Transcript Chapter 10 - Fulton County Schools

Sustaining Terrestrial Biodiversity:
The Ecosystem Approach
Core Case Study:
Reintroducing Wolves to Yellowstone
 Endangered
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1850-1900 two million
wolves were destroyed.
 Keystone
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Species
Species
Keeps prey away from open
areas near stream banks.
Vegetation reestablishes.
Species diversity expands.
How wolves have helped sustain
biodiversity in Yellowstone
 Less
elk on stream banks
 Growth of aspens, cottonwoods, willow trees
 Water temperature lower for trout
 Beavers have returned
 Scavengers and Grizzly feed on leftovers
 Coyote population lower which allows
increase in smaller animal population
 More food for eagles and hawks
Why is biodiversity important form of
natural capital?
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Structure and function of ecosystem
Control population of pest and other species
Options for adaptation
Supply of food
Medicines and drugs
Why Should We Care About
Biodiversity?
 Use
Value: For the
usefulness in terms
of economic and
ecological services.
 Nonuse Value:
existence, aesthetics,
bequest for future
generations.
• 34 hotspots identified by ecologists as important and
endangered centers of biodiversity.
Natural Capital
Forests
Ecological
Services
Support energy flow
and chemical cycling
Reduce soil erosion
Absorb and release
water
Economic
Services
Fuelwood
Lumber
Pulp to make paper
Mining
Purify water and air
Livestock grazing
Influence local and
regional climate
Recreation
Store atmospheric
carbon
Provide numerous
wildlife habitats
Jobs
3 Major types of forests based on age
structure
 Old-growth
 Second-growth
 Tree
plantation

Old-growth forest: uncut or
regenerated forest that has not
been seriously disturbed for
several hundred years.
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22% of world’s forest.
Hosts many species with
specialized niches.
Second-growth forest – natural secondary ecological
succession that develops after human activity or after
natural forces
Tree plantation –
managed tract of
trees, uniformly
aged trees, one or
few types of trees
Natural Capital Degradation
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 such as birds and butterflies
• Regional climate change from extensive clearing
• Release of CO2 into atmosphere
• Acceleration of flooding
Ways to reduce fuelwood crisis
 Plant
small
plantation of fast
growing trees
 Burn wood more
efficiently (wood
stove)
 Burn renewable
sun-dried roots of
guards and
squash plants
Kenya’s Green Belt Movement:
Individuals Matter
 Wangari
Maathai
founded the Green Belt
Movement.
 The main goal is to
organize poor women to
plant (for fuelwood) and
protect millions of trees.
 In 2004, awarded Nobel
peace prize.
Harvesting Trees
 Building
roads into previously inaccessible
forests paves the way for fragmentation,
destruction, and degradation.
Harmful effects of logging roads
 Increase
erosion and sediment runoff
 Habitat fragmentation
 Biodiversity loss
 Exposure to invasion by nonnatives
 Open access to farmers, ranchers, ORVs
 Logging roads disqualify the land for
protection as wilderness
Harvesting Trees
 Trees
can be harvested
individually from diverse
forests (selective cutting),
an entire forest can be cut
down (clear cutting), or
portions of the forest is
harvested (e.g. strip
cutting).
Benefits of selective cutting
 Reduces
crowding
 Removes diseased trees
 Encourages growth of younger trees
 Maintains a stand of trees of different species
and different ages
 Allows forest to be used of multiple purposes
Harvesting Trees
Effects of clear-cutting in the
state of Washington, U.S.
Trade-Offs
Clear-Cutting Forests
Advantages
Disadvantages
Higher timber yields
Reduces biodiversity
Maximum profits in
shortest time
Disrupts ecosystem
processes
Can reforest with fastgrowing trees
Destroys and
fragments wildlife
habitats
Short time to establish
new stand of trees
Leaves large openings
Needs less skill and
planning
Good for tree species
needing full or
moderate sunlight
Increases water
pollution, flooding, and
erosion on steep
slopes
Eliminates most
recreational value
Solutions
 We
can use forests
more sustainably by
emphasizing:
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Economic value of
ecological services.
Harvesting trees no
faster than they are
replenished.
Protecting old-growth
and vulnerable areas.
Solutions
Sustainable Forestry
• Identify and protect forest areas high in biodiversity
• Grow more timber on long rotations
• Rely more on selective cutting and strip cutting
• Stop clear-cutting on steep slopes
• Cease logging of old-growth forests
• Prohibit fragmentation of remaining large blocks
of forest
• Sharply reduce road building into uncut forest areas
• Leave most standing dead trees and fallen timber for
wildlife habitat and nutrient recycling
• Certify timber grown by sustainable methods
• Include ecological services of forests in estimating
their economic value
• Plant tree plantations on deforested and degraded land
• Shift government subsidies from harvesting trees to
planting trees
3 types of fires which can affect forest
ecosystems
 Surface
fire
 Crown fires
 Ground fires
Surface fire in Okefenokee Swamp, GA
Savannah, GA
Altamaha River
Brunswick, GA
Okefenokee Swamp
Fire, May 2007
600,000 acres scorched
Worst fire in Georgia
and Florida history
Fire Management
• To reduce fire damage:
– Set controlled surface fires (prescribed burns)
– Allow fires to burn on public lands if they don’t threaten
life and property
– Clear small areas around property subject to fire
Prescribed Burning
• Reduces the amount of dead and dying plant materials
that hinder plant growth
• Recycles nutrients from old plant growth for use by
growing plants
• Promotes germination, growth, and flowering of native
plants
• Increases the diversity of native plant life
• Controls encroachment of woody brush and trees into
grasslands, including invasive species
• Decreases the amount of flammable
organic matter on soil surface
Grassland Management
Recent studies in the
Southwest have shown
when burning is
returned to the
ecosystem and is
coupled with sound
grazing management,
desirable species
return more rapidly
than when either
procedure is applied
alone
Longleaf pine ecosystem
Longleaf pine and grassland forest of the Southern
Coastal Plain – an endangered ecosystem
• Fire climax community – species in ecosystem resistant to
fire and depend on fire
• Longleaf pine is the dominant tree species – w/o fire the
longleaf will be crowded out by other tree species
• One of the most diverse N. American ecosystems north of
the tropics – many endemic rare plants and animals
Grass stage
the longleaf
is protected
from
surface fire
while its tap
root
develops
deep into
the soil
The cone
of the
longleaf
pine can
remained
closed for
several
years and
open up
and
release its
seeds after
a fire
After the grass stage the longleaf pine
quickly grows upward to avoid ground fires
Gopher tortoise
Healthy Forest Restoration Act
Removes most fire resistant trees – promotes
growth of highly flammable young trees (not
good)
 Removing the large and medium trees leaves
behind highly flammable slash

