2.1 Ecosystem Structure
Ecosystems Have Living and
Nonliving Components
• Abiotic – Non-living
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Water
Air
Nutrients
Rocks
Heat
Solar energy
• Biotic- Living
• Any living or once living
Major Biotic and Abiotic Components of an
Ecosystem
Fig. 3-6, p. 59
Ecologists Study Interactions in Nature
• Ecology: Study of how organisms interact with each other and
their environment
• Species- A particular type of organism
• Populations- A group of individuals of the same species living
in the same place
• Communities-Populations of different species living in the
same place, and potentially interacting with each other
• Ecosystems-A community of different species interacting with
one another and with their nonliving environment of matter
and energy
• Habitat-An environment where a species lives
• Niche- How an organism makes a living (role/job)
Biosphere
Parts of the earth's air, water, and soil
where life is found
Ecosystem
A community of different species
interacting with one another and with
their nonliving environment of matter
and energy
Community
Populations of different species
living in a particular place, and
potentially interacting with each
other
Population
A group of individuals of the same
species living in a particular place
Organism
An individual living being
Cell
The fundamental structural and
functional unit of life
Molecule
Chemical combination of two or
more atoms of the same or different
elements
Atom
Smallest unit of a chemical element
that exhibits its chemical properties
Water
Hydrogen
Oxygen
Stepped Art
Fig. 3-5, p. 58
Food Chain vs. Food Web
• Food Chain – shows flow of energy from one
organism to another
Food Chain vs. Food Web
• Food web- shows flow of energy interconnected to
many organisms (all possible food chains)
Lake Michigan Food Web
Trophic Levels
• Trophic Level = feeding level (position of an organism
on a food chain)
Producers and Consumers
• Producers- (autotrophs “self-feeders”)--Plants
• Perform Photosynthesis:
• Use sun energy to make their own food
• Waste product is oxygen
• Consumers- (heterotrophs “other feeders”) –
Organisms that obtain nutrients from living things
• Primary consumers = Herbivore (eats plants)
• Secondary consumers – omnivores (eats both plants
and animals) primary consumers and producers
• Tertiary consumers- Carnivores(eat meat) other
consumers
Producers
Fig. 3-7a, p. 59
Consumers
Fig. 3-8a, p. 60
Producers and Consumers Are the Living
Components of Ecosystems (2)
• Decomposers
• Consumers that release nutrients
• Ex. Bacteria, Fungi
• Detritivores (scavenger)
• Feed on dead bodies of other organisms
• Ex. Earthworms, Vultures
Decomposer
Fig. 3-9a, p. 61
Detritivores and Decomposers
Fig. 3-10, p. 61
2.1.4 Ecological Pyramids
• Pyramids show differences that exist between
trophic levels
• Always a decrease of energy and biomass when
moving up a pyramid
• Only ~10% of the energy from the one level is passed
to the next level
• ~90% of energy is used released as heat (respiration)
• Three types of pyramids (biomass, numbers, energy)
Pyramid of Biomass
• Biomass (g m -2)
• Dry weight of all organic matter of a given trophic level in a
food chain or food web
Pyramid of Energy
• Pyramid of energy flow (J m-2 yr-1)
• Less chemical energy for higher trophic levels
Pyramid of Numbers
• Pyramid of numbers
• Shows the total number of organisms at each trophic
level
• Snapshot in time
Pyramid structure
• Bioaccumulation- concentration of toxins increases
in an individual organism’s tissues
• Biomagnification- concentration of toxins increases
as the trophic level increases
Biomagnification of DDT
What is DDT?
• Dichlorodiphenyltrichloroethane…that’s why we call
it DDT!!
• Insecticide used to fight malaria
• Started in 1948 to kill mosquitoes and fight spread of
malaria
• Stored in the fats of organisms, and biomagnifies
through the food chain
• Predatory bird populations suffered
• Banned in the US in 1972
2.1.7 Population Interactions
Competition (- / -)
• Competition – Two or more organisms in the same
community seek the same resource at the same
time.
• Two types
• Interspecific – between two different species
• Intraspecific- within an individual species
• Resources must be in limited supply (food, water,
light, shelter, space, mates)
• Mountain goat competition for mates
Inter or intra???
Predation ( + / -)
• Predation- One species killing another and
consuming it in the process
• Lions prey on wildebeests in Africa
Herbivory (+/-)
• Herbivory- consumption (grazing) of producers by
primary consumers
• Caterpillar eating leaf
Parasitism (+/-)
• Parasitism – Organism that lives on or in another
host organism
• Parasite benefits and host is harmed
• Tapeworm in human intestine
Mutualism (+/+)
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Mutualism- both organisms benefit from interactions
Best example is Lichen
Lichen is algae and a fungus
Fungus provides structure and algae provides food
source
Commensalism (+ / 0)
• Commensalism – One organism benefits and the
other organism is not affected
• Clownfish and the sea anemone
Ammensalism (- / 0 )
• One species is harmed and another species is not
affected.
• Ex. Algae blooms can lead to the death of many
species of fish, however the algae do not benefit
from the deaths of these individuals.
Neutralism (0 / 0)
• Two organisms do not affect each other
• Essentially they have no relationship
• Dandelions and salmon in a ecosystem (have little or
no effect on each other
Big Ideas
1. Some organisms produce the nutrients they need,
others survive by consuming other organisms, and
some recycle nutrients back to producer organisms.
2. Human activities are altering the flow of energy
through food chains and webs and the cycling of
nutrients within ecosystems and the biosphere.