Transcript Chapter9_2013x

Sustaining Biodiversity:
The Ecosystem Approach
Chapter 9
Key Questions
■
What are the major threats to forest ecosystems?
■
How should we manage and sustain forests?
■
How should we manage and sustain grasslands?
■
How should we manage and sustain parks and nature
reserves?
■
What is the ecosystem approach to sustaining
biodiversity?
■
How can humans help sustain the Earth’s biodiversity?
Human Impacts on Biodiversity
■
Human “footprint”
■
Disturbing the land- humans have disturbed
50 - 83% of Earth
■
Destruction of wetlandshalf world’s
wetlands lost in past 100 yrs
■
Deforestation
■
Aquatic biodiversity- 27% coral reefs
severely damaged75% fish are fished at or above limit
■
Premature extinctions- current extinction
rate likely 1,000 - 10,000 times greater than before
humans
Natural Capital
Degradation:
< 20,000
Orangutans leftdisappear at a rate
>2,000 per year
Section 9-1
What are the major threats to
forest ecosystems?
Major Services of Forests
Ecological
services of
world’s
forests
valued at
$33.2 trillion
per year!!!
Forests
Ecological
Services
Support energy
flow and
chemical cycling
>>>
Much greater than
Economic
Services
Fuelwood
Lumber
Reduce soil
erosion
Absorb and
release water
Purify water &
air
Influence local
and regional
climate
Store carbon
Provide wildlife
habitats
Pulp to make
paper
Mining
Livestock grazing
Recreation
Jobs- 1 of 4
people depend on
forests for living
Value of ecological
services much
greater than value of
economic services
Types of Forests
Old-growth- not seriously disrupted
for at least several hundred years
Second-growth - results from
secondary succession
Tree plantation
or tree farm managed tract of
uniformly aged trees of
one or two species. Clear
cut when commercially
valuable, then replanted.
Less diverse & less
sustainable than old or 2nd
Types of Forest Management
■
Even-aged management (industry
forestry) trees maintained @ about same age
and size- simplified tree plantation- 1-2 fastgrowing species harvested on rotation
cycle.EX: Clear cuttingEX: Seed tree
method: In the seed-tree method, 2-12 seed trees
per acre (5-30/ha) are left standing in order to
regenerate the forest. EX: Shelter wood method:
The method's objective is to establish new forest
reproduction under the shelter of the retained trees.
■
Rotation cycles: 25-30 years
(temperate), 6-10 years (tropical)EX: Strip
cutting (more sustainable)
■
Uneven-aged managementvariety of species w/ range of ages & sizes.
Goals: biodiversity, sustainable high quality
timber
EX: Selective cutting
Clear-cutting
Reduces biodiversity
Disrupts ecosystem processes
Destroys and fragments some
wildlife habitats
Leaves moderate to large openings
Increases soil erosion
Increases sediment water pollution and
flooding when done on steep slopes
Eliminates most recreational value for
several decades
Degradation of Forests from
Logging Roads
■
Increased erosion and
sediment runoff
■
Habitat fragmentation
■
Biodiversity loss
■
Pathways for pests,
diseases, and invasive
species
■
More accessible for
humans
Cleared plots
for grazing
Cleared plots
for agriculture
Highway
Tradeoffs of Clear-cutting Forests
Trade-Offs
Clear-Cutting Forests
Advantages
Disadvantages
Higher timber yields
Reduces biodiversity
Maximum economic return
in shortest time
Disrupts ecosystem processes
Can reforest with genetically
improved fast-growing trees
Destroys and fragments some
wildlife habitats
Leaves moderate to large openings
Short time to establish new
stand of trees
Needs less skill and planning
Increases soil erosion
Increases sediment water pollution and
flooding when done on steep slopes
Best way to harvest tree plantations
Good for tree species needing
full or moderate sunlight for growth
Eliminates most recreational value for
several decades
Harmful Effects of Deforestation
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 migratory species such as
birds and butterflies
• Regional climate change from extensive
clearing
• Releases CO2 into atmosphere from burning
and tree decay
• Accelerates flooding
© 2006 Brooks/Cole -
ABOUT 46% OF WORLD’S
FORESTS HAVE BEEN
CUT DOWN IN THE LAST
60 YEARS
Surface and Crown Fires
Least intense
More intense and destructive of life
Mature trees & animals escape
Help prevent more destructive fires
Free mineral nutrients from decomposing litter
Ground fire:
Release seeds from cones
underground surface fire, common in
Stimulate germination
northern peat bogs or
Help control diseases and insects
when there is significant dead wood on
Provide young tender vegetation to wildlife
forest floor (can be intense)
Section 9-2
How should we manage and
sustain forests?
Minimizing Forest Damage from Fire
■
■ Prescribed burning- reduce underbrush
■
Allow small fires in National Parks, forests &
wilderness to burn (if people & property not threatened)
■
Defensible space- clear 200 feet around buildings
Healthy Forests Initiative Law?
