Chapter 3
Ecosystem Ecology
Ecosystem Ecology Examines Interactions
Between the Living and Non-Living World
• Ecology- is the scientific study of interactions
among organisms and their environment.
• Ecosystem- A particular location on Earth
distinguished by its particular mix of
interacting components both biotic & abiotic.
• biotic (living: trees, birds, mammals, insects, fungi, bacteria)
• abiotic (nonliving: sunlight, temperature, soil, water, pH, nutrients)
Ecosystem Boundaries
• Some ecosystems, such as a caves and lakes have very
distinctive boundaries. However, in most ecosystems it is
difficult to determine where one ecosystems stops and the next
begins.
• Some ecosystems are large and some a very small.
Ecosystem Processes
• Even though it is helpful to
distinguish between two
different ecosystems,
ecosystems interact with other
ecosystems.
• Organisms can move from one
ecosystem to another
• (birds, insects)
• Ecosystems exchange energy & matter
• (carbon, nitrogen & other chemicals
dissolved in water and in the air)
• Changes in one ecosystem
can have far-reaching effects
on other ecosystems and the
global environment.
IOWA
Energy Flows through Ecosystems
Energy enters from the sun, moves among the living and nonliving components &
is ultimately emitted into the atmosphere. Energy must be constantly replenished by the sun.
Photosynthesis and Respiration
• Cellular Respiration is the
opposite of photosynthesis. It
converts glucose and oxygen into
energy required for metbolism.
CO2 and H2O are the by-products
for respiration.
• All organisms carry out
respiration. But overall,
producers perform more
photosynthesis than they do
respiration.
• The net effect is that excess
oxygen is released in the air
(breath), and excess carbon is
stored in the tissues (eat for energy).
Photosynthesis and Respiration
• Nearly all of the
energy that
powers
ecosystems comes
from the sun as
solar energy.
• Producers
(autotrophs) are
able to use the
suns energy to
produce usable
energy through
the process called
photosynthesis.
Trophic Levels, Food Chains, and Food Webs
• Producers
(autotrophs)- obtain
energy from the sun
through
photosynthesis.
• Consumers
(heterotrophs)- obtain
energy by consuming
other organisms.
Trophic Levels, Food Chains, and Food Webs
• Primary Consumers
(herbivores)- consume
producers.
• Secondary Consumers
(carnivores)- obtain their
energy by eating
primary consumers.
• Tertiary Consumers
(carnivores)- eat
secondary consumers
Trophic Levels, Food Chains, and Food Webs
• Scavengers (carnivores)-
eat dead animals. (vultures)
• Detrivores- organisms
that break down dead
tissues and waste
products into smaller
particles. (dung beetles)
• Decomposers- they
recycle nutrients from
dead tissues and wastes
back into the ecosystem.
(bacteria & fungi)
Food Chain- The sequence of consumption, where energy
is transferred from producers through tertiary consumers.
Food Web- A more realistic type of food chain that takes
into account the complexity of nature.
Energy Transfer Efficiency and Trophic
Pyramids
• Trophic pyramid- The
representation of the
distribution of energy among
trophic levels. (J or kcal)
• Ecological efficiency- The
proportion of consumed
energy that can be passed
from one trophic level to
another. (10% Rule)
Trophic Levels Pyramids
Biomass- The total mass of
organisms in an ecosystem
is measured in terms of
biomass. (g/m2 or kg)
Numbers- The total
number or organisms in
an ecosystem is measured
in terms of biomass.
Ecosystem Productivity
• Gross primary productivity
(GPP)- The total amount of
solar energy that the
producers in an ecosystem
capture via photosynthesis
over a given amount of time.
• Net primary productivity
(NPP)- The energy captured
(GPP) minus the energy
respired by producers.
NPP = GPP – Respiration by producers
Matter Cycles through the Biosphere
Matter does not enter or leave, but cycles through the biosphere in several forms.
Matter cycles through the biosphere
• Biosphere- The combination
of all ecosystems on Earth.
• Biogeochemical cycles- The
movement of matter within
and between ecosystems
involving biological,
geologic and chemical
processes.
1. The Hydrologic Cycle (Water Cycle)
2. The Carbon Cycle
3. The Nitrogen Cycle
4. The Phosphorus Cycle
The class will teaching this portion of the unit
PROJECT: Biogeochemical Cycles
The Hydrologic Cycle
• The movement of water through the
biosphere.
The Carbon Cycle
The Nitrogen Cycle
The Nitrogen Cycle
The Phosphorus Cycle
Ecosystems Respond to Disturbances & Provide Valuable Services.
Ecological Stability
• Ecological stability occurs as an ecosystem undergoes
dynamic changes in response to a changing environment
• Three aspects of stability in living systems:
• Inertia- the ability of a living system to resist being
disturbed or altered
• Constancy- the ability of a living system to stay within
limits imposed by available resources
• Resilience- the ability of a living system to bounce back
after an environmental disturbance
Ecosystems respond to disturbance
• Disturbance- An event caused by physical,
chemical or biological agents that results in
changes in population size or community
composition.
Watershed Studies
• The availability and quality
of water is a top priority for
scientists studying ecological
stability.
• Environmental scientists
interested in runoff, and the
flow of water, sediment or
pollutants will preform a
watershed study.
• Watershed- All of the land in
a given landscape that drains
into a particular stream,
river, lake or wetland.
The Intermediate Disturbance Hypothesis
• The intermediate
disturbance hypothesisstates that ecosystems
experiencing
moderately, frequent
disturbances are more
diverse than those with
high or low disturbance
levels.
Instrumental Values of Ecosystems
• Provisions - Goods that humans can use
directly, such as timber and fruit from trees
• Regulating services - The service
provided by natural systems that helps
regulate environmental conditions such as
biogeochemical cycles.
• Support Systems - The support services
that natural ecosystems provide such as
pollination of flowers, natural filters and pest control.
Instrumental Values of Ecosystems
• Resilience - Resilience of an ecosystem
ensures that it will continue to provide
benefits to humans. (Ability to withstand
storms, fire, and pollutants. This greatly depends on
species diversity.)
• Cultural Services - Ecosystems provide
cultural or aesthetic benefits to many
people. (spiritual enrichment, cognitive
development, reflection, recreation, and aesthetic
experiences)