Download Ecosystems

Ecosystems
Biosphere
Ecosystem
Communities
Populations
Organisms
Realm
of
Ecology
Realm of Ecology
• Species
– All organisms of the same kind that are
genetically similar enough to breed in nature
and produce live, fertile offspring
• Population
– All the members of a species living in an area at
the same time
Realm of Ecology, cont.
• Community
– All of the populations of organisms living and
interacting in a particular area
• Ecosystem
– Composed of a biological community and its
physical environment
Ecosystems
• Ecosystem
– A community of different species interacting
with one another and with their nonliving
environment
• Can be small or large, e.g. a stream or Great Plains
• Can be natural or artificial, e.g. cropfields
• All of the Earth’s ecosystems together make
up the biosphere
Biodiversity
• The forms of life that can best survive the
variety of conditions currently found on
earth
• Types of Biodiversity
– Genetic Diversity
– Species Diversity
– Ecological Diversity
Components of Ecosystems
• Biotic (living components)
– Producers = make their own food from compounds
obtained from their environment
• Photosynthesis = capturing sunlight to make sugars
• 6CO2 + 6H2O + sun  C6H12O6 + 6O2
– Consumers = get their energy and nutrients by feeding
on other organisms
• Aerobic respiration = uses oxygen to convert organic nutrients
into carbon dioxide and water
• C6H12O6 + 6O2  6CO2 + 6H20 + energy
Types of Consumers
• Herbivores
– Plant eaters
– Primary consumers
– Feed directly on producers
• Carnivores
– Meat eaters
– Feed on other consumers
– Secondary and tertiary consumers
Types of Consumers, cont.
• Omnivores
– Eat both plants and animals
• Scavenger
– Feed on dead organisms
• Decomposers
– Bacteria and fungi
– Complete the final breakdown and recycling of
organic materials
Components of Ecosystem
• Biotic (living components)
• Abiotic (nonliving components)
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Sunlight
Temperature
Precipitation
wind
Major components of an ecosystem in a field
Major components of a
freshwater pond ecosystem
How does energy flow through
ecosystems?
• Food chain
– The sequence of organisms, each of which is a source
of food for the next
– Energy enters most ecosystems as high quality sunlight,
which is converted to nutrients by producers. The
energy is then passes on to consumers.
– As each organism uses the high-quality energy in its
food to move, this energy is converted into low-quality
heat (2nd law of thermodynamics)
Model of a Food Chain
Food Chain
• Trophic Level
– All organisms that are the same number of
energy transfers away from the original source
of energy that enters an ecosystem
• Producers = 1st trophic level
• Primary consumers = 2nd trophic level
• Secondary consumers = 3rd trophic level
• But real ecosystems are more complex than
this …
Food Web
• Most consumers feed on more than one type
of organism
• Food web = complex network of many
interconnected food chains
Food
Web
Energy Transfer in a Food Web
• In a food chain or web, energy is transferred from
one trophic level to another, with some usable
energy degraded and lost to the environment as
heat.
• At each successive trophic level, some of the
available biomass isn’t digested and expelled as
waste
• Only a small portion of what is eaten is converted
into an organism’s biomass, and the amount of
usable energy available to each successive trophic
level declines (80-90% is lost)
Biomass Transfer
Pyramid of Energy Flow
• A diagram representing the flow of energy
through each trophic level in a food chain or
web
• With each energy transfer, only a small part
(typically 10%) of the usable energy
entering one trophic level is transferred to
the organisms at the next trophic level
Generalized pyramid of energy flow
Energy Pyramid
Energy Pyramid for Grassland