• Inholdings (private
ownership) within
parks threaten natural
resources
• Air pollution
Figure 10-23
NATURE RESERVES
• Ecologists call for protecting more land to help
sustain biodiversity, but powerful economic and
political interests oppose doing this.
– Currently 12% of earth’s land is protected
– Only 5% strictly protected from harmful human
activities
– Conservation biologists call for full protection of at
least 20% of earth’s land area representing multiple
examples of all biomes
NATURE RESERVES
• Large and medium-sized reserves with buffer zones
help protect biodiversity and can be connected by
corridors.
• Costa Rica has
consolidated its parks and
reserves into 8
megareserves designed to
sustain 80% if its
biodiversity.
Figure 10-10B
NATURE RESERVES
• A model biosphere
reserve that contains a
protected inner core
surrounded by two
buffer zones that
people can use for
multiple use.
Figure 10-25
• 34 hotspots identified by ecologists as important
and endangered centers of biodiversity.
Figure 10-26
NATURE RESERVES
• Wilderness is land legally set aside in a large
enough area to prevent or minimize harm from
human activities.
• Only a small percentage of the land area of the
United States has been protected as wilderness.