Download Ecosystem

Living in the Environment
16th Edition
Ecosystems: What are They and
How Do They Work?
Chapter 3
Key Concepts
• What is ecology?
• What basic processes keep us and
other organisms alive?
• What are the major components of
the ecosystem?
• What happens to energy in the
ecosystem?
• How do scientists study the
ecosystem?
• What are ecosystem services?
What is ecology?
The study of how organisms interact
with one another and with their nonliving environment.
(oikos “place to live”
of”)
logos “study
How nature is connected.
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
Subatomic Particles
Organisms
Prokaryotic Cell
DNA
(information
storage, no
nucleus)
Cell membrane
(transport of
raw materials)
Protein construction
and energy conversion
occur without specialized
internal structures
Protein
construction
Nucleus
(information storage)
Packaging
Eukaryotic Cell
Energy
conversion
Cell membrane
(transport of raw
materials and
finished products)
The Nature of Ecology
Ecosystem Organization
Organism
Any form of life
The Nature of Ecology
Ecosystem Organization
• Organism
– Any form of life
– Species
• Group of organisms
that resemble one
another
• Actually or potentially
breed with one
another
• Produce live, fertile
offspring
The Nature of Ecology
Ecosystem Organization
• Communities
– Populations of the different
species occupying a
particular place
– Biological community
• Populations
– Group of interacting
individual of the same
species that occupy a
specific area a the same
time.
• Organisms
– Any living organism
The Nature of Ecology
Ecosystem Organization
•Biosphere
All of the earth’s ecosystems
•Ecosystem
A community of different species
interacting with one another and
their nonliving environment
The Earth’s Life-Support Systems
•Atmosphere
Troposphere
Stratosphere
•Hydrosphere
•Lithosphere
•Biosphere
Sustaining Life of Earth
 One-way flow of
energy
 Sun
 Living materials and
living things
 Into the environment
 Cycling of matter
 Atoms, ions,
molecules needed for
survival
 Gravity
The Source of Energy
Ecosystem Concepts and Components
• Biomes
– “By-ohms”
– Land
ecosystems
– Distinct climate
and specific
life-forms
• Role of climate
– Long term
patterns of
weather
– Determines
what type of
life will thrive
• Aquatic life
zones
– freshwater
– ocean or
marine life
Ecosystem Boundaries: Ecotones
Figure 4-11 Page 72
Sun
Producers (rooted plants)
Producers (phytoplankton)
Primary consumers (zooplankton)
Secondary consumers (fish)
Dissolved
chemicals
Tertiary consumers
(turtles)
Sediment
Decomposers (bacteria and fungi)
Major components of freshwater ecosystem
Major components of a terrestrial ecosystem
Oxygen (O2)
Sun
Producer
Carbon dioxide (CO2)
Primary consumer
(rabbit)
Falling leaves
Precipitation
and twigs
Secondary consumer
(fox)
Producers
Soil decomposers
Water
Soluble mineral nutrients
Principles of Ecological Factors
Terrestrial Ecosystems
Aquatic Life Zones
Abiotic
factors
• Sunlight
• Temperature
• Precipitation
• Wind
• Latitude (distance from
equator)
• Altitude (distance
above sea level)
• Fire frequency
• Soil
• Light penetration
• Water currents
• Dissolved nutrient
concentrations
(especially N and P)
• Suspended solids
• Salinity
Principles of Ecological Factors
•Law of tolerance- the existence, abundance, and
distribution of a species in an ecosystem are
determined by whether the levels of one or more
physical or chemical factors fall within the range of
tolerance.
Optimum
Range
Zone of
Zone of
Physiological
Intolerance
Stress
Principles of Ecological Factors
•Limiting factors principle – too much or too little of
any abiotic factor can limit or prevent growth of a
population, even if all other factors are at or near
the optimum range of tolerance.
The Biotic Components of Ecosystems
• Producers
(autotrophs)
– Transform energy by
Photosynthesis
• Consumers
(heterotrophs)
– Transform energy by
Aerobic Respiration
• Decomposers
Ecosystems Use Sunlight As
Their Source of Energy
Conservation of Matter and
Energy Capture
Photosynthesis
6 CO2 + 6 H20
C6H12O6 + 6 O2
Respiration
C6H12O6 + 6 O2
6 CO2 + 6 H20
Trophic “Feeding” Levels
•
First Trophic Level
Producers (plants)
•
Second Trophic Level
Primary consumers
(herbivores)
–
•
Third Trophic Level
Secondary consumer
(carnivores)
–
•
Fourth Trophic Level
Feed directly on
producers
Feed on Primary
Consumers
Tertiary consumer
–
Feed on other
carnivores
Trophic Levels
• Omnivore
– Eat plants and animals
• Detritivores and Scavengers
– Feed on detritus, dead organisms, and waste
• Decomposers
– Break down dead organic material
– Release the resulting simpler compounds into the
soil
– Anaerobic respiration (absence of oxygen)
• Methane, ethyl alcohol, acetic acid, hydrogen sulfide
Detritus feeders
Bark beetle
engraving
Long-horned
beetle holes
Carpenter
ant
galleries
Decomposers
Termite and
carpenter
ant
work
Dry rot fungus
Wood
reduced
to powder
Time progression
Mushroom
Powder broken down by decomposers
into plant nutrients in soil
Biodiversity:
What is it and why is it important?
