Download SB4b Explain the flow of matter and energy through ecosystems by

SB4b
Explain the flow of matter and
energy through ecosystems by
•Arranging components of a food
chain according to energy flow
•Comparing the quantity of energy
in the steps of an energy pyramid
•Explaining the need for cycling of
major nutrients (C, O, H, N, P)
Ecosystems
Chapter 13.2 Page 402
An ecosystem
includes both
Biotic and Abiotic
factors.
Characteristics of Life:
BIOTIC
FACTORS
What is Life?
1) Made up of Cells
•
•
•
Smallest unit of life
Unicellular – Single-celled organism
Multicellular – Many-celled organism
2) Reproduction
•
•
•
Replacing yourself so the species doesn’t die out
Sexual – two cells from different parents unite
Asexual – a single parent
Life Continued…
1) Obtain and use energy
•
•
•
•
Chemical reactions used to power an organism’s
body
Gives energy for growth, reproduction, etc.
Three methods for obtaining energy:
• Photosynthesis
• Breaking down dead things
• Eating
All energy comes from the sun.
More about life…
1) Homeostasis
•
•
Keeping internal conditions “normal”
For example, body temperature and shivering
2) Based on a universal genetic
code
•
•
All organisms are based on a genetic code, usually
Deoxyribonucleic Acid (DNA)
Controls how you pass on your traits
And more about life …
1) Evolution
•
•
•
Organisms Change over time
Organism adapts, survives, reproduces, and passes
on traits that allowed it to adapt.
If an organism can’t adapt, it dies off (Natural
Selection)
2) Respond to the Environment
•
•
Organisms and species depend upon and
interconnect with one another
React to changes around the organism
And finally…
1) Grow and Develop
•
Organisms change over their lifetime; have a
distinct life cycle
Biotic
Biotic factors are
living things, such
as plants, animals,
fungi, and bacteria.
Biotic
Each organism plays a
particular role in the
ecosystem. For example,
earthworms play a key
role in enriching the soil.
Abiotic
Factors are nonliving things such
as moisture, temperature, wind,
sunlight, and soil. The balance
of these factors determines
which living things can survive in
a particular environment.
For example:
Coral reefs near salt
marshes have more
fish than reefs
farther out at sea.
Why?
Mangrove trees in
the marshes provide food
and shelter for newly
hatched fish.
Abiotic factors that affect
the growth of trees include
low levels of oxygen &
changing levels of salinity
due to daily tidal changes.
What are abiotic
factors?
• Temperature
• Sunlight
• Humidity
• Water
• Soil type
• Minerals

Moisture.
Copyright © 2010 Ryan P. Murphy

Temperature.
Copyright © 2010 Ryan P. Murphy

Wind.

Light.

Soil.

Nutrients.
Changing one
factor in an
ecosystem can
affect many
other factors.
An ecosystem is
a complex web of
connected
biotic and abiotic
factors.
You may not think of
yourself as part of the
ecosystem, but humans,
like other species, rely on
the environment for
survival. All species are
affected by changes to
biotic and abiotic factors
in an ecosystem.
Biodiversity
Biodiversity is the
assortment, or
variety, of living
things in an
ecosystem.
Species Diversity
An area with a high
level of biodiversity,
such as a rain forest,
has a large
assortment of
different species
living near one
another.
The amount of
biodiversity found
in an area depends
on many factors,
including moisture
and temperature.
Biodiversity
Varies
Naturally
There is a trend
towards more
species in warmer,
wetter areas and
fewer in colder and
drier areas.
Numbers of bird
species occupying
areas of North
America.
Biodiversity
There are
many
measures of
biodiversity.
Considering
species
diversity,
more diverse
communities
tend to be
more
productive.
Biodiversity
Remember, however, that this is one set of communities.
Why Worry About the Relationship
Between Biodiversity and
Community Stability?
Because this understanding is essential
for knowing how many species and of
what types can be lost before a
community collapses.
Science (2005) 309:90
We really don’t have a satisfying answer to this fundame
There are Biodiversity “Hotspots”
Biodiversity hotspots for tropical rain
forest and chaparral ecosystems.
Less than 1% of Earth’s surface supports 20% of known plant
species and probably a greater portion of animal species.
Biodiversity hotspots are significant for conservation plans.
Biodiversity is Being Lost Rapidly Through Extinction
How rapid is the current rate of extinction? The
number’s hard to pin down, but generally accepted
estimates put it at 10-100 times the rate before extensive
human–induced environmental modifications.
For example, in the U.S. ~ 225 vascular plant species
have become extinct in the past 50 years and about 650
of the remaining 20,000 species are threatened.
Dire
News
Not all agree
that we’re
seeing a mass
extinction, but
it’s clear
species loss
has
accelerated
sharply above
background.
What are the Causes of Accelerated Extinction?
Habitat loss
Pollution
Overharvesting
Introduction
of exotic
species &
diseases
Effect of rabbit
introduction to Australia
Climate change
Keystone Species
A keystone species is a
species that has an
unusually large effect
on its ecosystem.
An example of a keystone species is
the beaver. By felling trees to
construct dams, beavers change freeflowing stream havitats into ponds,
wetlands, and meadows. This
modification leads to a cascade of
changes within their ecosystem.
Refer to Figure 13.6
Page 404
Beavers as
Keystone Species
Keystone species form & maintain a
complex web of life. Whatever
happens to that species affects all
the other species connected to it.
Pop Quiz
Define the following:
1. Biotic & give example
2. Abiotic & give example
3. Biodiversity
4. Keystone species & give
example
HAVE A
GREAT DAY!