Download Ch 3 Notes - The Biosphere (2012

Ecology
Ch. 3 – The Biosphere
3.1 - What is Ecology?
• It is the scientific study of interaction
among organisms and between
organisms and their environment
What is the Biosphere?
• The biosphere is the combined portions
of the entire planet where life exists.
Levels of Organization
• To understand relationships within the
biosphere ecologists ask questions
about events and organisms that range
in complexity from a single individual to
the entire biosphere
Levels (con’t.)
• Species: a group of organisms so similar
to one another that they can breed and
produce fertile offspring.
• Populations: a group of individuals that
belong to the same species and live in
the same area.
• Communities: different populations that
live together in a defined area.
Levels (con’t.)
• Ecosystems: all the organisms that live in
a particular place, together with their
nonliving or physical environment.
• Biomes: a group of ecosystems that
have the same climate and dominant
communities.
Levels of Organization
Biotic and Abiotic Factors
• Biotic Factors – Any living part of the
environment with which an organism
might interact
– Ex. – animals, plants, mushrooms &
bacteria
• Abiotic Factors – Any nonliving part of
the environment
– Ex. – sunlight, heat, water, soil, etc.
Biotic and Abiotic Factors Together
• The differences between biotic and
abiotic factors are not always clear and
simple
• Many physical factors can be strongly
influenced by the activities of organisms
– Ex. – pond “muck” is a combination of soil
(abiotic) and leaf mold & decomposing
plant material (biotic)
Biotic and Abiotic Factors
Ecological Methods
Scientists use three basic approaches to
conduct ecological research. They are:
• Observing
• Experimenting
• Modeling
3-2 Energy, Producers, and Consumers
• What happens if your car runs out of
gas?
• What do you need before you can play in
a soccer game or run for 5 miles?
• Living systems need a constant input of
Energy.
Primary Producers
• Autotrophs
– Organisms that use energy from the
environment to make complex organic
compounds
– Also known as producers. Why?
– Two types
• Photosynthesis - Energy from the Sun
• Chemosynthesis - Life without Light
Primary Producers
• Primary Producers
– The first producers of energy-rich
compounds that are later used by
other organisms
• Energy from the Sun
– Capturing light energy and using it to
convert CO2 & H2O into O2 & Carbohydrates
• Energy without Light
– Using chemical energy to make
Carbohydrates
Sources of Energy
Consumers
• Heterotrophs
– Rely on other organisms for their energy
and food supply.
– Also known as consumers
• Why?
Consumers
• Types of Consumers
– Herbivores
• Obtain energy and nutrients by eating plant materials
– Carnivores –
• Kill and eat other animals
– Omnivores
• Eat both plants and animals
– Scavengers
• Consume the carcasses of dead animals
– Detritivores
• Feed on dead and decaying plant and animal remains
– Decomposers
• Chemically break down matter
Beyond Consumer Categories
• These simple categories often don’t
express the real complexities of nature.
• Examples:
– Hyenas (carnivores) will scavenge if they get
a chance
– Aquatic animals will eat a mixture of algae,
bits of animal carcasses, and detritus
3.3 Energy Flow in Ecosystems
• Energy flows through the ecosystem in
one direction.
Energy Flow in Ecosystems
Food Chain
• A series of steps in which organisms transfer
energy by eating and being eaten.
Food Web
• A network
of many
feeding
interactions
Food Web
Food Webs and Disturbance
• Relationships in Food Webs are not
simple.
• Disturbances do happen and their
effects can be dramatic.
• Example - Marine Food Web / Krill
Antarctic Food Web
Trophic Levels and
Ecological Pyramids
• Each level in a food chain or food web is
a trophic level.
• Each trophic level depends on the level
below it for energy.
What is a Trophic Level?
Ecological Pyramids
• Can be used to represent energy, matter
or number of individuals at each trophic
level
Energy Pyramid
• Only 10% of the energy available at one
trophic level makes it to the next level
• When one organism eats another,
energy is lost. Where does this energy
go?
Energy Pyramid
Biomass Pyramid
• Represents all the living tissue (food) at
each trophic level.
Biomass Pyramid
Pyramid of Numbers
• The number of individual organisms at
each trophic level usually decreases as
you go up the pyramid of numbers.
Pyramid of Numbers
3-4 Cycles of Matter
• Unlike the one-way flow of energy, matter is
recycled in the biosphere.
• Where does your body get the materials, such
as Carbon, it needs to function? __________
• Elements , chemical compounds and other
forms of matter are passed from one organism
to another through biogeochemical cycles.
Bio - ______ Geo - ______ Chemical - ______
Water Cycle
Other Biogeochemical Cycles
• Carbon Cycle - carbon is especially
important because it is the key ingredient
in all living organisms.
• Carbon is found in oceans, the air, and
certain types of rock.
Carbon
Cycle
• Nitrogen Cycle - All organisms require
nitrogen to make amino acids which are
used to build proteins.
Nitrogen Cycle
• Phosphorus Cycle - Unlike carbon
nitrogen and oxygen, phosphorous does
not enter the air, it remains mostly in
rock, soil minerals, and ocean sediments.
– Phosphorous is of great biological
importance for molecules like DNA
and RNA.
Phosphorous Cycle
Nutrient Limitation
• Primary Productivity: the rate at which
organic matter is created by a producer.
- Controlled by the availability of nutrients
in the environment
• How can a nutrient be a limiting factor
for an ecosystem?
- If even a single essential nutrient is in short
supply, primary productivity will be limited
Nutrient Limitation
• Limiting Nutrient
– the nutrient whose supply limits
productivity
– Ex. - If ample sunlight and water are
available, the primary productivity of
an ecosystem may be limited by the
availability of nutrients.
Nutrient Limitation
• In Soil
– Growth of crop plants is limited by one or more
nutrients that must be taken up by plants through
their roots
– That’s why farmers use fertilizers!
• In Aquatic Ecosystems
– Sometimes receive large amounts of a limiting
nutrient (runoff from fertilized fields)
– The result can be an Algal Bloom which can cover
the water’s surface and disrupt the ecosystem