Download What Shapes An Ecosystem?

ECOLOGY NOTES (Chapters 2-5)
Ecology is the study of the interactions between organisms
and their environment.
Ecologists study both the living and non-living parts of the
environment because they are interdependent. The living
factors in an environment are called biotic factors (plants,
animals, etc.). The non-living factors of the environment
are called abiotic factors (water, amount of sunlight,
temperature, humidity, soil composition, etc.)
Levels of Organization
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There are many levels of organization that ecologists may
study.
An individual living thing is an organism. (Examples: a
cat, a bear, a maple tree)
A population is a group of organisms of the same species
living in the same area. A species is a group of organisms
so similar that they can interbreed and produce fertile
offspring. (Examples: a maple tree stand, an apple
orchard, all of the cardinals in Winston-Salem, all of the
grey squirrels in your backyard)
A community is all of the different populations of living
things that live in the same area. (Example: all of the trees,
squirrels, cardinals, blue jays, crows, insects, etc. in your
backyard)
An ecosystem is all of the living organisms in a particular
environment AND the non-living factors that in their
environment (water, air quality, humidity, etc.).
A biome is a group of similar ecosystems that have the
same climate and similar communities of organisms.
(Examples: desert, tundra, tropical rainforest)
All of the portions of the Earth that support life make up
the biosphere (Earth).
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Ecological Methods
To gather information on populations, ecosystems, etc….
ecologists use 3 main methods: observing, experimenting,
and modeling.
Energy Flow
The main source of energy on Earth is the sun.
Organisms that capture energy directly from the sun to
produce food are called autotrophs or producers. Some
autotrophs use inorganic chemical compounds (like sulfur
or methane) to produce their own food.
Autotrophs that use the sun’s energy directly make food
using the process of photosynthesis. Photosynthesis
converts carbon dioxide, water and light energy (from the
sun) into sugars and oxygen.
Autotrophs that use chemicals to produce their food use a
process called chemosynthesis.
Organisms that cannot make their own food must consume
other organisms for their energy and they are called
heterotrophs or consumers.
There are many different types of heterotrophs:
1. Herbivores: eat plants (producers) only
2. Carnivores: eat meat (other consumers) only
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3. Omnivores: eat both plants and meat
4. Decomposers (detritivores): break down dead plant
and animal remains; recycle nutrients
Feeding relationships
Energy flows through an ecosystem in one direction from
the sun or inorganic chemicals to autotrophs (producers)
and then to various heterotrophs (consumers). The
relationships between producers and consumers connect
organisms into feeding networks based on who eats whom.
A food chain is a series of steps that shows how energy is
transferred by eating or being eaten.
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A food web is a more complex diagram that shows all of
the possible feeding relationships in an ecosystem.
Both food chains and food webs always start with a
producer(s). The arrows are drawn to show which way
energy is being transferred.
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Each step in a food chain or food web is called a trophic
level. Producers always make up the first trophic level.
Consumers make up the second, third, or higher trophic
levels. Each consumer depends on the trophic level below
it for energy.
Producers always begin the food chain, food web, or are
found at the base of an ecological pyramid-plants, algae,
phytoplankton….Producers have the most energy because
they use sunlight directly to make their own food
(photosynthesis).
Primary consumers come next, they are HERBIVORES
that feed on the producers-cows, grasshoppers, caterpillars,
deer, small fish…
Secondary consumers are CARNIVORES that eat the
herbivores-lion, hyenas, dogs, cats…
Tertiary or third-level consumers can be carnivores or
OMNIVORES that eat both producers and consumers.
Decomposers (bacteria/fungi) feed from all levels of a food
web or food chain once the organisms die.
Ecological Pyramids
An ecological pyramid is a diagram that shows the relative
amounts of energy or matter in each trophic level of a food
chain or food web. There are 3 types: energy pyramid,
biomass pyramid, and a pyramid of numbers.
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Energy pyramids show how much energy is passed from
one trophic level to the next. Only 10% of the energy
from one trophic level is transferred to the next trophic
level. This is because much of the energy that is being
consumed is used for life processes: respiration,
reproduction, movement. Producers are always found at
the base of the pyramid because they have the most
energy.
