Transcript 3.1 What is Ecology

Accelerated Bio Ecology Part II
Chapter 20: Community
Ecology
Chapter 22: Humans in the
Environment
20-1 Species Interactions of
Communities
Communities contain interacting populations of many species. 3 major types of
interactions between species:
1) PREDATION: predator eats all or part of an individual  the prey
 Predators survival depends on ability to capture food
 Adaptations of predators: venom, flesh-cutting teeth, sticky webs, speed
 Prey’s survival depends on ability to avoid capture
 Adaptations of prey: camouflage, chemical defenses (plants & animals),
mimicry (resembles another species) , thorns, spines
2) COMPETITION
• limited resources force competition among
living things in same niche.
• among same species = intraspecific
competition
• between different species = interspecific
competition
• all competition almost always produces
a winner and a loser (dies out)
• ex: two species of paramecium kept in
same culture…one species out competed
the other.
• the competitive exclusion principle:
no two species can occupy the same niche
at the same time.
• dividing resources can be a “truce” in the
competition for resources
• ex: one spruce tree can provide for three
different niches of warbler birds feeding on
high, middle, and low branches
• ** by dividing resources, competition helps
determine the number and types of species
in a community AND the niche each
species occupies
Predation, Herbivory and Keystone Species
• predator-prey: predators affect the amount of
prey and where prey can live and feed
• herbivore-plant: herbivores affect both the
size and distribution of plants and determine
where those plants can grow
• keystone species: a change in one species
can have drastic effects on many other
species in the community
• ex: Pacific NW: sea urchins eat giant kelp
stalks. Sea otters eat sea urchins.
• Otters are a keystone species- they keep
the sea urchin population in check
• Over hunting of the otters allowed urchin
population to explode  giant kelp forests
destroyed by urchin activity
• with no kelp, many animals were without
a habitat
• otters are now protected species, urchin
population is under control and kelp
forests have rebounded
3) Symbiotic Relationships
• symbiosis = “together living”.
• any relationship where 2 species live in
close association with each other.
• 3 main types of symbiotic relationships:
A) mutualism (“win-win”): Both benefit.
ex: sea anemone and clown fish. Clown
fish gets a protected home and the
anemone gets a defender when attacked
B) parasitism (“win-lose”): One benefits at the
harm of the other (host)
ex: tapeworm inside a human.
Tapeworm absorbs digested food of
host, the host’s cells starved for nutrition.
C) commensalism (“win-no harm/help”):
One benefits while the other is neither
harmed nor helped
ex: barnacles on a whale. Barnacles
benefit by motion of whale and the
movement of food particles over them.
No benefit or harm comes to the whale.
20-2 Ecological Succession: Primary and Secondary
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Succession: a progressive, predictable ecological change in a community
over time
In 1833, volcanic island of Krakatau completely destroyed by an eruption –
left completely barren.
2 years later, grasses are present
14 years later, 49 plant species and lizards, birds, insects, and bats
by 1929, a forest with 300 plant species were present.
today the island is a mature rainforest
HOW?: Primary Succession:
– begins with no remnants of the previous community
– pioneer species are first to colonize barren land
– ex: lichen (fungus and algae) turn rock into soil, turn N2 gas into
useful nitrogen forms, and add organic material to the soil
– certain grasses are also pioneer species
Secondary succession: occurs after a major event disturbs
a community (fire, flood, earthquake, hurricane)
• SOIL survives the disturbance
• plants re-colonize the area faster than in primary succession
• can also follow human activities like forest clearing and farming
• once plants are established, herbivores can move in and make
use of the food supply. Then, carnivores can move in
• if ecosystem is healthy, it may be restored to its natural state
prior to disturbance (the “climax” community)
• sometimes the human impact is so traumatic, a full recovery
through succession is not possible
Chapter 6:
Human Environmental Impact
“Humans affect regional and
global environments through
agriculture, development, and
industry in ways that have an
impact on the quality of Earth’s
natural resources, including soil,
water, and the atmosphere.”
• Humans:
– Rely on Earth’s life-support systems
– Affect our environment when we:
• Obtain food
• Eliminate waste products
• Build places to live
The Effect of Human Activity
• Agriculture - Supplies a dependable food source that can be stored
for later use
– Positives
• Enabled human settlements that ultimately led to modern civilization
– Negatives
• Impacts natural resources as >7 billion people!!! need
– Food
– Fresh water
– Fertile soil
– Fossil fuels (fertilizer & farm equipment)
• Development - Trend to move to suburbs & cities
– Positives
• High standard of living
– Negatives
• Produce lots of waste that affect air, water, & soil resources
• Uses up farmland
• Divides natural habitats into fragments
The Effect of Human Activity
• Industrial Growth – Industry & scientific know-how
– Positives
• Modern conveniences of life
• Comfortable homes, clothes, electronic devices
– Negatives
• Require energy and consume power
• Need to burn fossil fuels (coal, oil, & natural gas)
• Wastes discarded into air, water, & soil
Sustainable Development
• Renewable and Nonrenewable Resources
– Renewable – can be renewed or
replaced by a healthy ecosystem
• A single southern white pine
– Nonrenewable – natural processes
cannot replenish them in a reasonable
amount of time
• Fossil fuels (formed from buried
organic material over millions of
years)
• A whole forest of white pines
Sustainable Development
• Sustainable Resource Use
– Sustainable development
• Provides for human needs & wants
• Preserves the ecosystems that produce natural
resources
– What does it look like?
