Chapter 4:
Ecology
Environmental Science
Ecology

The study of
how organisms
interact with
one another
and with their
nonliving
environment
Levels of Organization
 Organism
 Population 
Community  Ecosystem  Biome
 Biosphere
Levels of Organization
What is a species?
 Species:
Individuals that are similar
enough to breed and produce fertile
offspring
EX: Horse X donkey = mule
64 chromosomes
62 chromosomes
63 chromosomes
Horses and donkeys are different species.
If you breed them, the result is a mule
which can NOT have offspring!
What is a population?
 Population:
a group of interacting
individuals of the SAME species that
occupy a specific area at the same time
All populations have some
genetic diversity…
Genetic
Diversity:
individuals
vary in their
genetic
makeup
All populations have some
genetic diversity…
 Genetic
diversity
can help
populations
survive under
changing
environmental
conditions.
 Example:
Sickle cell anemia
Populations can change in:
1.
2.
3.
4.
Size
Age distribution
Density
Genetic composition
Layers of the Earth:
Atmosphere, Hydrosphere, Lithosphere
Layers of the Atmosphere
1.
2.
Troposphere: inner layer, 0-11
miles
Stratosphere: filters UV, 11-30
miles
Hydrosphere

1.
2.
3.
Consists of:
Liquid water
Ice
Water vapor
Lithosphere
The
earth’s crust and upper
mantle
Life on Earth depends
on 3 factors:
1.
Energy from the sun
2.
Cycling of matter
3.
Gravity
Why is the sun so
important?
Lights
and warms the planet
 Supports photosynthesis (how
plants make their own food)
 Powers the cycling of matter
 Drives climate and weather
systems
Solar Energy

66% of solar energy
1.
2.
3.
Warms the troposphere and land
Evaporates water and cycles it
Generates wind
The remaining 34% is reflected
back to space (clouds, dust,
chemicals, land)

What is a biome?
 Biome:
large regions of land
characterized by
1.
2.
A distinct climate
Specific life forms (especially plants) that
are adapted to it
 Examples:
Tundra, Tropical Rainforest,
Desert, Temperate Forest, Grassland
Aquatic Life Zones
Freshwater
 Ocean (or marine)

Do ecosystems have distinct
boundaries?
 Usually
no.
 Ecosystems tend to merge with the next in
a transitional zone called an ecotone.
 An ecotone is a region containing a
mixture of species from the adjacent
ecosystems and often species not found
between either bordering ecosystem.
Major Components of
Ecosystems
 Abiotic
 Biotic
factors: non-living things
factors: living things
Non-living Components of
Ecosystems
 Law
of tolerance: the existence,
abundance, and distribution of a species
in an ecosystem are determined by what
physical and chemical factors can be
tolerated by that species
Non-living Components of
Ecosystems
 Limiting
factor: Sometimes one factor
may be more important to an ecosystem
than another
1.
2.
Too much or too little of any abiotic factor
can limit or prevent growth of a
population even if al other factors are at a
proper level
Example: limiting factors for aquatic
ecosystems
Limiting factors for aquatic
ecosystems include:
Temperature
Sunlight
 Dissolved oxygen
 Nutrient availability
 Salinity

Part II: Energy Transfer in
Ecosystems
Autotrophs vs. Heterotrophs
 Autotrophs
(aka producers): make their
own food from compounds obtained
from their environment
 Two ways:
1.
2.
Photosynthesis—using sunlight energy
Chemosynthsis—using chemical energy
 Examples:
Green plants, algae, phytoplankton, a
few types of bacteria
Autotrophs vs. Heterotrophs
 Heterotrophs
(aka consumers): get
energy and nutrients by feeding on other
organisms or their remains
 Anything that has to eat
 Classified into different groups based on
what they eat
Types of Consumers
 Herbivore:
plant eater
 Carnivore:
meat eater
Types of Consumers
 Omnivore:
plant and meat
eater

