Energy Flow in an Ecosystem
Bio 2.1.1 Analyze the flow of energy and cycling of
matter (water, carbon, nitrogen, and oxygen) through
ecosystems relating the significance of each to
maintaining the health and stability of an ecosystem.
Organisms and Their Environments
• Species interact with both other species
and their nonliving environment.
• Interdependence is a theme in ecology—
one change can affect all species in an
ecosystem.
• Ecologists recognize a hierarchy of
organization in the environment:
biosphere, ecosystem, community,
population, and organism.
Levels of Organization
• The Biosphere
• The broadest, most inclusive level of
organization is the biosphere, the
volume of Earth and its atmosphere that
supports life.
• Ecosystems
• An ecosystem includes all of the
organisms and the nonliving
environment found in a particular place.
Levels of Organization
• Communities, Populations, and
Organisms
• A community is all the
interacting organisms living in an
area.
• Below the community level of
organization is the population
level, where the focus is on the
individual organisms of a single
species.
Biotic and Abiotic Factors
• Both biotic, or living, factors and abiotic, or nonliving,
factors influence organisms.
• Acclimation
• Some organisms can adjust their tolerance to abiotic factors
through the process of acclimation.
• Control of Internal Conditions
• Conformers are organisms that do not regulate their internal
conditions; they change as their external environment
changes.
• Regulators use energy to control some of their internal
conditions.
• Escape from Unsuitable Conditions
• Some species survive unfavorable environmental conditions
by becoming dormant or by migrating.
The Niche
• A niche is a
way of life,
or a role in
an
ecosystem.
Producers
• Most producers are photosynthetic and
make carbohydrates by using energy
from the sun.
• Gross primary productivity is the rate at
which producers in an ecosystem
capture the energy of sunlight by
producing organic compounds.
• The rate at which biomass accumulates
is called net primary productivity.
Consumers
• Consumers obtain energy
by eating other organisms
and include herbivores,
omnivores, carnivores,
detritivores, and
decomposers.
Energy flow
• Food Chains and
Food Webs
• A single pathway
of energy transfer
is a food chain.
• A network
showing all paths
of energy transfer
is a food web.
Energy transfer
• Ecosystems contain only a few trophic levels because
there is a low rate of energy transfer between each
level.