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Chapter 5 - Topics
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Biomes
Biodiversity
How Do We Benefit from Biodiversity?
What Threatens Biodiversity?
Human-Caused Reductions in
Biodiversity
• Protecting Biodiversity
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SAVANNA
Serengeti National Park
Dry, thornshrubland,
Africa
http://www.summitelgin.org/grassland_web/Tropical%20Grasslands/Plan
ts.html
Impalas in African savannas
http://www.summitelgin.org/grassland_web/Tropical%20Grasslands/Animals.html
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Sudan
Deserts. The Encroaching Wilderness. Ed. Allan and Warren. 1993 Oxford University Press
Tranvsvaal, South Africa
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West Africa
Deserts. The Encroaching Wilderness. Ed. Allan and Warren. 1993 Oxford University Press
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•Low rain
•Deep roots
•Lots insects
•Plants store
water
•Adapted to
higher soil
salt levels
Joshua Tree National Park
•Plants,
animals
adapted =
heat, low
HOH, repel
enemies
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Chaco Canyon, San Juan Basin, New Mexico
http://www.ratical.com/southwest/ChacoCanyon.html
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WETLANDS
Okefenokee Swamp, Georgia
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Freshwater ecosystems are influenced by
surrounding terrestrial ecosystems. In turn, riparian
areas are productive because of nutrient deposition by
the river. Can also have pollutants transported by river
to terrestrial areas.
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Freshwater ecosystems are impacted by anything that
happens uphill or upstream from them.
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WETLANDS
Coastal wetlands – salt
marsh ecosystems
One most productive
systems in the world
Major breeding, nesting
habitat for waterfowl,
shorebirds
Highly human impacted Burn easily
Coral reefs - Most productive ecosystems in world
in terms of energy cycling; strongly impacted by
land uses from land (sewage wastes)
Tolerance Limits
Biosphere 2
Biodiversity
Biodiversity - the variety of living things - three
types essential:
• Genetic diversity - variety of different versions of
the same genes within a species
• Species diversity - number of different kinds of
organisms within an ecosystem
• Ecological diversity - complexity of a biological
community (number of niches, trophic levels, etc.)
Generally the greater the biodiversity in an ecosystem the
more resistant/resilient the system is to a disturbance.
How many
species are
there?
??? 50 million???
Biodiversity Hot Spots – rare and potentially
endangered species. Many hot spots contain
endemic species (species are found only in that
region)
Most of the world’s biodiversity - concentrated near the
equator (tropical rainforests, coral reefs), islands, coastal
areas, mountain tops
Costa Rica, taxonomists identifying
all insects in the country
How do we benefit
from biodiversity?
Where do we
collect most of
these species?
Food,
Drugs & Medicine
Ecological benefits,
Aesthetic & Cultural
benefits Mangosteens, Indonesia
What Threatens Biodiversity?
Human Activities That Reduce
Biodiversity
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Habitat destruction and fragmentation
Hunting and fishing
Commercial products and live specimens
Predator and pest control
Exotic species introduction
Diseases
Pollution
Genetic assimilation
Human Disturbance Map
Degraded grasslands
with sheep,
TUNDRA
Photo: B Hecht
Iceland
About 200 years ago,
the American
passenger pigeon was
the world’s most
abundant bird.
Population: 3-5 billion
Overhunting and
habitat destruction
caused its extinction.
Trade in Products from Endangered Species
Trade in Wildlife
About 75% of all saltwater tropical aquarium fish sold come
from coral reefs of the Philippines and Indonesia, where
they are commonly caught with dynamite or cyanide.
Live in a human ecosystem where humans are the top
predator!
SO Humans eliminated or drastically reduced the population
of top predators that might hunt or harm us, or eat our food
http://www.sel.barc.usda.gov/acari/index.html, http://www.dfwpest.com/scorpion.htm
cockroaches
Introduction
of Exotic Species
Stress
zone
Species
absent
Optimal range
Abundant species
Stress
zone
Fewer
species
Fewer
species
Species
absent
OPTIMUM ENVIRONMENT
Most species do not survive when introduced into different
habitats because they have specialized habitat
requirements. Others do well and most of our invasive
species are very effective in competing for limited
resources with native species.
Classic example of an invasive species –
considered by some to be the biggest threat to
biodiversity conservation (this is a western world
view)
Species Status?
• Endangered species – considered in imminent
danger of extinction
• Threatened species – likely to become
endangered (at least locally)
• Vulnerable species – naturally rare or have
been depleted by human activities to a level
that puts them at risk
Protecting Biodiversity
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Hunting and fishing laws
The Endangered Species Act (ESA) 1973
Recovery plans (rebuild pop)
Minimum viable populations
Private land and critical habitat (HCPs)
Reauthorization of the ESA-exp’d in 1992.
plants & animals above humans? what now???
• International wildlife treaties
(eg, Convention on International Trade in Endangered
Species-CITES, 1975)
Recovery Plans
Only 40 Florida
panthers
remain in the
Everglades. We
spend millions
of dollars to
protect them,
but the
population may
be too small to
be viable.
Protecting biodiversity conflicts with
indigenous community’s needs to survive and
obtain sufficient food for themselves
Pet parrots, Amazon Brazil,
TROPICAL FORESTS
Photo: K Vogt
Biomes & Biodiversity
• Biomes – life zones w similar climatic, soil, etc
conditions
• Biodiversity – variety of organisms
• Biodiversity hot spots – regions of threatened &
potentially endangered species
• Benefits of biodiversity – food, drugs/medicines,
ecological & aesthetic & cultural benefits
• Human-Caused Reductions in Biodiversity –
habitat destruction, fragmentation, hunting/fishing,
products, predator/pest control, exotic species intro,
diseases, pollution, genetic assimilation
• Protecting Biodiversity – laws, Endangered Species
Act, recovery & conservation plans, reintroductions,
minimum viable populations, international treaties