Sustaining Ecosystems
Chapter 10
Big Bad Wolf
• Listed as endangered on lower 48 states due to
hunting, poisoning, trapping by hunters and
ranchers
• Now its role is evident – culled bison, elk, etc.,
kept down coyote population, provide meat for
scavengers
• Reintroducing wolves has had positive effects
saving vegetation the herds would strip clean
Collapse in Yellowstone?
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Natural regulation – hands off approach
Elk have flourished from 3,000 to 20,000
Trees not growing b/c elk eat shoots
No trees hurts beavers
Fewer beavers less dams
Less dams, less sediment build up and meadow
production
• Yellowstone may allow elk to be hunted again
Ecotourism
• The Belize river is an example of successful
ecotourism
• Farmers allow strips of jungle to connect
preserves allowing monkeys a need corridor
• Visitors come to see the monkeys
• Locals make money supplying visitors with
room and board
Public lands in the US
• 42% public land – most of any nation, but
most is in Alaska (73%)
• Classified into 3 areas
– Multiple use lands
– Moderately restricted use lands
– Restricted use lands
Multiple use lands
• National forest system managed by the US
forest service
• To be managed under sustainable yield and
multiple use principle (except 15%
wilderness)
• Timber harvests, grazing, recreation,
wildlife conservation, mining, OHVs,
hunting, oil extraction, farming, and fishing
Multiple use lands
• National resource lands
• Managed by BLM (bureau of land
management) in western US
• Emphasis on providing domestic supply of
energy and strategic minerals
• Also preserves rangeland for grazing
Moderately restricted-use lands
• National wildlife refuges (508)
• Managed by US fish and wildlife
• 24% is designated wilderness (no vehicles,
mining, etc.)
• Most protect habitats for game animals
• Some areas allow oil extraction, mining,
logging, hunting, grazing and military
activities if DoI approve
Restricted use lands
• National park system (375)
• Managed by nation park service
• Goal is to preserve scenic and historic
heritage, protect habitats, provide recreation
• About 49% designated wilderness
• Cars only on paved roads, in nation
recreation areas some mining, oil, hunting is
allowed
Restricted use lands
• National wilderness preservation system
(630)
• Managed by NPS, NFS, FWS, and BLM
• Only open to hiking, camping, etc.
• Banned – roads, logging, grazing, mining,
buildings, commerce, etc.
Preservation vs conservation
• Preservation – keep habitats intact, primary
goal is maintaining biodiversity and
sustainability
• Conservation – use land for economic gain
including mining, logging, grazing
• They try to be sustainable, but have not
succeeded so far
Rangelands
• Grasslands suitable for cattle
• 3 billion ruminants (can digest cellulose)
mostly cattle, sheep and goats
• Grasses grow from base of plant
(potentially renewable if base is left intact)
• Rangelands currently being degraded by
desertification
Overgrazing
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Leads to soil compaction
Allows invasive species into rangeland
Lowers water holding capacity of soil
Exposes soil to erosion
• Major cause of desertification in arid and
semi-arid lands
Riparian zones
• Thin strips of lush vegetation along streams
• Prevents flooding by storing and releasing
water slowly
• Provides habitat (food, water, shade, nests)
• 65-75% of wildlife in western US depends
on riparian zones
• Cattle tend to trample riparian zones
Types of forest
• Tropical, temperate, and polar
• identified by climate
• about half the world’s forests are in the
tropics
• more than 60% of the remaining forests
reside in only 7 countries: US, Brazil,
Canada, Russia, China, Indonesia, and
Congo (Zaire)
Emergent
Birds,
invertebrates,
bats
Canopy
Birds,
reptiles,
amphibians,
lichens, mosses
Understory
Shade-tolerant
plants, birds,
squirrels,
lizards,
chipmunks
Snag
Floor
Rotting debris,
worms,
insects,
bacteria
Subsoil
Bole
Nematodes,
microrganisms
Fig. 23.6, p. 592
Losing forests
• At least 2 million sq. kilometers of forest
lost between 1990 and 1995 (three times the
size of Texas)
• Each year 160,000 sq. km lost
• As populations increase, rate of loss
increases
• At least 107 countries reported a net loss of
forest between 1990 and 1995
Virgin forests, 1620
Fig. 23.13a, p. 600
Virgin forests, 1998
Fig. 23.13b, p. 600
Annual Deforestation
Rates
More than 1%
loss
0.5–1% loss
0–0.5 loss
Stable or increased
forest
No data
Fig. 23.8, p. 594
Types of forest succession
• Old growth forest - rich biodiversity,
untouched for several hundred years, large
number of niches, large number of standing
dead trees (snags), fertile soil
• US lost 95-98% of its old growth forests
Types of forest succession
• Second growth forest - trees resulting from
succession after clear cut
• about 40% tropics second growth
• most of US is second growth
• second growth are undisturbed long enough
to reach a climax community, but lack
diversity, typically tree farms
Economic importance
• Worth $300 billion a year
• each year US consumes enough wood to fill
2 million boxcars
• Worldwide 55% of the wood is used for fuel
• one third of the wood is used as lumber
• since 1950 the demand for wood has
doubled and paper increased five fold
• demand is expected to double again by 2010
Ecological importance
• Forest slow flow of water out of a
watershed
• Allows aquifer to recharge/reduces runoff
and erosion
• influence climate - transpiration increases
air moisture and thus more rain/cooler in
that area (tropics)
• remove CO2
• buffer against noise, air pollutants
What’s a tree worth?
