Ecology Notes
What is ECOLOGY?

Ecology is a study of
connections in nature.

How organisms
interact with one
another and with their
nonliving
environment.
Figure 3-2
Levels of Organization
Organisms

The different forms of life on earth
Species

Organisms that can breed & produce fertile offspring
Population

A group of individual organisms
that belong to the same species
and live in the same area.
Community

Different populations that live &
interact in an area.
Ecosystem

The community plus their non-living
environment.
Biotic & Abiotic Factors of Ecosystems

Biotic (living)


Ex. – bacteria, animals, plants
Abiotic (non-living)

Ex. – humidity, solar energy, rocks, clouds
Biome

A group of ecosystems that have the same
climate

Ex. – Tundra, Taiga, Desert, Tropical Rainforest
Biosphere

All of the
combined portions
of the planet
where life exists,
including land,
water, and
atmosphere
Universe
Galaxies
Solar systems
Biosphere
Planets
Earth
Biosphere
Ecosystems
Ecosystems
Communities
Populations
Realm of ecology
Organisms
Organ systems
Communities
Organs
Tissues
Cells
Populations
Protoplasm
Molecules
Atoms
Organisms
Subatomic Particles
Fig. 3-2, p. 51
Energy Flow  Producers

Autotrophs - use solar energy or
chemical energy to make their own food
Chemosynthesis
Photosynthesis
Energy Flow Consumers
 Heterotrophs - get energy from the
food they eat

Herbivores – eats plants

Carnivores – eats animals (includes insects)

Omnivores – eats plants and animals

Detritovores – feed on dead matter (scavengers)

Decomposers – break down dead matter
Break it Down



Auto – self
Troph – feeding
Photo – light

Synthesis – make

Hetero – different

-vore – eat

Herb – plant

Carni – meat

Omni – all
Energy Flow 
Food Chains & Food Webs

Show how
energy &
nutrients move
from one
organism to
another through
the ecosystem
Energy Pyramid

Shows the amount of energy available at
each trophic level
Tertiary Consumer
Secondary Consumer
Primary Consumer
Producer
0.1%
1%
10%
100%
Energy Flow 
Losing Energy in Food Chains and Webs
 90%
of the
energy at each
energy level is
lost because
the organism
uses the
energy. (heat)
Energy Flow  Other Pyramids
Biomass pyramid – total amount of
living tissue
- Amount of potential food for each trophic
level
Pyramid of Numbers – # of individuals
at each level
- Does not always resemble a pyramid
- Forest – fewer producers than consumers
1 tree = lots of insects / birds
Interactions in an Ecosystem

Habitat – The area where an
organism or a population lives
Interactions in an Ecosystem

Niche - the total role of a species in
an ecosystem

All the physical and biological conditions a
species needs to live & reproduce in an ecosystem
Interactions in an Ecosystem 
Relationships

Predation – one organism captures and
feeds on another
Predator – Prey Cycle
SOURCE: Isle Royale Wolf/Moose Study | GRAPHIC: By Patterson Clark, The Washington Post - July 21, 2008
Interactions in an Ecosystem 
Relationships

Competition – organisms of the same or
different species attempt to use the same
resources at the same time
Interactions in an Ecosystem 
Relationships

Symbiosis – any relationship in which 2
species live closely together
Mutualism
 Commensalism
 Parasitism

Mutualism: Win-Win Relationship

Both of them benefit
Pollination of flowers by
insects
Oxpeckers and black rhinoceros
Commensalism: Using without harming

One is helped and has little or no effect on
the other
Burrs are carried by
animals. This helps
scatter the seeds for
the parent plant.
Parasitism: Sponging Off of Others

One benefits and the other is harmed
Mosquitos
Tapeworms
Carrying Capacity

The maximum # of individuals
that a given habitat can support
What is the carrying capacity?
Abundance of organisms
Upper limit of
tolerance
Few
No
organisms organisms
Population size
Lower limit of
tolerance
No
Few
organisms
organisms
Zone of
intolerance
Low
Zone of
physiological
stress
Optimum range
Temperature
Zone of
physiological
stress
Zone of
intolerance
High
Fig. 3-11, p. 58
4 Factors Determine Growth Rate
 1.
Birth rate
 2. Immigration
 3. Death rate
 4. Emigration
Which increase and which decrease
the population?
Limiting Factors
 Biotic
or abiotic resource that
limits size of population
Habitat Needs



Cover – shelter; trees, shrubs,
etc.
Water
Nutrients
Population Growth

Populations can grow until
competition for resources increases &
the carrying capacity is reached
Biosphere
Carbon
cycle
Phosphorus
cycle
Nitrogen
cycle
Water
cycle
Oxygen
cycle
Heat in the environment
Heat
Heat
Heat
Fig. 3-7, p. 55
CARBON CYCLE
Nitrogen Cycle
Nitrogen Fixation