Effects of the Healthy Forests Initiative -Timber Co. allowed to take large/medium
trees in Nat. Forests if they clear away smaller, fire-prone trees.
Criticized by fire scientists (large tree most fire resistant, logging creates slash)
Other problems:
Allowing for
cutting on basis
of “fire reduction”
allows decisionmaking process
to avoid public
input.
Read more
about this!
Online
links.
Sustainable Forestry
Solutions
Sustainable Forestry
• Grow more timber on long rotations
• Rely more on selective cutting and strip cutting
• No clear-cutting, seed-tree, or shelterwood cutting
on steeply sloped land
• No 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 trees and forests in
estimating economic value
© 2006 Brooks/Cole Thomson
Conserves
biodiversity,
water & soil
resources
Sustainable
management intensive
management of as little as 20%
of world’s forests could meet
current and future demand for
commercial wood / fiber
Combine aspects of a number
of management techniques
such as SELECTIVE
CUTTING.
Kenaf
Yields more paper
pulp per land area
than tree farms &
require less
pesticides &
herbicides.
Holds potential to
greatly reduce
pressure to cut trees
for paper.
Also hemp.
Tropical Deforestation
■
Rapid and increasing – over 11 football
fields lost per minute (Nature Conservancy
quotes 1 field per SECOND), half of historical
rainforests have been lost—most since 1950
■
Loss of biodiversity at least half world’s
terrestrial species live in tropical forests (on
6% of earth’s land)
■
■
Deforestation for croplands, logging and
ranching
Problems measuring deforestationsatellite images difficult, countries misreport,
varying definitions
■
Causes of tropical deforestation = pop.
Growth, poverty, gov. subsidies, debt, failure to
value ecological services
■
■
Burning: contributes CO2 to global
warming
Possible solutions - prevention &
restoration - see next slide
Protecting Tropical Forests
Solutions
Sustaining Tropical Forests
Prevention
Protect most diverse and endangered areas
Restoration
Reforestation
Educate settlers about sustainable
agriculture and forestry
Phase out subsidies that encourage
unsustainable forest use
Add subsidies that encourage
sustainable forest use
Rehabilitation of degraded areas
Protect forests with debt-for-nature swaps,
conservation easements, and conservation
concessions
Certify sustainably grown timber
Reduce illegal cutting
Reduce poverty
Slow population growth
Concentrate farming and ranching on
already-cleared areas
How should we manage and
sustain grasslands?
Section 9-3
Rangelands & Overgrazing
■
■
■
Rangelands = unfenced supply vegetation, for
grazing (grass-eating) and browsing (shrubeating) animals.
Grasslands ecological services; soil formation,
erosion control, nutrient cycling, storage of
atmospheric carbon dioxide in biomass, and
maintenance of biodiversity.
Overgrazing: caused a loss in productivity in as
much as 20% of the world’s rangeland.
We can manage rangelands
more sustainably
■
Control the number of grazing animals
■
Rotational grazing
Provide supplemental feed
Suppress the growth of unwanted invader plants by
use of herbicides, mechanical removal, or controlled
burning or use controlled, short-term trampling by
large numbers of livestock.
■
■
Restoration of a Stream Bank
Area restored in 10 years after banning grazing and off-road vehicles.
Ecological Restoration
“process of repairing damage caused
by humans to the biodiversity &
dynamics of natural ecosystems”
■
Restoration, rehabilitation and
replacement
■
Creating artificial ecosystems
Principles of Ecological Restoration:
1.
Mimic nature
2.
Recreate important ecological
niches
3.
Rely on pioneer, keystone and
foundational species and natural
ecological succession
4.
Control or remove nonnative
species
Accomplishments in Costa Rica: from a high deforester, to very low.
Present forest cover at 50% of nation (up from 21% in 1987)
Section 9-4
How should we manage and
sustain parks and nature reserves?
Types of US Public Lands(35% of US is
public land—large % in Alaska)
■
Multiple-use lands: National Forest System; Natural
Resource Lands (BLM)
■
Moderately restricted-use lands: Natural Wildlife Refuges
■
Restricted-use lands: National Park System (58 parks);
Natural Wilderness Preservation System
US Federal Public Lands
+Much in Alaska!
