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Ecology
What is Ecology?

Ecology is the study of interactions
of organisms and their environment.
Where does Energy Come From?
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All energy comes from the sun (either directly
or indirectly).
Energy flows in one direction -from the sun to
producers then through consumers. Energy is
not recycled! It is used or lost
as heat.
Producers/Autotrophs
Producer/Autotroph: Organisms that CAN
make their own food through photosynthesis
(Ex: plants, algae).
Process of Photosynthesis

sunlight
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Carbon Dioxide + Water
glucose + oxygen
chlorophyll
Consumers/Heterotrophs

Consumer/Heterotroph: Organisms that
CANNOT make their own food. They must
eat other organisms for energy.
 Herbivores- feed off plants
 Carnivores- feed off animals
 Omnivores- eat both plants and animals
 Detritivores/scavenger- feed on dead
remains (ex: earthworms, vultures)
Decomposers

Organisms that break down dead organic
matter and return nutrients to the soil for
producers

Ex: Bacteria, mushrooms, microorganisms
Feeding Relationships
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Food chain: series of steps in which organisms
transfer energy by eating and being eaten.
Food web: overlapping food chains
Trophic Level- each step in the food
chain/web.
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1st level: producer
2nd level: primary consumer
3rd level: secondary consumer
4th level: tertiary consumer
Examples of Food Webs
Ecological Pyramids
1. Energy Pyramid
 Shows the relative amount of energy available
at each trophic level.
 Organisms use about 10 percent of this
energy for life processes- the rest is lost as
heat.
Draw this pyramid and label
(Do not include examples- grass, mouse, snake, hawk)
2. Pyramid of Numbers

Shows the relative number of individual
organisms at each trophic level (draw the pyramid
below).
3. Biomass Pyramid

Represents the amount of living organic matter
at each trophic level. Typically, the greatest
biomass is at the base of the pyramid. (Draw the
pyramid below).
Biomass and amount of available energy
decreases as you go up the energy pyramid.
Recycling in the Biosphere

Unlike the one-way flow of energy, MATTER
IS RECYCLED through the ecosystem.

Matter is recycled because systems do not use
up matter, they transform it.
Water Cycle
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What is a cycle?
When rain falls on the ground, it either soaks into the
soil or runs across the surface of the soil.
When rainwater runs across the land, what body of
water might collect the rain?
From here, where might the water flow?
After the rain, the sun comes out and the land dries.
Where does the water that had been on the land go?
Water Cycle
Water moves between the ocean, atmosphere, and
land.
Steps of the water cycle:

Evaporation- water changes from liquid to gas

Transpiration- loss of water from a plant through
leaves.

Condensation-water vapor turns into tiny droplets

Precipitation- rain, snow, sleet, hail

Runoff- water comes from mountains, etc.

The Water Cycle
Plants vs animals

What is the relationship between plants and
animals?
Carbon-Oxygen Cycle
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Step 1:Carbon dioxide released into
atmosphere by volcanic activity, respiration,
human activity (burning fossil fuels), and
decomposition of matter.
Step 2: Plants take in the carbon dioxide and
use it to make food (photosynthesis).
Step 3: Food is passed along the food chain
from producer to consumers.
Nitrogen Cycle
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Nitrogen gas makes up 78% of earth’s
atmosphere- not usable to plants and animals.
Bacteria that live in the soil convert nitrogen
gas to a usable form for plants through
nitrogen fixation.
Plants take in the nitrates and pass them along
the food chain to animals.
Label and Id

Look at the worksheet. Label and identify
each cycle.
The Role of Climate

Climate: average, year-after-year conditions
of temperature and precipitation in a
particular region.
What Shapes An Ecosystem?
Climate: the average, year-after-year conditions of
temperature and precipitation in a particular region.
Biotic Factors: anything living that affects the
environment.
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Predators, animals, plants, bacteria
Abiotic Factors: anything non-living that affects the
environment.
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Water, soil, temperature, climate, rocks
Predation: one organism feeds on another
Predator: the eater
Prey: the food
Habitat: area where an organism lives

Ex: a tree
Niche: role or position a species has in its
environment.

Ex: the role of a predator feeding on its prey.
Interspecific competition: competition among
populations of different species:

Example: different birds competing for a place to
build a nest on a tree
Intraspecific competition: competition among
members of the same species

Example: two birds of the same species competing
for a mate.
Relationships among Organisms
Symbiosis: 2 or more organisms living together
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Mutualism: both species benefit
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Commensalism: one species benefits from
relationship, the other is unaffected.
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Ex: bee and flower
Ex: barnacles on whales
Parasitism: a parasite lives on or near the
host and harms the host.

