Chapter 4
Ecosystems and Communities
The Role of the Climate
 What is climate?
– The average, year after year conditions of
temperature and precipitation in a particular
region
 What is weather?
– The day to day condition of the earth’s
atmosphere at a particular time and place
What Causes Climate?
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The trapping of heat by the atmosphere
The latitude
Winds and ocean current (carry heat)
Amount of precipitation
The Greenhouse Effect
 What is the greenhouse effect?
– The natural situation in which heat is retained
by the layer of greenhouse gases
 What are greenhouse gases?
– Carbon dioxide, methane, water vapor, and a
few other atmospheric gases that trap heat
energy and maintain the Earth’s temperature
The Greenhouse Effect
Sunlight
Some heat
escapes
into space
Greenhouse
gases trap
some heat
Atmosphere
Latitude’s Effect on the Climate
 Earth is tilted on its axis so different areas
get a a different amount of solar radiation at
different times of the year
 Differences of latitude and this angle result
in 3 main climate zones: Polar,
Temperate, and Tropical
The Three Main Climate Zones
 Polar Zones
– Cold
– Located at the North and South Poles
 Temperate Zones
– Temperature ranges from cold to hot
– Located between the polar zones
 Tropical Zone
– Climate almost always warm
– Near equator
Heat Transport in the Biosphere
 The Earth is heated unevenly, so this drives
winds and ocean currents
 The wind and ocean currents help balance
this unequal heating
Quiz 4-1
 What are the 3 main climate zones?
 What are the main factors that
determine climate?
 What is the greenhouse effect?
Bonus
What is the difference between
weather and climate?
Biotic and Abiotic Factors
 Remember an ecosystem includes all living and
nonliving factors
 Biotic factors are the living factors in the
community example: birds, mushrooms, trees,
grass….
 Abiotic Factors are the nonliving factors that
shape an ecosystem example: soil, water,
sunlight, space, wind….
Name the Biotic and Abiotic
Factors
Shaping an Ecosystem
 The biotic and abiotic factors determine the
survival and growth of an organism and the
productivity of the ecosystem in which the
organism lives
 Together these factors determine if an
ecosystem is a suitable habitat for an
organism
Habitats and Niches
 What is a habitat?
– The area in which the organism lives which
includes the biotic and abiotic factors
– Address
 What is a niche?
– The full range of physical and biological
conditions in which an organism lives and the
way the organism uses those conditions
– Job
Habitat Versus Niche
 Habitat
 A gopher tortoise needs
pine flatwoods with sandy
soil
 Niche
 A gopher tortoise
eats herbaceous
plants and creates
homes in which
other organisms live
in
Habitat Versus Niche
 A niche will include all aspects of how that
organism interacts and effects the ecosystem
in which it lives in
 Examples: Its place in the food web, when it
reproduces, what biotic and abiotic factors it
needs to survive, etc
Niches and Competition
 No two species can share the same niche in
the same habitat (can have similar niches
but not the same)
 When this occurs there will be competition
Competition
 Competition occurs when organisms (same
or different species) attempt to use the
same resource at the same time and same
place
 What is a resource?
– Any necessity of life
Competition
 The lion is competing with
the vulture for the carcass
 The plants are all
competing for space,
water, sunlight, and
nutrients
The Competitive Exclusive
Principle
 No two species can
occupy the same niche
at the same time and
the same place
 If this occurs they will
compete until there is
a winner and a loser
Types of Relationships in
Ecosystems
 Predation
 Symbiosis
– Mutualism
– Commensalism
– Parasitism
What is Predation?
 An interaction in which an organism
captures and feeds on another organism
 Example: Bear eating a fish
What is Symbiosis?
 Any relationship in two species live closely
together
 3 main types
– Mutualism
– Commensalism
– Parasitism
Symbiosis
 Mutualism- Both Benefit
– Example: Bees & flowers, ants and aphids
 Commensalism- One Benefits and the
other does not benefit
– Example: Moss growing on trees
 Parasitism- One benefits while the other
species is harmed
– Example: tapeworm, mosquitoes, fleas
Quiz 4-2 A
 What is the difference between an abiotic factor
and a biotic factor?
 What is a niche?
 What happens if two species have the same niche
in the same place? (Hint: The Competitive
Exclusive Principle)
 What are 3 types of symbiosis?
Bonus
Give an example of mutualism
Ecological Succession
 The gradual change in living
communities that follows a
disturbance
 The only thing that is constant is change!
Ecological Succession
 A community will gradually change over
time through a predictable series of changes
until it reaches a “stable” point called the
climax community
Ecological Succesion
 Two types
– Primary Succession
– Secondary Succession
Primary Succession
 The development of a community that
occurs on bare rock or where no soil exists
(Volcanic eruptions)
 When you start there is no soil
 The first species to populate the area are
called pioneer species
– These are usually lichen
Primary Succession
Secondary Succession
 The sequential replacement of species that
follows a disturbance
 Disturbances can include fires, floods,
logging, a fallen tree
 Disturbance can be good!
 Disturbances open up resources for other
plants or organisms to use
Importance of Fire in Florida
 The majority of Florida is made up of pine
forests
 Pine trees need lots of light
 Disturbances will kill off competing
vegetation and allow pine trees to reproduce
Importance of Fire in Florida
 Prescribed fires help
prevent wildfires
 Promotes biodiversity
 Kills pests (ticks, etc)
 REMEMBER: Fire a
natural part of our
ecosystem
Biomes
 What is a biome?
– A group of ecosystems
that have the same
climate and dominant
communities
 Organisms are adapted
to live in certain
biomes
What Creates a Biome?
 The climate
 The soil
 The communities that inhabit it
Organism’s Tolerance
 Many organisms are adapted to the
conditions of the biome
 They have tolerance
– Ability to survive and reproduce under
conditions that differ from their optimal
conditions
The Major Biomes
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Tropical rain forest
Tropical dry forest
Tropical savanna
Desert
Temperate grassland
Temperate woodland and shrubland
Temperate forest
Northwestern coniferous forest
Boreal forest
Tundra
Questions?
 “No problem can be solved by the same
consciousness that created it. We need to
see the world anew.”
 Albert Einstein
Quiz 4.2B
 What is the difference between primary
and secondary succession?
 What is a pioneer species?
 What is tolerance?
Bonus
Why is fire important to Florida?