Transcript Sustaining Terrestrial Biodiversity

Sustaining Terrestrial
Biodiversity
Chapter 10
Case Study: Gray Wolves
Case Study: Gray Wolves
• 1800: 350,000 gray wolves in 48 states
• 1850-1900 most were shot, trapped, and poisoned by ranchers,
hunters, and government employees.
• Keystone predator: kept down bison, elk, caribou, mule deer, and
coyote populations. Devastated vegetation such as willow and
aspen trees. Increased soil erosion.
• U.S. Endangered Species Act of 1973: only a few hundred remained
• 1987: Let’s reintroduce gray wolves into Yellowstone National Park
• Much objection
• 1995 & 1996: 41 gray wolves caught in Canada and brought to
Yellowstone
• 2008: removed from protection under the Endangered Species Act
in Montana, Wyoming, and Utah.
“There is no solution, I assure you, to save
Earth’s biodiversity other than preservation
of natural environments in reserves large
enough to maintain wild populations
sustainably”
E.O. Wilson
U.S. Endangered Species Act
• 1. Identify and list endangered and
threatened species
• 2. Forbids federal agencies to carry out,
fund, or authorize projects that would
damage habitat
• 3. All commercial shipments of
wildlife/products enter or leave the country
through 9 ports
How do we get forests?
Succession
• Mature forests DO NOT spring up
overnight
• You start off with bare land
• Then, they undergo changes in their
species composition over long periods of
time. This is called ecological succession
Succession
• Colonizing or pioneer species show up
first
• Examples:
• Overtime, these species are replaced by
other species who are then replaced by
other species.
2 Types of Succession
1. Primary Succession
2. Secondary Succession
• Depends on conditions present at the
beginning of the process
Primary Succession
• The gradual establishment of biotic
communities in lifeless areas where there
is no soil in a terrestrial ecosystem or no
bottom sediment in an aquatic system.
• Basically, starting from scratch
Primary Succession
• Examples: bare rock from a retreating
glacier, newly cooled lava, an abandoned
highway or parking lot
Primary Succession
Takes a long time
1. Weathering of rock to release nutrients
2. Pioneer species (lichens and mosses) attach
themselves to the rock
100s to 1000s years later…
3. Soil has enough nutrients to support larger plant
species (herbs, grasses, low shrubs)
4. Trees that like sun replace low shrubs
5. Trees that can tolerate shade then grow
Primary Succession
Secondary Succession
• More common
• A series of communities or ecosystems
with different species develop in places
containing soil or bottom sediment.
Secondary Succession
• Examples: abandoned farmland, burned or
cut forests, heavily polluted streams,
flooded land
Secondary Succession
Plants can start growing in a few days or
weeks
1. Weeds
2. Grasses, small shrubs
3. Small pines
4. Pines with understory of oak and hickory
trees
5. Mature oak and hickory forest
Secondary Succession
The Major Threats to Forest
Ecosystems
Forests
• 30% of Earth’s land surface
• What are some economic services we get
from forests?
• What are some ecological services we get
from forests?
Economic Services from Forests
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Fuelwood
Lumber
Pulp to make paper
Recreation
Jobs
Ecological Services from Forests
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Support energy flow and chemical cycling
Reduce soil erosion
Absorb and release water
Purify water and air
Store atmospheric carbon
Provide numerous wildlife habitats
2 Types of Forest
1. Old-Growth (Primary Growth)
2. Second-Growth
Old-Growth Forests
• An uncut or regenerated forest that has
not been seriously disturbed by human
activities or natural disasters for 200 years
or more.
• Tons of biodiversity because contains a lot
of niches
Old-Growth Forest
Second-Growth Forest
• A stand of trees resulting from secondary
ecological succession.
• Develop after trees in an area have been
removed by human activities
Tree Plantation
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“Tree farm” or “Commercial forest”
Uniformly aged trees
Harvested by clear cutting
Ecological disadvantage: the cycle can
degrade the soil
• Economic benefit: Produce wood for paper
mills
Tree Plantation
Logging
• You gotta have a road -> habitat
fragmentation, invasives, opens land to
others
Ways to cut trees
1. Selective Cutting: older trees cut down
(the better type)
2. Clear-cutting: let’s cut them all down!
Efficient, but clearly harmful
Why is clear-cutting so bad?
• If you cut down ALL of the trees near
water, water runoff increases.
• The runoff increases erosion
• Nutrients are gone and vegetation dies
• Barren ground that can be eroded further
IT NEVER STOPS!
IS THIS A POSITIVE OR NEGATIVE
FEEDBACK LOOP?
Clear Cutting
Advantages:
1. High timber yields
2. Max profits in short time
3. Can reforest with fast-growing trees
4. Good for species who need full sunlight
Clear Cutting
Disadvantages:
1. Reduces biodiversity (“Shade-grown
Certified Coffee”)
2. Destroys and fragments habitats
3. Increases water pollution, flooding, and
erosion
4.Eliminates recreational value.
Sustainable Logging
• Strip Cutting: clear-cutting a strip of trees
along the contour of the land to allow for
quick regeneration
Illegal Logging
• Takes place in 70 countries (Africa and
Southeast Asia)
• 73-80% of logging is illegal in Indonesia
Other Threats to Forests
Forest Fires
1. Surface Fires
2. Crown Fires
Surface Fires
• Burn only undergrowth and leaf litter on
the forest floor.
