Download Ecology

Energy Flow in
Ecosystems and
Biogeochemical
Cycles
Hierarchy of ecology
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Organism - individual living
thing
Population- a group of the
same species
Community – a group of
different species
Ecosystem – all organisms as
well as nonliving things in an
area
Biome - a major regional or
global community of organism
- can be as small as the
microorganisms living on your
skin or as large as the entire
biosphere
What’s an Ecosystem?
 An
ecosystem consists of all the organisms (biotic) in
a community and the environment (abiotic) with
which they interact.
 Biotic
- living things
plants animals, fungi, bacteria
 Abiotic
- non-living things
Moisture, temperature, wind,
sunlight, & soil
Biodiversity
The assortment, or variety, of living things in an
ecosystem
KEYSTONE Species = a species that has an unusually
large effect on its ecosystem
Producer
Energy flow
Chemical cycling
Herbivore
(primary consumer)
Carnivore
(secondary
consumer)
Detritivores
(decomposers)
Energy flows THROUGH ecosystems – open system
Nutrients cycle WITHIN ecosystems – closed system
Break down
organic materials
into simpler
cpmpounds
Get their energy
from non-living
sources and make
their own food
Get their energy
by eating living, or
once living,
resources, such as
plants and animals
Energy Flow in Ecosystems
 Almost
all energy used in
ecosystems comes from
the sun
 From there it flows
through a food chain or
web and exits the
ecosystem in the form of
heat, light, kinetic or
chemical energy
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A food chain is a sequence
that links species by their
feeding relation
A
food web is a model
that shows the
complex network of
feeding relationships
and flow of energy
within an ecosystem
Types of Consumers
 Decomposers
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Herbivores – eat only plants
Carnivores – eat only animals
Omnivores – eat both plants and animals
Detritivores – eat detritis or dead and dying organic matter
Decomposers - - detritivores that break down organic matter into
simpler compounds (example : fungi)
 Energy
pyramids show the efficiency of energy
transfer between trophic levels
 Generally 10% of energy is transferred
 Food chains never get beyond 4-5 trophic levels
Carnivores that eat secondary consumers
Carnivores that eat herbivores
Herbivores because they are the first consumer
above the producer
The first , or bottom, trophic level
Biogeochemical Cycle
Consumers
Producers
Detritivores
Nutrients
available
to producers
Abiotic
reservoir
Biogeochemical Cycling of Nutrients
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The movement of a particular chemical through the
biological and geological, or living and non-living
parts of an ecosystem.
Most ecosystems require a constant inflow of energy
from the sun. In terms of matter, such as oxygen and
carbon, the Earth is a closed system and it recycles its
resources.
Water cycle
Oxygen cycle
Carbon cycle
Nitrogen cycle
Phosphorous cycle
Water Cycle
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Solar energy drives the global water
cycle
– Precipitation
– Evaporation
– Transpiration
Water cycles between the land,
oceans, and atmosphere
Forest destruction and irrigation affect
the water cycle
Transport
over land
Solar energy
Net movement of
water vapor by wind
Precipitation
over ocean
Evaporation
from ocean
Precipitation
over land
Evaporation and
transpiration from
land
Percolation
through
soil
Runoff and
groundwater
Carbon Cycle
•
Abiotic reservoirs = atmosphere,
sedimentary rocks, dissolved carbon in
oceans, and fossil fuels
– Taken from the atmosphere by
photosynthesis
– Used to make organic molecules
– Decomposed by detritivores
– Returned to the atmosphere by cellular
respiration
CO2 in atmosphere
Photosynthesis
Cellular
respiration
Burning of
fossil fuels
and wood
Primary
consumers
Carbon compounds
in water
Detritus
Decomposition
Higher-level
consumers
Global warming:
CO2 lets sunlight
through but retains
the heat radiated
from Earth.
Human activities and natural
processes add CO2 to the
atmosphere, increasing the effect.
Photosynthesis removes
CO2 from the atmosphere,
decreasing the effect.
CO2
CO2 in the
atmosphere
CO2 CO2
Nitrogen Cycle
The nitrogen cycle relies heavily on bacteria
•
Atmospheric N2 is not available to
plants
– Soil bacteria convert gaseous
N2 to usable ammonium (NH4+)
and nitrate (NO3-)
– Some NH4+ and NO3- are made
by chemical reactions in the
atmosphere
80%
Nitrogen in atmosphere (N2)
Nitrogen
fixation
Assimilation
by plants
Nitrogen-fixing
bacteria in root
nodules of legumes
Detritivores
Decomposition
Ammonium (NH4)
Nitrogen-fixing
soil bacteria
Nitrates
(NO3–)
Nitrifying
bacteria
Denitrifying
bacteria
Phosphorus Cycle
Depends on the weathering of rock
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Phosphorus and other soil minerals
are recycled locally
Weathering of rock adds PO43- to
soil
– Slow process makes amount of
phosphorus available to plants
low
Runoff
Sedimentation