Scavenger:
feed on dead
organisms (vultures
and flies)
Types of Consumers
 Detritivore:
feed on detritussmall parts of dead
organisms or feces
(crabs, termites,
earthworms)
 Decomposers:
recycle organic
matter (bacteria
and fungi)
What is biodiversity?
A
renewable resource; different life forms
and life-sustaining processes that can best
survive the variety of conditions currently
found on the earth
 The whole earth is not the same!!
Types of biodiversity
 Genetic
diversity: every organism, even in
the same species, has unique DNA
 Species diversity: habitats have a variety
of different living organisms
 Ecological diversity: various types of
communities on the planet (forests,
deserts, streams, lakes, oceans, etc.)
 Functional diversity: biological and
chemical processes or functions such as
energy flow and matter cycling needed
for the survival of living organisms
Why is biodiversity important?
 Gives
us resources that sustain us, make
our lives better, and help our economy
(food, wood, fibers, energy, raw materials,
chemicals, medicines, etc.)
 Provides
us with free recycling,
purification, and natural pest control
Loss of Biodiversity
 Reduces
the availability of ecosystem
services
 Decreases the ability of species,
communities, and ecosystems to adapt to
changing environmental conditions
 Biodiversity
is nature’s insurance policy
against disasters!!!
Energy Transfer: Food Chain
 Trophic
level: each step in a food chain
or food web
 Arrows represent flow of energy
 Only 10% of the energy passes from one
level to the next.
 Be able to identify producer, primary
consumer, secondary consumer, tertiary
consumer, and quaternary consumer
Food Webs
Same rules
from food
chains apply.

Sometimes
a consumer
can be on
more than
one trophic
level.
Ex. Owl- secondary
consumer and tertiary consumer

Ecological
Efficiency
 The
percent of
usable energy
transferred as
biomass from one
trophic level to the
next—normally 10%
Pyramid of
Energy Flow
 Illustrates
energy
loss for a simple
food chain passing
a 90% energy loss
with each transfer
Pyramid of
Numbers
 The
number of
organisms at each
level
Biomass Pyramid
 Represents
the
storage of biomass
at different levels
 Biomass= mass per
area
Part III: Biogeochemical
Cycles
Energy & Matter
Energy
can move through an
ecosystem.
Matter also cycles through the
ecosystem.
Matter is never destroyed, only
transformed.
Biogeochemical Cycles
 The
nutrient atoms, ions, and molecules
that organisms need to live, grow, and
reproduce are continuously cycled from
the non-living environment (air, water, soil,
and rock) to living organisms and then
back again.
Biogeochemical Cycles
 Four
atoms of elements make up 90% of
the bodies of most organims:




Carbon
Hydrogen
Oxygen
Nitrogen
 These
same molecules are passed around
again and again in the biosphere through
biogeochemical cycles.
Biogeochemical Cycles

3 Types of Cycles:
1.
Hydrologic—Water
Biogeochemical Cycles

3 Types of Cycles:
2.
Atmospheric—Gaseous
Biogeochemical Cycles
3 Types of
Cycles:

3.
Sedimentary
—Not
Gaseous
Main Processes of Water Cycle

Evaporation: water to vapor
Transpiration: evaporation
from plants


Condensation: vapor to water

Precipitation: rain, etc.
Main Processes of Water Cycle

Infiltration: movement of water
into the soil

Percolation: flow of water into
ground water

Runoff: movement back to the
sea
Dew Point
Temperature at which
condensation occurs

Absolute Humidity
Amount of water vapor found
in the air

Ground Water
Water stored in the cracks and
pores of rocks

Aquifer
Water-laden rock

Water Table
The level below which the
ground is completely saturated
with water

Chapter 4 Vocabulary Part
I
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Ecology
Organism
Population
Genetic diversity
Habitat
Community
Ecosystem
Biosphere
Atmosphere
Hydrosphere
Lithosphere
12.
13.
14.
15.
16.
17.
18.
19.
Greenhouse
effect
Biome
Climate
Ecotone
Abiotic
Biotic
Autotroph
Heterotroph
Chapter 4 Vocabulary Part II
20.
21.
22.
23.
24.
25.
26.
27.
28.
Herbivore
Carnivore
Omnivore
Scavenger
Detritivore
Detritus feeder
Decomposer
Food Chain
Trophic Level
29.
30.
31.
32.
33.
34.
35.
36.
Food Web
Biomass
Nutrient
Water cycle
Carbon cycle
Nitrogen cycle
Phosphorus cycle
Sulfur cycle
(Can number 1-17 if
you want!!)
Study for Test (1/22 & 1/23)
 All
vocabulary
 All notes: Ch. 4 Ecology Part I and Part II,
Biogeochemical Cycles notes and
pictures
 Know how to create/analyze a food
chain or food web (name each trophic
level, how to do the arrows, etc.)