Download Chapter 3 Ecology Notes

Ecology
Chapter 3
What is an Ecology?
• All of the earth’s inhabitants are
interwoven in a complex web of
relationships
• Ecology- the study of the interactions of
living organisms with one another and
with their physical environment (water,
soil, etc.)
What is an Ecosystem?
• Habitat - place where a particular population of
a species lives. Many different species that live
together in a habitat are called a community.
• Ecosystem - ecological system consists of a
community and all the physical aspects of a
habitat (abiotic factors, ex. water, rocks) and
living aspects (biotic factors,ex. other organisms)
Ecosystem Image
Item
Plant
Soil
Bacteria
Oxygen
Fungi
Abiotic
Biotic
Ecosystems support
• The number of
species living within
an ecosystem is a
measure of its
biodiversity.
• What is the
biodiversity of
Hattiesburg? Biotic
factors? Abiotic
factors
diverse communities
Ecological Methods
• Ecologist study the ecosystem
with 3 approaches
• Observation
• what species live here?
• Experimentation
• how do the plants react to
different temperatures?
• Modeling
Energy Flow in Ecosystems
• The flow of energy is
the most important
factor that controls
what kinds of
organisms live in an
ecosystem and how
many organisms the
ecosystem can support.
Primary Energy Source
• Most life on Earth depends on photosynthetic organisms,
which capture the Sun’s energy and stores it as chemical
energy in organic molecules.
• The rate at which organic material is produced by
photosynthetic organisms in an ecosystem is called primary
productivity. This determines the amount of energy
available in an ecosystem.
• Organisms that first capture the energy (autotrophs) make
energy-storing molecules.
• All other organisms are heterotrophs (consume plants or
other organisms to obtain energy).
Trophic Levels
• The lowest trophic level are the producers (the base).
At the second trophic level are herbivores (organisms
that eat mainly plants or other primary producers).
• At the third trophic level are consumers called
carnivores (animals that eat herbivores). Some animals,
such as bears and humans are both herbivores and
carnivores: they are called omnivores.
• Scavengers are organisms that obtain their energy from
the organic wastes and dead bodies that are produced
at all trophic levels (vultures). Bacteria and fungi are
known as decomposers because they cause decay (puts
nutrients back into the soil).
• Sometimes you have a fourth level…
carnivores eating other carnivores,
called a tertiary consumer.
• Animals often feed at several trophic
levels which creates a complicated food
web.
Item
Bear
Squirrel
Cheetah
Oak Tree
Human
Grass
Eagle
Trophic Level (1, 2, 3, or 4)
Energy is Lost in a Food Chain
• During every transfer of energy within an
ecosystem, energy is lost as heat. The amount
of useful energy available to do work decreases
as energy passes through an ecosystem.
• At each trophic level, the energy stored by the
organism is about 1/10 of that stored by the
organisms in the level below.
Pyramid of Energy
• Energy (Ecological) Pyramid – diagram in which each trophic
level is represented by a block, and the blocks are stacked on top
of one another with the lowest trophic level on the bottom. The
width of each block is determined by the amount of energy stored
in the organisms at that trophic level.
• Most pyramids are only 3-4 levels. Too much energy
allow more levels.
is lost to
• Biomass – the dry weight of tissue and other organic matter found
in a specific ecosystem. Each higher level on the pyramid contains
only 10% of the biomass found in the trophic level below.
Ecosystems Recycle Material
• All organisms require carbon, hydrogen,
oxygen, nitrogen, phosphorus, and sulfur in
relatively large quantities.
• The paths of water, carbon, nitrogen, and
phosphorus pass from the nonliving
environment to living organisms, such as the
trees from the atmosphere, water, or soil; stays
for a time in the living organism; then returns
to the nonliving environment.
Carbon Cycle
Nitrogen Cycle