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Does not cause harm to the soil, water, and climate
Consumes as little energy and material as possible
Flexible to survive environmental stress/disasters
Takes into account human economic systems as well
as ecosystem goods and services
• SURVIVE AND IMPROVE
Using Resources Wisely: Soil
• Why is it needed?
– When healthy, supports agriculture and forestry
– Topsoil – absorbs/retains moisture but allows water
to drain
• What are we doing to destroy it?
– Allowing soil erosion – nutrients are washed
away with rain
• Desertification – over-plowing, overgrazing,
allowing land to be barren between plantings
• Deforestation – loss of forests
– Forests help to hold soil in place, absorb
CO2, absorb freshwater
 How can we protect it?
 Leaving stems and roots in place between plantings
 Crop-rotation
 Contour Plowing and Terracing – creating steps to
prevent water and soil from flowing downward
 Creating tree farms (makes trees a renewable resource)
Using Resources Wisely: Freshwater
• Why is it needed?
– Drinking water
– Industry
– Transportation
– Energy
– Waste Disposal
• What are we doing to destroy it?
– Overuse (Ogallala aquifer – took 1
million years to collect)
– Pollution
• factories, oil spills
• Industrial/Agricultural Chemicals
– Biomagnification – pollutants (like DDT, PCBs, heavy metals)
magnify as they move through the food chain from primary
producers to primary consumers, etc.
• Residential Sewage ()
Freshwater Resources
• How can we protect it?
– Protection of natural resources involved in water cycle
• Plants can filter out pollutants
– Watershed conservation – protecting
all inter-connected bodies of water
– Pollution control
• Sewage treatment
• Decrease pesticide use
– Use biological controls instead
of poisonous sprays
• Water conservation
– Drip irrigation
Using Resources Wisely: Atmospheric
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Why is it needed?
– Oxygen
– Absorption of UV radiation
– Regulation of global temperature
What are we doing to destroy it?
– Pollution (Industry, Burning Fossil Fuels)
• Smog - Ground Level Ozone
– Causes respiratory diseases
• Acid Rain – nitrogen and sulfur oxides mixing
with precipitation
– Damages plants, releases toxic elements from soil
• Greenhouse Gases – burning of fossil fuels releases CO2, CH4 and H2O
– Releases carbon dioxide into the air, contributes to global warming and
climate change
• Particulates – microscopic particles of ash and dust released by industry
– Can be inhaled and cause respiratory problems
How can we protect it?
– Emission standards
– Clean-air regulations
– Unleaded gasoline
Biodiversity:total of all the genetically-based
variation in all organisms in the biosphere
• Value of Biodiversity
– Ecosystem Diversity - variety of habitats, communities, and
ecological processes in that biosphere
• 1.8 million species already identified!
• 30 million more estimated yet to be discovered!!
– Species Diversity - number of different organisms in a
particular area
– Genetic Diversity – sum total of all different forms of genetic
information carried by a particular species
• Benefits of Biodiversity
• Sources of medicines
• Genetic diversity used to increase pest resistance
• Keystone species (if removed) can change entire
ecosystem
Biodiversity
• Threats to Biodiversity
– Altering habitats
– Hunting
– Introducing Invasive Species
– Releasing Pollution
– Contributing to Climate Change
• Conserving Biodiversity
– Protect Individual Species
– Preserve Habitats and Ecosystems
– Consider Local Interests
Meeting Ecological Challenges
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Ecological Footprint – total area of functioning land and water ecosystems
needed both to provide the resources an individual or population uses and to
make harmless the wastes that an individual or population generates
• The average American has an ecological footprint that is:
– 4x larger than global average
– 2x that of England
– >2x that of Japan
– 6x that of China
Ozone Layer
• Why is it needed?
– Ozone Layer – molecules of O3
– At ground level = pollutant
– Upper atmosphere = protection
against harmful UV radiation which
can cause cancer, eye damage and
decreased immunity
• What are we doing to destroy it?
– Primary problem is CFCs
(Chloroflurocarbons)
• Found in refrigerants, aerosol
cans and plastic foams
• How can we protect it?
– CFCs banned in the late 80’s
(Montreal Protocol), however residual
CFCs can remain in the atmosphere
for more than 30 years!!
Fisheries
• What is the problem?
– Despite increased efforts and new
technology, seafood catch
numbers continue to decline
• What are we doing to destroy it?
– Overfishing: Fish thought to be a
renewable resource
– Death rates (commercial
fishing) surpassed the birth
rates of the fish
• How can we protect it?
– Regulations put in place to limit
fish catches
– Certain areas closed to fishing
until populations recovered
(Sustainable Fisheries Act)
– Aquaculture – farming of aquatic
animals
Climate Change
• What’s the Problem?
– Global warming – increase in average
temperature of our planet (0.74ºC between
1906 and 2005) with 11 of the 12 warmest
years occurring between 1995-2006
– Melting sea ice
– Rising seal levels
• What are we doing to destroy it?
– Enhanced Greenhouse Effect not allowing
solar heat to move back into outer space
• Burning fossil fuels
• Automobile exhaust
• Industrial pollution
• How can we protect it?
– Alternative energy sources (water, wind,
solar)
– Decrease our ecological footprint