Ex: tapeworms and ticks on animals
Mutualism
Commensalism
Parasitism- tapeworm in mammal
How do Ecosystems Change?
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Ecological succession: natural changes in an
ecosystem in response to disturbances
(natural disasters).
Two Types: Primary and Secondary
Primary Succession
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Primary Succession: the formation of new
land caused by volcano, avalanche, glacier.
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No soil exists
Pioneer organisms -first organisms to exist after
primary succession (Ex: moss and lichen)
Series of Events in Primary
Succession
Bare Rock- Primary Succession
Pioneer Organisms- Lichen
Pioneer Organisms- Moss
Secondary Succession
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Secondary Succession- follows the
destruction of the land caused by a
disturbance that leaves the soil intact.
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Causes: fire, flood, cut land, drought, windstorm
Does NOT remove soil.
Climax Community: the point of growth
after succession when the plants are most
stable and mature (trees).
Series of Events in Secondary
Succession
Secondary Succession
Click on the website below to
complete the succession computer
lab assignment.

http://ilo.ecb.org/SourceFiles/succession.swf
Ecological Populations
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Population – group of organisms of the
same species living in the same area.
Population Size/Density – Number of
organisms in population
Population growth –change in population
over time (increase, decrease, stay same).
Biotic Potential – highest rate of
reproduction under ideal conditions
Factors that Affect Population Size
1) # of births
2) # of deaths
3) # of individuals entering or leaving the area:
 Immigration – movement of individuals
INTO an area over a given period of time.
 Emigration – movement of individuals
OUT of an area over a given period of time.
Population
Graphs
Exponential Growth: J-Curve
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Occurs when the individuals of a population
reproduce at a constant rate.
Not realistic because populations usually a
limit to their resources.
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At first, the number of individuals in an exponentially
growing population increases slowly. Over time, however,
the population becomes larger until it approaches an
infinitely large size. Under ideal conditions with unlimited
resources, any population can grow exponentially.
 Graph is called J-Curve
 Doesn’t exist in many populations.
 Can be seen in bacteria (b/c population size
doubles every 20 minutes).
Logistic Growth- S Curve
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A realistic growth curve
Most populations show this curve because
resources are limited.
Population grows fast (exponentially) then slows
or stops because it reaches its carrying capacity.
Carrying Capacity: the maximum number of
individuals a population can support.
Logistic Growth- S Curve
Carrying capacity
Time (hours)
Limiting Factors
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Limiting Factors - anything that keeps organisms
from reaching their biotic potential
Density Dependent Factor- organism is responsible
for doing:
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Competition
Predation
Parasitism
Disease
Human Impacts
Density Independent Factor- organism has no control
over.
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Natural Disasters
Predator – Prey
Population Graph
60
2400
50
2000
40
1600
30
1200
20
800
10
400
0
1955 1960
0
1965
1970
1975
Moose
1980
Wolves
1985
1990
1995
Human Population Growth
Curve
Industrial
Revolution
begins
Agriculture
begins
Plowing
and
irrigation
Bubonic
plague
Age Distribution Graph
U.S. Population
Males
Females
Rwandan Population
Males
Females
Human Impacts on
the Environment
What is Biodiversity?
Why is it Important?
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Biodiversity: the variety of life in an area.
Importance of Biodiversity:
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Organisms need to interact with other organisms in
a community.
Other organisms suffer when the organism they
feed upon is removed from the area or food chain.
Ecosystem balance, 02 for humans, diverse diets,
clothing and building materials, medicines.
Loss of Biodiversity can lead to…
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Threatened species: when a population of a
species quickly declines.
Endangered Species. when numbers become
so low that extinction is possible.
Extinction- the disappearance of a species
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Ex: African elephants went from a population of
about 3 million in 1970’s to 700,000 in the
1990’s.
Endangered Species in GA
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Purple pitcherplant—Sarracenia purpurea
Loggerhead Sea Turtle—Caretta caretta
How is Biodiversity Measured?
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Measured by counting the number of species
that live in an area.
More biodiversity in a tropical rain forest than
in a cornfield.
Causes of Biodiversity
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Introduction of non-native/exotic species
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Habitat Loss
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Changing a rain forest into a pasture
Habitat Fragmentation
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Introduce new species to environment on purpose
or by accident can cause problems to native
species.
Cutting in roads across a forest area
Habitat Degradation
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Damage to habitat by pollution
Bioaccumulation and
Biomagnification
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Bioaccumulation- the process of pollutants
entering a food chain usually at producer
level.
Biomagnification: the tendency of
pollutants to concentrate as they move from
one trophic level to the next in a food chain.
 Even small concentrations of chemicals in
the environment can find their way into
organisms in high enough dosages to
cause problems.
History of DDT