• One tree is worth about $196,250
• This is the amount of money in services the
tree provides to the planet
• Air filtration, oxygen production, soil
fertility, erosion control, water recycling,
humidity control, habitats
• A tree is typically sold for $590
Emergent
Birds,
invertebrates,
bats
Canopy
Birds,
reptiles,
amphibians,
lichens, mosses
Understory
Shade-tolerant
plants, birds,
squirrels,
lizards,
chipmunks
Snag
Floor
Rotting debris,
worms,
insects,
bacteria
Subsoil
Bole
Nematodes,
microrganisms
Fig. 23.6, p. 592
Tree products
• There are over 20 categories of products
from trees
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lumber
charcoal
drugs
oils
dyes
nuts/fruits
Norther spotted owl
• What is the importance of the spotted owl?
• By being listed as threatened by fish and
wildlife, its habitat, old growth douglas fir,
must be protected
• Logging is opposed to this because of the
large loss of revenue
Canada’s link to forestry
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Largest exporter of timber $30 billion
10% of jobs directly related
lost 60% old growth
90% involves clear cutting
one half of the remaining temperate forest
in Canada, scheduled for clear cut
• losing an acre every 12 seconds
Tropical forest loss
• Being cut at an alarming rate
• rate is increasing with population growth
and economic demand
• South America most severe, but rate of loss
is higher in Southeast Asia and Central
America
Madagascar
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Fourth largest island (off east side of Africa)
160,000 species unique to the island
slash and burn has devoured habitat
cut forests allowed massive erosion
most eroded country in the world
will lose at least half its biodiversity
trying to reform using reforestation, but
population scheduled to double (2025)
MADAGASCAR
INDIAN
OCEAN
Existing rain forest
Former rain forest
Southern spiny desert
Western tropical deciduous
forest
Fig. 23.17, p. 607
How bad is it?
• If current trends in rain forest degradation
remain…
• estimated 20% forest species gone by 2022
• 50% by 2042
• worst extinction in 65 million years
• way to go humans!!
Sustainable forestry
• By harvesting nuts, berries, resins, dyes,
oils, etc. over the course of 50 years would
yield greater profit than would harvesting
the lumber
• But it is long term gain vs. being able to
harvest trees now and move to a new area
(more profit b/c you cut more trees)
Fig. 23.11a, p. 596
Selective Cutting
Cut 2
Cut 1
Fig. 23.11b, p. 596
Shelterwood Cutting
Fig. 23.11c, p. 596
Seed-Tee Cutting
Clear-Cutting
Fig. 23.11d, p. 596
Uncut
Cut
Cut
Cut
Uncut
3–5 years ago 1 year ago
6–10 years ago
Strip Cutting
Fig. 23.11e, p. 596
Cause of tropical deforestation
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Population growth, poverty, govt. policy
landless poor use forest for food/money
govt. makes timber cheap to boost economy
finance roads, mines, logging, oil, and dams
creates needs for small shops, lodging
business moves in, need for housing
half of deforestation from inexperienced
farmers trying to farm new land
How to help biodiversity
• Preserve more land in the world 6% now
should be 10% minimum
• Reserves should be at least 3,900 sq miles
• Set up biosphere reserves (5 or more)
– Core (no human activity)
– Buffer zone (research activity)
– Buffer zone 2 (limited human activity/tourism)
• Create corridors between reserves
Further protection
• National Wild and scenic rivers system
– River cannot be altered or developed
• National Trails System
– Not enough funding or management to
successfully maintain currently
Best defense
• Educate yourself
• Educate others
• Support charities like Sierra Club, Nature
Conservancy, World Wildlife Fund, Audubon
Society, etc.
• Get out and enjoy the outdoors while helping to
protect it
• Remember, it’s your world, don’t let others ruin it!
Good Job Everyone!
• No go out and hug a tree!!