Biomass pyramids show the amount of potential food
available for each trophic level in an ecosystem. The total
amount of living tissue within a given trophic level is called
biomass.
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A pyramid of numbers is based on the number of individual
organisms at each trophic level.
Cycles of Matter
Energy only flows one-way through an ecosystem BUT
matter is recycled within and between ecosystems.
Matter can cycle through ecosystems because it is not used
up but transformed.
Every living organism needs nutrients to build tissues and
carry out essential life functions. Nutrients are passed
between organisms and the environment in cycles.
Carbon Cycle
Carbon plays many roles in the environment: ingredient in
living tissues, part of the skeleton, found in rocks, forms
carbon dioxide gas (CO2), used by plants in photosynthesis,
given off by plants and animals during respiration.
Four main processes move carbon through its cycle:
1. Photosynthesis, respiration, and decomposition
take up and release carbon and oxygen.
2. Erosion and volcanic activity release carbon dioxide
to the atmosphere and oceans.
3. Burial/decomposition of dead organisms and their
conversion to coal and fossil fuels store carbon.
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4. Mining, cutting, burning forests and fossil fuels
release carbon dioxide into the atmosphere.
Climate
Climate is an abiotic factor that refers to the average yearafter-year conditions of temperature and precipitation in an
area.
The Greenhouse Effect
Temperatures remain within a suitable range for life
because of the insulating actions of the atmosphere
surrounding the Earth.
Carbon dioxide, methane, water and other atmospheric
gases trap heat energy and maintain Earth’s temperature
range.
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What Shapes An Ecosystem?
Biotic and Abiotic Factors
Biotic factors are all of the organisms (living things)
another organism may interact with.
Abiotic Factors are the physical, or non-living factors that
shape an ecosystem-temperature, precipitation, humidity,
wind, nutrient availability, soil type, and sunlight.
Biotic and abiotic factors determine the survival and
growth of an organism and the productivity of the
ecosystem in which the organism lives.
The area where an organism lives is called its habitat. A
habitat includes biotic and abiotic factors.
The niche is an organism’s job or role in its habitat. It
includes its place in the food web (trophic level-producer,
consumer…), what type of food the organism eats, the
physical conditions it needs to survive, how and when it
reproduces…
No two species can occupy the same niche in the same
habitat.
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Community Interactions
Organisms in ecological communities interact constantly.
This shapes the ecosystem.
Three types of interactions can affect an ecosystem:
competition, predation, and symbiosis.
1. Competition: occurs when organisms of the same or
different species try to use an ecological resource in
the same place at the same time.
 A resource can be: water, nutrients, light, food, space,
and mates.
 Competitive exclusion principle: no two species can
occupy the same niche in the same habitat at the same
time.
2. Predation: (predator-prey relationship); one
organism hunts and kills another for food (energy).
The predator is the hunter and the prey is the animal
that is killed.
3. Symbiosis: Two different species live closely
together.
a. Mutualism: (+,+), type of symbiosis where both
organisms benefit; example-CLOWNFISH/SEA
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ANEMONE, ANTS/APHIDS, FLOWERING
PLANTS/POLLINATORS
b. Commensalism: (+,0), type of symbiosis where
one organism benefits and the other is neither
helped nor harmed; EXAMPLEBARNACLES/WHALES, ORCHIDS/TREES
C. Parasitism: (+,-) One organism lives on or inside
the other (host) and harms it, one is helped the
other is harmed. EXAMPLES-TICK/DOG,
TAPEWORM/DOG. FLEAS, TICKS, LICE…
Ecological Succession:
Succession occurs when one ecosystem replaces another,
for example, a pond gradually fills in and becomes a
meadow.
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Ecosystems can change in response to human and natural
disturbances.
Primary succession occurs where no soil exists-bare rock,
land formed from volcanic eruptions. There is no soil, just
ash and rock.
The first species to populate such an area are called
pioneer species. Lichens and moss are common pioneer
species.
Secondary succession occurs when a disturbance changes
an ecosystem without removing soil-abandoned farmland,
fire-destroyed areas.
All succession ends in a climax community, a stable,
mature community of organisms that changes very little
over time.
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