This is the first step of the nitrogen cycle
where specialized bacteria convert gaseous
nitrogen to ammonia that can be used by
plants. This is done by cyanobacteria or
bacteria living in the nodules on the root of
various plants.
Nitrification

Ammonia is converted to nitrite, then to
nitrate
Assimilation
Plant
roots absorb ammonium ions and
nitrate ions for use in making molecules suc
as DNA, amino acids and proteins.
Ammonification

After nitrogen has served its purpose in
living organisms, decomposing bacteria
convert the nitrogen-rich compounds,
wastes, and dead bodies into simpler
compounds such as ammonia.
Denitrification
•Nitrate ions and nitrite ions are converted into
nitrous oxide gas and nitrogen gas.
This happens when a soil nutrient is reduced
and released into the atmosphere as a gas.
Biomagnification
 Concentration
of toxin at
higher trophic
levels
Succession

The process where plants & animals
of a particular area are replaced by
other more complex species over
time.
Stages of Succession
Land – rock  lichen  small shrubs 
large shrubs  small trees  large trees
Primary Succession
 When
the starting
point is an ABIOTIC
environment
 Volcano
 Flood
Secondary Succession

When an
EXISTING
ecosystem is
disturbed
 Fire/lightning
 Disease
 Hurricanes
 Human
activities
Credit: Jeff Schmaltz, NASA's MODIS Rapid Response Team
Fig 10.7 Diagram of bog
succession.
Wetland Succession
1
Wetland
Succession
Sedges and
floating plants
close over the
open water,
trapping
sediments in
their roots, and
gradually
drying out the
pond.
2
3
© 2003 John Wiley and Sons Publishers
CLIMATE: A BRIEF INTRO.
Weather - local, short-term conditions such as
temperature and precipitation
 Climate - a region’s average weather
conditions over a long time


Latitude and elevation help determine climate
BIOMES:

Large terrestrial regions characterized
by similar climate, soil, plants, and
animals
Biomes Around the World
DESERT BIOMES

The evaporation is greater than the
precipitation (usually less than 25
cm). Covers 30% of the earth.
DESERT BIOMES

Variations in
annual
temperature (red)
and precipitation
(blue) in tropical,
temperate and
cold deserts.
Figure 5-12
FOREST BIOMES

Forests have enough precipitation to support
stands of trees and are found in tropical,
temperate, and polar regions.
FOREST BIOMES

Variations in
annual temperature
(red) and
precipitation (blue)
in tropical,
temperate, and
polar forests.
Figure 5-19
Taiga (evergreen coniferous forest)

Just south of the tundra (northern part of N.
America), it covers 11% of earth’s land. Its
winters are long, dry & cold. Some places have
sunlight 6 to 8 hours a day. The summers are
short and mild, w/ sunlight 19 hours a day.
MOUNTAIN BIOMES (Taiga)
High-elevation
islands of
biodiversity
 Often have snowcovered peaks that
reflect solar
radiation and
gradually release
water to lowerelevation streams
and ecosystems.

Evergreen Coniferous Forests

Consist mostly of
cone-bearing
evergreen trees
that keep their
needles year-round
to help the trees
survive long and
cold winters.
Tropical Rainforest

Near the equator. It has warm
temperatures, high humidity & heavy
rainfall.
Tropical Rain Forest

Tropical rain
forests have heavy
rainfall and a rich
diversity of
species.
Found near the
equator.
 Have year-round
uniformity warm
temperatures and
high humidity.

Tropical Rain Forest

Filling such niches enables species to avoid
or minimize competition and coexist
Temperate Rain Forests

Coastal areas support huge cone-bearing
evergreen trees such as redwoods and
Douglas fir in a cool moist environment.
Temperate Deciduous Forest

It has moderate temperatures, long, warm
summers, cold winters &lots of rain. Trees
include oaks, hickory, maple, and beech.
Temperate Deciduous Forest

Most of the trees
survive winter by
dropping their
leaves, which
decay and
produce a
nutrient-rich soil.
Grassland

The rainfall is erratic & fires are
common. It has & shrubs that are
good for grazing animals.
GRASSLANDS AND CHAPARRAL
BIOMES

Variations in
annual
temperature
(red) and
precipitation
(blue).
Figure 5-14
Savanna

The tropical & subtropical grassland.
It is warm all year long with
alternating wet & dry seasons.
Chaparral (temperate grassland)

These are coastal areas. Winters are mild
& wet, w/ summers being long, hot, &
dry.
Chaparral

Chaparral has a
moderate
climate but its
dense thickets
of spiny shrubs
are subject to
periodic fires.
Temperate Grasslands

The cold winters
and hot dry
summers have deep
and fertile soil that
make them ideal for
growing crops and
grazing cattle.
Tundra (polar grasslands)

Covers 10% of earth’s land. Most of the year,
these treeless plains are bitterly cold with ice
& snow. It has a 6 to 8 week summer w/
sunlight nearly 24 hours a day.
Polar Grasslands

Polar grasslands
are covered with
ice and snow
except during a
brief summer.