National parks and preserves
National forests
(and Xs) National wildlife refuges
Managing US Public Lands
principles of public land use
Conservationists
Developers
Protecting biodiversity is a primary goal Sell public lands / resources @ less than
market value
No subsidies or tax breaks for use of
resources
Slash funding for regulation
Public should get fair compensation for Cut old growth forests in national
use
forests and replace with tree plantations
Users are responsible for environmental Open all public land to oil, mining, offdamage
roading and commercial development
Alternative views from developers and
industry
Eliminate Nat. Park Service, mine
without royalties, repeal Endangered
Species Act, …
Managing US National Forests
■
Status of US forests- 30% of USA forested, more wood grown than cut
more forests now than in 1920 (old growth forests decreasing)
■
Importance of national forests
■
Management of forests
■
Lost revenue from timber sales- timber sales from US federal land lost
taxpayer money in 97 of past 100 years
■
Controversies of logging national forests- 10x more $ and 7x more jobs
added to economy by using national forests for recreation, hunting & fishing
■
Tree-free fibers and paper- agricultural residues, kenaf & industrial hemp
Logging in U.S. National Forests
TradeOffs
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
Damages nearby rivers and fisheries
Provides jobs in nearby communities
Promotes economic growth
in nearby communities
*Recreation in national forests provides
more local jobs and income for local
communities than logging
Decreases recreational opportunities
Fig. 8-17, p. 168
Global Outlook: Threats to National Parks
■
■
Too little protection
■
Illegal wood collection, logging, poaching, and mining
■
Too little money to support the parks
■
Too small to sustain biodiversity
■
Invasions from nonnative species
■
Too many visitors to US national parks
■
Traffic jams and air pollution in US parks
■
Underpaid park officials
■
Harm from dirt bikes, dune buggies, and snowmobiles
Wilderness Protection in US
■
Mostly a losing battle
■
Wilderness Act of 1964
■
National Wilderness Preservation System
■
Protected wilderness increased 10 fold since 1970
■
Most protected areas are small (4.6% of US land is protected as
wilderness)
■
Only 81 of 233 distinct US ecosystems are protected
■
Efforts to expand wilderness areas in the US
Section 9-5
What is the ecosystem approach to
sustaining biodiversity?
The Species Approach
The Ecosystem Approach
Goal
Goal
Protect species
from
premature
extinction
Strategy
• Identify endangered
species
• Protect their critical
habitats
Tactics
• Legally protect
endangered species
• Manage habitat
• Propagate endangered
species in captivity
• Reintroduce species
into suitable habitats
Protect populations of species
in their natural habitats
Strategy
Preserve sufficient areas of
habitats in different biomes
and aquatic systems
Tactics
• Protect habitat areas through
private purchase or
government action
• Eliminate or reduce
populations of nonnative
species from protected areas
• Manage protected areas to
sustain native species
• Restore degraded ecosystems
Human
Impacts on
Biodiversity
Biodiversity Hot Spots
especially rich in plant
and animal species:
contains at least 1500
native plant species
in great danger of
species extinction: has
lost at least 70% of its
original habitat
a unique area with
species found
nowhere else.
Animation
Biodiversity hot-spots
interaction.
Section 9-6
How can we help to sustain
aquatic biodiversity?
General Patterns of Marine Biodiversity
■
■
■
■
■
■
■
■
■
Greatest biodiversity in coral reefs, estuaries,
and deep-sea floor
Biodiversity is higher near coasts than open sea
Biodiversity is higher on the ocean bottom than
the surface
Human Impacts
Loss and degradation of habitat is greatest threat
Damage to coral reefs and other habitats
Dredging / trawler operations destroy bottom habitats
Overfishing
Premature extinction
Degradation of the Ocean Floor
The collapse of Canada’s 500-year-old
Atlantic cod fishery
Why Is It Difficult to Protect Marine
Biodiversity?
■ Coastal development
■ Unseen pollution
■ Lack of protection in international waters
■ “Tragedy of the Commons”
Major commercial fishing methods
Biodiversity SeminarAdditional Question
■Identify specific fishing practices that
are considered unsustainable. Discuss
sustainable alternatives and their longterm economic & environmental
viability.
Managing Fisheries - Solutions
Fishery Regulations
Set catch limits well below the maximum
sustainable yield
Bycatch
Use wide-meshed nets to allow escape of smaller
fish
Improve monitoring and enforcement of
regulations
Use net escape devices for seabirds and sea
turtles
Economic Approaches
Sharply reduce or eliminate fishing subsidies
Ban throwing edible and marketable fish back into
the sea
Charge fees for harvesting fish & shellfish from
publicly owned offshore waters
Aquaculture
Restrict coastal locations for fish farms
Certify sustainable fisheries
Control pollution more strictly
Protected Areas
Establish no-fishing areas
Depend more on herbivorous fish species
Establish more marine protected areas
Nonative Invasions
Kill organisms in ship ballast water
Rely more on integrated coastal management
Filter organisms from ship ballast water
Consumer Information
Label sustainably harvested fish
Dump ballast water far at sea and
replace with deep-sea water
Publicize overfished and
Fig. 8-30, p. 181
What Can We Do?
EO Wilson’s Priorities
■
■
■
■
■
■
■
■
Preserve world’s biological “hot spots”
Save the old-growth forest
Map world biodiversity so we know what we have
Identify and protect marine “hot spots”
Protect and restore lakes and streams
Ensure the full range of ecosystem types in the conservation
strategy
Make conservation profitable
Initiate worldwide ecological restoration projects
Two big ideas
■
Value and Protect