• Spare most mature trees and almost all
wildlife
Surface Fires: GOOD
Benefits:
1. Burn away flammable ground material
2. Free valuable minerals nutrients in leaf
litter
3. Release seeds from pinecones
4. Stimulate germination of tree seeds
5. Control tree disease and insects
Prescribed Fire / Controlled
Burns
• Surface fires used to prevent any other
bigger fire
• Pine trees
Crown Fires
• Extremely hot
• Burns whole trees and kills wildlife, can be
a threat to humans
• Usually not too bad of a problem unless
done intentionally
• Habitat losses, air pollution, and increases
in atmospheric carbon dioxide
Disease and Insects
• Accidental or deliberate
Sudden Oak Death!
Climate Change
• Some trees are sensitive to heat
Ex) Sugar Maples (ahhh maple syrup)
• Warmer temperatures could attract insects
and pests
• Drier conditions means more fires
Deforestation
• Temporary or permanent removal of large
expanses of forest for agriculture,
settlements, or other uses.
• We have reduced Earth’s original forests
by 46%. Losses concentrated in Latin
America, Asia, and Africa
GOOD NEWS
• In 2007, it was reported that in several
countries (including USA…yeah!) there
was very little forest cut down and even
some gains!
Effects of Deforestation
• Decreased soil fertility from erosion
• Runoff of eroded soil into aquatic systems
• Premature extinction of species with specialized
niches
• Loss of habitat for native species and migratory
species
• Regional climate change from extensive clearing
• Acceleration of flooding
Case Study: USA
• We’re doing well!
• Between 1620 and 1920 we basically
decimated all of the forests
• But now those forests have returned as
second-growth forests and more grows
each year than is cut down!
• 40% of our forests are protected in
National Parks
Tropical Rainforests
• Cover the land area equal to 48 states,
once thought to cover twice this much
• Brazil and Indonesia (72% of original
rainforest) are where losses are greatest
• Half of world’s known species live in
tropical rainforests
Why cut them down?
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Agriculture
Timber
Poverty
Population Growth
Government Policies
Orangutans in Indonesia
• http://www.youtube.com/watch?v=ZJOrgA
E8XMw&safe=active
Greenbelt Movement
• Project started by Wangari Maathai in
Kenya to re-plant native trees to decrease
soil erosion and improve the quality of
lives by providing fuel wood
Grasslands
Ecological Services
• Nutrient cycling
• Soil formation
• Control erosion
• Store carbon dioxide
Grasslands
• Rangelands: wide-open, non-restricted
areas for grazing by grass-eating livestock
• Pastures: fenced areas that are
maintained by ranchers through planting of
domesticated grasses or shrubs
Sustaining Grasslands
• Grass grows from the base of the blade,
so if grazing is controlled and limited, it
can be a sustainable practice
• When too many livestock are allowed to
feed, this leads to overgrazing, exposing
topsoil to erosion and compacting the soil,
decreasing water retention properties
Sustaining Grasslands
• Rotational grazing: livestock are rotated
from one field to another over the course
of a year
Maintaining Grasslands
Fires
• Eliminate other competitive plants
• Increases availability of nutrients
National Parks
• First established in U.S.
National Parks
Label your map
National Parks
A. Everglades
B. Yellowstone
C. Grand Canyon
D. Yosemite
E. Great Smoky Mts
1. Most visited; known
for Appalachian trail
2. Burmese pythons are
invasive here
3. Proposed site of a dam that
was blocked by Sierra Club in
1960s
4. Gray wolves were
reintroduced here in 1995
National Parks
• 1,110 parks in 120 countries
• Not big enough to hold large species and
lots of invasives
• Developing Nations: not enough money to
properly regulate so a lot of illegal activity
occurs.
U.S.
• 58 major national parks
• Problem: too many people want to visit
causing noise pollution, eroded walkways,
and, overall, too much stress on what is
supposed to be a peaceful environment.
National Parks
• Only 5% of the Earth’s surface is truly protected
in parks, meaning we have reserved 95% of the
Earth’s surface for human use.
Reserves
• Large reserves are better because they
provide greater habitat diversity and
minimize exposure to natural disturbances
Buffer Zone Concept
• Protecting an inner core by establishing 2
buffer zones.
• In these buffer zones, resources can be
extracted in a sustainable way.
• No resource extraction from core area.
Habitat Corridors
• Best way to give large animals the space
they need
• Advantage: provide safe migration
between ecosystems
• Disadvantage: Can allow invasive
species to move into an ecosystem where
they do not belong
Costa Rica: The happiest place
in the world!
• Covered in Tropical Rainforests
• Much was removed from 1963-1983 for
ranching
• 1970s they created a system of reserves
and parks to protect their forests
• Protects more land than any other country!
They make all their money from tourism.
Controversy in the U-S-A
• 1964 Wilderness Act: allowed government to
protect undeveloped tracts of public land from
development
• Protected land increased 10 fold between 1970
and 2007
• BUT only 1.8% of it is in the continental 48
states
• 42nd in land protection
• Only 4 of 413 are large enough to sustain the
species they contain
Technical Differences
• National Park: Hunting, commercial fishing, livestock
grazing, mining and logging are all strictly prohibited on
national park land.
• National Forest: forests and grasslands are open to
commercial activities like logging, livestock, as well as
recreational activities like camping, hunting, and fishing.
• U.S. Wilderness: wilderness areas allow regulated
hunting. They prohibit logging, mining, and motorized
vehicles, but some resource extraction and livestock
grazing persists in areas where those activities occurred
prior to its wilderness status.