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Transcript of Ecosystems
Biotic (living or once living)
All biotic factors have 4 basic needs
which are different from wants.
Biotic factors include:
- Producers, consumers (herbivores, carnivores, omnivores), decomposers, and scavengers.
Carnivores that kill and eat other animals (prey) are called predators.
Every organism in an environment has a role to play. This role is called their niche.
All biotic factors have adapted to
meet their basic needs.
An adaptation is a characteristic that helps biotic factors
to survive and reproduce in their environment.
An ecosystem is the interactions between abiotic and biotic factors in an environment.
3 symbiotic relationships
- mutualism, commensalism,
A food chain is a model that shows how
energy is passed from organism to organism.
Food webs show several
interconnecting food chains.
Very little energy is passed on from
one organism to the next. Most of the
energy an organism consumes is used
for itself and not stored in cells.
Because energy is lost, consumers
have to eat a lot of food to get their
A pyramid of numbers shows the
number of organisms being consumed
at each level of the food chain.
The total mass of all the organisms
in an ecosystem is called biomass.
Your ecological footprint is the impact
you have on Earth.
4 ways to help protect the environment:
- Reduce, reuse, recycle, recover.
Try to do them in this order.
Sustainability means that resources are being renewed as quickly as they are being used up.
Pollutants have disrupted many ecosystems.
PCB's (polychlorinated biphenyl) in paints and packing materials have leaked into the water and ground.
Mercury was disposed of as waste and leaked into the water supply.
DDT is a pesticide that was commonly used in the 40s-60s to kill harmful insects.
All of these pollutants have had harmful effects on ecosystems.
Pollutants move from level to level in a food web. However pollutants accumulate in higher level consumers. This is called biomagnification.
This has led to some species being threatened, endangered, or extinct.
Threatened: Numbers are declining.
Endangered: Is so rare that it is almost extinct.
Extinct: When a species no longer exists.
What is the leading cause of species extinction?
Cycles in Ecosystems
Consists of evaporation, transpiration, condensation, precipitation and run-off.
Evaporation and transpiration move water from the Earth into the atmosphere.
Condensation and precipitation return water to the Earth.
Carbon is put into the environment in many ways.
Biotic factors exhaling
Burning of fossil fuels
Carbon is taken out of the environment by photosynthesis.
Changes in Ecosystems
Succession is the predictable pattern of change in an ecosystem.
Pioneer Species: Is the first species to arrive in an area where no life has previously been. Ex) Lichen
Primary Succession: Occurs where no life had existed.
Lichens produce acids that break down rock. The soil they produce is poor, but mosses and ferns are able to survive. Once more, and higher quality soil appears, grass and plants begin to appear. Over time, grasses are replaced by small trees with shallow roots and then larger trees start to grow. This may take hundreds even thousands of years.
Secondary succession is the same as primary succession but it occurs in an area that had once supported life.
Ex) Re-growth after forest fires.
Changes also occur as a result of
Bioinvasion is the introduction of a non-native species into an ecosystem.
This could have negative effects if the species does not have any natural enemies to control their population.
Ecologists use environmental monitoring to check the condition of an ecosystem.
Environmental monitoring compares the results of investigations done at different times.
Biotic and abiotic factors can be monitored.
Ex) Temperature, number of birds
Monitoring happens throughout many years to get accurate data.
What types of animals are good to monitor?
Amphibians are excellent animals to monitor because they are very sensitive to changes in an ecosystem.
This makes amphibians great indicator species.
Ecologists use indicator species to help monitor ecosystems.
Extirpated: Extinct from only an area or areas but survive in other parts of the world.
Introduced Species also compete against other biotic
factors which could disrupt the balance of an ecosystem.
Changes to an ecosystem would also happen if
a keystone species were to be removed.
A keystone species plays a critical role in
maintaining the structure and balance of an
ecosystem. Ex) Sea Otters eat sea urchin which
Other factors also affect
and change ecosystems.
Limiting factors such as temperature and availability of basic needs can determine a species growth, population, size and distribution.
The study of this interaction is called
The scientists who study ecology
are called ecologists