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ECOSYSTEMS
CHAPTER 10
WHAT IS AN ECOSYSTEM?
An ecosystem is all the living things and
nonliving things in a given area
 Examples of ecosystems:
◦ Forests, deserts, grasslands, rivers,
beaches, and coral reefs

Abiotic Vs. Biotic Factors

Abiotic factors: the nonliving parts of an
ecosystem
◦ Ex. Sunlight, temperature, air, water, soil

Biotic factors: the living OR once-living
things in an ecosystem
◦ Ex. Bacterium, dead organisms(fallen leaves),
decayed plant matter in soil, people, animals,
trees, etc
Parts of an Ecosystem
Habitat: the place within an ecosystem that
provides food, water, shelter, and other biotic
and abiotic factors that an organism needs to
survive and reproduce
 Population: All the organisms of the same
species that live in the same area at the same
time
 Community: ALL of the populations living in
the SAME area at the SAME time

Too Many Fish in the Sea?

Most populations change over time.
◦ Increase = production of offspring
◦ Decrease = death of individuals
◦ Move = changes in abiotic/biotic factors

How can you determine if an area contains too much of
something?
You could calculate the population density!

Population Density: the size of a population compared to
the amount of space available
◦ POPULATION DENSITY FORMULA:
number of individuals
unit area or volume of space
Relationships Within Ecosystems
How does a niche differ from a habitat?
 A habitat is a PLACE within an ecosystem
that provides abiotic and biotic factors
that an organism needs to survive and
reproduce.
 A niche is the WAY a species interacts
with abiotic and biotic factors to obtain
the needs to survive

◦ Example: different food source
Relationships within an ecosystem
continued….
Competition: describes the demand for
resources such as food, water, and shelter,
in short supply in a community.
 ** Competition limits population size


Overpopulation: occurs when a
population becomes so large that it
causes damage to the environment
Relationships within Ecosystems

Predation: the act of one organism, a
predator, feeding on another organism, its
prey.
 Ex. Dragonfly
capturing a fly-Dragonfly is the ????
And Fly is the????

Symbiosis: a close, long term relationship
between two species that usually involves
an exchange
3 Types of Symbiosis

Mutualism: a relationship in which both
organisms benefit

Commensalism: a relationship in which
ONE organism benefits but NEITHER is
harmed

Parasitism: relationship in which ONE
organism benefits and the other is
harmed