DDT stands for dichloro, diphenyl trichloroethane.
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Developed and used during WWII- given to
soldiers to help with lice & mosquitoes.
Heavily used in US from 1940s to 1970’s:
sprayed in public areas to kill mosquitoes.
Banned from US in 1972, but continues to be
used in other countries.
Used in Africa to kill mosquitoes and help
with spread of Malaria.
Rachel Carson
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DDT a serious problem…decline in bird
populations (top of food chain) and caused thin
egg shells.
Silent Spring written by Carson helped to bring
about formation of EPA and banning of DDT
Bird populations showed dramatic recovery
Even today, traces of DDT have been found in
every organism tested—even in human breast
milk throughout world
Human Impact on Land
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SOIL EROSION – is the wearing away of surface soil
by water and wind. Overplowing removes soil.
Desertification – the process of turning once
productive areas into deserts from a combination of
farming, overgrazing, and drought.
Deforestation: loss of forest leads to erosion.
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Takes away habitats for organisms to live.
Decreases the process of photosynthesis
Soil Erosion
Deforestation
Solutions to Land Depletion
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Contour plowing- fields
plowed across the slope
of the land
Leaving stems and roots
of the previous year’s
crops in place to hold
soil.
Replant trees that are cut
down.
Human Impact on Water
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Oil Spills threaten our water supply.
Improperly discarded chemicals can enter
streams and rivers.
Domestic sewage entering water ways
can cause an increase in bacteria growth.
Overfishing: fish stocks are harvested
faster than they can reproduce.
Water Resources
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What is being done?
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Limiting the catch of
fish
Certain fishing grounds
have been temporarily
closed
Aquaculture - farming of
aquatic organisms (see
picture to right)
Air Resources
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Smog - a mixture of chemicals that occurs as a graybrown haze in the atmosphere
The burning of fossil fuels can release pollutants that
cause smog and other problems in the atmosphere.
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This leads to toxins that enter the mouth, nose and lungs
causing health problems over the long term.
Gases released from the burning of fossil fuels combine
with water vapor to form ACID RAIN
Acid rain kills plants and changes the chemistry of soils
What is being done?
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Technology to control emissions from factory smokestacks
Strict automobile emission standards and clean air
regulations
Acid Rain
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"Acid rain" : term used to describe several ways that acids fall
out of the atmosphere.
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Wet deposition (acidic rain, fog, snow)
Dry depostion (acidic gases and particles).
Primary Cause of Acid Rain: sulfur dioxide (SO2) and
nitrogen oxides (NOx).
In the US, about 2/3 of all SO2 and 1/4 of all NOx comes from
electric power generation that relies on burning fossil fuels
like coal.
Acid rain occurs when these gases react in the atmosphere
with water, oxygen, and other chemicals to form various
acidic compounds. Sunlight increases the rate of most of these
reactions. The result is a mild solution of sulfuric acid and
nitric acid.
Air Resource Depletion
Global Warming
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Global Warming: the term used to describe an
increase in the average temperature of the
biosphere.
Temperatures have risen 0.5 degrees over the
last 120 years.
Estimated increase of 2˚C by end of 21st century
Even 1.3˚C affects polar ice cap melting (sea
level could rise 100 m, gradually going in 150
km or more)
Why is this a problem?
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Polar ice caps will continue to melt and could
rise enough to flood some low lying coastal
areas.
Storms and other weather disturbances could
become more frequent and severe.
Heat favors rodents, weeds, and insects that
reproduce and spread quickly.
Global Warming
Sunlight
Some heat
escapes
into space
Greenhouse
gases trap
some heat
Atmosphere
Earth’s
surface
Global Warming- The Cause?
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Human activities such as burning fossil fuels
and cutting down/burning forests has added
Carbon Dioxide into the atmosphere faster
than the carbon cycle can remove it.
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Possible Solutions: decrease the burning of fossil
fuels and deforestation.
Not all agree on the main cause and some
suggest that the rise in temperatures is due to
natural variations in climate.
Ozone Depletion
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The stratosphere, or "good" ozone layer extends
protects life on Earth from the sun's harmful
ultraviolet (UV) rays.
This natural shield has been gradually depleted by
man-made chemicals like chlorofluorocarbons
(CFCs).
A depleted ozone shield allows more UV from the
sun to reach the ground, leading to more cases of
skin cancer, cataracts, and other health problems.
What are CFC’s
(chlorofluorocarbons)
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CFC’s act as catalysts that enable UV light to
break apart ozone molecules.
CFC’s are chemicals that were once widely
used in:
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Aersol cans
Production of plastic foams
As coolants in refrigerators, freezers and air
conditioners.
Where do we see the Ozone
Problem?
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First problem sign of the ozone layer was a
gap or hole in the layer over Antarctica during
winter.
Over past 20 years the hole is getting larger.
Similar hole now appears over the Arctic.
By 1995, the northern ozone hole had grown
enough to expose parts of the US to higherthan-normal levels of UV.
Ozone Depletion
Ozone Depletion