The different life-forms and
life-sustaining processes.
Biodiversity:
What is it and why is it important?
Kinds of biodiversity include:
• Genetic diversity
– Variety in the genetic makeup among
individuals within a species
• Species diversity
– Variety among species found in different
habitats of the planet
• Ecological diversity
– Variety of biological communities
• Functional diversity
– Biological and chemical processes or
functions needed for survival
Connections: Food Webs and Energy Flow in
Ecosystems
Food chains – sequence of organisms each of
which is a food source for the next.
Connections: Food Webs and Energy Flow in
Ecosystems
Food webs – a
network of
interconnected
food chains
ECOLOGY
Food Web – chains assembled into one
large web.
ECOLOGY
Ecological Pyramid
A food chain that
shows the
relationship
between the
organisms in each
trophic level.
Ecological Pyramids
• Pyramid of
energy flow
• Ecological
efficiency
– Range 5%-20%
– Typically 10%
• Pyramid of
biomass
• Pyramid of
numbers
Ecological Pyramids of
Numbers
The figures represent number of
individuals counted at each trophic level.
Ecological Pyramids of Biomass
• The total dry weight of organisms in a
particular trophic level is referenced as
“biomass”.
BIOMASS
=
# of organisms
x
the weight of an
average individual
Ecological Pyramids of
Biomass
Ecological Pyramids of Energy
Energy in ecosystems flows from producers
to consumers.
Energy is depicted in kilocalories.
Primary producers convert only about 1%
of the energy in available sunlight.
The average amount of energy that is
available to the next trophic level is about
10%.
Ecological Pyramids of Energy
Primary Productivity of Ecosystems
• Gross Primary Productivity (GPP)
– Rate at which an ecosystem’s producers convert
solar energy into chemical energy as biomass
– kg/m2/year (kcal/m2/year)
• Net Primary Productivity (NPP)
– Difference between the rate at which producers
store energy as biomass and the rate at which
producers use chemical energy stored as biomass
Primary Productivity of Ecosystems
Connections: Matter Cycling in
Ecosystems
• Biogeochemical (nutrient) cycles
– Hydrologic cycle (H2O)
– Atmospheric cycles (C,N)
– Sedimentary cycles (S,P)
Hydrologic (Water) Cycle

Hydrologic (Water) Cycle
• Absolute humidity
– The amount of
water vapor found
in a mass of air
(g water/kg air)
• Relative humidity
– The amount of
water vapor in a
certain amount of
air, expressed as a
percentage the
maximum amount it
could hold at that
temperature
• Condensation nuclei
– tiny particles on which
droplets of water form
• Dew point
– Temperature at which
condensation occurs
Affects of Human Activity on the
Water Cycle
• Withdrawing large quantities of water
• Clearing vegetation
–
–
–
–
Increased runoff
Reduced infiltration
Increased flooding
Soil erosion
• Modifying water quality
– Adding nutrients
– Other pollutants
The Carbon Cycle (Terrestrial)
The Carbon Cycle (Aquatic)
http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp29/animations/ch
29/1_carbon_cycle.swf
Carbon Cycle
Human Activities Affecting the
Carbon Cycle
• Clearing tree
• Burning fossil fuels and wood
Gaseous Nitrogen (N2)
In Atmosphere
Nitrogen
Fixation
by industry for
agriculture
Food Webs
On Land
Fertilizers
Nitrogen Fixation
bacteria convert to ammonia
(NH3) ; this dissolves to form
ammonium (NH4+)
uptake by
autotrophs
excretion,
death,
decomposition
NO3 –
in soil
Nitrogenous Wastes,
Remains In Soil
Ammonification
NH3, NH4+
in soil
uptake by
autotrophs
bacteria, fungi convert the
residues to NH3 , this
Denitrification
by bacteria
2. Nitrification
bacteria convert NO2- to
nitrate (NO3-)
dissolves to form NH4+
loss by
leaching
1. Nitrification
bacteria convert NH4+
to nitrite (NO2–)
The Nitrogen Cycle
NO2 –
in soil
loss by
leaching
Nitrogen Cycle
Human Activities Affecting The
Nitrogen Cycle
• Burning fossil fuels
– Acid rain
• Animal waste
• Removing N from topsoil
• Adding N to aquatic systems
The Phosphorus Cycle
Human Activities Affecting the
Phosphorus Cycle
• Mining
• Forest removal
• Adding phosphorus to aquatic systems
– eutrophication
The Sulfur
Cycle
How Do Ecologists Learn About
Ecosystems?
Field research
Remote sensing
Geographic information systems (GIS)
Laboratory research
Systems analysis
GIS and Systems Analysis
Ecosystem Services
and Sustainability
•Using renewable
solar energy as an
energy source
•Recycling the
chemical nutrients
organisms need for
survival, growth,
and reproduction.