Trade-Offs
Logging in U.S. National Forests
Advantages
Disadvantages
Helps meet country’s
timber needs
Provides only 4% of timber
needs
Cut areas grow back
Ample private forest land
to meet timber needs
Keeps lumber and
paper prices down
Has little effect on timber
and paper prices
Provides jobs in
nearby communities
Damages nearby rivers and
fisheries
Promotes economic
growth in nearby
communities
Recreation in national
forests provides more local
jobs and income for local
communities than logging
Decreases recreational
opportunities
Ways we use wood inefficiently
 Inefficient
use of
construction
materials
 Excess packaging
 Junk mail
 Inadequate paper
recycling
 Failure to reuse
wooden shipping
containers
Examples of cash crops grown on land
which was once a tropical rainforest
 Sugarcane
 Bananas
 Pineapples
 Soybean
 Palm
oil
 Coffee
Ways to protect tropical forests
 Educate
settlers about sustainable
agriculture and forestry
 Add subsidies that encourage sustainable
forest use
 Protect forests with debt-for-nature swap and
conservation easements
 Reduce illegal harvesting
 Certify sustainable grown timber
Ecological services provided by
grasslands
 Soil
formation
 Erosion control
 Nutrient cycling
 Storage atmospheric carbon
 Gene pools for crossbreeding grain crops
 Maintaining biodiversity
 Provide habitat and food
Effects of overgrazing
 Decrease
grass cover
 Exposes soil to erosion by water and wind
 Soil compaction
 Enhances invasion by sagebrush, mesquite,
cactus, and cheat grass
Rangeland Management: A
sustainable approach
o Grasslands and herbivores can coexist
o Rangeland and pasture use must be adjusted to the
carrying capacity of the land
o Cattle can be shifted from one pasture to another
o Fencing and planned distribution of water sources can
help promote a more uniform use of rangeland
o Periodic burns also help
NATIONAL PARKS
 Countries
have established more than 1,100
national parks, but most are threatened by
human activities.
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Local people invade park for wood, cropland,
and other natural resources.
Loggers, miners, and wildlife poachers also
deplete natural resources.
Many are too small to sustain large-animal
species.
Many suffer from invasive species.
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.
NATURE RESERVES
• Geographic Information System (GIS) mapping can be used to
understand and manage ecosystems.
– Identify areas to establish and connect nature reserves in large
ecoregions to prevent fragmentation.
– Developers can use GIS to design housing developments with
the least environmental impact.
The World Wildlife
Federation (WWF) is
researching how to
connect these giant
panda habitats using
wildlife corridors so
the pandas can find
new food sources and
potential mates
Benefits of habitat corridors
• Helps support more species
• Allow species to migrate naturally
• Allow wildlife to shift their native range if
necessary
Problems associated with habitat corridors
(threats to isolated populations)
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Allowing movement of nonnative species
Disease can move between habitats
Fire can move between habitats
Increase exposure of migrating animals to natural predators
Increase exposure to hunters
Costly to acquire, protect, and manage
Examples of ecological restoration
 Replanting
forests
 Restoring grasslands
 Restoring wetlands and stream banks
 Reclaiming urban industrialized areas (known
as brownfield sites)
 Reintroducing native species
 Removing invasive species
 Removing unnecessary dams
How do scientists “speed up” the recovery
of ecosystems?
 Restoration:
trying to return to a condition as
similar as possible to original state.
 Rehabilitation: attempting to turn a
degraded ecosystem back to being
functional.
 Replacement: replacing a degraded
ecosystem with another type of ecosystem.
 Creating artificial ecosystems: such as
artificial wetlands for flood reduction and
sewage treatment.
Restoring a stream
bank eroded away from
poor stewardship
Razing a
dam
Artificial Reef
Restoration of longleaf pine forest
ECOLOGICAL RESTORATION
 Five
basic science-based principles for
ecological restoration:
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Identify cause.
Stop abuse by eliminating or sharply reducing
factors.
Reintroduce species if necessary.
Protect area form further degradation.
Use adaptive management to monitor efforts,
assess successes, and modify strategies.
Pacific loon
THE END